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In the beginning was the hollowed-out tree trunk, one of the first tubes to be crafted by human hand. With a vast array of models in the plant world to inspire him, Homo sapiens had a much easier job inventing the tube than the wheel for which, by contrast, nature had no example to offer. Bamboo and reed are just two examples of plants with hollow stalks. Nature already knew the value of the tubular form, which combines high stability with the capacity to Transport essential substances for growth, such as water and nutrients, out of the earth.
In technical terms, a tube or pipe is a cylindrical, hard hollow body which usually has a round cross-section but can also be oval, square, rectangular or more complex in profile. It is used on the one hand to convey liquid, gas and solid matter and, on the other, as a construction element. Whatever its purpose, the term covers all sizes and diameters, from the smallest needle pipes right up to wind tunnels. No other profile shape with the same material cross-section has such a high flexural strength, which is what makes the tube so important as a load-bearing element in building.
Tubes for transporting purposes
In the past, people always tried to settle close to water. As the size of the settlements grew, it became increasingly difficult to get the water from the source - the spring, pond, river or lake - to the different dwellings. At first, people used open conduits - initially simple trenches, later stone canals. When the springs and sources were exhausted, aqueducts were used to carry water from the mountains into the towns. Some 300 years A.D., the Romans transported water from the Campagna into their capital and some of their impressive waterways can still be marvelled at in modern-day Europe.
Later, the open canals were covered over and used as closed conduits - and thus the pipeline was born. People were also quick to realize the benefits of closed pipes against open canals for removing waste water. Early pipe materials included wood and stoneware (fired clay), but also easy-to-work metals such as bronze, copper and lead. The first closed pipelines were made around 4,000 years ago of fired clay. The oldest metal pipelines date back to 200 years B.C., first made of bronze and later lead. Lead pipes were cast and chiefly used to Transport water. Copper pipes meanwhile were made from chased copper plate which was rolled and subsequently soldered together.
The advent of an economical method of producing large quantities of cast iron in the 14th century laid the foundation for the manufacture of iron pipes. Gunsmiths and cannon-makers were amongst the first to produce iron pipes. Cast iron pipes were used as early as the 15th century to carry water - some dating back to the 16th century are still in use today. Cast iron pipes also accompanied the development of a public gas supply network, for which compression-proof pipes were a matter of safety and therefore absolutely essential.
As more economical steelmaking methods were developed, an opportunity opened up for this material to be used for pipes. The first were forge-welded out of hoop steel, a method already known to gunsmiths in the Middle Ages. Around , the invention of crossrolling by the Mannesmann brothers also made it possible to produce seamless pipes and tubes. With their thicker walls, seamless pipes offered greater stability at a relatively low weight. Oil-prospectors used such pipes to reach deeper reservoirs and by doing so were able to satisfy the growing demand for mineral oil which accompanied the early days of motorisation. The fact that mineral oil could be transported economically over long distances through a pipeline pushed up the demand for steel pipes even further. Soon, pipelines came to be the biggest market in this area, with demand reaching several million tonnes of welded and seamless pipes every year.
The crucial importance of how a pipe is made for the economic efficiency and environment-friendliness of industrial plant can be illustrated with the contemporary example of seamless boiler pipes with inner ribs. For years the power industry has been aiming to reduce fuel consumption and thereby cut CO2 emissions by stepping up efficiency. This can be done by working with higher operating pressures and temperatures. Consequently, plans have been made to set up new power plant in the first decades of the next century, which will run with pressure levels of up to 350 bar (today's maximum is 300 bar), at operating temperatures of around 700 "C (as opposed to 600 'C) and with efficiency increased from fts current 40% to 50%. Operating parameters of this kind can only be used for suitabie products and materials, of which seamless boiler pipes with inner ribs are one example. On account of their internal geometry, these pipes substantially improve the heat transfer between heating and the vapour phase on the inside of the pipe.
Pipes made of nonferrous metals and plastics Thanks to its good corrosion resistance, copper can be used to make pipes for the chemical industry, refrigeration technology and shipbuilding. Alongside their application for installation purposes, the usually seamless copper pipes are also used in capacitors and heat exchangers. For corrosive materials, low temperatures or stringent demands on the purity of the material carried by the pipe, Aluminium and Aluminium alloys are used in pipe construction. Meanwhile, thanks to its high resistance to many aggressive materials, titanium is well- suited to use in chemical engineering.
Plastics belong to the group of newer pipe materials. With the development of methods for producing plastics on an industrial scale in the s, it also became possible to manufacture plastic pipes economically. By the middle of the 30s, plastics were already being used in Germany to make pressure pipelines. Among the chief advantages of plastics are their high corrosion resistance and a substantial chemical resistance to aggressive media. Moreover, the smooth surfaces mean that plastic pipes are not prone to incrustation, which can have a very detrimental effect on their conveying capacity. Pipes supplying drinking water are mostly made of polyethylene (PE) or polyvinyl chloride (PVC). Like ABS (acrylonftrile-butadiene-styrene copolymer) plastics, these two materials are also used for gas pipelines. Thermoplastic materials - alongside PE and PVC these include PP (polypropylene) and PVDF (polyvinylidenefluoride) - can also be used for industrial pipelines. Beyond these, PB (polybutene) and PE-X (cross- linked polyethylene) are also widespread in pipe-making. Plastic pipes find application in areas such as heating technology, shipbuilding, underwater pipelines (the crossing below a river floor from one bank to the other), irrigating and drainage plant, and well-building.
The right choice of material has a crucial bearing on the economic efficiency and safety of a pipe system. Materials therefore have to be selected according to the demands of each specific application. In steel boiler construction, for example, pipes must be made of steel with high temperature stability plus heat and scaling resistance, while special corrosion resistance is all-important in the chemical and foodstuffs industries. Meanwhile, the mineral-oil processing industry requires heat- proof or press-water-resistant steels for its pipes, gas liquefaction and separation, on the other hand, need materials which have special strength at low temperatures. This broad and highly diversified range of requirements has put a fantastic array of materials to use in pipe- making. Alongside the iron and steel, nonferrous metals and plastics mentioned above, these also take in concrete, clay, porcelain, glass and ceramics.
In addition to liquids and gases, solid matter, broken down, as dust or mixed with water in slurry form, is also pumped through pipelines. Gravel, sand or even iron ore can be conveyed in this manner. Pneumatic transportation of grain, dust and chips through pipes is also a widespread practice. Pneumatic tube conveyors, which similarly work with air, are another important mode of transporting solid matter.
Pipes may be several meters in diameter and pipelines many kilometers in length. At the other end of the scale are conduits with tiny, barely perceptible dimensions. One example of their use is as cannulas in medicine - a collective term referring to instruments with a variety of applications, including infusions, injections and transfusions. Their outer diameter ranges from over 5 millimeters to as little as 0.20 millimeters. Cannulas are made of high-quality grades of stainless steel, brass, silver or nickel silver (an alloy of copper, nickel and zinc, sometimes admixed with traces of lead, iron or tin), but also plastics such as polyethylene, polypropylene or Teflon. Often, different materials are combined with one another to produce the individual components. These tiny tubes must have extremely pronounced elastic properties. They may bend but under no circumstances snap. Their surfaces are often nickel[-plated and always highly polished, sometimes even on the inside. The best-known cannulas are hypodermic needles which, in their most common form as sterile disposable syringes, guarantee aseptic use without costly preparation for reutilisation.
Tubes for construction
No matter where we look in our cities today, we can be sure to see tubular steel constructions. They have become an indispensable element of modern building technology. Once again, we took the idea from nature: in tube-shaped straws, bamboo shoots, quills and bones, Mother Nature demonstrated the successful marriage of beauty and function. Yet these excellent static properties remained unexploited until the advent of welding technology made it possible to connect virtually all dimensions of pipes perfectly and with the necessary interaction of forces for use as construction elements.
As an extremely lightweight building element, steel tube combines high strength with low weight. Steel tubes are used as deck supports in shipbuilding, supports in steel superstructures and binders in building construction. They are used as tubular and lattice masts for overhead and overland transmission lines, for trains and trams, and for lighting. Bridges, railings, observation towers, diving platforms, television towers and roof constructions in halls or sports stadiums are all further examples. Steel tube is also a popular" building element for constructions in temporary use, such as halls, sheds, bridges, spectator stands, podiums and other structures for public events, supporting structures and scaffolding, from the small-scale for house renovation right up to building scaffolds.
In plant engineering, steel tube is used to make ladders, shelves, work tables and subframes for machinery and plant. Steel tube also found its way as a construction element into precision components for machinery and equipment. Shafts and rolls or cylinders in hydraulics and pneumatics are just two examples. Beyond these applications, a great volume of steel tube is used in the cycle industry, camping equipment manufacture, the furniture industry, vehicle and car making and the domestic appliances industry.
Be it on water, over land or in the air, the various modes of Transport would be lost without tubes and pipes. Pipes and tubular construction elements are to be found in ships, planes, trains and motor vehicles. A great variety of pipes and tubular profiles are used in car making, both in connection with the motor and with the chassis and bodywork sections. Most recent developments put them to a far more varied range of uses than before, from air suction pipes and exhaust systems through chassis components right up to side-impact tubes in doors and other safety features. One German car makers new lightweight concept takes as its basic subassembly a three-dimensional frame made up of complex Aluminium extruded sections joined together with the aid of pressure-diecast intersections.
Pipes in everyday use
We come into contact with pipes and tubes on a daily basis. It starts in the morning when we go to clean our teeth and squeeze the toothpaste from this tube, which is nothing other than a tube-shaped flexible container. We write notes with a pen, comprising one or more tubes with a smaller tube - the cartridge or refill - inside it. This is the modern equivalent of the quill, a pointed and split tube used in ancient times as a writing instrument and still used today for Arabic script.
We are surrounded everywhere we go and on a virtually constant basis by tubes and pipes, whether at home, on the move or at work. They take the form of lamp stands and furniture elements in chairs or shelves, curtain rails, telescopic aerials on portable and car radios, and rods on umbrellas or sunshades. And when we water the plants or hang out the washing, tubes are our constant companion - on the watering can or the clothes-horse. Pipes Transport electricity, water and gas directly into our homes. Tubes protect visitors to the Duesseldorf Trade Fair Center from the rigours of the Rhineland weather. Pipe constructions are responsible for a pleasant indoor temperature and prevent the hall roofs from falling on our heads. Civil engineers and architects choose special section tube constructions for windows and doors in preference to other solutions. Tubes even have a role to play in our leisure time, providing us with bicycles, training apparatus and sports equipment.
Musical pipes
Musical instrument-making would be unthinkable without tubes and pipes. The tuba illustrates the connection particularly well: the name of this brass instrument is nothing other than the Latin word for tube. Other brass and pipe instruments also take the tube form. The reed used in a variety of wind instruments such as the clarinet, saxophone, bassoon or oboe is a flexible piece of cane which is fixed into the mouthpiece of the instrument or acts as a mouthpiece itself. Organ pipes also rely on the tube shape to create their sound. They are made of lead and tin, zinc or copper and are still crafted today according to a centuries-old Tradition.
CD stands in the shape of organ pipes make for an original link between two musical words. These CD stands are just under two meters in length, accommodate up to 50 CDs and, if required, can be supplied with interior lighting. Normally out of sight but critically important for good sound quality are the bass-reflex pipes found in loudspeakers. With the proper dimensions in length and diameter, these pipes help to reproduce low-pitched tones without any distortion as a result of unwanted flow noise.
Through tubes and pipes flows the lifeblood of progress and without them our lives would not be nearly as comfortable. They make everyday life easier, safer, more attractive, more varied and more interesting. More to the point, though, they have become indispensable for our existence, shaping the development of our lives to lasting effect in the past and undoubtedly continuing to do so in the future.
©copyright Rolf Diederichs 1.May , /DB:Article /AU:Kunzelmann_B /CN:DE /CT:general /CT:steel /ED:-05(a) Compliance. Compliance with the requirements of this subpart is required in all details.
(b) Inspections and analyses. Chemical analyses and tests required by this subchapter must be made within the United States, unless otherwise approved in writing by the Associate Administrator, in accordance with subpart I of part 107 of this chapter. Inspections and verification must be performed by—
(1) An independent inspection agency approved in writing by the Associate Administrator, in accordance with subpart I of part 107 of this chapter; or
(2) For DOT Specifications 3B, 3BN, 3E, 4B, 4BA, 4B240ET, 4AA480, 4L, 8, 8AL, 4BW, 4E, 4D (with a water capacity less than 1,100 cubic inches) and Specification 39 (with a marked service pressure 900 psig or lower), and manufactured within the United States, a competent inspector of the manufacturer.
(c) Duties of inspector. The inspector shall determine that each cylinder made is in conformance with the applicable specification. Inspections shall conform to CGA C-11 (IBR, see § 171.7 of this subchapter) except as otherwise specified in the applicable specification.
(1) Seamless cylinders. Seamless cylinders shall be inspected in accordance with Section 5 of CGA C-11. For cylinders made by the billet-piercing process, billets must be inspected and shown to be free from piping (laminations), cracks, excessive segregation and other injurious defects after parting or, when applicable, after nick and cold break.
(2) Welded cylinders. Welded cylinders shall be inspected in accordance with Section 6 of CGA C-11. Note: The recommended locations for test specimens are depicted in Figures 1 through 5 in appendix A to subpart C of part 178.
(3) Non-refillable cylinders. Non-refillable cylinders shall be inspected in accordance with Section 7 of CGA C-11
(4) Inspector's report. The inspector shall prepare a report containing, at a minimum, the applicable information listed in CGA C-11. Any additional information or markings that are required by the applicable specification must be shown on the test report. The signature of the inspector on the reports certifies that the processes of manufacture and heat treatment of cylinders were observed and found satisfactory. The inspector must furnish the completed test reports required by this subpart to the maker of the cylinder and, upon request, to the purchaser. The test report must be retained by the inspector for 15 years from the original test date of the cylinder.
(d) Defects and attachments. Cylinders must conform to the following:
(1) A cylinder may not be constructed of material with seams, cracks or laminations, or other injurious defects.
(2) Metal attachments to cylinders must have rounded or chamfered corners or must be protected in such a manner as to prevent the likelihood of causing puncture or damage to other hazardous materials packages. This requirement applies to anything temporarily or permanently attached to the cylinder, such as metal skids.
(e) Safety devices. Pressure relief devices and protection for valves, safety devices, and other connections, if applied, must be as required or authorized by the appropriate specification, and as required in § 173.301 of this subchapter.
(f) Markings. Markings on a DOT Specification cylinder must conform to applicable requirements.
(1) Each cylinder must be marked with the following information:
(i) The DOT specification marking must appear first, followed immediately by the service pressure. For example, DOT-3A.
(ii) The serial number must be placed just below or immediately following the DOT specification marking.
(iii) A symbol (letters) must be placed just below, immediately before or following the serial number. Other variations in sequence of markings are authorized only when necessitated by a lack of space. The symbol and numbers must be those of the manufacturer. The symbol must be registered with the Associate Administrator; duplications are not authorized.
(iv) The inspector's official mark and date of test (such as 5-95 for May ) must be placed near the serial number. This information must be placed so that dates of subsequent tests can be easily added. An example of the markings prescribed in this paragraph (f)(1) is as follows:
DOT-3A
XY
AB 5-95
Or;
DOT-3A--XY
AB 5-95
Where:
DOT-3A = specification number
= service pressure
= serial number
XY = symbol of manufacturer
AB = inspector's mark
5-95 = date of test
(2) Additional required marking must be applied to the cylinder as follows:
(i) The word “spun” or “plug” must be placed near the DOT specification marking when an end closure in the finished cylinder has been welded by the spinning process, or effected by plugging.
(ii) As prescribed in specification 3HT (§ 178.44) or 3T (§ 178.45), if applicable.
(3) Marking exceptions. A DOT 3E cylinder is not required to be marked with an inspector's mark or a serial number.
(4) Unless otherwise specified in the applicable specification, the markings on each cylinder must be stamped plainly and permanently on the shoulder, top head, or neck.
(5) The size of each marking must be at least 0.25 inch or as space permits.
(6) Other markings are authorized provided they are made in low stress areas other than the side wall and are not of a size and depth that will create harmful stress concentrations. Such marks may not conflict with any DOT required markings.
(7) Marking exceptions. A DOT 8 or 8AL cylinder is not required to be marked with the service pressure.
(8) Tare weight or mass weight, and water capacity marking. DOT-specification 4B, 4BA, 4BW, and 4E cylinders used in liquefied compressed gas service manufactured after December 28, , must be marked with the tare weight or mass weight. Additionally, the cylinder must be permanently marked with the water capacity. The owner of the cylinder must ensure it is marked with the following information, as applicable:
(i) Tare weight. The tare weight for a cylinder 25 pounds or less at the time of manufacture, with a lower tolerance of 3 percent and an upper tolerance of 1 percent; or for a cylinder exceeding 25 pounds at the time of manufacture, with a lower tolerance of 2 percent and an upper tolerance of 1 percent. The tare weight marking must be the actual weight of the fully assembled cylinder, including the valve(s) and other permanently affixed appurtenances. Removable protective cap(s) or cover(s) must not be included in the cylinder tare weight. Tare weight shall be abbreviated “TW”; or
(ii) Mass weight. The mass weight for a cylinder 25 pounds or less at the time of manufacture, with a lower tolerance of 3 percent and an upper tolerance of 1 percent; or the mass weight marking for a cylinder exceeding 25 pounds at the time of manufacture, with a lower tolerance of 2 percent and an upper tolerance of 1 percent. The mass weight marking must be the actual weight of the fully assembled cylinder, excluding valve(s) and removable protective cap(s) or cover(s). Mass weight shall be abbreviated “MW”; and
(iii) Water capacity. The water capacity for a cylinder 25 pounds water capacity or less, with a tolerance of minus 1 percent and no upper tolerance; or for a cylinder exceeding 25 pounds water capacity, with a tolerance of minus 0.5 percent and no upper tolerance. The marked water capacity of the cylinder must be the capacity of the cylinder at the time of manufacture. Water capacity shall be abbreviated “WC”.
(g) Manufacturer's reports. At or before the time of delivery to the purchaser, the cylinder manufacturer must have all completed certification documents listed in CGA C-11. The manufacturer of the cylinders must retain the reports required by this subpart for 15 years from the original test date of the cylinder.
[Amdt. 178-114, 61 FR , May 23, , as amended at 66 FR , Aug. 28, ; 67 FR , Aug. 8, ; 68 FR , Dec. 31, ; 76 FR , July 20, ; 83 FR , Nov. 7, ; 85 FR , Nov. 25, ; 85 FR , Dec. 28, ]
(a) Type size and service pressure. In addition to the requirements of § 178.35, cylinders must conform to the following:
(1) A DOT-3A cylinder is a seamless steel cylinder with a water capacity (nominal) not over 1,000 pounds and a service pressure of at least 150 psig.
(2) A DOT-3AX is a seamless steel cylinder with a water capacity not less than 1,000 pounds and a service pressure of at least 500 psig, conforming to the following requirements:
(i) Assuming the cylinder is to be supported horizontally at its two ends only and to be uniformly loaded over its entire length consisting of the weight per unit of length of the straight cylindrical portion filled with water and compressed to the specified test pressure; the sum of two times the maximum tensile stress in the bottom fibers due to bending, plus that in the same fibers (longitudinal stress), due to hydrostatic test may not exceed 80 percent of the minimum yield strength of the steel at such maximum stress. Wall thickness must be increased when necessary to meet the requirement.
(ii) To calculate the maximum longitudinal tensile stress due to bending, the following formula must be used:
S = Mc/I
(iii) To calculate the maximum longitudinal tensile stress due to hydrostatic test pressure, the following formula must be used:
S = A1 P/A2
where:
S = tensile stress—p.s.i.;
M = bending moment-inch pounds—(wl2)/8;
w = weight per inch of cylinder filled with water;
l = length of cylinder-inches;
c = radius (D)/(2) of cylinder-inches;
I = moment of inertia—0. (D4−d4) inches fourth;
D = outside diameter-inches;
d = inside diameter-inches;
A1 = internal area in cross section of cylinder-square inches;
A2 = area of metal in cross section of cylinder-square inches;
P = hydrostatic test pressure-psig.
(b) Steel. Open-hearth or electric steel of uniform quality must be used. Content percent may not exceed the following: Carbon, 0.55; phosphorous, 0.045; sulphur, 0.050.
(c) Identification of material. Material must be identified by any suitable method, except that plates and billets for hot-drawn cylinders must be marked with the heat number.
(d) Manufacture. Cylinders must be manufactured using equipment and processes adequate to ensure that each cylinder produced conforms to the requirements of this subpart. No fissure or other defect is permitted that is likely to weaken the finished cylinder appreciably. A reasonably smooth and uniform surface finish is required. If not originally free from such defects, the surface may be machined or otherwise treated to eliminate these defects. The thickness of the bottoms of cylinders welded or formed by spinning is, under no condition, to be less than two times the minimum wall thickness of the cylindrical shell; such bottom thicknesses must be measured within an area bounded by a line representing the points of contact between the cylinder and floor when the cylinder is in a vertical position.
(e) Welding or brazing. Welding or brazing for any purpose whatsoever is prohibited except as follows:
(1) Welding or brazing is authorized for the attachment of neckrings and footrings which are non-pressure parts and only to the tops and bottoms of cylinders having a service pressure of 500 psig or less. Cylinders, neckrings, and footrings must be made of weldable steel, the carbon content of which may not exceed 0.25 percent except in the case of X steel which may be used with proper welding procedures.
(2) As permitted in paragraph (d) of this section.
(3) Cylinders used solely in anhydrous ammonia service may have a 1⁄2 inch diameter bar welded within their concave bottoms.
(f) Wall thickness. For cylinders with service pressure less than 900 psig, the wall stress may not exceed 24,000 psig. A minimum wall thickness of 0.100 inch is required for any cylinder over 5 inches outside diameter. Wall stress calculation must be made by using the following formula:
S = [P(1.3D2 + 0.4d2)]/(D2−d2)
Where:
S = wall stress in psi;
P = minimum test pressure prescribed for water jacket test or 450 psig whichever is the greater;
D = outside diameter in inches;
d = inside diameter in inches.
(g) Heat treatment. The completed cylinder must be uniformly and properly heat-treated prior to tests.
(h) Openings in cylinders and connections (valves, fuse plugs, etc.) for those openings. Threads are required on openings.
(1) Threads must be clean cut, even, without checks, and to gauge.
(2) Taper threads, when used, must be of length not less than as specified for American Standard taper pipe threads.
(3) Straight threads having at least 6 engaged threads are authorized. Straight threads must have a tight fit and calculated shear strength of at least 10 times the test pressure of the cylinder. Gaskets, adequate to prevent leakage, are required.
(i) Pressure testing. Each cylinder must successfully withstand a pressure test as follows:
(1) The test must be by water-jacket or direct expansion method as prescribed in CGA C-1 (IBR; see § 171.7 of this subchapter). The testing equipment must be calibrated as prescribed in CGA C-1. All testing equipment and pressure indicating devices must be accurate within the parameters defined in CGA C-1.
(2) Each cylinder must be tested to a minimum of 5⁄3 times service pressure.
(3) The minimum test pressure must be maintained for at least 30 seconds and sufficiently longer to ensure complete expansion. Any internal pressure applied after heat-treatment and previous to the official test may not exceed 90 percent of the test pressure. If, due to failure of the test apparatus or operator error, the test pressure cannot be maintained, the test may be repeated in accordance with CGA C-1, section 5.7.2.
(4) Permanent, volumetric expansion may not exceed 10 percent of the total volumetric expansion at test pressure.
(j) Flattening test. A flattening test must be performed on one cylinder taken at random out of each lot of 200 or less, by placing the cylinder between wedge shaped knife edges having a 60° included angle, rounded to 1⁄2-inch radius. The longitudinal axis of the cylinder must be at a 90-degree angle to knife edges during the test. For lots of 30 or less, flattening tests are authorized to be made on a ring at least 8 inches long cut from each cylinder and subjected to same heat treatment as the finished cylinder.
(k) Physical test. A physical test must be conducted to determine yield strength, tensile strength, elongation, and reduction of area of material as follows:
(1) The test is required on 2 specimens cut from 1 cylinder taken at random out of each lot of 200 or less. For lots of 30 or less, physical tests are authorized to be made on a ring at least 8 inches long cut from each cylinder and subjected to same heat treatment as the finished cylinder.
(2) Specimens must conform to the following:
(i) Gauge length of 8 inches with a width of not over 11⁄2 inches, a gauge length of 2 inches with a width of not over 11⁄2 inches, or a gauge length of at least 24 times thickness with width not over 6 times thickness is authorized when cylinder wall is not over 3⁄16 inch thick.
(ii) The specimen, exclusive of grip ends, may not be flattened. Grip ends may be flattened to within 1 inch of each end of the reduced section.
(iii) When size of cylinder does not permit securing straight specimens, the specimens may be taken in any location or direction and may be straightened or flattened cold, by pressure only, not by blows. When specimens are so taken and prepared, the inspector's report must show in connection with record of physical tests detailed information in regard to such specimens.
(iv) Heating of a specimen for any purpose is not authorized.
(3) The yield strength in tension must be the stress corresponding to a permanent strain of 0.2 percent of the gauge length. The following conditions apply:
(i) The yield strength must be determined by either the “offset” method or the “extension under load” method as prescribed in ASTM E 8 (IBR, see § 171.7 of this subchapter).
(ii) In using the “extension under load” method, the total strain (or “extension under load”) corresponding to the stress at which the 0.2-percent permanent strain occurs may be determined with sufficient accuracy by calculating the elastic extension of the gauge length under appropriate load and adding thereto 0.2 percent of the gauge length. Elastic extension calculations must be based on an elastic modulus of 30,000,000. In the event of controversy the entire stress-strain diagram must be plotted and the yield strength determined from the 0.2 percent offset.
(iii) For the purpose of strain measurement, the initial strain must be set while the specimen is under a stress of 12,000 psig and the strain indicator reading must be set at the calculated corresponding strain.
(iv) Cross-head speed of the testing machine may not exceed 1⁄8 inch per minute during yield strength determination.
(l) Acceptable results for physical and flattening tests. Either of the following is an acceptable result:
(1) An elongation at least 40 percent for a 2-inch gauge length or at least 20 percent in other cases and yield strength not over 73 percent of tensile strength. In this instance, the flattening test is not required.
(2) An elongation at least 20 percent for a 2-inch gauge length or 10 percent in other cases and a yield strength not over 73 percent of tensile strength. In this instance, the flattening test is required, without cracking, to 6 times the wall thickness.
(m) Leakage test. All spun cylinders and plugged cylinders must be tested for leakage by gas or air pressure after the bottom has been cleaned and is free from all moisture subject to the following conditions and limitations:
(1) Pressure, approximately the same as but no less than service pressure, must be applied to one side of the finished bottom over an area of at least 1⁄16 of the total area of the bottom but not less than 3⁄4 inch in diameter, including the closure, for at least 1 minute, during which time the other side of the bottom exposed to pressure must be covered with water and closely examined for indications of leakage. Except as provided in paragraph (n) of this section, a cylinder that is leaking must be rejected.
(2) A spun cylinder is one in which an end closure in the finished cylinder has been welded by the spinning process.
(3) A plugged cylinder is one in which a permanent closure in the bottom of a finished cylinder has been effected by a plug.
(4) As a safety precaution, if the manufacturer elects to make this test before the hydrostatic test, the manufacturer should design the test apparatus so that the pressure is applied to the smallest area practicable, around the point of closure, and so as to use the smallest possible volume of air or gas.
(n) Rejected cylinders. Reheat treatment is authorized for rejected cylinders. Subsequent thereto, cylinders must pass all prescribed tests to be acceptable. Repair by welding or spinning is not authorized. Spun cylinders rejected under the provisions of paragraph (m) of this section may be removed from the spun cylinder category by drilling to remove defective material, tapping and plugging.
[Amdt. 178-114, 61 FR , May 23, , as amended at 62 FR , Oct. 1, ; 66 FR , , Aug. 28, ; 67 FR , Aug. 8, ; 68 FR , Dec. 31, ; 73 FR , Oct. 1, ; 85 FR , Dec. 28, ]
(a) Type, size and service pressure. In addition to the requirements of § 178.35, cylinders must conform to the following:
(1) A DOT-3AA cylinder is a seamless steel cylinder with a water capacity (nominal) of not over 1,000 pounds and a service pressure of at least 150 psig.
(2) A DOT-3AAX cylinder is a seamless steel cylinder with a water capacity of not less than 1,000 pounds and a service pressure of at least 500 psig, conforming to the following requirements:
(i) Assuming the cylinder is to be supported horizontally at its two ends only and to be uniformly loaded over its entire length consisting of the weight per unit of length of the straight cylindrical portion filled with water and compressed to the specified test pressure; the sum of two times the maximum tensile stress in the bottom fibers due to bending, plus that in the same fibers (longitudinal stress), due to hydrostatic test pressure may not exceed 80 percent of the minimum yield strength of the steel at such maximum stress. Wall thickness must be increased when necessary to meet the requirement.
(ii) To calculate the maximum tensile stress due to bending, the following formula must be used:
S = Mc/I
(iii) To calculate the maximum longitudinal tensile stress due to hydrostatic test pressure, the following formula must be used:
S = A1P/A2
Where:
S = tensile stress-p.s.i.;
M = bending moment-inch pounds (wl2)/8;
w = weight per inch of cylinder filled with water;
l = length of cylinder-inches;
c = radius (D)/(2) of cylinder-inches;
I = moment of inertia-0. (D4−d4) inches fourth;
D = outside diameter-inches;
d = inside diameter-inches;
A1 = internal area in cross section of cylinder-square inches;
A2 = area of metal in cross section of cylinder-square inches;
P = hydrostatic test pressure-psig.
(b) Authorized steel. Open-hearth, basic oxygen, or electric steel of uniform quality must be used. A heat of steel made under the specifications in table 1 of this paragraph (b), check chemical analysis of which is slightly out of the specified range, is acceptable, if satisfactory in all other respects, provided the tolerances shown in table 2 of this paragraph (b) are not exceeded. When a carbon-boron steel is used, a hardenability test must be performed on the first and last ingot of each heat of steel. The results of this test must be recorded on the Record of Chemical Analysis of Material for Cylinders required by § 178.35. This hardness test must be made 5⁄16-inch from the quenched end of the Jominy quench bar and the hardness must be at least Rc 33 and no more than Rc 53. The following chemical analyses are authorized:
Table 1—Authorized Materials
Designation X (percent) (see Note 1) NE- (percent) (see Note 1) (percent) (see Note 1) (percent) (see Note 1) Carbon-boron (percent) Inter- mediate manganese (percent) Carbon 0.25/0.35 0.28/0.33 0.10/0.20 0.20/0.30 0.27-0.37 0.40 max. Manganese 0.40/0.90 0.70/0.90 0.50/0.75 0.50/0.75 0.80-1.40 1.35/1.65. Phosphorus 0.04 max 0.04 max 0.04 max 0.04 max 0.035 max 0.04 max. Sulfur 0.05 max 0.04 max 0.04 max 0.04 max 0.045 max 0.05 max. Silicon 0.15/0.35 0.20/0.35 0.60/0.90 0.60/0.90 0.3 max. 0.10/0.30. Chromium 0.80/1.10 0.40/0.60 0.50/0.65 0.50/0.65. Molybdenum 0.15/0.25 0.15/0.25 Zirconium 0.05/0.15 0.05/0.15 Nickel 0.40/0.70 Boron 0./0.003. Note 1: This designation may not be restrictive and the commercial steel is limited in analysis as shown in this table.Table 2—Check Analysis Tolerances
Element Limit or maximum specified(c) Identification of material. Material must be identified by any suitable method except that plates and billets for hot-drawn cylinders must be marked with the heat number.
(d) Manufacture. Cylinders must be manufactured using equipment and processes adequate to ensure that each cylinder produced conforms to the requirements of this subpart. No fissure or other defects is permitted that is likely to weaken the finished cylinder appreciably. A reasonably smooth and uniform surface finish is required. If not originally free from such defects, the surface may be machined or otherwise treated to eliminate these defects. The thickness of the bottoms of cylinders welded or formed by spinning is, under no condition, to be less than two times the minimum wall thickness of the cylindrical shell; such bottom thicknesses must be measured within an area bounded by a line representing the points of contact between the cylinder and floor when the cylinder is in a vertical position.
(e) Welding or brazing. Welding or brazing for any purpose whatsoever is prohibited except as follows:
(1) Welding or brazing is authorized for the attachment of neckrings and footrings which are non-pressure parts, and only to the tops and bottoms of cylinders having a service pressure of 500 psig or less. Cylinders, neckrings, and footrings must be made of weldable steel, the carbon content of which may not exceed 0.25 percent except in the case of X steel which may be used with proper welding procedure.
(2) As permitted in paragraph (d) of this section.
(f) Wall thickness. The thickness of each cylinder must conform to the following:
(1) For cylinders with a service pressure of less than 900 psig, the wall stress may not exceed 24,000 psi. A minimum wall thickness of 0.100 inch is required for any cylinder with an outside diameter of over 5 inches.
(2) For cylinders with service pressure of 900 psig or more the minimum wall must be such that the wall stress at the minimum specified test pressure may not exceed 67 percent of the minimum tensile strength of the steel as determined from the physical tests required in paragraphs (k) and (l) of this section and must be not over 70,000 psi.
(3) Calculation must be made by the formula:
S = [P(1.3D2 + 0.4d2)]/(D2−d2)
Where:
S = wall stress in psi;
P = minimum test pressure prescribed for water jacket test or 450 psig whichever is the greater;
D = outside diameter in inches;
d = inside diameter in inches.
(g) Heat treatment. The completed cylinders must be uniformly and properly heat treated prior to tests. Heat treatment of cylinders of the authorized analyses must be as follows:
(1) All cylinders must be quenched by oil, or other suitable medium except as provided in paragraph (g)(5) of this section.
(2) The steel temperature on quenching must be that recommended for the steel analysis, but may not exceed °F.
(3) All steels must be tempered at a temperature most suitable for that steel.
(4) The minimum tempering temperature may not be less than °F except as noted in paragraph (g)(6) of this section.
(5) Steel X may be normalized at a temperature of °F instead of being quenched and cylinders so normalized need not be tempered.
(6) Intermediate manganese steels may be tempered at temperatures not less than °F., and after heat treating each cylinder must be submitted to a magnetic test to detect the presence of quenching cracks. Cracked cylinders must be rejected and destroyed.
(7) Except as otherwise provided in paragraph (g)(6) of this section, all cylinders, if water quenched or quenched with a liquid producing a cooling rate in excess of 80 percent of the cooling rate of water, must be inspected by the magnetic particle, dye penetrant or ultrasonic method to detect the presence of quenching cracks. Any cylinder designed to the requirements for specification 3AA and found to have a quenching crack must be rejected and may not be requalified. Cylinders designed to the requirements for specification 3AAX and found to have cracks must have cracks removed to sound metal by mechanical means. Such specification 3AAX cylinders will be acceptable if the repaired area is subsequently examined to assure no defect, and it is determined that design thickness requirements are met.
(h) Openings in cylinders and connections (valves, fuse plugs, etc.) for those openings. Threads are required on openings.
(1) Threads must be clean cut, even, without checks, and to gauge.
(2) Taper threads, when used, must be of a length not less than as specified for American Standard taper pipe threads.
(3) Straight threads having at least 6 engaged threads are authorized. Straight threads must have a tight fit and a calculated shear strength of at least 10 times the test pressure of the cylinder. Gaskets, adequate to prevent leakage, are required.
(i) Pressure testing. Each cylinder must successfully withstand a pressure test as follows:
(1) The test must be by water-jacket or direct expansion method as prescribed in CGA C-1 (IBR; see § 171.7 of this subchapter). The testing equipment must be calibrated as prescribed in CGA C-1. All testing equipment and pressure indicating devices must be accurate within the parameters defined in CGA C-1.
(2) Each cylinder must be tested to a minimum of 5⁄3 times service pressure.
(3) The minimum test pressure must be maintained for at least 30 seconds and sufficiently longer to ensure complete expansion. Any internal pressure applied after heat-treatment and previous to the official test may not exceed 90 percent of the test pressure. If, due to failure of the test apparatus or operator error, the test pressure cannot be maintained, the test may be repeated in accordance with CGA C-1, section 5.7.2.
(4) Permanent, volumetric expansion may not exceed 10 percent of the total volumetric expansion at test pressure.
(j) Flattening test. A flattening test must be performed on one cylinder, taken at random out of each lot of 200 or fewer, by placing the cylinder between wedge shaped knife edges, having a 60-degree included angle, rounded to 1⁄2-inch radius. The longitudinal axis of the cylinder must be at a 90-degree angle to the knife edges during the test. For lots of 30 or fewer, flattening tests are authorized to be made on a ring at least eight (8) inches long, cut from each cylinder and subjected to the same heat treatment as the finished cylinder. Cylinders may be subjected to a bend test in lieu of the flattening test. Two bend test specimens must be taken in accordance with ISO -1:(E) or ASTM E290 (IBR, see § 171.7 of this subchapter), and must be subjected to the bend test specified therein.
(k) Physical test. A physical test must be conducted to determine yield strength, tensile strength, elongation, and reduction of area of material as follows:
(1) The test is required on 2 specimens cut from 1 cylinder taken at random out of each lot of 200 or less. For lots of 30 or less, physical tests are authorized to be made on a ring at least 8 inches long cut from each cylinder and subjected to the same heat treatment as the finished cylinder.
(2) Specimens must conform to the following:
(i) Gauge length of 8 inches with a width of not over 11⁄2 inches, a gauge length of 2 inches with a width of not over 11⁄2 inches, or a gauge length of at least 24 times the thickness with width not over 6 times thickness when the thickness of the cylinder wall is not over 3⁄16 inch.
(ii) The specimen, exclusive of grip ends, may not be flattened. Grip ends may be flattened to within 1 inch of each end of the reduced section.
(iii) When size of cylinder does not permit securing straight specimens, the specimens may be taken in any location or direction and may be straightened or flattened cold, by pressure only, not by blows. When specimens are so taken and prepared, the inspector's report must show in connection with record of physical tests detailed information in regard to such specimens.
(iv) Heating of a specimen for any purpose is not authorized.
(3) The yield strength in tension must be the stress corresponding to a permanent strain of 0.2 percent of the gauge length. The following conditions apply:
(i) The yield strength must be determined by either the “offset” method or the “extension under load” method as prescribed in ASTM E 8 (IBR, see § 171.7 of this subchapter).
(ii) In using the “extension under load” method, the total strain (or “extension under load”) corresponding to the stress at which the 0.2 percent permanent strain occurs may be determined with sufficient accuracy by calculating the elastic extension of the gauge length under appropriate load and adding thereto 0.2 percent of the gauge length. Elastic extension calculations must be based on an elastic modulus of 30,000,000. In the event of controversy, the entire stress-strain diagram must be plotted and the yield strength determined from the 0.2 percent offset.
(iii) For the purpose of strain measurement, the initial strain must be set while the specimen is under a stress of 12,000 psi, the strain indicator reading being set at the calculated corresponding strain.
(iv) Cross-head speed of the testing machine may not exceed 1⁄8 inch per minute during yield strength determination.
(l) Acceptable results for physical, flattening and bend tests. An acceptable result for physical and flattening tests is elongation of at least 20 percent for 2 inches of gauge length or at least 10 percent in other cases. Flattening is required, without cracking, to 6 times the wall thickness of the cylinder. An acceptable result for the alternative bend test is no crack when the cylinder is bent inward around the mandrel until the interior edges are not further apart than the diameter of the mandrel.
(m) Leakage test. All spun cylinders and plugged cylinders must be tested for leakage by gas or air pressure after the bottom has been cleaned and is free from all moisture. Pressure, approximately the same as but no less than the service pressure, must be applied to one side of the finished bottom over an area of at least 1⁄16 of the total area of the bottom but not less than 3⁄4 inch in diameter, including the closure, for at least one minute, during which time the other side of the bottom exposed to pressure must be covered with water and closely examined for indications of leakage. Except as provided in paragraph (n) of this section, a cylinder must be rejected if there is any leaking.
(1) A spun cylinder is one in which an end closure in the finished cylinder has been welded by the spinning process.
(2) A plugged cylinder is one in which a permanent closure in the bottom of a finished cylinder has been effected by a plug.
(3) As a safety precaution, if the manufacturer elects to make this test before the hydrostatic test, the manufacturer should design the test apparatus so that the pressure is applied to the smallest area practicable, around the point of closure, and so as to use the smallest possible volume of air or gas.
(n) Rejected cylinders. Reheat treatment is authorized for rejected cylinders. Subsequent thereto, cylinders must pass all prescribed tests to be acceptable. Repair by welding or spinning is not authorized. Spun cylinders rejected under the provision of paragraph (m) of this section may be removed from the spun cylinder category by drilling to remove defective material, tapping and plugging.
[Amdt. 178-114, 61 FR , May 23, , as amended at 65 FR , Sept. 29, ; 66 FR , Aug. 28, ; 67 FR , Aug. 8, ; 68 FR , Dec. 31, ; 76 FR , July 20, ; 85 FR , Dec. 28, ; 89 FR , Apr. 10, ]
(a) Type, size, and service pressure. A DOT 3B cylinder is seamless steel cylinder with a water capacity (nominal) of not over 1,000 pounds and a service pressure of at least 150 to not over 500 psig.
(b) Steel. Open-hearth or electric steel of uniform quality must be used. Content percent may not exceed the following: carbon, 0.55; phosphorus, 0.045; sulphur, 0.050.
(c) Identification of material. Material must be identified by any suitable method except that plates and billets for hot-drawn cylinders must be marked with the heat number.
(d) Manufacture. Cylinders must be manufactured using equipment and processes adequate to ensure that each cylinder produced conforms to the requirements of this subpart. No fissure or other defect is permitted that is likely to weaken the finished cylinder appreciably. A reasonably smooth and uniform surface finish is required. If not originally free from such defects, the surface may be machined or otherwise treated to eliminate these defects. The thickness of the bottoms of cylinders welded or formed by spinning is, under no condition, to be less than two times the minimum wall thickness of the cylindrical shell; such bottom thicknesses to be measured within an area bounded by a line representing the points of contact between the cylinder and floor when the cylinder is in a vertical position.
(e) Welding or brazing. Welding or brazing for any purpose whatsoever is prohibited except as follows:
(1) Welding or brazing is authorized for the attachment of neckrings and footrings which are non-pressure parts, and only to the tops and bottoms of cylinders having a service pressure of 500 psig or less. Cylinders, neckrings, and footrings must be made of weldable steel, carbon content of which may not exceed 0.25 percent except in the case of X steel which may be used with proper welding procedure.
(2) As permitted in paragraph (d) of this section.
(f) Wall thickness. The wall stress may not exceed 24,000 psi. The minimum wall thickness is 0.090 inch for any cylinder with an outside diameter of 6 inches. Calculation must be made by the following formula:
S = [P(1.3D2 + 0.4d2)]/(D2−d2)
Where:
S = wall stress in psi;
P = at least two times service pressure or 450 psig, whichever is the greater;
D = outside diameter in inches;
d = inside diameter in inches.
(g) Heat treatment. The completed cylinders must be uniformly and properly heat-treated prior to tests.
(h) Openings in cylinders and connections (valves, fuse plugs, etc.) for those openings. Threads, conforming to the following, are required on all openings:
(1) Threads must be clean cut, even, without checks, and to gauge.
(2) Taper threads when used, must be of a length not less than as specified for American Standard taper pipe threads.
(3) Straight threads having at least 4 engaged threads are authorized. Straight threads must have a tight fit, and calculated shear strength at least 10 times the test pressure of the cylinder. Gaskets, adequate to prevent leakage, are required.
(i) Pressure testing. Each cylinder must successfully withstand a pressure test as follows:
(1) The test must be by water-jacket or direct expansion method as defined in CGA C-1 (IBR; see § 171.7 of this subchapter). The testing equipment must be calibrated as prescribed in CGA C-1. All testing equipment and pressure indicating devices must be accurate within the parameters defined in CGA C-1.
(2) Cylinders must be tested as follows:
(i) Each cylinder to at least two (2) times its service pressure; or
(ii) One (1) cylinder out of each lot of 200 or fewer to at least three (3) times its service pressure. When one (1) cylinder out of each lot of 200 or less is tested to at least 3 times service pressure, the balance of the lot must be pressure tested by the proof pressure, water-jacket or direct expansion test method as prescribed in CGA C-1. The cylinders must be subjected to at least 2 times service pressure and show no defect. If, due to failure of the test apparatus or operator error, the test pressure cannot be maintained, the test may be repeated in accordance with CGA C-1 5.7.2 or 7.1.2, as appropriate. Determination of expansion properties is not required.
(3) When each cylinder is tested to the minimum test pressure, the minimum test pressure must be maintained at least 30 seconds and sufficiently longer to ensure complete expansion. Any internal pressure applied after heat-treatment and previous to the official test may not exceed 90 percent of the test pressure. If, due to failure of the test apparatus or operator error, the test pressure cannot be maintained, the test may be repeated in accordance with CGA C-1, section 5.7.2.
(4) Permanent volumetric expansion may not exceed 10 percent of total volumetric expansion at test pressure.
(j) Flattening test. A flattening test must be performed on one cylinder taken at random out of each lot of 200 or less, by placing the cylinder between wedge shaped knife edges having a 60° included angle, rounded to 1⁄2-inch radius. The longitudinal axis of the cylinder must be at a 90-degree angle to knife edges during the test. For lots of 30 or less, flattening tests are authorized to be made on a ring at least 8 inches long cut from each cylinder and subjected to same heat treatment as the finished cylinder.
(k) Physical test. A physical test must be conducted to determine yield strength, tensile strength, elongation, and reduction of area of material, as follows:
(1) The test is required on 2 specimens cut from 1 cylinder taken at random out of each lot of 200 or less. For lots of 30 or less, physical tests are authorized to be made on a ring at least 8 inches long cut from each cylinder and subjected to same heat treatment as the finished cylinder.
(2) Specimens must conform to the following:
(i) Gauge length of 8 inches with a width of not over 11⁄2 inches; or a gauge length of 2 inches with a width of not over 11⁄2 inches; or a gauge length at least 24 times the thickness with a width not over 6 times thickness is authorized when a cylinder wall is not over 3⁄16 inch thick.
(ii) The specimen, exclusive of grip ends, may not be flattened. Grip ends may be flattened to within one inch of each end of the reduced section.
(iii) When size of cylinder does not permit securing straight specimens, the specimens may be taken in any location or direction and may be straightened or flattened cold, by pressure only, not by blows. When specimens are so taken and prepared, the inspector's report must show in connection with record of physical tests detailed information in regard to such specimens.
(iv) Heating of a specimen for any purpose is not authorized.
(3) The yield strength in tension must be the stress corresponding to a permanent strain of 0.2 percent of the gauge length. The following conditions apply:
(i) The yield strength must be determined by either the “offset” method or the “extension under load” method as prescribed in ASTM E 8 (IBR, see § 171.7 of this subchapter).
(ii) In using the “extension under load” method, the total strain (or “extension under load”) corresponding to the stress at which the 0.2 percent permanent strain occurs may be determined with sufficient accuracy by calculating the elastic extension of the gauge length under appropriate load and adding thereto 0.2 percent of the gauge length. Elastic extension calculations must be based on an elastic modulus of 30,000,000. In the event of controversy, the entire stress-strain diagram must be plotted and the yield strength determined from the 0.2 percent offset.
(iii) For the purpose of strain measurement, the initial strain must be set while the specimen is under a stress of 12,000 psi, and the strain indicator reading being set at the calculated corresponding strain.
(iv) Cross-head speed of the testing machine may not exceed 1⁄8 inch per minute during yield strength determination.
(l) Acceptable results for physical and flattening tests. Either of the following is an acceptable result:
(1) An elongation of at least 40 percent for a 2-inch gauge length or at least 20 percent in other cases and yield strength not over 73 percent of tensile strength. In this instance, the flattening test is not required.
(2) An elongation of at least 20 percent for a 2-inch gauge length or 10 percent in other cases and yield strength not over 73 percent of tensile strength. Flattening is required, without cracking, to 6 times the wall thickness.
(m) Leakage test. All spun cylinders and plugged cylinders must be tested for leakage by gas or air pressure after the bottom has been cleaned and is free from all moisture, subject to the following conditions and limitations:
(1) Pressure, approximately the same as but no less than service pressure, must be applied to one side of the finished bottom over an area of at least 1⁄16 of the total area of the bottom but not less than 3⁄4 inch in diameter, including the closure, for at least one minute, during which time the other side of the bottom exposed to pressure must be covered with water and closely examined for indications of leakage. Except as provided in paragraph (n) of this section, a cylinder must be rejected if there is any leaking.
(2) A spun cylinder is one in which an end closure in the finished cylinder has been welded by the spinning process.
(3) A plugged cylinder is one in which a permanent closure in the bottom of a finished cylinder has been effected by a plug.
(4) As a safety precaution, if the manufacturer elects to make this test before the hydrostatic test, he should design his apparatus so that the pressure is applied to the smallest area practicable, around the point of closure, and so as to use the smallest possible volume of air or gas.
(n) Rejected cylinders. Reheat treatment of rejected cylinders is authorized. Subsequent thereto, cylinders must pass all prescribed tests to be acceptable. Repair by welding or spinning is not authorized. Spun cylinders rejected under the provisions of paragraph (m) of this section may be removed from the spun cylinder category by drilling to remove defective material, tapping and plugging.
(o) Marking. Markings may be stamped into the sidewalls of cylinders having a service pressure of 150 psig if all of the following conditions are met:
(1) Wall stress at test pressure may not exceed 24,000 psi.
(2) Minimum wall thickness must be not less than 0.090 inch.
(3) Depth of stamping must be no greater than 15 percent of the minimum wall thickness, but may not exceed 0.015 inch.
(4) Maximum outside diameter of cylinder may not exceed 5 inches.
(5) Carbon content of cylinder may not exceed 0.25 percent. If the carbon content exceeds 0.25 percent, the complete cylinder must be normalized after stamping.
(6) Stamping must be adjacent to the top head.
[Amdt. 178-114, 61 FR , May 23, , as amended by 66 FR , , Aug. 28, ; 67 FR , Aug. 8, ; 68 FR , Dec. 31, ; 85 FR , Dec. 28, ]
(a) Type, size and service pressure. A DOT 3BN cylinder is a seamless nickel cylinder with a water capacity (nominal) not over 125 pounds water capacity (nominal) and a service pressure at least 150 to not over 500 psig.
(b) Nickel. The percentage of nickel plus cobalt must be at least 99.0 percent.
(c) Identification of material. The material must be identified by any suitable method except that plates and billets for hot-drawn cylinders must be marked with the heat number.
(d) Manufacture. Cylinders must be manufactured using equipment and processes adequate to ensure that each cylinder produced conforms to the requirements of this subpart. No defect is permitted that is likely to weaken the finished cylinder appreciably. A reasonably smooth and uniform surface finish is required. Cylinders closed in by spinning process are not authorized.
(e) Welding or brazing. Welding or brazing for any purpose whatsoever is prohibited except that welding is authorized for the attachment of neckrings and footrings which are nonpressure parts, and only to the tops and bottoms of cylinders. Neckrings and footrings must be of weldable material, the carbon content of which may not exceed 0.25 percent. Nickel welding rod must be used.
(f) Wall thickness. The wall stress may not exceed 15,000 psi. A minimum wall thickness of 0.100 inch is required for any cylinder over 5 inches in outside diameter. Wall stress calculation must be made by using the following formula:
S = [P(1.3D2 + 0.4d2)] / (D2 − d2)
Where:
S = wall stress in psi;
P = minimum test pressure prescribed for water jacket test or 450 psig whichever is the greater;
D = outside diameter in inches;
d = inside diameter in inches.
(g) Heat treatment. The completed cylinders must be uniformly and properly heat-treated prior to tests.
(h) Openings in cylinders and connections (valves, fuse plugs, etc.) for those openings. Threads conforming to the following are required on openings:
(1) Threads must be clean cut, even, without checks, and to gauge.
(2) Taper threads, when used, to be of length not less than as specified for American Standard taper pipe threads.
(3) Straight threads having at least 6 engaged threads are authorized. Straight threads must have a tight fit and a calculated shear strength of at least 10 times the test pressure of the cylinder. Gaskets, adequate to prevent leakage, are required.
(i) Pressure testing. Each cylinder must successfully withstand a pressure test as follows:
(1) The test must be by water-jacket or direct expansion method as prescribed in CGA C-1 (IBR; see § 171.7 of this subchapter). The testing equipment must be calibrated as prescribed in CGA C-1. All testing equipment and pressure indicating devices must be accurate within the parameters defined in CGA C-1.
(2) Each cylinder must be tested to a minimum of at least two (2) times its service pressure.
(3) The minimum test pressure must be maintained at least 30 seconds and sufficiently longer to ensure complete expansion. Any internal pressure applied after heat-treatment and previous to the official test may not exceed 90 percent of the test pressure. If, due to failure of the test apparatus or operator error, the test pressure cannot be maintained, the test may be repeated in accordance with CGA C-1, section 5.7.2.
(4) Permanent volumetric expansion may not exceed 10 percent of total volumetric expansion at test pressure.
(j) Flattening test. A flattening test must be performed on one cylinder taken at random out of each lot of 200 or less, by placing the cylinder between wedge shaped knife edges having a 60° included angle, rounded to 1⁄2-inch radius. The longitudinal axis of the cylinder must be at a 90-degree angle to knife edges during the test. For lots of 30 or less, flattening tests are authorized to be made on a ring at least 8 inches long cut from each cylinder and subjected to same heat treatment as the finished cylinder.
(k) Physical test. A physical test must be conducted to determine yield strength, tensile strength, elongation, and reduction of area of material, as follows:
(1) The test is required on 2 specimens cut from 1 cylinder taken at random out of each lot of 200 or less. For lots of 30 or less, physical tests are authorized to be made on a ring at least 8 inches long cut from each cylinder and subjected to same heat treatment as the finished cylinder.
(2) Specimens must conform to the following:
(i) A gauge length of 8 inches with a width of not over 11⁄2 inches, a gauge length of 2 inches with a width of not over 11⁄2 inches, or a gauge length of at least 24 times the thickness with a width not over 6 times thickness is authorized when a cylinder wall is not over 3⁄16 inch thick.
(ii) The specimen, exclusive of grip ends, may not be flattened. Grip ends may be flattened to within one inch of each end of the reduced section.
(iii) When size of cylinder does not permit securing straight specimens, the specimens may be taken in any location or direction and may be straightened or flattened cold, by pressure only, not by blows. When specimens are so taken and prepared, the inspector's report must show in connection with record of physical tests detailed information in regard to such specimens.
(iv) Heating of a specimen for any purpose is not authorized.
(3) The yield strength in tension must be the stress corresponding to a permanent strain of 0.2 percent of the gauge length. The following conditions apply:
(i) The yield strength must be determined by either the “offset” method or the “extension under load” method as prescribed in ASTM E 8 (IBR, see § 171.7 of this subchapter).
(ii) In using the “extension under load” method, the total strain (or “extension under load”) corresponding to the stress at which the 0.2 percent permanent strain occurs may be determined with sufficient accuracy by calculating the elastic extension of the gauge length under appropriate load and adding thereto 0.2 percent of the gauge length. Elastic extension calculations must be based on an elastic modulus of 30,000,000. In the event of controversy, the entire stress-strain diagram must be plotted and the yield strength determined from the 0.2 percent offset.
(iii) For the purpose of strain measurement, the initial strain must be set while the specimen is under a stress of 12,000 psi, and the strain indicator reading must be set at the calculated corresponding strain.
(iv) Cross-head speed of the testing machine may not exceed 1⁄8 inch per minute during yield strength determination.
(l) Acceptable results for physical and flattening tests. Either of the following is an acceptable result:
(1) An elongation of at least 40 percent for a 2 inch gauge length or at least 20 percent in other cases and yield point not over 50 percent of tensile strength. In this instance, the flattening test is not required.
(2) An elongation of at least 20 percent for a 2 inch gauge length or 10 percent in other cases and a yield point not over 50 percent of tensile strength. Flattening is required, without cracking, to 6 times the wall thickness.
(m) Rejected cylinders. Reheat treatment is authorized for rejected cylinders. Subsequent thereto, cylinders must pass all prescribed tests to be acceptable. Repair by welding is not authorized.
[Amdt. 178-114, 61 FR , May 23, , as amended by 66 FR , , , Aug. 28, ; 67 FR , Aug. 8, ; 68 FR , Dec. 31, ; 85 FR , Dec. 28, ]
(a) Type, size, and service pressure. A DOT 3E cylinder is a seamless steel cylinder with an outside diameter not greater than 2 inches nominal, a length less than 2 feet and a service pressure of 1,800 psig.
(b) Steel. Open-hearth or electric steel of uniform quality must be used. Content percent may not exceed the following: Carbon, 0.55; phosphorus, 0.045; sulphur, 0.050.
(d) Manufacture. Cylinders must be manufactured by best appliances and methods. No defect is permitted that is likely to weaken the finished cylinder appreciably. A reasonably smooth and uniform surface finish is required. The thickness of the spun bottom is, under no condition, to be less than two times the minimum wall thickness of the cylindrical shell; such bottom thickness must be measured within an area bounded by a line representing the points of contact between the cylinder and floor when the cylinder is in a vertical position.
(e) Openings in cylinders and connections (valves, fuse plugs, etc.) for those openings. Threads conforming to the following are required on openings.
(1) Threads must be clean cut, even, without checks, and to gauge.
(2) Taper threads, when used, must be of length not less than as specified for American Standard taper pipe threads.
(3) Straight threads having at least 4 engaged threads are authorized. Straight threads must have a tight fit and a calculated shear strength of at least 10 times the test pressure of the cylinder. Gaskets, adequate to prevent leakage, are required.
(f) Pressure testing. Cylinders must be tested as follows:
(1) One cylinder out of each lot of 500 or fewer must be subjected to a hydrostatic test pressure of 6,000 psig or higher.
(2) The cylinder referred to in paragraph (f)(1) of this section must burst at a pressure higher than 6,000 psig without fragmenting or otherwise showing lack of ductility, or must hold a pressure of 12,000 psig for 30 seconds without bursting. In which case, it must be subjected to a flattening test without cracking to six times wall thickness between knife edges, wedge shaped 60 degree angle, rounded out to a 1⁄2 inch radius. The inspector's report must be suitably changed to show results of latter alternate and flattening test. The testing equipment must be calibrated as prescribed in CGA C-1 (IBR, see § 171.7 of this subchapter). All testing equipment and pressure indicating devices must be accurate within the parameters defined in CGA C-1.
(3) The remaining cylinders of the lot must be pressure tested by the proof pressure water-jacket or direct expansion test method as prescribed in CGA C-1. Cylinders must be examined under pressure of at least 3,000 psig and not to exceed 4,500 psig and show no defect. Cylinders tested at a pressure in excess of 3,600 psig must burst at a pressure higher than 7,500 psig when tested as specified in paragraph (f)(2) of this section. The pressure must be maintained for at least 30 seconds and sufficiently longer to ensure complete examination. The testing equipment must be calibrated as prescribed in CGA C-1. All testing equipment and pressure indicating devices must be accurate within the parameters defined in CGA C-1. If, due to failure of the test apparatus or operator error, the test pressure cannot be maintained, the test may be repeated in accordance with CGA C-1 5.7.2 or 7.1.2, as appropriate. Determination of expansion properties is not required.
(g) Leakage test. All spun cylinders and plugged cylinders must be tested for leakage by gas or air pressure after the bottom has been cleaned and is free from all moisture subject to the following conditions and limitations:
(1) A pressure, approximately the same as but not less than the service pressure, must be applied to one side of the finished bottom over an area of at least 1⁄16 of the total area of the bottom but not less than 3⁄4 inch in diameter, including the closure, for at least one minute, during which time the other side of the bottom exposed to pressure must be covered with water and closely examined for indications of leakage. Accept as provided in paragraph (h) of this section, a cylinder must be rejected if there is any leakage.
(2) A spun cylinder is one in which an end closure in the finished cylinder has been welded by the spinning process.
(3) A plugged cylinder is one in which a permanent closure in the bottom of a finished cylinder has been effected by a plug.
(4) As a safety precaution, if the manufacturer elects to make this test before the hydrostatic test, the manufacturer shall design the test apparatus so that the pressure is applied to the smallest area practicable, around the point of closure, and so as to use the smallest possible volume of air or gas.
(h) Rejected cylinders. Reheat treatment is authorized for rejected cylinders. Subsequent thereto, cylinders must pass all prescribed tests to be acceptable. Repair by welding or spinning is not authorized. Spun cylinders rejected under the provisions of paragraph (g) of this section may be removed from the spun cylinder category by drilling to remove defective material, tapping and plugging.
(i) Marking. Markings required by § 178.35 must be stamped plainly and permanently on the shoulder, top head, neck or sidewall of each cylinder.
[Amdt. 178-114, 61 FR , May 23, , as amended by 66 FR , Aug. 28, ; 85 FR , Dec. 28, ]
(a) Type, size and service pressure. A DOT 3HT cylinder is a seamless steel cylinder with a water capacity (nominal) of not over 150 pounds and a service pressure of at least 900 psig.
(b) Authorized steel. Open hearth or electric furnace steel of uniform quality must be used. A heat of steel made under the specifications listed in Table 1 in this paragraph (b), a check chemical analysis that is slightly out of the specified range is acceptable, if satisfactory in all other respects, provided the tolerances shown in Table 2 in this paragraph (b) are not exceeded. The maximum grain size shall be 6 or finer. The grain size must be determined in accordance with ASTM E 112-88 (IBR, see § 171.7 of this subchapter). Steel of the following chemical analysis is authorized:
Table 1—Authorized Materials
Designation AISITable 2—Check Analysis Tolerances
Element Limit or maximum specified (percent) Tolerance(c) Identification of material. Material must be identified by any suitable method. Steel stamping of heat identifications may not be made in any area which will eventually become the side wall of the cylinder. Depth of stamping may not encroach upon the minimum prescribed wall thickness of the cylinder.
(d) Manufacture. Cylinders must be manufactured using equipment and processes adequate to ensure that each cylinder produced conforms to the requirements of this subpart. No fissure or other defect is permitted that is likely to weaken the finished container appreciably. The general surface finish may not exceed a roughness of 250 RMS. Individual irregularities such as draw marks, scratches, pits, etc., should be held to a minimum consistent with good high stress pressure vessel manufacturing practices. If the cylinder is not originally free of such defects or does not meet the finish requirements, the surface may be machined or otherwise treated to eliminate these defects. The point of closure of cylinders closed by spinning may not be less than two times the prescribed wall thickness of the cylindrical shell. The cylinder end contour must be hemispherical or ellipsoidal with a ratio of major-to-minor axis not exceeding two to one and with the concave side to pressure.
(e) Welding or brazing. Welding or brazing for any purpose whatsoever is prohibited, except that welding by spinning is permitted to close the bottom of spun cylinders. Machining or grinding to produce proper surface finish at point of closure is required.
(f) Wall thickness.
(1) Minimum wall thickness for any cylinder must be 0.050 inch. The minimum wall thickness must be such that the wall stress at the minimum specified test pressure may not exceed 75 percent of the minimum tensile strength of the steel as determined from the physical tests required in paragraph (m) of this section and may not be over 105,000 psi.
(2) Calculations must be made by the formula:
S = [P(1.3D2 + 0.4d2)] / (D2 − d2)
Where:
S = Wall stress in psi;
P = Minimum test pressure prescribed for water jacket test;
D = Outside diameter in inches;
d = Inside diameter in inches.
(3) Wall thickness of hemispherical bottoms only permitted to 90 percent of minimum wall thickness of cylinder sidewall but may not be less than 0.050 inch. In all other cases, thickness to be no less than prescribed minimum wall.
(g) Heat treatment. The completed cylinders must be uniformly and properly heated prior to tests. Heat treatment of the cylinders of the authorized analysis must be as follows:
(1) All cylinders must be quenched by oil, or other suitable medium.
(2) The steel temperature on quenching must be that recommended for the steel analysis, but may not exceed °F.
(3) The steel must be tempered at a temperature most suitable for the particular steel analysis but not less than 850 °F.
(4) All cylinders must be inspected by the magnetic particle or dye penetrant method to detect the presence of quenching cracks. Any cylinder found to have a quenching crack must be rejected and may not be requalified.
(h) Openings in cylinders and connections (valves, fuse plugs, etc.) for those openings. Threads conforming to the following are required on openings:
(1) Threads must be clean cut, even, without cracks, and to gauge.
(2) Taper threads, when used, must be of length not less than as specified for National Gas Tapered Thread (NGT) as required by American Standard Compressed Gas Cylinder Valve Outlet and Inlet Connections.
(3) Straight threads having at least 6 engaged threads are authorized. Straight threads must have a tight fit and a calculated shear stress of at least 10 times the test pressure of the cylinder. Gaskets, adequate to prevent leakage, are required.
(i) Pressure testing. Each cylinder must successfully withstand a pressure test as follows:
(1) The test must be by water-jacket or direct expansion method as prescribed in CGA C-1 (IBR; see § 171.7 of this subchapter). The testing equipment must be calibrated as prescribed in CGA C-1. All testing equipment and pressure indicating devices must be accurate within the parameters defined in CGA C-1.
(2) Each cylinder must be tested to minimum of 5⁄3 times service pressure.
(3) The minimum test pressure must be maintained at least 30 seconds and sufficiently longer to ensure complete expansion. Any internal pressure applied after heat-treatment and previous to the official test may not exceed 90 percent of the test pressure. If, due to failure of the test apparatus or operator error, the test pressure cannot be maintained, the test may be repeated in accordance with CGA C-1, section 5.7.2.
(4) Permanent volumetric expansion may not exceed 10 percent of total volumetric expansion at test pressure.
(j) Cycling tests. Prior to the initial shipment of any specific cylinder design, cyclic pressurization tests must have been performed on at least three representative samples without failure as follows:
(1) Pressurization must be performed hydrostatically between approximately zero psig and the service pressure at a rate not in excess of 10 cycles per minute. Adequate recording instrumentation must be provided if equipment is to be left unattended for periods of time.
(2) Tests prescribed in paragraph (j)(1) of this section must be repeated on one random sample out of each lot of cylinders. The cylinder may then be subjected to a burst test.
(3) A lot is defined as a group of cylinders fabricated from the same heat of steel, manufactured by the same process and heat treated in the same equipment under the same conditions of time, temperature, and atmosphere, and may not exceed a quantity of 200 cylinders.
(4) All cylinders used in cycling tests must be destroyed.
(k) Burst test. One cylinder taken at random out of each lot of cylinders must be hydrostatically tested to destruction.
(l) Flattening test. A flattening test must be performed on one cylinder taken at random out of each lot of 200 or less, by placing the cylinder between wedge shaped knife edges having a 60° included angle, rounded to 1⁄2-inch radius. The longitudinal axis of the cylinder must be at a 90-degree angle to knife edges during the test. For lots of 30 or less, flattening tests are authorized to be made on a ring at least 8 inches long cut from each cylinder and subjected to same heat treatment as the finished cylinder.
(m) Physical tests. A physical test must be conducted to determine yield strength, tensile strength, elongation, and reduction of area of material, as follows:
(1) Test is required on 2 specimens cut from 1 cylinder taken at random out of each lot of cylinders.
(2) Specimens must conform to the following:
(i) A gauge length of at least 24 times the thickness with a width not over six times the thickness. The specimen, exclusive of grip ends, may not be flattened. Grip ends may be flattened to within one inch of each end of the reduced section. When size of cylinder does not permit securing straight specimens, the specimens may be taken in any location or direction and may be straightened or flattened cold by pressure only, not by blows. When specimens are so taken and prepared, the inspector's report must show in connection with the record of physical tests detailed information in regard to such specimens.
(ii) Heating of a specimen for any purpose is not authorized.
(3) The yield strength in tension must be the stress corresponding to a permanent strain of 0.2 percent of the gauge length.
(i) The yield strength must be determined by either the “offset” method or the “extension under load” method as prescribed in ASTM E 8 (IBR, see § 171.7 of this subchapter).
(ii) In using the “extension under load” method, the total strain (or “extension under load”) corresponding to the stress at which the 0.2 percent permanent strain occurs may be determined with sufficient accuracy by calculating the elastic extension of the gauge length under appropriate load and adding thereto 0.2 percent of the gauge length. Elastic extension calculations must be based on an elastic modulus of 30,000,000. In the event of controversy, the entire stress-strain diagram must be plotted and the yield strength determined from the 0.2 percent offset.
(iii) For the purpose of strain measurement, the initial strain must be set while the specimen is under a stress of 12,000 psi, the strain indicator reading being set at the calculated corresponding strain.
(iv) Cross-head speed of the testing machine may not exceed 1⁄8 inch per minute during yield strength determination.
(n) Magnetic particle inspection. Inspection must be performed on the inside of each container before closing and externally on each finished container after heat treatment. Evidence of discontinuities, which in the opinion of a qualified inspector may appreciably weaken or decrease the durability of the cylinder, must be cause for rejection.
(o) Leakage test. All spun cylinders and plugged cylinders must be tested for leakage by dry gas or dry air pressure after the bottom has been cleaned and is free from all moisture, subject to the following conditions and limitations:
(1) Pressure, approximately the same as but not less than service pressure, must be applied to one side of the finished bottom over an area of at least 1⁄16 of the total area of the bottom but not less than 3⁄4 inch in diameter, including the closure, for at least one minute, during which time the other side of the bottom exposed to pressure must be covered with water and closely examined for indications of leakage. Except as provided in paragraph (q) of this section, a cylinder must be rejected if there is leakage.
(2) A spun cylinder is one in which an end closure in the finished cylinder has been welded by the spinning process.
(3) A plugged cylinder is one in which a permanent closure in the bottom of a finished cylinder has been effected by a plug.
(4) As a safety precaution, if the manufacturer elects to make this test before the hydrostatic test, the manufacturer should design the test apparatus so that the pressure is applied to the smallest area practicable, around the point of closure, and so as to use the smallest possible volume of air or gas.
(p) Acceptable results of tests. Results of the flattening test, physical tests, burst test, and cycling test must conform to the following:
(1) Flattening required without cracking to ten times the wall thickness of the cylinder.
(2) Physical tests:
(i) An elongation of at least 6 percent for a gauge length of 24 times the wall thickness.
(ii) The tensile strength may not exceed 165,000 p.s.i.
(3) The burst pressure must be at least 4⁄3 times the test pressure.
(4) Cycling-at least 10,000 pressurizations.
(q) Rejected cylinders. Reheat treatment is authorized for rejected cylinders. Subsequent thereto, cylinders must pass all prescribed tests to be acceptable. Repair by welding or spinning is not authorized. For each cylinder subjected to reheat treatment during original manufacture, sidewall measurements must be made to verify that the minimum sidewall thickness meets specification requirements after the final heat treatment.
(r) Marking.
(1) Cylinders must be marked by low stress type steel stamping in an area and to a depth which will insure that the wall thickness measured from the root of the stamping to the interior surface is equal to or greater than the minimum prescribed wall thickness. Stamping must be permanent and legible. Stamping on side wall not authorized.
(2) The rejection elastic expansion (REE), in cubic cm (cc), must be marked on the cylinder near the date of test. The REE for a cylinder is 1.05 times its original elastic expansion.
(3) Name plates are authorized, provided that they can be permanently and securely attached to the cylinder. Attachment by either brazing or welding is not permitted. Attachment by soldering is permitted provided steel temperature does not exceed 500 °F.
(s) Inspector's report. In addition to the requirements of § 178.35, the inspector's report must indicate the rejection elastic expansion (REE), in cubic cm (cc).
[Amdt. 178-114, 61 FR , May 23, , as amended at 62 FR , Oct. 1, ; 65 FR , Sept. 29, ; 66 FR , Aug. 28, ; 67 FR , Aug. 8, ; 68 FR , , Dec. 31, ; 85 FR , Dec. 28, ]
(a) Type, size, and service pressure. A DOT 3T cylinder is a seamless steel cylinder with a minimum water capacity of 1,000 pounds and a minimum service pressure of 1,800 psig. Each cylinder must have integrally formed heads concave to pressure at both ends. The inside head shape must be hemispherical, ellipsoidal in which the major axis is two times the minor axis, or a dished shape falling within these two limits. Permanent closures formed by spinning are prohibited.
(b) Material, steel. Only open hearth, basic oxygen, or electric furnace process steel of uniform quality is authorized. The steel analysis must conform to the following:
Analysis Tolerances
Element Ladle analysis Check Analysis Under Over Carbon 0.35 to 0.50 0.03 0.04 Manganese 0.75 to 1.05 0.04 0.04 Phosphorus (max) 0.035 0.01 Sulphur (max) 0.04 0.01 Silicon 0.15 to 0.35 0.02 0.03 Chromium 0.80 to 1.15 0.05 0.05 Molybdenum 0.15 to 0.25 0.02 0.02(1) A heat of steel made under the specifications in the table in this paragraph (b), the ladle analysis of which is slightly out of the specified range, is acceptable if satisfactory in all other aspects. However, the check analysis tolerances shown in the table in this paragraph (b) may not be exceeded except as approved by the Department.
(2) Material with seams, cracks, laminations, or other injurious defects is not permitted.
(3) Material used must be identified by any suitable method.
(c) Manufacture. General manufacturing requirements are as follows:
(1) Surface finish must be uniform and reasonably smooth.
(2) Inside surfaces must be clean, dry, and free of loose particles.
(3) No defect of any kind is permitted if it is likely to weaken a finished cylinder.
(4) If the cylinder surface is not originally free from the defects, the surface may be machined or otherwise treated to eliminate these defects provided the minimum wall thickness is maintained.
(5) Welding or brazing on a cylinder is not permitted.
(d) Wall thickness. The minimum wall thickness must be such that the wall stress at the minimum specified test pressure does not exceed 67 percent of the minimum tensile strength of the steel as determined by the physical tests required in paragraphs (j) and (k) of this section. A wall stress of more than 90,500 p.s.i. is not permitted. The minimum wall thickness for any cylinder may not be less than 0.225 inch.
(1) Calculation of the stress for cylinders must be made by the following formula:
S = [P(1.3D2 + 0.4d2)] / (D2 − d2)
Where:
S = Wall stress in psi;
P = Minimum test pressure, at least 5⁄3 service pressure;
D = Outside diameter in inches;
d = Inside diameter in inches.
(2) Each cylinder must meet the following additional requirement which assumes a cylinder horizontally supported at its two ends and uniformly loaded over its entire length. This load consists of the weight per inch of length of the straight cylindrical portion filled with water compressed to the specified test pressure. The wall thickness must be increased when necessary to meet this additional requirement:
(i) The sum of two times the maximum tensile stress in the bottom fibers due to bending (see paragraph (d)(2)(ii) of this section), plus the maximum tensile stress in the same fibers due to hydrostatic testing (see paragraph (d)(2)(iii) of this section) may not exceed 80 percent of the minimum yield strength of the steel at this maximum stress.
(ii) The following formula must be used to calculate the maximum tensile stress due to bending:
S = Mc / I
Where:
S = Tensile stress in psi;
M = Bending moment in inch-pounds (wl2/8);
I = Moment of inertia—0. (D4−d4) in inches fourth;
c = Radius (D/2) of cylinder in inches;
w = Weight per inch of cylinder filled with water;
l = Length of cylinder in inches;
D = Outside diameter in inches;
d = Inside diameter in inches.
(iii) The following formula must be used to calculate the maximum longitudinal tensile stress due to hydrostatic test pressure:
S = A1 P / A2
Where:
S = Tensile stress in psi;
A1 = Internal area in cross section of cylinder in square inches;
P = Hydrostatic test pressure-psig;
A2 = Area of metal in cross section of cylinder in square inches.
(e) Heat treatment. Each completed cylinder must be uniformly and properly heat treated prior to testing, as follows:
(1) Each cylinder must be heated and held at the proper temperature for at least one hour per inch of thickness based on the maximum thickness of the cylinder and then quenched in a suitable liquid medium having a cooling rate not in excess of 80 percent of water. The steel temperature on quenching must be that recommended for the steel analysis, but it must never exceed °F.
(2) After quenching, each cylinder must be reheated to a temperature below the transformation range but not less than °F., and must be held at this temperature for at least one hour per inch of thickness based on the maximum thickness of the cylinder. Each cylinder must then be cooled under conditions recommended for the steel.
(f) Openings. Openings in cylinders must comply with the following:
(1) Openings are permitted on heads only.
(2) The size of any centered opening in a head may not exceed one half the outside diameter of the cylinder.
(3) Openings in a head must have ligaments between openings of at least three times the average of their hole diameter. No off-center opening may exceed 2.625 inches in diameter.
(4) All openings must be circular.
(5) All openings must be threaded. Threads must be in compliance with the following:
(i) Each thread must be clean cut, even, without any checks, and to gauge.
(ii) Taper threads, when used, must be the American Standard Pipe thread (NPT) type and must be in compliance with the requirements of NBS Handbook H-28 (IBR, see § 171.7 of this subchapter).
(iii) Taper threads conforming to National Gas Taper thread (NGT) standards must be in compliance with the requirements of NBS Handbook H-28.
(iv) Straight threads conforming with National Gas Straight thread (NGS) standards are authorized. These threads must be in compliance with the requirements of NBS Handbook H-28.
(g) Pressure testing. Each cylinder must successfully withstand a pressure test as follows:
(1) The test must be by water-jacket or direct expansion method as prescribed in CGA C-1 (IBR; see § 171.7 of this subchapter). The testing equipment must be calibrated as prescribed in CGA C-1. All testing equipment and pressure indicating devices must be accurate within the parameters defined in CGA C-1.
(2) Each cylinder must be tested to minimum of 5⁄3 times service pressure.
(3) The minimum test pressure must be maintained at least 30 seconds and sufficiently longer to ensure complete expansion. Any internal pressure applied after heat-treatment and prior to the official test may not exceed 90 percent of the test pressure. If, due to failure of the test apparatus or operator error, the test pressure cannot be maintained, the test may be repeated in accordance with CGA C-1, section 5.7.2.
(4) Permanent volumetric expansion may not exceed 10 percent of total volumetric expansion at test pressure.
(h) Ultrasonic examination. After the hydrostatic test, the cylindrical section of each vessel must be examined in accordance with ASTM E 213 for shear wave and E 114 for straight beam (IBR, Standard see § 171.7 of this subchapter). The equipment used must be calibrated to detect a notch equal to five percent of the design minimum wall thickness. Any discontinuity indication greater than that produced by the five percent notch must be cause for rejection of the cylinder, unless the discontinuity is repaired within the requirements of this specification.
(i) Basic requirements for tension and Charpy impact tests. Cylinders must be subjected to a tension and Charpy impact as follows:
(1) When the cylinders are heat treated in a batch furnace, two tension specimens and three Charpy impact specimens must be tested from one of the cylinders or a test ring from each batch. The lot size represented by these tests may not exceed 200 cylinders.
(2) When the cylinders are heat treated in a continuous furnace, two tension specimens and three Charpy impact specimens must be tested from one of the cylinders or a test ring from each four hours or less of production. However, in no case may a test lot based on this production period exceed 200 cylinders.
(3) Each specimen for the tension and Charpy impact tests must be taken from the side wall of a cylinder or from a ring which has been heat treated with the finished cylinders of which the specimens must be representative. The axis of the specimens must be parallel to the axis of the cylinder. Each cylinder or ring specimen for test must be of the same diameter, thickness, and metal as the finished cylinders they represent. A test ring must be at least 24 inches long with ends covered during the heat treatment process so as to simulate the heat treatment process of the finished cylinders it represents.
(4) A test cylinder or test ring need represent only one of the heats in a furnace batch provided the other heats in the batch have previously been tested and have passed the tests and that such tests do not represent more than 200 cylinders from any one heat.
(5) The test results must conform to the requirements specified in paragraphs (j) and (k) of this section.
(6) When the test results do not conform to the requirements specified, the cylinders represented by the tests may be reheat treated and the tests repeated. Paragraph (i)(5) of this section applies to any retesting.
(j) Basic conditions for acceptable physical testing. The following criteria must be followed to obtain acceptable physical test results:
(1) Each tension specimen must have a gauge length of two inches with a width not exceeding one and one-half inches. Except for the grip ends, the specimen may not be flattened. The grip ends may be flattened to within one inch of each end of the reduced section.
(2) A specimen may not be heated after heat treatment specified in paragraph (d) of this section.
(3) The yield strength in tension must be the stress corresponding to a permanent strain of 0.2 percent of the gage length.
(i) This yield strength must be determined by the “offset” method or the “extension under load” method described in ASTM E 8 (IBR, see § 171.7 of this subchapter).
(ii) For the “extension under load” method, the total strain (or extension under load) corresponding to the stress at which the 0.2 percent permanent strain occurs may be determined with sufficient accuracy by calculating the elastic extension of the gage length under appropriate load and adding thereto 0.2 percent of the gage length. Elastic extension calculations must be based on an elastic modulus of 30,000,000. However, when the degree of accuracy of this method is questionable the entire stress-strain diagram must be plotted and the yield strength determined from the 0.2 percent offset.
(iii) For the purpose of strain measurement, the initial strain must be set with the specimen under a stress of 12,000 p.s.i. and the strain indicator reading set at the calculated corresponding strain.
(iv) The cross-head speed of the testing machine may not exceed 1⁄8 inch per minute during the determination of yield strength.
(4) Each impact specimen must be Charpy V-notch type size 10 mm × 10 mm taken in accordance with paragraph 11 of ASTM A 333 (IBR, see § 171.7 of this subchapter). When a reduced size specimen is used, it must be the largest size obtainable.
(k) Acceptable physical test results. Results of physical tests must conform to the following:
(1) The tensile strength may not exceed 155,000 p.s.i.
(2) The elongation must be at least 16 percent for a two-inch gage length.
(3) The Charpy V-notch impact properties for the three impact specimens which must be tested at 0 °F may not be less than the values shown as follows:
Size of specimen (mm) Average value(4) After the final heat treatment, each vessel must be hardness tested on the cylindrical section. The tensile strength equivalent of the hardness number obtained may not be more than 165,000 p.s.i. (Rc 36). When the result of a hardness test exceeds the maximum permitted, two or more retests may be made; however, the hardness number obtained in each retest may not exceed the maximum permitted.
(l) Rejected cylinders. Reheat treatment is authorized for rejected cylinders. However, each reheat treated cylinder must subsequently pass all the prescribed tests. Repair by welding is not authorized.
(m) Markings. Marking must be done by stamping into the metal of the cylinder. All markings must be legible and located on a shoulder.
(n) Inspector's report. In addition to the requirements of § 178.35, the inspector's report for the physical test report, must indicate the average value for three specimens and the minimum value for one specimen for each lot number.
[Amdt. 178-114, 61 FR , May 23, , as amended at 66 FR , , Aug. 28, ; 67 FR , Aug. 8, ; 68 FR , Aug. 14, ; 68 FR , , Dec. 31, ; 85 FR , Dec. 28, ]
(a) Size and service pressure. A DOT 3AL cylinder is a seamless aluminum cylinder with a maximum water capacity of pounds and minimum service pressure of 150 psig.
(b) Authorized material and identification of material. The material of construction must meet the following conditions:
(1) Starting stock must be cast stock or traceable to cast stock.
(2) Material with seams, cracks, laminations, or other defects likely to weaken the finished cylinder may not be used.
(3) Material must be identified by a suitable method that will identify the alloy, the aluminum producer's cast number, the solution heat treat batch number and the lot number.
(4) The material must be of uniform quality. Only the following heat treatable aluminum alloys in table 1 and 2 are permitted as follows:
Table 1—Heat or Cast Analysis for Aluminum; Similar to “Aluminum Association”1 Alloy
[CHEMICAL ANALYSIS IN WEIGHT PERCENT2]
SiTable 2—Mechanical Property Limits
Alloy and temper Tensile strength—PSI Elongation—percent minimum for 2″ or 4D 1 size specimen Ultimate—minimum Yield—minimum -T6 38,000 35,000 2 14 1 “D” represents specimen diameters. When the cylinder wall is greater than 3⁄16 inch thick, a retest without reheat treatment using the 4D size specimen is authorized if the test using the 2 inch size specimen fails to meet elongation requirements. 2 When cylinder wall is not over 3⁄16-inch thick, 10 percent elongation is authorized when using a 24t × 6t size test specimen.(5) All starting stock must be 100 percent ultrasonically inspected, along the length at right angles to the central axis from two positions at 90° to one another. The equipment and continuous scanning procedure must be capable of detecting and rejecting internal defects such as cracks which have an ultrasonic response greater than that of a calibration block with a 5⁄64-inch diameter flat bottomed hole.
(6) Cast stock must have uniform equiaxed grain structure not to exceed 500 microns maximum.
(7) Any starting stock not complying with the provisions of paragraphs (b)(1) through (b)(6) of this section must be rejected.
(c) Manufacture. Cylinders must be manufactured in accordance with the following requirements:
(1) Cylinder shells must be manufactured by the backward extrusion method and have a cleanliness level adequate to ensure proper inspection. No fissure or other defect is acceptable that is likely to weaken the finished cylinder below the design strength requirements. A reasonably smooth and uniform surface finish is required. If not originally free from such defects, the surface may be machined or otherwise conditioned to eliminate these defects.
(2) Thickness of the cylinder base may not be less than the prescribed minimum wall thickness of the cylindrical shell. The cylinder base must have a basic torispherical, hemispherical, or ellipsoidal interior base configuration where the dish radius is no greater than 1.2 times the inside diameter of the shell. The knuckle radius may not be less than 12 percent of the inside diameter of the shell. The interior base contour may deviate from the true torispherical, hemispherical or ellipsoidal configuration provided that—
(i) Any areas of deviation are accompanied by an increase in base thickness;
(ii) All radii of merging surfaces are equal to or greater than the knuckle radius;
(iii) Each design has been qualified by successfully passing the cycling tests in this paragraph (c); and
(iv) Detailed specifications of the base design are available to the inspector.
(3) For free standing cylinders, the base thickness must be at least two times the minimum wall thickness along the line of contact between the cylinder base and the floor when the cylinders are in the vertical position.
(4) Welding or brazing is prohibited.
(5) Each new design and any significant change to any acceptable design must be qualified for production by testing prototype samples as follows:
(i) Three samples must be subjected to 100,000 pressure reversal cycles between zero and service pressure or 10,000 pressure reversal cycles between zero and test pressure, at a rate not in excess of 10 cycles per minute without failure.
(ii) Three samples must be pressurized to destruction and failure may not occur at less than 2.5 times the marked cylinder service pressure. Each cylinder must remain in one piece. Failure must initiate in the cylinder sidewall in a longitudinal direction. Rate of pressurization may not exceed 200 psig per second.
(6) In this specification “significant change” means a 10 percent or greater change in cylinder wall thickness, service pressure, or diameter; a 30 percent or greater change in water capacity or base thickness; any change in material; over 100 percent increase in size of openings; or any change in the number of openings.
(d) Wall thickness. The minimum wall thickness must be such that the wall stress at the minimum specified test pressure will not exceed 80 percent of the minimum yield strength nor exceed 67 percent of the minimum ultimate tensile strength as verified by physical tests in paragraph (i) of this section. The minimum wall thickness for any cylinder with an outside diameter greater than 5 inches must be 0.125 inch. Calculations must be made by the following formula:
S = [P(1.3D2 + 0.4d2)] / (D2 − d2)
Where:
S = Wall stress in psi;
P = Prescribed minimum test pressure in psig (see paragraph (g) of this section);
D = Outside diameter in inches; and
d = Inside diameter in inches.
(e) Openings. Openings must comply with the following requirements:
(1) Openings are permitted in heads only.
(2) The size of any centered opening in a head may not exceed one-half the outside diameter of the cylinder.
(3) Other openings are permitted in the head of a cylinder if:
(i) Each opening does not exceed 2.625 inches in diameter, or one-half the outside diameter of the cylinder; whichever is less;
(ii) Each opening is separated from each other by a ligament; and
(iii) Each ligament which separates two openings must be at least three times the average of the diameters of the two openings.
(4) All openings must be circular.
(5) All openings must be threaded. Threads must comply with the following:
(i) Each thread must be clean cut, even, without checks, and to gauge.
(ii) Taper threads, when used, must conform to one of the following:
(A) American Standard Pipe Thread (NPT) type, conforming to the requirements of NBS Handbook H-28 (IBR, see § 171.7 of this subchapter);
(B) National Gas Taper Thread (NGT) type, conforming to the requirements of NBS Handbook H-28; or
(C) Other taper threads conforming to other standards may be used provided the length is not less than that specified for NPT threads.
(iii) Straight threads, when used, must conform to one of the following:
(A) National Gas Straight Thread (NGS) type, conforming to the requirements of NBS Handbook H-28;
(B) Unified Thread (UN) type, conforming to the requirements of NBS Handbook H-28;
(C) Controlled Radius Root Thread (UN) type, conforming to the requirements of NBS Handbook H-28; or
(D) Other straight threads conforming to other recognized standards may be used provided that the requirements in paragraph (e)(5)(iv) of this section are met.
(iv) All straight threads must have at least 6 engaged threads, a tight fit, and a factor of safety in shear of at least 10 at the test pressure of the cylinder. Shear stress must be calculated by using the appropriate thread shear area in accordance with NBS Handbook H-28.
(f) Heat treatment. Prior to any test, all cylinders must be subjected to a solution heat treatment and aging treatment appropriate for the aluminum alloy used.
(g) Pressure testing. Each cylinder must successfully withstand a pressure test as follows:
(1) The test must be by water-jacket or direct expansion method as prescribed in CGA C-1 (IBR; see § 171.7 of this subchapter). The testing equipment must be calibrated as prescribed in CGA C-1. All testing equipment and pressure indicating devices must be accurate within the parameters defined in CGA C-1.
(2) The minimum test pressure must be the greater of the following:
(i) 450 psig regardless of service pressure;
(ii) Two (2) times the service pressure for cylinders having service pressure less than 500 psig; or
(iii) 5⁄3 times the service pressure for cylinders having a service pressure of 500 psig or greater.
(3) The minimum test pressure must be maintained at least 30 seconds and sufficiently longer to ensure complete expansion. Any internal pressure applied after heat treatment and prior to the official test may not exceed 90 percent of the test pressure. If, due to failure of the test apparatus or operator error, the test pressure cannot be maintained, the test may be repeated in accordance with CGA C-1, section 5.7.2, however, if a second failure to maintain the test pressure occurs the cylinder being tested must be rejected.
(4) Permanent volumetric expansion may not exceed 10 percent of total volumetric expansion at test pressure.
(h) Flattening test. One cylinder taken at random out of each lot must be subjected to a flattening test as follows:
(1) The test must be between knife edges, wedge shaped, having a 60° included angle, and rounded in accordance with the following table. The longitudinal axis of the cylinder must be at an angle 90° to the knife edges during the test. The flattening test table is as follows:
Table 3—Flattening Test Table
Cylinder wall thickness in inches Radius in inches Under .150 .500 .150 to .249 .875 .250 to .349 1.500 .350 to .449 2.125 .450 to .549 2.750 .550 to .649 3.500 .650 to .749 4.125(2) An alternate bend test in accordance with ASTM E 290 using a mandrel diameter not more than 6 times the wall thickness is authorized to qualify lots that fail the flattening test of this section without reheat treatment. If used, this test must be performed on two samples from one cylinder taken at random out of each lot of 200 cylinders or less.
(3) Each test cylinder must withstand flattening to nine times the wall thickness without cracking. When the alternate bend test is used, the test specimens must remain uncracked when bent inward around a mandrel in the direction of curvature of the cylinder wall until the interior edges are at a distance apart not greater than the diameter of the mandrel.
(i) Mechanical properties test. Two test specimens cut from one cylinder representing each lot of 200 cylinders or less must be subjected to the mechanical properties test, as follows:
(1) The results of the test must conform to at least the minimum acceptable mechanical property limits for aluminum alloys as specified in paragraph (b) of this section.
(2) Specimens must be 4D bar or gauge length 2 inches with width not over 11⁄2 inch taken in the direction of extrusion approximately 180° from each other; provided that gauge length at least 24 times thickness with width not over 6 times thickness is authorized, when cylinder wall is not over 3⁄16 inch thick. The specimen, exclusive of grip ends, may not be flattened. Grip ends may be flattened to within one inch of each end of the reduced section. When the size of the cylinder does not permit securing straight specimens, the specimens may be taken in any location or direction and may be straightened or flattened cold by pressure only, not by blows. When such specimens are used, the inspector's report must show that the specimens were so taken and prepared. Heating of specimens for any purpose is forbidden.
(3) The yield strength in tension must be the stress corresponding to a permanent strain of 0.2 percent of the gauge length.
(i) The yield strength must be determined by either the “offset” method or the “extension under load” method as prescribed in ASTM B 557 (IBR, see § 171.7 of this subchapter).
(ii) In using the “extension under load” method, the total strain (or “extension under load”) corresponding to the stress at which the 0.2 percent permanent strain occurs may be determined with sufficient accuracy by calculating the elastic extension of the gauge length under appropriate load and adding thereto 0.2 percent of the gauge length. Elastic extension calculations must be based on an elastic modulus of 10,000,000 psi. In the event of controversy, the entire stress-strain diagram must be plotted and the yield strength determined from the 0.2 percent offset.
(iii) For the purpose of strain measurement, the initial strain must be set while the specimen is under a stress of 6,000 psi, the strain indicator reading being set at the calculated corresponding strain.
(iv) Cross-head speed of the testing machine may not exceed 1⁄8 inch per minute during yield strength determination.
(j) Rejected cylinder. Reheat treatment of rejected cylinders is authorized one time. Subsequent thereto, cylinders must pass all prescribed tests to be acceptable.
(k) Duties of inspector. In addition to the requirements of § 178.35, the inspector shall:
(1) Verify compliance with the provisions of paragraph (b) of this section by:
(i) Performing or witnessing the performance of the chemical analyses on each melt or cast lot or other unit of starting material; or
(ii) Obtaining a certified chemical analysis from the material or cylinder manufacturer for each melt, or cast of material; or
(iii) Obtaining a certified check analysis on one cylinder out of each lot of 200 cylinders or less, if a certificate containing data to indicate compliance with the material specification is obtained.
(2) The inspector must verify ultrasonic inspection of all material by inspection or by obtaining the material producer's certificate of ultrasonic inspection. Ultrasonic inspection must be performed or verified as having been performed in accordance with paragraph (b)(5) of this section.
(3) The inspector must also determine that each cylinder complies with this specification by:
(i) Selecting the samples for check analyses performed by other than the material producer;
(ii) Verifying that the prescribed minimum thickness was met by measuring or witnessing the measurement of the wall thickness; and
(iii) Verifying that the identification of material is proper.
(4) Prior to initial production of any design or design change, verify that the design qualification tests prescribed in paragraph (c)(6) of this section have been performed with acceptable results.
(l) Definitions.
(1) In this specification, a “lot” means a group of cylinders successively produced having the same:
(i) Size and configuration;
(ii) Specified material of construction;
(iii) Process of manufacture and heat treatment;
(iv) Equipment of manufacture and heat treatment; and
(v) Conditions of time, temperature and atmosphere during heat treatment.
(2) In no case may the lot size exceed 200 cylinders, but any cylinder processed for use in the required destructive physical testing need not be counted as being one of the 200.
(m) Inspector's report. In addition to the information required by § 178.35, the record of chemical analyses must also include the alloy designation, and applicable information on iron, titanium, zinc, magnesium and any other applicable element used in the construction of the cylinder.
[Amdt. 178-114, 61 FR , May 23, , as amended at 66 FR , Aug. 28, ; 67 FR , Aug. 8, ; 68 FR , Dec. 31, ; 77 FR , Oct. 5, ; 85 FR , Dec. 28, ]
(a) Type, size, and service pressure. A DOT 4DS cylinder is either a welded stainless steel sphere (two seamless hemispheres) or circumferentially welded cylinder both with a water capacity of not over 100 pounds and a service pressure of at least 500 but not over 900 psig.
(b) Steel. Types 304, 321 and 347 stainless steel are authorized with proper welding procedure. A heat of steel made under the specifications in table 1 in this paragraph (b), check chemical analysis of which is slightly out of the specified range, is acceptable, if satisfactory in all other respects, provided the tolerances shown in table 2 in this paragraph (b) are not exceeded, except as approved by Associate Administrator. The following chemical analyses are authorized:
Table 1—Authorized Materials
Stainless steels 304 (percent) 321 (percent) 347 (percent) Carbon (max) 0.08 0.08 0.08 Manganese (max) 2.00 2.00 2.00 Phosphorus (max) .030 .030 .030 Sulphur (max) .030 .030 .030 Silicon (max) .75 .75 .75 Nickel 8.0/11.0 9.0/13.0 9.0/13.0 Chromium 18.0/20.0 17.0/20.0 17.0/20.0 Molybdenum Titanium (1) Columbium (2) 1 Titanium may not be more than 5C and not more than 0.60%. 2 Columbium may not be less than 10C and not more than 1.0%.Table 2—Check Analysis Tolerances
Element Limit or maximum specified (percent) Tolerance (percent) over the maximum limit or under the minimum limit Under minimum limit Over maximum limit Carbon To 0.15 incl 0.01 0.01 Manganese Over 1.15 to 2.50 incl 0.05 0.05 Phosphorus1 All ranges .01 Sulphur All ranges .01 Silicon Over 0.30 to 1.00 incl .05 .05 Nickel Over 5.30 to 10.00 incl .10 .10 Over 10.00 to 14.00 incl .15 .15 Chromium Over 15.00 to 20.00 incl .20 .20 Titanium All ranges .05 .05 Columbium All ranges .05 .05 1 Rephosphorized steels not subject to check analysis for phosphorus.(c) Identification of material. Materials must be identified by any suitable method.
(d) Manufacture. Cylinders must be manufactured using equipment and processes adequate to ensure that each cylinder produced conforms to the requirements of this subpart. No defect is permitted that is likely to weaken the finished cylinder appreciably, a reasonably smooth and uniform surface finish is required. No abrupt change in wall thickness is permitted. Welding procedures and operators must be qualified in accordance with CGA Pamphlet C-3 (IBR, see § 171.7 of this subchapter). All seams of the sphere or cylinder must be fusion welded. Seams must be of the butt type and means must be provided for accomplishing complete penetration of the joint.
(e) Attachments. Attachments to the container are authorized by fusion welding provided that such attachments are made of weldable stainless steel in accordance with paragraph (b) of this section.
(f) Wall thickness. The minimum wall thickness must be such that the wall stress at the minimum specified test pressure may not be over 60,000 psig. A minimum wall thickness of 0.040 inch is required for any diameter container. Calculations must be made by the following formulas:
(1) Calculation for sphere must be made by the formula:
S = PD / 4tE
Where:
S = Wall stress in psi;
P = Test pressure prescribed for water jacket test, i.e., at least two times service pressure, in psig;
D = Outside diameter in inches;
t = Minimum wall thickness in inches;
E = 0.85 (provides 85 percent weld efficiency factor which must be applied in the girth weld area and heat zones which zone must extend a distance of 6 times wall thickness from center of weld);
E = 1.0 (for all other areas).
(2) Calculation for a cylinder must be made by the formula:
S = [P(1.3D2 + 0.4d2)] / (D2 − d2)
Where:
S = Wall stress in psi;
P = Test pressure prescribed for water jacket test, i.e., at least two times service pressure, in psig;
D = Outside diameter in inches;
d = Inside diameter in inches.
(g) Heat treatment. The seamless hemispheres and cylinders may be stress relieved or annealed for forming. Welded container must be stress relieved at a temperature of 775 °F ±25° after process treatment and before hydrostatic test.
(h) Openings in container. Openings must comply with the following:
(1) Each opening in the container must be provided with a fitting, boss or pad of weldable stainless steel securely attached to the container by fusion welding.
(2) Attachments to a fitting, boss, or pad must be adequate to prevent leakage. Threads must comply with the following:
(i) Threads must be clean cut, even, without checks, and tapped to gauge.
(ii) Taper threads to be of length not less than as specified for American Standard taper pipe threads.
(iii) Straight threads having at least 4 engaged threads, to have tight fit and calculated shear strength at least 10 times the test pressure of the container; gaskets required, adequate to prevent leakage.
(i) Process treatment. Each container must be hydraulically pressurized in a water jacket to at least 100 percent, but not more than 110 percent, of the test pressure and maintained at this pressure for a minimum of 3 minutes. Total and permanent expansion must be recorded and included in the inspector's report.
(j) Pressure testing. Each cylinder must successfully withstand a pressure test as follows:
(1) The test must be by water-jacket or direct expansion method as prescribed in CGA C-1 (IBR; see § 171.7 of this subchapter). The testing equipment must be calibrated as prescribed in CGA C-1. All testing equipment and pressure indicating devices must be accurate within the parameters defined in CGA C-1.
(2) Each cylinder must be tested to a minimum of at least two (2) times its service pressure.
(3) The minimum test pressure must be maintained at least 30 seconds and sufficiently longer to ensure complete expansion. Any internal pressure applied after heat-treatment and prior to the official test may not exceed 90 percent of the test pressure. If, due to failure of the test apparatus or operator error, the test pressure cannot be maintained, the test may be repeated in accordance with CGA C-1, section 5.7.2.
(4) Permanent volumetric expansion may not exceed 10 percent of the total volumetric expansion at test pressure.
(5) The cylinder must then be inspected. Any wall thickness lower than that required by paragraph (f) of this section must be cause for rejection. Bulges and cracks must be cause for rejection. Welded joint defects exceeding requirements of paragraph (k) of this section are cause for rejection.
(k) Radiographic inspection. Radiographic inspection is required on all welded joints which are subjected to internal pressure, except that at the discretion of the disinterested inspector, openings less than 25 percent of the container diameter need not be subjected to radiographic inspection. Evidence of any defects likely to seriously weaken the container is cause for rejection. Radiographic inspection must be performed subsequent to the hydrostatic test.
(l) Burst test. One container taken at random out of 200 or less must be hydrostatically tested to destruction. Rupture pressure must be included as part of the inspector's report.
(m) Flattening test. A flattening test must be performed as follows:
(1) For spheres the test must be at the weld between parallel steel plates on a press with welded seam at right angles to the plates. Test one sphere taken at random out of each lot of 200 or less after the hydrostatic test. Any projecting appurtenances may be cut off (by mechanical means only) prior to crushing.
(2) For cylinders the test must be between knife edges, wedge shaped, 60° angle, rounded to 1⁄2-inch radius. Test one cylinder taken at random out of each lot of 200 or less, after the hydrostatic test.
(n) Acceptable results for flattening and burst tests. Acceptable results for flattening and burst tests are as follows:
(1) Flattening required to 50 percent of the original outside diameter without cracking.
(2) Burst pressure must be at least 3 times the service pressure.
(o) Rejected containers. Repair of welded seams by welding prior to process treatment is authorized. Subsequent thereto, containers must be heat treated and pass all prescribed tests.
(p) Duties of inspector. In addition to the requirements of § 178.35, the inspector must verify that all tests are conducted at temperatures between 60 °F and 90 °F.
(q) Marking. Markings must be stamped plainly and permanently on a permanent attachment or on a metal nameplate permanently secured to the container by means other than soft solder.
[Amdt. 178-114, 61 FR , May 23, , as amended at 66 FR , , Aug. 28, ; 67 FR , Aug. 8, ; 68 FR , Dec. 31, ; 85 FR , Dec. 28, ]
(a) Type, size, pressure, and application. A DOT 4B is a welded or brazed steel cylinder with water capacity (nominal) not over 1,000 pounds and a service pressure of at least 150 but not over 500 psig. Longitudinal seams must be forged lap-welded or brazed. Cylinders closed in by spinning process are not authorized.
(b) Steel. Open-hearth, electric or basic oxygen process steel of uniform quality must be used. Content percent may not exceed the following: Carbon, 0.25; phosphorus, 0.045; sulphur, 0.050. The cylinder manufacturer must maintain a record of intentionally added alloying elements.
(c) Identification of material. Pressure-retaining materials must be identified by any suitable method that does not compromise the integrity of the cylinder. Plates and billets for hotdrawn cylinders must be marked with the heat number.
(d) Manufacture. Cylinders must be manufactured using equipment and processes adequate to ensure that each cylinder produced conforms to the requirements of this subpart. No defect is permitted that is likely to weaken the finished cylinder appreciably. A reasonably smooth and uniform surface finish is required. Exposed bottom welds on cylinders over 18 inches long must be protected by footrings. Welding procedures and operators must be qualified in conformance with CGA C-3 (IBR, see § 171.7 of this subchapter). Seams must be made as follows:
(1) Brazing materials. Brazing materials must be by copper brazing, by copper alloy brazing, or by silver alloy brazing. Copper alloy composition must be: Copper, 95 percent minimum; Silicon, 1.5 percent to 3.85 percent; Manganese, 0.25 percent to 1.10 percent.
(2) Brazed circumferential seams. Heads attached by brazing must have a driving fit with the shell, unless the shell is crimped, swedged, or curled over the skirt or flange of the head, and be thoroughly brazed until complete penetration by the brazing material of the brazed joint is secured. Depth of brazing of the joint must be at least four (4) times the minimum thickness of shell metal.
(3) Welded circumferential seams. Circumferential seams are permitted by the welding process.
(4) Longitudinal seams in shells. Longitudinal seams must be a forged lap joint design. When brazed, the plate edge must be lapped at least eight (8) times the thickness of the plate, laps being held in position, substantially metal to metal, by riveting or electric spot-welding; brazing must be done by using a suitable flux and by placing brazing material on one side of seam and applying heat until this material shows uniformly along the seam of the other side.
(e) Welding or brazing. Only the attachment of neckrings, footrings, handles, bosses, pads, and valve protection rings to the tops and bottoms of cylinders by welding or brazing is authorized. Attachments and the portion of the cylinder to which they are attached must be made of weldable steel, the carbon content of which may not exceed 0.25 percent except in the case of X steel, which may be used with proper welding procedure.
(f) Wall thickness. The wall thickness of the cylinder must comply with the following requirements:
(1) For cylinders with outside diameters over 6 inches, the minimum wall thickness must be 0.090 inch. In any case, the minimum wall thickness must be such that calculated wall stress at minimum test pressure (paragraph (i)(4) of this section) may not exceed the following values:
(i) 24,000 psig for cylinders without longitudinal seam.
(ii) 22,800 psig for cylinders having copper brazed or silver alloy brazed longitudinal seam.
(iii) 18,000 psig for cylinders having forged lapped welded longitudinal seam.
(2) Calculation must be made by the formula:
S = [P(1.3D2 + 0.4d2)]/(D2 − d2)
Where:
S = wall stress in psig;
P = minimum test pressure prescribed for water jacket test or 450 psig whichever is the greater;
D = outside diameter in inches; and
d = inside diameter in inches.
(g) Heat treatment. Cylinder heads, bodies or the completed cylinder, formed by drawing or pressing, must be uniformly and properly heat treated by an applicable method shown in table 1 of appendix A of this part before tests.
(h) Opening in cylinders. Openings in cylinders must comply with the following:
(1) Any opening must be placed on other than a cylindrical surface.
(2) Each opening in a spherical type of cylinder must be provided with a fitting, boss, or pad of weldable steel securely attached to the cylinder by fusion welding.
(3) Each opening in a cylindrical type cylinder, except those for pressure relief devices, must be provided with a fitting, boss, or pad, securely attached to container by brazing or by welding.
(4) If threads are used, they must comply with the following:
(i) Threads must be clean cut, even without checks, and tapped to gauge.
(ii) Taper threads must be of a length not less than as specified for American Standard taper pipe threads.
(iii) Straight threads, must have at least four (4) engaged threads, must have tight fit and a calculated shear strength at least ten (10) times the test pressure of the cylinder; gaskets are required for straight threads and must be of sufficient quality to prevent leakage.
(iv) A brass fitting may be brazed to the steel boss or flange on cylinders used as component parts of handheld fire extinguishers.
(5) The closure of a fitting, boss, or pad must be adequate to prevent leakage.
(i) Pressure testing. Each cylinder must successfully withstand a pressure test as follows:
(1) Lot testing.
(i) At least one (1) cylinder randomly selected out of each lot of 200 or fewer must be tested by the water jacket or direct expansion method as prescribed in CGA C-1 (IBR; see § 171.7 of this subchapter). The testing equipment must be calibrated as prescribed in CGA C-1. All testing equipment and pressure indicating devices must be accurate within the parameters defined in CGA C-1.
(ii) Each cylinder must be tested to a minimum of 2 times service pressure.
(iii) The minimum test pressure must be maintained at least 30 seconds and sufficiently longer to ensure complete expansion. Any internal pressure applied after heat-treatment and prior to the official test may not exceed 90 percent of the test pressure. If, due to failure of the test apparatus or operator error, the test pressure cannot be maintained, the test may be repeated in accordance with CGA C-1, section 5.7.2.
(iv) Permanent volumetric expansion may not exceed 10 percent of the total volumetric expansion at test pressure.
(2) Pressure testing.
(i) The remaining cylinders in the lot must be tested by the proof pressure, water-jacket, or direct expansion test method as prescribed in CGA C-1. The minimum test pressure must be maintained for the specific timeframe and the testing equipment must be calibrated as prescribed in CGA C-1. Further, all testing equipment and pressure indicating devices must be accurate within the parameters defined in CGA C-1. If, due to failure of the test apparatus or operator error, the test pressure cannot be maintained, the test may be repeated in accordance with CGA C-1, sections 5.7.2 or 7.1.2, as appropriate. Determination of expansion properties is not required.
(ii) Each cylinder must be tested to a minimum of at least two (2) times service pressure and show no defect.
(j) Mechanical test. A mechanical test must be conducted to determine yield strength, tensile strength, elongation as a percentage, and reduction of area of material as a percentage as follows:
(1) Testing is required on two (2) specimens removed from one (1) cylinder, or part thereof, heat-treated as required, as illustrated in appendix A to this subpart. For lots of 30 or fewer, mechanical tests are authorized to be made on a ring at least 8 inches long removed from each cylinder and subjected to the same heat treatment as the finished cylinder.
(2) Specimens must comply with the following:
(i) When a cylinder wall is 3⁄16 inch thick or less, one the following gauge lengths is authorized: A gauge length of 8 inches with a width not over 11⁄2 inches, a gauge length of 2 inches with a width not over 11⁄2 inches, or a gauge length at least twenty-four (24) times the thickness with a width not over six (6) times the thickness.
(ii) The specimen, exclusive of grip ends, may not be flattened. Grip ends may be flattened to within one inch of each end of the reduced section.
(iii) When the size of a cylinder does not permit securing straight specimens, the specimens may be taken in any location or direction and may be straightened or flattened cold, by pressure only, not by blows. When specimens are taken and prepared using this method, the inspector's report must show detailed information regarding such specimens in connection with the record of mechanical tests.
(iv) Heating of a specimen for any purpose is not authorized.
(3) The yield strength in tension must be the stress corresponding to a permanent strain of 0.2 percent of the gauge length. The following conditions apply:
(i) The yield strength must be determined by either the “offset” method or the “extension under load” method as prescribed in ASTM E 8 (IBR, see § 171.7 of this subchapter).
(ii) In using the “extension under load” method, the total strain (or “extension under load”) corresponding to the stress at which the 0.2 percent permanent strain occurs may be determined with sufficient accuracy by calculating the elastic extension of the gauge length under appropriate load and adding thereto 0.2 percent of the gauge length. Elastic extension calculations must be based on an elastic modulus of 30,000,000. In the event of controversy, the entire stress-strain diagram must be plotted and the yield strength determined from the 0.2 percent offset.
(iii) For strain measurement, the initial strain reference must be set while the specimen is under a stress of 12,000 psig, and strain indicator reading must be set at the calculated corresponding strain.
(iv) Cross-head speed of the testing machine may not exceed 1⁄8 inch per minute during yield strength determination.
(v) The yield strength must not exceed 73 percent of the tensile strength.
(k) Elongation. Mechanical test specimens must show at least a 40 percent elongation for a 2-inch gauge length or at least 20 percent in other cases. However, elongation percentages may be reduced numerically by 2 percent for 2-inch specimens, and by 1 percent in other cases, for each 7,500 psig increase of tensile strength above 50,000 psig. The tensile strength may be incrementally increased by four increments of 7,500 psig for a maximum total of 30,000 psig.
(l) Flattening test —
(1) Cylinders. After pressure testing, a flattening test must be performed on one cylinder taken at random out of each lot of 200 or fewer by placing the cylinder between wedge-shaped knife edges having a 60 degree included angle, rounded to a half-inch radius. The longitudinal axis of the cylinder must be at a 90-degree angle to knife edges during the test. For lots of 30 or fewer, flattening tests are authorized to be performed on a ring of at least 8 inches long removed from each cylinder and subjected to the same heat treatment as the finished cylinder.
(2) Pipes. When cylinders are constructed of lap welded pipe, an additional flattening test is required, without evidence of cracking, up to six (6) times the wall thickness. In such case, the rings (crop ends) removed from each end of the pipe, must be tested with the weld 45 °F or less from the point of greatest stress.
(m) Acceptable results for flattening tests. There must be no evidence of cracking of the sample when it is flattened between flat plates to no more than six (6) times the wall thickness. If this test fails, one additional sample from the same lot may be taken. If this second sample fails, the entire lot must be rejected.
(n) Rejected cylinders. Reheat treatment is authorized for a rejected cylinder in accordance with this paragraph (n). After reheat treatment, a cylinder must pass all prescribed tests in this section to be considered acceptable. Repair of brazed seams by brazing and welded seams by welding is authorized. For cylinders with an outside diameter of less than or equal to six (6) inches, welded seam repairs greater than one (1) inch in length shall require reheat treatment of the cylinder. For cylinders greater than an outside diameter of 6 inches, welded seam repairs greater than three (3) inches in length shall require reheat treatment.
(o) Markings.
(1) Markings must be as required as in § 178.35 and in addition must be stamped plainly and permanently in any of the following locations on the cylinder:
(i) On shoulders and top heads whose wall thickness is not less than 0.087-inch thick;
(ii) On side wall adjacent to top head for side walls which are not less than 0.090 inch thick;
(iii) On a cylindrical portion of the shell that extends beyond the recessed bottom of the cylinder, constituting an integral and non-pressure part of the cylinder;
(iv) On a metal plate attached to the top of the cylinder or permanent part thereof; sufficient space must be left on the plate to provide for stamping at least six retest dates; the plate must be at least 1⁄16-inch thick and must be attached by welding, or by brazing. The brazing rod must melt at a temperature of °F. Welding or brazing must be along all the edges of the plate;
(v) On the neck, neckring, valve boss, valve protection sleeve, or similar part permanently attached to the top of the cylinder; or
(vi) On the footring permanently attached to the cylinder, provided the water capacity of the cylinder does not exceed 30 pounds.
(2) Embossing the cylinder head or sidewall is not permitted.
[85 FR , Dec. 28, , as amended at 87 FR , Dec. 27, ]
(a) Type, size, pressure, and application. A DOT 4BA cylinder is a cylinder, either spherical or cylindrical design, with a water capacity of 1,000 pounds or less and a service pressure range of 225 to 500 psig. Closures made by the spinning process are not authorized.
(1) Spherical type cylinder designs are permitted to have only one circumferentially welded seam.
(2) Cylindrical type cylinder designs must be of circumferentially welded or brazed construction; longitudinally brazed or silver-soldered seams are also permitted.
(b) Steel. The steel used in the construction of the cylinder must be as specified in table 1 of appendix A to this part. The cylinder manufacturer must maintain a record of intentionally added alloying elements.
(c) Identification of material. Pressure-retaining material must be identified by any suitable method that does not compromise the integrity of the cylinder. Plates and billets for hotdrawn cylinders must be marked with the heat number.
(d) Manufacture. Cylinders must be manufactured using equipment and processes adequate to ensure that each cylinder produced conforms to the requirements of this subpart. No defect is permitted that is likely to weaken the finished cylinder appreciably. A reasonably smooth and uniform surface finish is required. Exposed bottom welds on cylinders over 18 inches long must be protected by footrings.
(1) Seams must be made as follows:
(i) Minimum thickness of heads and bottoms must be not less than 90 percent of the required thickness of the side wall.
(ii) Circumferential seams must be made by welding or by brazing. Heads attached by brazing must have a driving fit with the shell unless the shell is crimped, swedged, or curled over the skirt or flange of the head and must be thoroughly brazed until complete penetration by the brazing material of the brazed joint is secured. Depth of brazing from end of the shell must be at least four (4) times the thickness of shell metal.
(iii) Longitudinal seams in shells must be made by copper brazing, copper alloy brazing, or by silver alloy brazing. Copper alloy composition must be: Copper 95 percent minimum, Silicon 1.5 percent to 3.85 percent, Manganese 0.25 percent to 1.10 percent. The melting point of the silver alloy brazing material must be in excess of 1,000 °F. The plate edge must be lapped at least eight times the thickness of plate, laps being held in position, substantially metal to metal, by riveting or by electric spot-welding. Brazing must be done by using a suitable flux and by placing brazing material on one side of seam and applying heat until this material shows uniformly along the seam of the other side. Strength of longitudinal seam: Copper brazed longitudinal seam must have strength at least 3⁄2 times the strength of the steel wall.
(2) Welding procedures and operators must be qualified in conformance with CGA C-3 (IBR, see § 171.7 of this subchapter).
(e) Welding or brazing. Welding or brazing of any attachment or opening to the heads of cylinders is permitted provided the carbon content of the steel does not exceed 0.25 percent except in the case of × steel, which may be used with proper welding procedure.
(f) Wall thickness. The minimum wall thickness of the cylinder must meet the following conditions:
(1) For any cylinder with an outside diameter of greater than 6 inches, the minimum wall thickness is 0.078 inch. In any case, the minimum wall thickness must be such that the calculated wall stress at the minimum test pressure may not exceed the lesser value of any of the following:
(i) The value shown in table 1 of appendix A to this part, for the material under consideration;
(ii) One-half of the minimum tensile strength of the material determined as required in paragraph (j) of this section;
(iii) 35,000 psig; or
(iv) Further provided that wall stress for cylinders having copper brazed longitudinal seams may not exceed 95 percent of any of the above values. Measured wall thickness may not include galvanizing or other protective coating.
(2) Cylinders that are cylindrical in shape must have the wall stress calculated by the formula:
S = [P(1.3D2 + 0.4d2)]/(D2 − d2)
Where:
S = wall stress in psig;
P = minimum test pressure prescribed for water jacket test;
D = outside diameter in inches; and
d = inside diameter in inches.
(3) Cylinders that are spherical in shape must have the wall stress calculated by the formula:
S = PD/4tE
Where:
S = wall stress in psig;
P = minimum test pressure prescribed for water jacket test;
D = outside diameter in inches;
t = minimum wall thickness in inches;
E = 0.85 (provides 85 percent weld efficiency factor which must be applied in the circumferential weld area and heat affected zones which zone must extend a distance of 6 times wall thickness from center line of weld); and
E = 1.0 (for all other areas).
(4) For a cylinder with a wall thickness less than 0.100 inch, the ratio of tangential length to outside diameter may not exceed 4.1.
(g) Heat treatment. Cylinders must be heat treated in accordance with the following requirements:
(1) Each cylinder must be uniformly and properly heat treated prior to test by the applicable method shown in table 1 of appendix A to this part. Heat treatment must be accomplished after all forming and welding operations, except that when brazed joints are used, heat treatment must follow any forming and welding operations, but may be done before, during or after the brazing operations (see paragraph (m) of this section for weld repairs).
(2) Heat treatment is not required after the welding or brazing of weldable low carbon parts to attachments of similar material which have been previously welded or brazed to the top or bottom of cylinders and properly heat treated, provided such subsequent welding or brazing does not produce a temperature in excess of 400 °F in any part of the top or bottom material.
(h) Openings in cylinders. Openings in cylinders must comply with the following requirements:
(1) Any opening must be placed on other than a cylindrical surface.
(2) Each opening in a spherical type cylinder must be provided with a fitting, boss, or pad of weldable steel securely attached to the container by fusion welding.
(3) Each opening in a cylindrical type cylinder must be provided with a fitting, boss, or pad, securely attached to container by brazing or by welding.
(4) If threads are used, they must comply with the following:
(i) Threads must be clean-cut, even, without checks and tapped to gauge.
(ii) Taper threads must be of a length not less than that specified for American Standard taper pipe threads.
(iii) Straight threads, having at least 4 engaged threads, must have a tight fit and a calculated shear strength of at least 10 times the test pressure of the cylinder. Gaskets, adequate to prevent leakage, are required.
(i) Pressure testing. Each cylinder must successfully withstand a pressure test as follows:
(1) Lot testing.
(i) At least one (1) cylinder randomly selected out of each lot of 200 or fewer must be tested by water jacket or direct expansion method as prescribed in CGA C-1 (IBR, see § 171.7 of this subchapter). The testing equipment must be calibrated as prescribed in CGA C-1. All testing equipment and pressure indicating devices must be accurate within the parameters defined in CGA C-1.
(ii) The selected cylinder must be tested to a minimum of two (2) times service pressure.
(iii) The minimum test pressure must be maintained at least 30 seconds and sufficiently longer to ensure complete expansion. Any internal pressure applied after heat-treatment and prior to the official test may not exceed 90 percent of the test pressure. If, due to failure of the test apparatus or operator error, the test pressure cannot be maintained, the test may be repeated in accordance with CGA C-1, section 5.7.2.
(iv) Permanent volumetric expansion may not exceed 10 percent of the total volumetric expansion at test pressure.
(2) Pressure testing.
(i) The remaining cylinders in the lot must be tested by the proof pressure, water-jacket, or direct expansion test method as prescribed in CGA C-1. The minimum test pressure must be maintained for the specific timeframe and the testing equipment must be calibrated as prescribed in CGA C-1. Further, all testing equipment and pressure indicating devices must be accurate within the parameters defined in CGA C-1.
(ii) Each cylinder must be tested to a minimum of two (2) times service pressure and show no defect. If, due to failure of the test apparatus or operator error, the test pressure cannot be maintained, the test may be repeated in accordance with CGA C-1 5.7.2 or 7.1.2, as appropriate. Determination of expansion properties is not required.
(j) Mechanical test.
(1) A mechanical test must be conducted to determine yield strength, tensile strength, elongation as a percentage, and reduction of area of material as a percentage, as follows:
(i) Cylinders. Testing is required on two (2) specimens removed from one cylinder or part thereof taken at random out of each lot of 200 or fewer. Samples must be removed after heat treatment as illustrated in appendix A to this subpart.
(ii) Spheres. Testing is required on two (2) specimens removed from the sphere or flat representative sample plates of the same heat of material taken at random from the steel used to produce the spheres. Samples (including plates) must be taken from each lot of 200 or fewer. The flat steel from which two specimens are to be removed must receive the same heat treatment as the spheres themselves. Samples must be removed after heat treatment as illustrated in appendix A to this subpart.
(2) Specimens must comply with the following:
(i) When a cylinder wall is 3⁄16 inch thick or less, one the following gauge lengths is authorized: A gauge length of 8 inches with a width not over 11⁄2 inches, a gauge length of 2 inches with a width not over 11⁄2 inches, or a gauge length at least twenty-four (24) times the thickness with a width not over six (6) times the thickness.
(ii) The specimen, exclusive of grip ends, may not be flattened. Grip ends may be flattened to within one inch of each end of the reduced section.
(iii) When size of the cylinder does not permit securing straight specimens, the specimens may be taken in any location or direction and may be straightened or flattened cold, by pressure only, not by blows. When specimens are so taken and prepared, the inspector's report must show with the record of physical tests detailed information in regard to such specimens.
(iv) Heating of a specimen for any purpose is not authorized.
(3) The yield strength in tension must be the stress corresponding to a permanent strain of 0.2 percent of the gauge length. The following conditions apply:
(i) The yield strength must be determined by either the “offset” method or the “extension under load” method as prescribed in ASTM E 8 (IBR, see § 171.7 of this subchapter).
(ii) In using the “extension under load” method, the total strain (or “extension under load”), corresponding to the stress at which the 0.2 percent permanent strain occurs may be determined with sufficient accuracy by calculating the elastic extension of the gauge length under appropriate load and adding thereto 0.2 percent of the gauge length. Elastic extension calculations must be based on an elastic modulus of 30,000,000. In the event of controversy, the entire stress-strain diagram must be plotted and the yield strength determined from the 0.2 percent offset.
(iii) For strain measurement, the initial strain reference must be set while the specimen is under a stress of 12,000 psig, and the strain indicator reading must be set at the calculated corresponding strain.
(k) Elongation. Mechanical test specimens must show at least a 40 percent elongation for a 2-inch gauge length or at least 20 percent in other cases. However, elongation percentages may be reduced numerically by 2 percent for 2-inch specimens, and by 1 percent in other cases, for each 7,500 psig increase of tensile strength above 50,000 psig. The tensile strength may be incrementally increased by four increments of 7,500 psig for a maximum total of 30,000 psig.
(l) Tests of welds. Except for brazed seams, welds must be tested as follows:
(1) Tensile test. A specimen must be removed from one cylinder of each lot of 200 or fewer, or welded test plate. The welded test plate must be of one of the heats in the lot of 200 or fewer which it represents, in the same condition and approximately the same thickness as the cylinder wall except that in no case must it be of a lesser thickness than that required for a quarter size Charpy impact specimen. The weld must be made by the same procedures and subjected to the same heat treatment as the major weld on the cylinder. The specimen must be taken from across the major seam and must be prepared and tested in conformance with and must meet the requirements of CGA C-3. Should this specimen fail to meet the requirements, one additional specimen must be taken from two additional cylinders or welded test plates from the same lot and tested. If either of these latter two specimens fail to meet the requirements, the entire lot represented must be rejected.
(2) Guided bend test. A root bend test specimen must be removed from the cylinder or welded test plate that was used for the tensile test specified in paragraph (l)(1) of this section. The specimen must be taken from across the circumferential seam and must be prepared and tested in conformance with and must meet the requirements of CGA C-3. Should this specimen fail to meet the requirements, one additional specimen must be taken from two additional cylinders or welded test plates from the same lot and tested. If either of these latter two specimens fail to meet the requirements, the entire lot represented must be rejected.
(3) Alternate guided-bend test. This test may be used and must be as required by CGA C-3. The specimen must be bent until the elongation at the outer surface, adjacent to the root of the weld, between the lightly scribed gage lines a to b, must be at least 20 percent, except that this percentage may be reduced for steels having a tensile strength in excess of 50,000 psig, as provided in paragraph (k) of this section. Should the specimen fail to meet the requirements, one additional specimen must be taken from two additional cylinders or welded test plates from the same lot and tested. If any of these latter two specimens fail to meet the requirements, the entire lot represented must be rejected.
(m) Rejected cylinders. Reheat treatment is authorized for a rejected cylinder in accordance with this paragraph (m). After reheat, a cylinder must pass all prescribed tests in this section to be acceptable. Repair of brazed seams by brazing and welded seams by welding is considered authorized. For cylinders with an outside diameter of less than or equal to six (6) inches, welded seam repairs greater than one (1) inch in length shall require reheat treatment of the cylinder. For cylinders greater than an outside diameter of six (6) inches, welded seam repairs greater than three (3) inches in length shall require reheat treatment.
(n) Markings.
(1) Markings must be as required in § 178.35 and in addition must be stamped plainly and permanently in one of the following locations on the cylinder:
(i) On shoulders and top heads whose wall thickness is not less than 0.087 inch thick;
(ii) On side wall adjacent to top head for side walls not less than 0.090 inch thick;
(iii) On a cylindrical portion of the shell that extends beyond the recessed bottom of the cylinder constituting an integral and non-pressure part of the cylinder;
(iv) On a plate attached to the top of the cylinder or permanent part thereof; sufficient space must be left on the plate to provide for stamping at least six retest dates; the plate must be at least 1⁄16 inch thick and must be attached by welding, or by brazing at a temperature of at least °F., throughout all edges of the plate;
(v) On the neck, neckring, valve boss, valve protection sleeve, or similar part permanently attached to the top of the cylinder; or
(vi) On the footring permanently attached to the cylinder, provided the water capacity of the cylinder does not exceed 30 pounds.
(2) [Reserved]
[85 FR , Dec. 28, ]
(a) Type, size, and service pressure. A DOT 4D cylinder is a welded steel sphere (two seamless hemispheres) or circumferentially welded cylinder (two seamless drawn shells) with a water capacity not over 100 pounds and a service pressure of at least 300 but not over 500 psig. Cylinders closed in by spinning process are not authorized.
(b) Steel. Open-hearth or electric steel of uniform and weldable quality must be used. Content may not exceed the following: Carbon, 0.25; phosphorus, 0.045; sulphur, 0.050, except that the following steels commercially known as X and Type 304, 316, 321, and 347 stainless steels may be used with proper welding procedure. A heat of steel made under table 1 in this paragraph (b), check chemical analysis of which is slightly out of the specified range, is acceptable, if satisfactory in all other respects, provided the tolerances shown in table 2 in this paragraph (b) are not exceeded, except as approved by the Associate Administrator. The following chemical analyses are authorized:
Table 1—X Steel
X Percent Carbon 0.25/0.35. Manganese 0.40/0.60. Phosphorus 0.04 max. Sulphur 0.05 max Silicon 0.15/0.35. Chromium 0.80/1.10. Molybdenum 0.15/0.25. Zirconium None. Nickel None.Table 2—Authorized Stainless Steels
Stainless steels 304Table 3—Check Analysis Tolerances
Element Limit or maximum specified(c) Identification of material. Material must be identified by any suitable method except that plates and billets for hotdrawn cylinders must be marked with the heat number.
(d) Manufacture. Cylinders must be manufactured using equipment and processes adequate to ensure that each cylinder produced conforms to the requirements of this subpart. No defect is permitted that is likely to weaken the finished container appreciably. A reasonably smooth and uniform surface finish is required. Welding procedures and operators must be qualified in accordance with CGA Pamphlet C-3 (IBR, see § 171.7 of this subchapter).
(e) Wall thickness. The wall stress at the minimum test pressure may not exceed 24,000 psi, except where steels commercially known as X, types 304, 316, 321, and 347 stainless steels are used, stress at the test pressures may not exceed 37,000 psi. The minimum wall thickness for any container having a capacity of 1,100 cubic inches or less is 0.04 inch. The minimum wall thickness for any container having a capacity in excess of 1,100 cubic inches is 0.095 inch. Calculations must be done by the following:
(1) Calculation for a “sphere” must be made by the formula:
S = PD / 4tE
Where:
S = wall stress in psi;
P = test pressure prescribed for water jacket test, i.e., at least two times service pressure, in psig;
D = outside diameter in inches;
t = minimum wall thickness in inches;
E = 0.85 (provides 85 percent weld efficiency factor which must be applied in the girth weld area and heat affected zones which zone must extend a distance of 6 times wall thickness from center line of weld);
E = 1.0 (for all other areas).
(2) Calculation for a cylinder must be made by the formula:
S = [P(1.3D2 + 0.4d2)] / (D2 − dT12)
Where:
S = wall stress in psi;
P = test pressure prescribed for water jacket test, i.e., at least two times service pressure, in psig;
D = outside diameter in inches;
d = inside diameter in inches.
(f) Heat treatment. The completed cylinders must be uniformly and properly heat-treated prior to tests.
(g) Openings in container. Openings in cylinders must comply with the following:
(1) Each opening in the container, except those for safety devices, must be provided with a fitting, boss, or pad, securely attached to the container by brazing or by welding or by threads. If threads are used, they must comply with the following:
(i) Threads must be clean cut, even, without checks, and tapped to gauge.
(ii) Taper threads must be of a length not less than that specified for American Standard taper pipe threads.
(iii) Straight threads, having at least 4 engaged threads, must have a tight fit and calculated shear strength of at least 10 times the test pressure of the container. Gaskets, adequate to prevent leakage, are required.
(2) Closure of a fitting, boss, or pad must be adequate to prevent leakage.
(h) Pressure testing. Each cylinder must successfully withstand a pressure test as follows:
(1) Lot testing.
(i) At least one cylinder selected at random out of each lot of 200 or fewer must be tested by water-jacket or direct expansion as prescribed in CGA C-1 (IBR; see § 171.7 of this subchapter). The testing equipment must be calibrated as prescribed in CGA C-1. All testing equipment and pressure indicating devices must be accurate within the parameters defined in CGA C-1.
(ii) The selected cylinder must be tested to a minimum of three (3) times service pressure.
(iii) The minimum test pressure must be maintained be maintained at least 30 seconds and sufficiently longer to ensure complete expansion. Any internal pressure applied after heat-treatment and prior to the official test may not exceed 90 percent of the test pressure. If, due to failure of the test apparatus or operator error, the test pressure cannot be maintained, the test may be repeated in accordance with CGA C-1, section 5.7.2.
(iv) Permanent volumetric expansion may not exceed 10 percent of the total volumetric expansion at test pressure.
(2) Pressure testing.
(i) The remaining cylinders in each lot must be tested by the proof pressure water-jacket or direct expansion test method as prescribed in CGA C-1. The minimum test pressure must be maintained for the specific timeframe and the testing equipment must be calibrated as prescribed in CGA C-1. Further, all testing equipment and pressure indicating devices must be accurate within the parameters defined in CGA C-1. Determination of expansion properties is not required.
(ii) Each cylinder must be tested to a minimum of two (2) times service pressure and show no defect. If, due to failure of the test apparatus or operator error, the test pressure cannot be maintained, the test may be repeated in accordance with CGA C-1 5.7.2 or 7.1.2, as appropriate.
(3) Alternative volumetric expansion testing. As an alternative to the testing prescribed in paragraphs (h)(1) and (2) of this section, every cylinder may be volumetrically expansion tested by the water jacket or direct expansion test method. The testing equipment must be calibrated as prescribed in CGA C-1. All testing equipment and pressure indicating devices must be accurate within the parameters defined in CGA C-1.
(i) Each cylinder must be tested to a minimum of at least two (2) times its service pressure.
(ii) The minimum test pressure must be maintained at least 30 seconds and sufficiently longer to ensure complete expansion. Any internal pressure applied after heat-treatment and previous to the official test may not exceed 90 percent of the test pressure. If, due to failure of the test apparatus or operator error, the test pressure cannot be maintained, the test may be repeated in accordance with CGA C-1, section 5.7.2.
(iii) Permanent volumetric expansion may not exceed 10 percent of total volumetric expansion at test pressure.
(i) Flattening test for spheres and cylinders. Spheres and cylinders must be subjected to a flattening test as follows:
(1) One sphere taken at random out of each lot of 200 or less must be subjected to a flattening test as follows:
(i) The test must be performed after the hydrostatic test.
(ii) The test must be between parallel steel plates on a press with a welded seam at right angles to the plates. Any projecting appurtenances may be cut off (by mechanical means only) prior to crushing.
(2) One cylinder taken at random out of each lot of 200 or less must be subjected to a flattening test, as follows:
(i) The test must be performed after the hydrostatic test.
(ii) The test must be between knife edges, wedge shaped, 60° angle, rounded to 1⁄2 inch radius. For lots of 30 or less, physical tests are authorized to be made on a ring at least 8 inches long cut from each cylinder and subjected to the same heat treatment as the finished cylinder.
(j) Physical test and specimens for spheres and cylinders. Spheres and cylinders must be subjected to a physical test as follows:
(1) Physical test for spheres are required on 2 specimens cut from a flat representative sample plate of the same heat taken at random from the steel used to produce the sphere. This flat steel from which the 2 specimens are to be cut must receive the same heat-treatment as the spheres themselves. Sample plates must be taken for each lot of 200 or less spheres.
(2) Specimens for spheres must have a gauge length 2 inches with a width not over 11⁄2 inches, or a gauge length at least 24 times the thickness with a width not over 6 times the thickness is authorized when a wall is not over 3⁄16 inch thick.
(3) Physical test for cylinders is required on 2 specimens cut from 1 cylinder taken at random out of each lot of 200 or less. For lots of 30 or less, physical tests are authorized to be made on a ring at least 8 inches long cut from each cylinder and subjected to the same heat treatment as the finished cylinder.
(4) Specimens for cylinders must conform to the following:
(i) A gauge length of 8 inches with a width not over 11⁄2 inches, or a gauge length of 2 inches with a width not over 11⁄2 inches, or a gauge length at least 24 times the thickness with a width not over 6 times the thickness is authorized when a cylinder wall is not over 3⁄16 inch thick.
(ii) The specimen, exclusive of grip ends, may not be flattened. Grip ends may be flattened to within 1 inch of each end of the reduced section. Heating of the specimen for any purpose is not authorized.
(5) The yield strength in tension must be the stress corresponding to a permanent strain of 0.2 percent of the gauge length. The following conditions apply:
(i) The yield strength must be determined by either the “offset” method or the “extension under load” method as prescribed in ASTM E 8 (IBR, see § 171.7 of this subchapter).
(ii) In using the “extension under load” method, the total strain (or “extension under load”) corresponding to the stress at which the 0.2 percent permanent strain occurs may be determined with sufficient accuracy by calculating the elastic extension of the gauge length under appropriate load and adding thereto 0.2 percent of the gauge length. Elastic extension calculations must be based on an elastic modulus of 30,000,000. In the event of controversy, the entire stress-strain diagram must be plotted and the yield strength determined from the 0.2 percent offset.
(iii) For the purpose of strain measurement, the initial strain must be set while the specimen is under a stress of 12,000 psi and the strain indicator reading being set at the calculated corresponding strain.
(iv) Cross-head speed of the testing machine may not exceed 1⁄8 inch per minute during yield strength determination.
(k) Acceptable results for physical and flattening tests. Either of the following is an acceptable result:
(1) An elongation of at least 40 percent for a 2 inch gauge length or at least 20 percent in other cases and yield strength not over 73 percent of tensile strength. In this instance, the flattening test is not required.
(2) An elongation of at least 20 percent for a 2 inch gauge length or 10 percent in other cases. Flattening is required to 50 percent of the original outside diameter without cracking.
(l) Rejected cylinders. Reheat-treatment is authorized for rejected cylinders. Subsequent thereto, containers must pass all prescribed tests to be acceptable. Repair of welded seams by welding prior to reheat-treatment is authorized.
(m) Marking. Marking on each container by stamping plainly and permanently are only authorized where the metal is at least 0.09 inch thick, or on a metal nameplate permanently secured to the container by means other than soft solder, or by means that would not reduce the wall thickness.
[Amdt. 178-114, 61 FR , May 23, , as amended at 66 FR , , Aug. 28, ; 67 FR , Aug. 8, ; 68 FR , Dec. 31, ; 85 FR , Dec. 28, ]
(a) Type, spinning process, size and service pressure. A DOT 4B240ET cylinder is a brazed type cylinder made from electric resistance welded tubing. The maximum water capacity of this cylinder is 12 pounds or 333 cubic inches and the service must be 240 psig. The maximum outside diameter of the shell must be five inches and maximum length of the shell is 21 inches. Cylinders closed in by a spinning process are authorized.
(b) Steel. Open-hearth, basic oxygen, or electric steel of uniform quality must be used. Plain carbon steel content may not exceed the following: Carbon, 0.25; phosphorus, 0.045; sulfur, 0.050. The addition of other elements for alloying effect is prohibited.
(c) Identification of material. Material must be identified by any suitable method.
(d) Manufacture. Cylinders must be manufactured using equipment and processes adequate to ensure that each cylinder produced conforms to the requirements of this subpart. No defect is permitted that is likely to weaken the finished cylinder appreciably. A reasonably smooth and uniform surface finish is required. Heads may be attached to shells by lap brazing or may be formed integrally. The thickness of the bottom of cylinders welded or formed by spinning is, under no condition, to be less than two times the minimum wall thickness of the cylindrical shell. Such bottom thicknesses must be measured within an area bounded by a line representing the points of contact between the cylinder and the floor when the cylinder is in a vertical position. Seams must conform to the following:
(1) Circumferential seams must be by brazing only. Heads must be attached to shells by the lap brazing method and must overlap not less than four times the wall thickness. Brazing material must have a melting point of not less than °F. Heads must have a driving fit with the shell unless the shell is crimped, swedged, or curled over the skirt or flange of the head and be thoroughly brazed until complete penetration of the joint by the brazing material is secured. Brazed joints may be repaired by brazing.
(2) Longitudinal seams in shell must be by electric resistance welded joints only. No repairs to longitudinal joints is permitted.
(3) Welding procedures and operators must be qualified in accordance with CGA C-3 (IBR, see § 171.7 of this subchapter).
(e) Welding or brazing. Only the attachment, by welding or brazing, to the tops and bottoms of cylinders of neckrings, footrings, handles, bosses, pads, and valve protection rings is authorized. Provided that such attachments and the portion of the container to which they are attached are made of weldable steel, the carbon content of which may not exceed 0.25 percent.
(f) Wall thickness. The wall stress must be at least two times the service pressure and may not exceed 18,000 psi. The minimum wall thickness is 0.044 inch. Calculation must be made by the following formula:
S = [P(1.3D2 + 0.4d2)] / (D2 − d2)
Where:
S = wall stress in psig;
P = 2 times service pressure;
D = outside diameter in inches;
d = inside diameter in inches.
(g) Heat treatment. Heads formed by drawing or pressing must be uniformly and properly heat treated prior to tests. Cylinders with integral formed heads or bases must be subjected to a normalizing operation. Normalizing and brazing operations may be combined, provided the operation is carried out at a temperature in excess of the upper critical temperature of the steel.
(h) Openings in cylinders. Openings in cylinders must comply with the following:
(1) Each opening in cylinders, except those for safety devices, must be provided with a fitting, boss, or pad, securely attached to the cylinder by brazing or by welding or by threads. A fitting, boss, or pad must be of steel suitable for the method of attachment employed, and which need not be identified or verified as to analysis, except that if attachment is by welding, carbon content may not exceed 0.25 percent. If threads are used, they must comply with the following:
(i) Threads must be clean cut, even without checks, and tapped to gauge.
(ii) Taper threads to be of length not less than as specified for American Standard taper pipe threads.
(iii) Straight threads, having at least 4 engaged threads, to have tight fit and calculated shear strength at least 10 times the test pressure of the cylinder; gaskets required, adequate to prevent leakage.
(2) Closure of a fitting, boss, or pad must be adequate to prevent leakage.
(i) Pressure testing. Each cylinder must successfully withstand a pressure test as follows:
(1) Lot testing.
(i) At least one (1) cylinder selected at random out of each lot of 200 or fewer must be tested by water-jacket or direct expansion method as prescribed in CGA C-1 (IBR; see § 171.7 of this subchapter). The testing equipment must be calibrated as prescribed in CGA C-1. All testing equipment and pressure indicating devices must be accurate within the parameters defined in CGA C-1.
(ii) Each cylinder must be tested to a minimum of two (2) times service pressure.
(iii) The minimum test pressure must be maintained at least 30 seconds and sufficiently longer to ensure complete expansion. Any internal pressure applied after heat-treatment and prior to the official test may not exceed 90 percent of the test pressure. If, due to failure of the test apparatus or operator error, the test pressure cannot be maintained, the test may be repeated in accordance with CGA C-1, section 5.7.2.
(iv) Permanent volumetric expansion may not exceed 10 percent of the total volumetric expansion at test pressure.
(2) Pressure testing.
(i) The remaining cylinders in each lot must be tested by the proof pressure water-jacket or direct expansion test method as prescribed in CGA C-1. The minimum test pressure must be maintained for the specific timeframe and the testing equipment must be calibrated as prescribed in CGA C-1. All testing equipment and pressure indicating devices must be accurate within the parameters defined in CGA C-1.
(ii) Each cylinder must be tested to a minimum of two (2) times service pressure and show no defect. If, due to failure of the test apparatus or operator error, the test pressure cannot be maintained, the test may be repeated in accordance with CGA C-1 5.7.2 or 7.1.2. Determination of expansion properties is not required.
(3) Burst testing.
(i) For purposes of burst testing, each 1,000 cylinders or fewer successively produced each day constitutes a lot. All cylinders of a lot must be of identical size, construction heat treatment, finish, and quality.
(ii) One cylinder must be selected from each lot and be hydrostatically pressure tested to destruction. If this cylinder bursts below five (5) times the service pressure, then two additional cylinders from the same lot as the previously tested cylinder must be selected and subjected to this test. If either of these cylinders fails by bursting below five (5) times the service pressure then the entire lot must be rejected. All testing equipment and pressure indicating devices must be accurate within the parameters defined in CGA C-1.
(i) Pressure testing. Each cylinder must successfully withstand a pressure test as follows:
(1) Lot testing.
(i) At least one (1) cylinder selected at random out of each lot of 200 or fewer must be tested by water-jacket or direct expansion method as prescribed in CGA C-1 (IBR; see § 171.7 of this subchapter). The testing equipment must be calibrated as prescribed in CGA C-1. All testing equipment and pressure indicating devices must be accurate within the parameters defined in CGA C-1.
(ii) Each cylinder must be tested to a minimum of two (2) times service pressure.
(iii) The minimum test pressure must be maintained at least 30 seconds and sufficiently longer to ensure complete expansion. Any internal pressure applied after heat-treatment and prior to the official test may not exceed 90 percent of the test pressure. If, due to failure of the test apparatus or operator error, the test pressure cannot be maintained, the test may be repeated in accordance with CGA C-1, section 5.7.2.
(iv) Permanent volumetric expansion may not exceed 10 percent of the total volumetric expansion at test pressure.
(2) Pressure testing.
(i) The remaining cylinders in each lot must be tested by the proof pressure water-jacket or direct expansion test method as prescribed in CGA C-1. The minimum test pressure must be maintained for the specific timeframe and the testing equipment must be calibrated as prescribed in CGA C-1. All testing equipment and pressure indicating devices must be accurate within the parameters defined in CGA C-1.
(ii) Each cylinder must be tested to a minimum of two (2) times service pressure and show no defect. If, due to failure of the test apparatus or operator error, the test pressure cannot be maintained, the test may be repeated in accordance with CGA C-1 5.7.2 or 7.1.2. Determination of expansion properties is not required.
(3) Burst testing.
(i) For purposes of burst testing, each 1,000 cylinders or fewer successively produced each day constitutes a lot. All cylinders of a lot must be of identical size, construction heat treatment, finish, and quality.
(ii) One cylinder must be selected from each lot and be hydrostatically pressure tested to destruction. If this cylinder bursts below five (5) times the service pressure, then two additional cylinders from the same lot as the previously tested cylinder must be selected and subjected to this test. If either of these cylinders fails by bursting below five (5) times the service pressure then the entire lot must be rejected. All testing equipment and pressure indicating devices must be accurate within the parameters defined in CGA C-1.
(j) Flattening test. Following the hydrostatic test, one cylinder taken at random out of each lot of 200 or less, must be subjected to a flattening test that is between knife edges, wedge shaped, 60° angle, rounded to 1⁄2 inch radius.
(k) Physical test. A physical test must be conducted to determine yield strength, tensile strength, elongation, and reduction of area of material, as follows:
(1) The test is required on 2 specimens cut from 1 cylinder, or part thereof heat-treated as required, taken at random out of each lot of 200 or less in the case of cylinders of capacity greater than 86 cubic inches and out of each lot of 500 or less for cylinders having a capacity of 86 cubic inches or less.
(2) Specimens must conform to the following:
(i) A gauge length of 8 inches with a width not over 11⁄2 inches, a gauge length of 2 inches with a width not over 11⁄2 inches, or a gauge length at least 24 times the thickness with a width not over 6 times the thickness is authorized when a cylinder wall is not over 3⁄16 inch thick.
(ii) The specimen, exclusive of grip ends, may not be flattened. Grip ends may be flattened to within one inch of each end of the reduced section.
(iii) When size of cylinder does not permit securing straight specimens, the specimens may be taken in any location or direction and may be straightened or flattened cold by pressure only, not by blows. When specimens are so taken and prepared, the inspector's report must show in connection with record of physical tests detailed information in regard to such specimens.
(iv) Heating of a specimen for any purpose is not authorized.
(3) The yield strength in tension must be the stress corresponding to a permanent strain of 0.2 percent of the gauge length. The following conditions apply:
(i) The yield strength must be determined by either the “offset” method or the “extension under load” method as prescribed in ASTM E 8 (IBR, see § 171.7 of this subchapter).
(ii) In using the “extension under load” method, the total strain (or “extension under load”) corresponding to the stress at which the 0.2 percent permanent strain occurs may be determined with sufficient accuracy by calculating the elastic extension of the gauge length under appropriate load and adding thereto 0.2 percent of the gauge length. Elastic extension calculations must be based on an elastic modulus of 30,000,000. In the event of controversy, the entire stress-strain diagram must be plotted and the yield strength determined from the 0.2 percent offset.
(iii) For the purpose of strain measurement, the initial strain must be set while the specimen is under a stress of 12,000 psi and the strain indicator reading being set at the calculated corresponding strain.
(iv) Cross-head speed of the testing machine may not exceed 1⁄8 inch per minute during yield strength determination.
(l) Acceptable results for physical and flattening tests. Acceptable results for the physical and flattening tests are an elongation of at least 40 percent for a 2 inch gauge length or at least 20 percent in other cases and a yield strength not over 73 percent of tensile strength. In this instance the flattening test is required, without cracking, to six times the wall thickness with a weld 90° from the direction of the applied load. Two rings cut from the ends of length of pipe used in production of a lot may be used for the flattening test provided the rings accompany the lot which they represent in all thermal processing operations. At least one of the rings must pass the flattening test.
(m) Leakage test. All spun cylinders and plugged cylinders must be tested for leakage by gas or air pressure after the bottom has been cleaned and is free from all moisture, subject to the following conditions:
(1) Pressure, approximately the same as but no less than service pressure, must be applied to one side of the finished bottom over an area of at least 1⁄16 of the total area of the bottom but not less than 3⁄4 inch in diameter, including the closure, for at least 1 minute, during which time the other side of the bottom exposed to pressure must be covered with water and closely examined for indications of leakage. Except as provided in paragraph (n) of this section, cylinders which are leaking must be rejected.
(2) A spun cylinder is one in which an end closure in the finished cylinder has been welded by the spinning process.
(3) A plugged cylinder is one in which a permanent closure in the bottom of a finished cylinder has been effected by a plug.
(4) As a safety precaution, if the manufacturer elects to make this test before the hydrostatic test, he should design his apparatus so that the pressure is applied to the smallest area practicable, around the point of closure, and so as to use the smallest possible volume of air or gas.
(n) Rejected cylinders. Repairs of rejected cylinders is authorized. Cylinders that are leaking must be rejected, except that:
(1) Spun cylinders rejected under the provisions of paragraph (m) of this section may be removed from the spun cylinder category by drilling to remove defective material, tapping, and plugging.
(2) Brazed joints may be rebrazed.
(3) Subsequent to the operations noted in paragraphs (n)(1) and (n)(2) of this section, acceptable cylinders must pass all prescribed tests.
(o) Marking. Markings on each cylinder must be by stamping plainly and permanently on shoulder, top head, neck or valve protection collar which is permanently attached to the cylinders and forming an integral part thereof, provided that cylinders not less than 0.090 inch thick may be stamped on the side wall adjacent to top head.
[Amdt. 178-114, 61 FR , May 23, , as amended at 66 FR , Aug. 28, ; 67 FR , Aug. 8, ; 68 FR , , Dec. 31, ; 85 FR , Dec. 28, ]
(a) Type, size, and service pressure. A DOT 4AA480 cylinder is a welded steel cylinder having a water capacity (nominal) not over 1,000 pounds water capacity and a service pressure of 480 psig. Closures welded by spinning process not permitted.
(b) Steel. The limiting chemical composition of steel authorized by this specification must be as shown in table I of appendix A to this part.
(c) Identification of material. Material must be identified by any suitable method except that plates and billets for hotdrawn cylinders must be marked with the heat number.
(d) Manufacture. Cylinders must be manufactured using equipment and processes adequate to ensure that each cylinder produced conforms to the requirements of this subpart. No defect is permitted that is likely to weaken the finished cylinder appreciably. A reasonably smooth and uniform surface finish is required. Exposed bottom welds on cylinders over 18 inches long must be protected by footrings. Minimum thickness of heads and bottoms may not be less than 90 percent of the required thickness of the side wall. Seams must be made as follows:
(1) Circumferential seams must be welded. Brazing is not authorized.
(2) Longitudinal seams are not permitted.
(3) Welding procedures and operators must be qualified in accordance with CGA C-3 (IBR, see § 171.7 of this subchapter).
(e) Welding. Only the welding of neckrings, footrings, bosses, pads, and valve protection rings to the tops and bottoms of cylinders is authorized. Provided that such attachments are made of weldable steel, the carbon content of which does not exceed 0.25 percent.
(f) Wall thickness. The wall thickness of the cylinder must conform to the following:
(1) For cylinders with an outside diameter over 5 inches, the minimum wall thickness is 0.078 inch. In any case, the minimum wall thickness must be such that the calculated wall stress at the minimum test pressure (in paragraph (i) of this section) may not exceed the lesser value of either of the following:
(i) One-half of the minimum tensile strength of the material determined as required in paragraph (j) of this section; or
(ii) 35,000 psi.
(2) Calculation must be made by the formula:
S = [P(1.3D2 + 0.4d2)] / (D2 − d2)
Where:
S = wall stress in psi;
P = minimum test pressure prescribed for water jacket test;
D = outside diameter in inches;
d = inside diameter in inches.
(3) The ratio of tangential length to outside diameter may not exceed 4.0 for cylinders with a wall thickness less than 0.100 inch.
(g) Heat treatment. Each cylinder must be uniformly and properly heat treated prior to tests. Any suitable heat treatment in excess of °F is authorized except that liquid quenching is not permitted. Heat treatment must be accomplished after all forming and welding operations. Heat treatment is not required after welding weldable low carbon parts to attachments of similar material which have been previously welded to the top or bottom of cylinders and properly heat treated, provided such subsequent welding does not produce a temperature in excess of 400 °F., in any part of the top or bottom material.
(h) Openings in cylinders. Openings in cylinders must conform to the following:
(1) All openings must be in the heads or bases.
(2) Each opening in the cylinder, except those for safety devices, must be provided with a fitting boss, or pad, securely attached to the cylinder by welding or by threads. If threads are used they must comply with the following:
(i) Threads must be clean-cut, even without checks and cut to gauge.
(ii) Taper threads to be of length not less than as specified for American Standard taper pipe threads.
(iii) Straight threads having at least 6 engaged threads, must have a tight fit and a calculated shear strength at least 10 times the test pressure of the cylinder. Gaskets, adequate to prevent leakage, are required.
(3) Closure of a fitting, boss or pad must be adequate to prevent leakage.
(i) Pressure testing. Each cylinder must successfully withstand a pressure test as follows:
(1) Lot testing.
(i) At least one (1) cylinder selected at random out of each lot of 200 or fewer must be tested by water-jacket or direct expansion method as prescribed in CGA C-1 (IBR; see § 171.7 of this subchapter). The testing equipment must be calibrated as prescribed in CGA C-1. All testing equipment and pressure indicating devices must be accurate within the parameters defined in CGA C-1.
(ii) The selected cylinder must be tested to a minimum of two (2) times service pressure.
(iii) The minimum test pressure must be maintained at least 30 seconds and sufficiently longer to ensure complete expansion. Any internal pressure applied after heat-treatment and prior to the official test may not exceed 90 percent of the test pressure. If, due to failure of the test apparatus or operator error, the test pressure cannot be maintained, the test may be repeated in accordance with CGA C-1, section 5.7.2.
(iv) Permanent volumetric expansion may not exceed 10 percent of the total volumetric expansion at test pressure.
(v) If the selected cylinder fails, then two (2) additional specimens must be selected at random from the same lot and subjected to the prescribed testing. If either of these fails the test, then each cylinder in that lot must be tested as prescribed in paragraph (i)(l) of this section.
(2) Pressure testing.
(i) The remaining cylinders in each lot must be tested by the proof pressure, water-jacket, or direct expansion test method as prescribed in CGA C-1. The minimum test pressure must be maintained for the specific timeframe and the testing equipment must be calibrated as prescribed in CGA C-1. Further, all testing equipment and pressure indicating devices must be accurate within the parameters defined in CGA C-1.
(ii) Each cylinder must be tested to a minimum of two (2) times service pressure and show no defect. A cylinder showing a defect must be rejected unless it may be requalified under paragraph (m) of this section. If, due to failure of the test apparatus or operator error, the test pressure cannot be maintained, the test may be repeated in accordance with CGA C-1 5.7.2 or 7.1.2, as appropriate. Determination of expansion properties is not required.
(j) Physical test. A physical test must be conducted to determine yield strength, tensile strength, elongation, and reduction of area of material, as follows:
(1) The test is required on 2 specimens cut from one cylinder having passed the hydrostatic test, or part thereof heat-treated as required, taken at random out of each lot of 200 or less.
(2) Specimens must conform to the following:
(i) A gauge length of 8 inches with a width not over 11⁄2 inches, a gauge length of 2 inches with a width not over 11⁄2 inches, or a gauge length at least 24 times the thickness with a width not over 6 times thickness is authorized when the cylinder wall is not over 3⁄16 inch thick.
(ii) The specimen, exclusive of grip ends, may not be flattened. Grip ends may be flattened to within one inch of each end of the reduced section.
(iii) When size of cylinder does not permit securing straight specimens, the specimens may be taken in any location or direction and may be straightened or flattened cold, by pressure only, not by blows. When specimens are so taken and prepared, the inspector's report must show in connection with record of physical tests detailed information in regard to such specimens.
(iv) Heating of a specimen for any purpose is not authorized.
(3) The yield strength in tension must be the stress corresponding to a permanent strain of 0.2 percent of the gauge length. The following conditions apply:
(i) The yield strength must be determined by either the “offset” method or the “extension under load” method as prescribed in ASTM E 8 (IBR, see § 171.7 of this subchapter).
(ii) In using the “extension under load” method, the total strain (or “extension under load”), corresponding to the stress at which the 0.2 percent permanent strain occurs may be determined with sufficient accuracy by calculating the elastic extension of the gauge length under appropriate load and adding thereto 0.2 percent of the gauge length. Elastic extension calculations must be based on an elastic modulus of 30,000,000. In the event of controversy, the entire stress-strain diagram must be plotted and the yield strength determined from the 0.2 percent offset.
(iii) For the purpose of strain measurement, the initial strain reference must be set while the specimen is under a stress of 12,000 psi and the strain indicator reading being set at the calculated corresponding strain.
(iv) Cross-head speed of the testing machine may not exceed 1⁄8 inch per minute during yield strength determination.
(k) Elongation. Physical test specimens must show at least a 40 percent elongation for 2-inch gauge lengths or at least a 20 percent elongation in other cases. Except that these elongation percentages may be reduced numerically by 2 for 2-inch specimens and by 1 in other cases for each 7,500 psi increment of tensile strength above 50,000 psi to a maximum of four such increments.
(l) Tests of welds. Welds must be tested as follows:
(1) Tensile test. A specimen must be cut from one cylinder of each lot of 200 or less, or a welded test plate. The welded test plate must be of one of the heats in the lot of 200 or less which it represents, in the same condition and approximately the same thickness as the cylinder wall except that it may not be of a lesser thickness than that required for a quarter size Charpy impact specimen. The weld must be made by the same procedures and subjected to the same heat treatment as the major weld on the cylinder. The specimens must be taken across the major seam and must be prepared and tested in accordance with and must meet the requirements of CGA Pamphlet C-3. Should this specimen fail to meet the requirements, specimens may be taken from two additional cylinders or welded test plates from the same lot and tested. If either of the latter specimens fail to meet the requirements, the entire lot represented must be rejected.
(2) Guided bend test. A root bend test specimen must be cut from the cylinder or a welded test plate, used for the tensile test specified in paragraph (l)(1) of this section. Specimens must be taken from across the major seam and must be prepared and tested in accordance with and must meet the requirements of CGA Pamphlet C-3.
(3) Alternate guided-bend test. This test may be used and must be as required by CGA Pamphlet C-3. The specimen must be bent until the elongation at the outer surface, adjacent to the root of the weld, between the lightly scribed gage lines-a to b, is at least 20 percent, except that this percentage may be reduced for steels having a tensile strength in excess of 50,000 psi, as provided in paragraph (k) of this section.
(m) Rejected cylinders. Reheat treatment of rejected cylinders is authorized. Subsequent thereto, cylinders must pass all prescribed tests to be acceptable. Repair of welded seams by welding is authorized.
(n) Markings. Markings must be stamped plainly and permanently in one of the following locations on the cylinder:
(1) On shoulders and top heads not less than 0.087 inch thick.
(2) On neck, valve boss, valve protection sleeve, or similar part permanently attached to top end of cylinder.
(3) On a plate attached to the top of the cylinder or permanent part thereof: sufficient space must be left on the plate to provide for stamping at least six retest dates: the plate must be at least 1⁄16 inch thick and must be attached by welding or by brazing at a temperature of at least °F, throughout all edges of the plate.
(4) Variations in location of markings authorized only when necessitated by lack of space.
[Amdt. 178-114, 61 FR , May 23, , as amended at 66 FR , Aug. 28, ; 67 FR , Aug. 8, ; 68 FR , , Dec. 31, ; 85 FR , Dec. 28, ]
(a) Type, size, service pressure, and design service temperature. A DOT 4L cylinder is a fusion welded insulated cylinder with a water capacity (nominal) not over 1,000 pounds water capacity and a service pressure of at least 40 but not greater than 500 psig conforming to the following requirements:
(1) For liquefied hydrogen service, the cylinders must be designed to stand on end, with the axis of the cylindrical portion vertical.
(2) The design service temperature is the coldest temperature for which a cylinder is suitable. The required design service temperatures for each cryogenic liquid is as follows:
Cryogenic liquid Design service temperature Argon Minus 320 °F or colder. Helium Minus 452 °F or colder. Hydrogen Minus 42 3 °F or colder. Neon Minus 411 °F or colder. Nitrogen Minus 320 °F or colder. Oxygen Minus 320 °F or colder.(b) Material. Material use in the construction of this specification must conform to the following:
(1) Inner containment vessel (cylinder). Designations and limiting chemical compositions of steel authorized by this specification must be as shown in table 1 in paragraph (o) of this section.
(2) Outer jacket. Steel or aluminum may be used subject to the requirements of paragraph (o)(2) of this section.
(c) Identification of material. Material must be identified by any suitable method.
(d) Manufacture. Cylinders must be manufactured using equipment and processes adequate to ensure that each cylinder produced conforms to the requirements of this subpart and to the following requirements:
(1) No defect is permitted that is likely to weaken the finished cylinder appreciably. A reasonably smooth and uniform surface finish is required. The shell portion must be a reasonably true cylinder.
(2) The heads must be seamless, concave side to the pressure, hemispherical or ellipsoidal in shape with the major diameter not more than twice the minor diameter. Minimum thickness of heads may not be less than 90 percent of the required thickness of the sidewall. The heads must be reasonably true to shape, have no abrupt shape changes, and the skirts must be reasonably true to round.
(3) The surface of the cylinder must be insulated. The insulating material must be fire resistant. The insulation on non-evacuated jackets must be covered with a steel jacket not less than 0.060-inch thick or an aluminum jacket not less than 0.070 inch thick, so constructed that moisture cannot come in contact with the insulating material. If a vacuum is maintained in the insulation space, the evacuated jacket must be designed for a minimum collapsing pressure of 30 psig differential whether made of steel or aluminum. The construction must be such that the total heat transfer, from the atmosphere at ambient temperature to the contents of the cylinder, will not exceed 0. Btu per hour, per Fahrenheit degree differential in temperature, per pound of water capacity of the cylinder. For hydrogen, cryogenic liquid service, the total heat transfer, with a temperature differential of 520 Fahrenheit degrees, may not exceed that required to vent 30 SCF of hydrogen gas per hour.
(4) For a cylinder having a design service temperature colder than minus 320 °F, a calculation of the maximum weight of contents must be made and that weight must be marked on the cylinder as prescribed in § 178.35.
(5) Welding procedures and operations must be qualified in accordance with CGA Pamphlet C-3 (IBR, see § 171.7 of this subchapter). In addition, an impact test of the weld must be performed in accordance with paragraph (l) of this section as part of the qualification of each welding procedure and operator.
(e) Welding. Welding of the cylinder must be as follows:
(1) All seams of the cylinder must be fusion welded. A means must be provided for accomplishing complete penetration of the joint. Only butt or joggle butt joints for the cylinder seams are authorized. All joints in the cylinder must have reasonably true alignment.
(2) All attachments to the sidewalls and heads of the cylinder must be by fusion welding and must be of a weldable material complying with the impact requirements of paragraph (l) of this section.
(3) For welding the cylinder, each procedure and operator must be qualified in accordance with the sections of CGA Pamphlet C-3 that apply. In addition, impact tests of the weld must be performed in accordance with paragraph (l) of this section as part of the qualification of each welding procedure and operator.
(4) Brazing, soldering and threading are permitted only for joints not made directly to the cylinder body. Threads must comply with the requirements of paragraph (h) of this section.
(f) Wall thickness. The minimum wall thickness of the cylinder must be such that the calculated wall stress at the minimum required test pressure may not exceed the least value of the following:
(1) 45,000 psi.
(2) One-half of the minimum tensile strength across the welded seam determined in paragraph (l) of this section.
(3) One-half of the minimum tensile strength of the base metal determined as required in paragraph (j) of this section.
(4) The yield strength of the base metal determined as required in paragraph (l) of this section.
(5) Further provided that wall stress for cylinders having longitudinal seams may not exceed 85 percent of the above value, whichever applies.
(6) Calculation must be made by the following formula:
S = [P(1.3D2 + 0.4d2)] / (D2 − d2)
where:
S = wall stress in pounds psi;
P = minimum test pressure prescribed for pressure test in psig;
D = outside diameter in inches;
d = inside diameter in inches.
(g) Heat treatment. Heat treatment is not permitted.
(h) Openings in cylinder. Openings in cylinders must conform to the following:
(1) Openings are permitted in heads only. They must be circular and may not exceed 3 inches in diameter or one third of the cylinder diameter, whichever is less. Each opening in the cylinder must be provided with a fitting, boss or pad, either integral with, or securely attached to, the cylinder body by fusion welding. Attachments to a fitting, boss or pad may be made by welding, brazing, mechanical attachment, or threading.
(2) Threads must comply with the following:
(i) Threads must be clean-cut, even, without checks and cut to gauge.
(ii) Taper threads to be of a length not less than that specified for NPT.
(iii) Straight threads must have at least 4 engaged threads, tight fit and calculated shear strength at least 10 times the test pressure of the cylinder. Gaskets, which prevent leakage and are inert to the hazardous material, are required.
(i) Pressure testing. Each cylinder, before insulating and jacketing, must successfully withstand a pressure test as follows:
(1) The cylinder must be tested by the proof pressure, water-jacket, or direct expansion test method as prescribed in CGA C-1 (IBR; see § 171.7 of this subchapter). The testing equipment must be calibrated as prescribed in CGA C-1. All testing equipment and pressure indicating devices must be accurate within the parameters defined in CGA C-1.
(2) Each cylinder must be tested to a minimum of two (2) times service pressure.
(3) The minimum test pressure must be maintained at least 30 seconds. Any internal pressure applied after heat-treatment and prior to the official test may not exceed 90 percent of the test pressure. If, due to failure of the test apparatus or operator error, the test pressure cannot be maintained, the test may be repeated in accordance with CGA C-1 5.7.2 or 7.1.2. Determination of expansion properties is not required.
(4) There must be no evidence of leakage, visible distortion or other defect.
(j) Physical test. A physical test must be conducted to determine yield strength, tensile strength, and elongation as follows:
(1) The test is required on 2 specimens selected from material of each heat and in the same condition as that in the completed cylinder.
(2) Specimens must conform to the following:
(i) A gauge length of 8 inches with a width not over 11⁄2 inches, a gauge length of 2 inches with width not over 11⁄2 inches, or a gauge length at least 24 times thickness with a width not over 6 times thickness (authorized when cylinder wall is not over 1⁄16 inch thick).
(ii) The specimen, exclusive of grip ends, may not be flattened. Grip ends may be flattened to within one inch of each end of the reduced section.
(iii) When size of the cylinder does not permit securing straight specimens, the specimens may be taken in any location or direction and may be straightened or flattened cold by pressure only, not by blows. When specimens are so taken and prepared, the inspector's report must show in connection with record of physical tests detailed information in regard to such specimens.
(iv) Heating of a specimen for any purpose is not authorized.
(3) The yield strength in tension must be the stress corresponding to a permanent strain of 0.2 percent of the gauge length. The following conditions apply:
(i) The yield strength must be determined by either the “offset” method or the “extension under load” method as prescribed in ASTM E 8 (IBR, see § 171.7 of this subchapter).
(ii) In using the “extension under load” method, the total strain (or “extension under load”), corresponding to the stress at which the 0.2 percent permanent strain occurs may be determined with sufficient accuracy by calculating the elastic expansion of the gauge length under appropriate load and adding thereto 0.2 percent of the gauge length. Elastic extension calculations must be based on the elastic modulus of the material used. In the event of controversy, the entire stress-strain diagram must be plotted and the yield strength determined from the 0.2 percent offset.
(iii) For the purpose of strain measurement, the initial strain reference must be set while the specimen is under a stress of 12,000 psi and the strain indicator reading being set at the calculated corresponding strain.
(iv) Cross-head speed of the testing machine may not exceed 1⁄8 inch per minute during yield strength determination.
(k) Acceptable results for physical tests. Physical properties must meet the limits specified in paragraph (o)(1), table 1, of this section, for the particular steel in the annealed condition. The specimens must show at least a 20 percent elongation for a 2-inch gage length. Except that the percentage may be reduced numerically by 2 for each 7,500 psi increment of tensile strength above 100,000 psi to a maximum of 5 such increments. Yield strength and tensile strength must meet the requirements of paragraph (o)(1), table 1, of this section.
(l) Tests of welds. Welds must be tested as follows:
(1) Tensile test. A specimen must be cut from one cylinder of each lot of 200 or less, or welded test plate. The welded test plate must be of one of the heats in the lot of 200 or less which it represents, in the same condition and approximately the same thickness as the cylinder wall except that it may not be of a lesser thickness than that required for a quarter size Charpy impact specimen. The weld must be made by the same procedures and subjected to the same heat treatment as the major weld on the cylinder. The specimen must be taken across the major seam and must be prepared in accordance with and must meet the requirements of CGA Pamphlet C-3. Should this specimen fail to meet the requirements, specimens may be taken from two additional cylinders or welded test plates from the same lot and tested. If either of the latter specimens fails to meet the requirements, the entire lot represented must be rejected.
(2) Guided bend test. A “root” bend test specimen must be cut from the cylinder or welded test plate, used for the tensile test specified in paragraph (l)(1) of this section and from any other seam or equivalent welded test plate if the seam is welded by a procedure different from that used for the major seam. Specimens must be taken across the particular seam being tested and must be prepared and tested in accordance with and must meet the requirements of CGA Pamphlet C-3.
(3) Alternate guided-bend test. This test may be used and must be as specified in CGA Pamphlet C-3. The specimen must be bent until the elongation at the outer surface, adjacent to the root of the weld, between the lightly scribed gage lines a to b, is at least 20 percent, except that this percentage may be reduced for steels having a tensile strength in excess of 100,000 psig, as provided in paragraph (c) of this section.
(4) Impact tests. One set of three impact test specimens (for each test) must be prepared and tested for determining the impact properties of the deposited weld metal—
(i) As part of the qualification of the welding procedure.
(ii) As part of the qualification of the operators.
(iii) For each “heat” of welding rodor wire used.
(iv) For each 1,000 feet of weld made with the same heat of welding rod or wire.
(v) All impact test specimens must be of the charpy type, keyhole or milled U-notch, and must conform in all respects to ASTM E 23 (IBR, see § 171.7 of this subchapter). Each set of impact specimens must be taken across the weld and have the notch located in the weld metal. When the cylinder material thickness is 2.5 mm or thicker, impact specimens must be cut from a cylinder or welded test plate used for the tensile or bend test specimens. The dimension along the axis of the notch must be reduced to the largest possible of 10 mm, 7.5 mm, 5 mm or 2.5 mm, depending upon cylinder thickness. When the material in the cylinder or welded test plate is not of sufficient thickness to prepare 2.5 mm impact test specimens, 2.5 mm specimens must be prepared from a welded test plate made from 1⁄8 inch thick material meeting the requirements specified in paragraph (o)(1), table 1, of this section and having a carbon analysis of .05 minimum, but not necessarily from one of the heats used in the lot of cylinders. The test piece must be welded by the same welding procedure as used on the particular cylinder seam being qualified and must be subjected to the same heat treatment.
(vi) Impact test specimens must be cooled to the design service temperature. The apparatus for testing the specimens must conform to requirements of ASTM Standard E 23. The test piece, as well as the handling tongs, must be cooled for a length of time sufficient to reach the service temperature. The temperature of the cooling device must be maintained within a range of plus or minus 3 °F. The specimen must be quickly transferred from the cooling device to the anvil of the testing machine and broken within a time lapse of not more than six seconds.
(vii) The impact properties of each set of impact specimens may not be less than the values in the following table:
Size of specimen Minimum(viii) When the average value of the three specimens equals or exceeds the minimum value permitted for a single specimen and the value for more than one specimen is below the required average value, or when the value for one specimen is below the minimum value permitted for a single specimen, a retest of three additional specimens must be made. The value of each of these retest specimens must equal or exceed the required average value. When an erratic result is caused by a defective specimen, or there is uncertainty in test procedure, a retest is authorized.
(m) Radiographic examination. Cylinders must be subject to a radiographic examination as follows:
(1) The techniques and acceptability of radiographic inspection must conform to the standards set forth in CGA Pamphlet C-3.
(2) One finished longitudinal seam must be selected at random from each lot of 100 or less successively produced and be radiographed throughout its entire length. Should the radiographic examination fail to meet the requirements of paragraph (m)(1) of this section, two additional seams of the same lot must be examined, and if either of these fail to meet the requirements of (m)(1) of this section, only those passing are acceptable.
(n) Rejected cylinders. Reheat treatment of rejected cylinders is authorized. Subsequent thereto, cylinders must pass all prescribed tests to be acceptable. Welds may be repaired by suitable methods of fusion welding.
(o) Authorized materials of construction. Authorized materials of construction are as follows:
(1) Inner containment vessel (cylinder). Electric furnace steel of uniform quality must be used. Chemical analysis must conform to ASTM A 240/A 240M (IBR, see § 171.7 of this subchapter), Type 304 stainless steel. Chemical analysis must conform to ASTM A240, Type 304 Stainless Steel. A heat of steel made under table 1 and table 2 in this paragraph (o)(1) is acceptable, even though its check chemical analysis is slightly out of the specified range, if it is satisfactory in all other respects, provided the tolerances shown in table 3 in this paragraph (o)(1) are not exceeded. The following chemical analyses and physical properties are authorized:
Table 1—Authorized Materials
Designation Chemical analysis, limits in percent Carbon 1 0.08 max. Manganese 2.00 max. Phosphorus 0.045 max. Sulphur 0.030 max. Silicon 1.00 max. Nickel 8.00-10.50. Chromium 18.00-20.00. Molybdenum None. Titanium None. Columbium None. 1 The carbon analysis must be reported to the nearest hundredth of one percent.Table 2—Physical Properties
Physical properties (annealed) Tensile strength, p.s.i. (minimum) 75,000 Yield strength, p.s.i. (minimum) 30,000 Elongation in 2 inches (minimum) percent 30.0 Elongation other permissible gauge lengths (minimum) percent 15.0Table 3—Check Analysis Tolerances
Elements Limit or specified range (percent) Tolerance over the maximum limit or under the minimum limit Carbon To 0.030, incl 0.005 Over 0.30 to 0.20, incl 0.01 Manganese To 1.00 incl .03 Over 1.00 to 3.00, incl 0.04 Phosphorus 1 To 0.040, incl 0.005 Over 0.040 to 0.020 incl 0.010 Sulphur To .40 incl 0.005 Silicon To 1.00, incl 0.05 Nickel Over 5.00 to 10.00, incl 0.10 Over 10.00 to 20.00, incl 0.15 Chromium Over 15.00 to 20.00, incl 0.20 1 Rephosphorized steels not subject to check analysis for phosphorus.(2) Outer jacket.
(i) Nonflammable cryogenic liquids. Cylinders intended for use in the transportation of nonflammable cryogenic liquid must have an outer jacket made of steel or aluminum.
(ii) Flammable cryogenic liquids. Cylinders intended for use in the transportation of flammable cryogenic liquid must have an outer jacket made of steel.
(p) Markings.
(1) Markings must be stamped plainly and permanently on shoulder or top head of jacket or on a permanently attached plate or head protective ring.
(2) The letters “ST”, followed by the design service temperature (for example, ST-423F), must be marked on cylinders having a design service temperature of colder than minus 320 °F only. Location to be just below the DOT mark.
(3) The maximum weight of contents, in pounds (for example, “Max. Content 51 #”), must be marked on cylinders having a design service temperature colder than minus 320 °F only. Location to be near symbol.
(4) Special orientation instructions must be marked on the cylinder (for example, THIS END UP), if the cylinder is used in an orientation other than vertical with openings at the top of the cylinder.
(5) If the jacket of the cylinder is constructed of aluminum, the letters “AL” must be marked after the service pressure marking. Example: DOT-4L150 AL.
(6) Except for serial number and jacket material designation, each marking prescribed in this paragraph (p) must be duplicated on each cylinder by any suitable means.
(q) Inspector's report. In addition to the information required by § 178.35, the inspector's reports must contain information on:
(1) The jacket material and insulation type;
(2) The design service temperature
(°F); and
(3) The impact test results, on a lot basis.
[Amdt. 178-114, 61 FR , May 23, , as amended at 66 FR , Aug. 28, ; 67 FR , Aug. 8, ; 68 FR , Dec. 31, ; 85 FR , Dec. 28, ]
(a) Type, size, and service pressure. A DOT 4DA is a welded steel sphere (two seamless hemispheres) or a circumferentially welded cylinder (two seamless drawn shells) with a water capacity not over 100 pounds and a service pressure of at least 500 but not over 900 psig.
(b) Steel. Open-hearth or electric steel of uniform quality must be used. A heat of steel made under table 1 in this paragraph (b), check chemical analysis of which is slightly out of the specified range, is acceptable, if satisfactory in all other respects, provided the tolerances shown in table 2 in this paragraph (b) are not exceeded except as approved by the Associate Administrator. The following chemical analyses are authorized:
Table 1—Authorized Materials
Percent Carbon 0.28/0.33. Manganese 0.40/0.60. Phosphorus 0.040 max. Sulfur 0.040 max. Silicon 0.15/0.35. Chromium 0.80/1.10. Molybdenum 0.15/0.25.Table 2—Check Analysis Tolerances
Element Limit or maximum specified (percent) Tolerance (percent) over the maximum limit or under the minimum limit Under minimum limit Over maximum limit Carbon Over 0.15 to 0.40 incl .03 .04 Manganese To 0.60 incl .03 .03 Phosphorus1 All ranges .01 Sulphur All ranges .01 Silicon To 0.30 incl .02 .03 Over 0.30 to 1.00 incl .05 .05 Chromium To 0.90 incl .03 .03 Over 0.90 to 2.10 incl .05 .05 Molybdenum To 0.20 incl .01 .01 Over 0.20 to 0.40, incl .02 .02 1 Rephosphorized steels not subject to check analysis for phosphorus.(c) Identification of material. Materials must be identified by any suitable method except that plates and billets for hot-drawn containers must be marked with the heat number.
(d) Manufacture. Cylinders must be manufactured in accordance with the following requirements:
(1) By best appliances and methods. No defect is acceptable that is likely to weaken the finished container appreciably. A reasonably smooth and uniform surface finish is required. No abrupt change in wall thickness is permitted. Welding procedures and operators must be qualified in accordance with CGA Pamphlet C-3 (IBR, see § 171.7 of this subchapter).
(2) All seams of the sphere or cylinders must be fusion welded. Seams must be of the butt or joggle butt type and means must be provided for accomplishing complete penetration of the joint.
(e) Welding. Attachments to the container are authorized by fusion welding provided that such attachments are made of weldable steel, the carbon content of which may not exceed 0.25 percent except in the case of steel.
(f) Wall thickness. The minimum wall thickness must be such that the wall stress at the minimum specified test pressure may not exceed 67 percent of the minimum tensile strength of the steel as determined from the physical and burst tests required and may not be over 70,000 p.s.i. For any diameter container, the minimum wall thickness is 0.040 inch. Calculations must be made by the formulas in (f)(1) or (f)(2) of this section:
(1) Calculation for a sphere must be made by the following formula:
S = PD / 4tE
Where:
S = wall stress in pounds psi;
P = test pressure prescribed for water jacket test, i.e., at least 2 times service pressure, in psig;
D = outside diameter in inches;
t = minimum wall thickness in inches;
E = 0.85 (provides 85 percent weld efficiency factor which must be applied in the girth weld area and heat affected zones which zone must extend a distance of 6 times wall thickness from center line of weld);
E = 1.0 (for all other areas).
(2) Calculation for a cylinder must be made by the following formula:
S = [P(1.3D2 + 0.4d2)] / (D2 − d2)
Where:
S = wall stress in pounds psi;
P = test pressure prescribed for water jacket test, i.e., at least 2 times service pressure, in psig;
D = outside diameter in inches;
d = inside diameter in inches.
(g) Heat treatment. The completed containers must be uniformly and properly heat-treated prior to tests. Heat-treatment of containers of the authorized analysis must be as follows:
(1) All containers must be quenched by oil, or other suitable medium except as provided in paragraph (g)(4) of this section.
(2) The steel temperature on quenching must be that recommended for the steel analysis, but may not exceed 1,750 °F.
(3) The steel must be tempered at the temperature most suitable for the analysis except that in no case shall the tempering temperature be less than 1,000 °F.
(4) The steel may be normalized at a temperature of 1,650 °F instead of being quenched, and containers so normalized need not be tempered.
(5) All cylinders, if water quenched or quenched with a liquid producing a cooling rate in excess of 80 percent of the cooling rate of water, must be inspected by the magnetic particle or dye penetrant method to detect the presence of quenching cracks. Any cylinder found to have a quench crack must be rejected and may not be requalified.
(h) Openings in container. Openings in the container must comply with the following requirements:
(1) Each opening in the container must be provided with a fitting, boss, or pad of weldable steel securely attached to the container by fusion welding.
(2) Attachments to a fitting, boss, or pad must be adequate to prevent leakage. Threads must comply with the following:
(i) Threads must be clean cut, even, without checks, and tapped to gauge.
(ii) Taper threads to be of length not less than as specified for American Standard taper pipe threads.
(iii) Straight threads, having at least 4 engaged threads, to have tight fit and calculated shear strength at least 10 times the test pressure of the container; gaskets required, adequate to prevent leakage.
(i) Pressure testing. Each cylinder must successfully withstand a pressure test as follows:
(1) The test must be by water-jacket or direct expansion method as prescribed in CGA C-1 (IBR; see § 171.7 of this subchapter). The testing equipment must be calibrated as prescribed in CGA C-1. All testing equipment and pressure indicating devices must be accurate within the parameters defined in CGA C-1.
(2) Each cylinder must be tested to a minimum of two (2) times service pressure.
(3) The minimum test pressure must be maintained at least 30 seconds and sufficiently longer to ensure complete expansion. Any internal pressure applied after heat-treatment and prior to the official test may not exceed 90 percent of the test pressure. If, due to failure of the test apparatus or operator error, the test pressure cannot be maintained, the test may be repeated in accordance with CGA C-1, section 5.7.2.
(4) Permanent volumetric expansion may not exceed 10 percent of the total volumetric expansion at test pressure.
(j) Burst test. One container taken at random out of 200 or less must be hydrostatically tested to destruction. The rupture pressure must be included as part of the inspector's report.
(k) Flattening test. Spheres and cylinders must be subjected to a flattening test as follows:
(1) Flattening test for spheres. One sphere taken at random out of each lot of 200 or less must be subjected to a flattening test as follows:
(i) The test must be performed after the hydrostatic test.
(ii) The test must be at the weld between the parallel steel plates on a press with a welded seam, at right angles to the plates. Any projecting appurtenances may be cut off (by mechanical means only) prior to crushing.
(2) Flattening test for cylinders. One cylinder taken at random out of each lot of 200 or less, must be subjected to a flattening test as follows:
(i) The test must be performed after the hydrostatic test.
(ii) The test cylinder must be placed between wedge-shaped knife edges having a 60° angle, rounded to a 1⁄2-inch radius.
(l) Radiographic inspection. Radiographic examinations is required on all welded joints which are subjected to internal pressure, except that at the discretion of the disinterested inspector, openings less than 25 percent of the sphere diameter need not be subjected to radiographic inspection. Evidence of any defects likely to seriously weaken the container must be cause for rejection.
(m) Physical test and specimens for spheres and cylinders. Spheres and cylinders must be subjected to a physical test as follows:
(1) A physical test for a sphere is required on 2 specimens cut from a flat representative sample plate of the same heat taken at random from the steel used to produce the sphere. This flat steel from which the 2 specimens are to be cut must receive the same heat-treatment as the spheres themselves. Sample plates to be taken for each lot of 200 or less spheres.
(2) Specimens for spheres have a gauge length of 2 inches with a width not over 11⁄2 inches, or a gauge length at least 24 times thickness with a width not over 6 times thickness is authorized when wall of sphere is not over 3⁄16 inch thick.
(3) A physical test for cylinders is required on 2 specimens cut from 1 cylinder taken at random out of each lot of 200 or less.
(4) Specimens for cylinder must conform to the following:
(i) A gauge length of 8 inches with a width not over 11⁄2 inches, a gauge length of 2 inches with a width not over 11⁄2 inches, a gauge length at least 24 times thickness with a width not over 6 times thickness is authorized when a cylinder wall is not over 3⁄16 inch thick.
(ii) The specimen, exclusive of grip ends, may not be flattened. Grip ends may be flattened to within 1 inch of each end of the reduced section.
(iii) Heating of a specimen for any purpose is not authorized.
(5) The yield strength in tension must be the stress corresponding to a permanent strain of 0.2 percent of the gauge length. The following conditions apply:
(i) The yield strength must be determined by either the “offset” method or the “extension under load” method as prescribed in ASTM E 8 (IBR, see § 171.7 of this subchapter).
(ii) In using the “extension under load” method, the total strain (or “extension under load”) corresponding to the stress at which the 0.2 percent permanent strain occurs may be determined with sufficient accuracy by calculating the elastic extension of the gauge length under appropriate load and adding thereto 0.2 percent of the gauge length. Elastic extension calculations must be based on an elastic modulus of 30,000,000. In the event of controversy, the entire stress-strain diagram must be plotted and the yield strength determined from the 0.2 percent offset.
(iii) For the purpose of strain measurement, the initial strain must be set while the specimen is under a stress of 12,000 psi and the strain indicator reading being set at the calculated corresponding strain.
(iv) Cross-head speed of the testing machine may not exceed 1⁄8 inch per minute during yield strength determination.
(n) Acceptable results for physical, flattening, and burst tests. The following are acceptable results of the physical, flattening and burst test:
(1) Elongation must be at least 20 percent for a 2-inch gauge length or 10 percent in other cases.
(2) Flattening is required to 50 percent of the original outside diameter without cracking.
(3) Burst pressure must be at least 3 times service pressure.
(o) Rejected containers. Reheat-treatment of rejected cylinders is authorized. Subsequent thereto, containers must pass all prescribed tests to be acceptable. Repair of welded seams by welding prior to reheat-treatment is authorized.
(p) Marking. Markings on each container must be stamped plainly and permanently on a permanent attachment or on a metal nameplate permanently secured to the container by means other than soft solder.
[Amdt. 178-114, 61 FR , May 23, , as amended at 66 FR , , Aug. 28, ; 67 FR , Aug. 8, ; 67 FR , Sept. 27, ; 68 FR , Dec. 31, ; 85 FR , Dec. 28, ]
(a) Type and service pressure. A DOT 8 cylinder is a seamless cylinder with a service pressure of 250 psig. The following steel is authorized:
(1) A longitudinal seam if forge lap welded;
(2) Attachment of heads by welding or by brazing by dipping process; or
(3) A welded circumferential body seam if the cylinder has no longitudinal seam.
(b) Steel. Open-hearth, electric or basic oxygen process steel of uniform quality must be used. Content percent may not exceed the following: Carbon, 0.25; phosphorus, 0.045; sulphur, 0.050.
(c) Identification of steel. Materials must be identified by any suitable method except that plates and billets for hot-drawn cylinders must be marked with the heat number.
(d) Manufacture. Cylinders must be manufactured using equipment and processes adequate to ensure that each cylinder produced conforms to the requirements of this subpart. No defect is acceptable that is likely to weaken the finished cylinder appreciably. A reasonably smooth and uniform surface finish is required. Welding procedures and operators must be qualified in accordance with CGA Pamphlet C-3 (IBR, see § 171.7 of this subchapter).
(e) Exposed bottom welds. Exposed bottom welds on cylinders over 18 inches long must be protected by footrings.
(f) Heat treatment. Body and heads formed by drawing or pressing must be uniformly and properly heat treated prior to tests.
(g) Openings. Openings in the cylinders must comply with the following:
(1) Standard taper pipe threads are required;
(2) Length may not be less than as specified for American Standard pipe threads; tapped to gauge; clean cut, even, and without checks.
(h) Pressure testing. Each cylinder must successfully withstand a pressure test as follows:
(1) Lot testing.
(i) At least one (1) cylinder selected at random out of each lot of 200 or fewer must be tested by water-jacket or direct expansion method as prescribed in CGA C-1 (IBR; see § 171.7 of this subchapter). The testing equipment must be calibrated as prescribed in CGA C-1. All testing equipment and pressure indicating devices must be accurate within the parameters defined in CGA C-1.
(ii) The selected cylinder must be tested to a minimum of 750 psig.
(iii) The minimum test pressure must be maintained at least 30 seconds and sufficiently longer to ensure complete expansion. Any internal pressure applied after heat-treatment and prior to the official test may not exceed 90 percent of the test pressure. If, due to failure of the test apparatus or operator error, the test pressure cannot be maintained, the test may be repeated in accordance with CGA C-1, section 5.7.2.
(iv) Permanent volumetric expansion may not exceed 10 percent of the total volumetric expansion at test pressure.
(v) If the selected cylinder passes the volumetric expansion test, each remaining cylinder in the lot must be pressure tested in accordance with paragraph (h)(2) of this section. If the selected cylinder fails, each cylinder in the lot must be tested by water-jacket or direct expansion method as prescribed in CGA C-1 at 750 psig. Each cylinder with a permanent expansion that does not exceed 10% is acceptable.
(2) Pressure testing.
(i) If the selected cylinder passes the water-jacket or direct expansion test, the remaining cylinders in each lot must be pressure tested by the proof pressure, water-jacket or direct expansion test method as prescribed in CGA C-1. The minimum test pressure must be maintained for the specific timeframe and the testing equipment must be calibrated as prescribed in CGA C-1. Further, all testing equipment and pressure indicating devices must be accurate within the parameters defined in CGA C-1.
(ii) Each cylinder must be tested between 500 and 600 psig and show no defect. If, due to failure of the test apparatus or operator error, the test pressure cannot be maintained, the test may be repeated in accordance with CGA C-1 section 5.7.2 or 7.1.2, as appropriate. Determination of expansion properties is not required.
(i) Leakage test. Cylinders with bottoms closed in by spinning must be subjected to a leakage test by setting the interior air or gas pressure to not less than the service pressure. Cylinders which leak must be rejected.
(j) Physical test. A physical test must be conducted as follows:
(1) The test is required on 2 specimens cut longitudinally from 1 cylinder or part thereof taken at random out of each lot of 200 or less, after heat treatment.
(2) Specimens must conform to a gauge length of 8 inches with a width not over 11⁄2 inches, a gauge length of 2 inches with width not over 11⁄2, or a gauge length at least 24 times thickness with a width not over 6 times thickness is authorized when a cylinder wall is not over 3⁄16 inch thick.
(3) The yield strength in tension must be the stress corresponding to a permanent strain of 0.2 percent of the gauge length. The following conditions apply:
(i) The yield strength must be determined by either the “offset” method or the “extension under load” method as prescribed in ASTM E 8 (IBR, see § 171.7 of this subchapter).
(ii) In using the “extension under load” method, the total strain (or “extension under load”) corresponding to the stress at which the 0.2 percent permanent strain occurs may be determined with sufficient accuracy by calculating the elastic extension of the gauge length under appropriate load and adding thereto 0.2 percent of the gauge length. Elastic extension calculations must be based on an elastic modulus of 30,000,000. In the event of controversy, the entire stress-strain diagram must be plotted and the yield strength determined from the 0.2 offset.
(iii) For the purpose of strain measurement, the initial strain must be set while the specimen is under a stress of 12,000 psi and the strain indicator reading being set at the calculated corresponding strain.
(iv) Cross-head speed of the testing machine may not exceed 1⁄8 inch per minute during yield strength determination.
(4) Yield strength may not exceed 73 percent of tensile strength. Elongation must be at least 40 percent in 2 inch or 20 percent in other cases.
(k) Rejected cylinders. Reheat treatment of rejected cylinder is authorized. Subsequent thereto, cylinders must pass all prescribed tests to be acceptable. Repair by welding is authorized.
(l) Porous filling.
(1) Cylinders must be filled with a porous material in accordance with the following:
(i) The porous material may not disintegrate or sag when wet with solvent or when subjected to normal service;
(ii) The porous filling material must be uniform in quality and free of voids, except that a well drilled into the filling material beneath the valve is authorized if the well is filled with a material of such type that the functions of the filling material are not impaired;
(iii) Overall shrinkage of the filling material is authorized if the total clearance between the cylinder shell and filling material, after solvent has been added, does not exceed 1⁄2 of 1 percent of the respective diameter or length, but not to exceed 1⁄8 inch, measured diametrically and longitudinally;
(iv) The clearance may not impair the functions of the filling material;
(v) The installed filling material must meet the requirements of CGA C-12 (IBR, see § 171.7 of this subchapter); and
(vi) Porosity of filling material may not exceed 80 percent except that filling material with a porosity of up to 92 percent may be used when tested with satisfactory results in accordance with CGA Pamphlet C-12.
(2) When the porosity of each cylinder is not known, a cylinder taken at random from a lot of 200 or less must be tested for porosity. If the test cylinder fails, each cylinder in the lot may be tested individually and those cylinders that pass the test are acceptable.
(3) For filling that is molded and dried before insertion in cylinders, porosity test may be made on a sample block taken at random from material to be used.
(4) The porosity of the filling material must be determined. The amount of solvent at 70 °F for a cylinder:
(i) Having shell volumetric capacity above 20 pounds water capacity (nominal) may not exceed the following:
Percent porosity of filler Maximum acetone solvent percent shell capacity by volume 90 to 92 43.4 87 to 90 42.0 83 to 87 40.0 80 to 83 38.6 75 to 80 36.2 70 to 75 33.8 65 to 70 31.4(ii) Having volumetric capacity of 20 pounds or less water capacity (nominal), may not exceed the following:
Percent porosity of filler Maximum acetone solvent percent shell capacity by volume 90 to 92 41.8 83 to 90 38.5 80 to 83 37.1 75 to 80 34.8 70 to 75 32.5 65 to 70 30.2(m) Tare weight. The tare weight is the combined weight of the cylinder proper, porous filling, valve, and solvent, without removable cap.
(n) Duties of inspector. In addition to the requirements of § 178.35, the inspector is required to—
(1) Certify chemical analyses of steel used, signed by manufacturer thereof; also verify by, check analyses of samples taken from each heat or from 1 out of each lot of 200 or less, plates, shells, or tubes used.
(2) Verify compliance of cylinder shells with all shell requirements; inspect inside before closing in both ends; verify heat treatment as proper; obtain all samples for all tests and for check analyses; witness all tests; verify threads by gauge; report volumetric capacity and minimum thickness of wall noted.
(3) Prepare report on manufacture of steel shells in form prescribed in § 178.35. Furnish one copy to manufacturer and three copies to the company that is to complete the cylinders.
(4) Determine porosity of filling and tare weights; verify compliance of marking with prescribed requirements; obtain necessary copies of steel shell reports; and furnish complete reports required by this specification to the person who has completed the manufacture of the cylinders and, upon request, to the purchaser. The test reports must be retained by the inspector for fifteen years from the original test date of the cylinder.
(o) Marking.
(1) Marking on each cylinder must be stamped plainly and permanently on or near the shoulder, top head, neck or valve protection collar which is permanently attached to the cylinder and forming integral part thereof.
(2) Tare weight of cylinder, in pounds and ounces, must be marked on the cylinder.
(3) Cylinders, not completed, when delivered must each be marked for identification of each lot of 200 or less.
[Amdt. 178-114, 61 FR , May 23, , as amended at 66 FR , Aug. 28, ; 67 FR , Sept. 27, ; 67 FR , Aug. 8, ; 68 FR , , Dec. 31, ; 85 FR , Dec. 28, ]
(a) Type and service pressure. A DOT 8AL cylinder is a seamless steel cylinder with a service pressure of 250 psig. However, the attachment of heads by welding or by brazing by dipping process and a welded circumferential body seam is authorized. Longitudinal seams are not authorized.
(b) Authorized steel. The authorized steel is as specified in table I of appendix A to this part.
(c) Identification of steel. Material must be identified by any suitable method except that plates and billets for hot-drawn cylinders must be marked with heat number.
(d) Manufacture. Cylinders must be manufactured using equipment and processes adequate to ensure that each cylinder produced conforms to the requirements of this subpart. No defect is permitted that is likely to weaken the finished cylinder appreciably. A reasonably smooth and uniform surface finish is required. Welding procedures and operators must be qualified in accordance with CGA Pamphlet C-3 (IBR, see § 171.7 of this subchapter).
(e) Footrings. Exposed bottom welds on cylinders over 18 inches long must be protected by footrings.
(f) Welding or brazing. Welding or brazing for any purpose whatsoever is prohibited except as follows:
(1) The attachment to the tops or bottoms of cylinders of neckrings, footrings, handlers, bosses, pads, and valve protecting rings is authorized provided that such attachments and the portion of the container to which they are attached are made of weldable steel, the carbon content of which may not exceed 0.25 percent.
(2) Heat treatment is not required after welding or brazing weldable low carbon parts to attachments, specified in paragraph (f)(1) of this section, of similar material which have been previously welded or brazed to the top or bottom of cylinders and properly heat treated, provided such subsequent welding or brazing does not produce a temperature in excess of 400 °F in any part of the top or bottom material.
(g) Wall thickness; wall stress. The wall thickness/wall stress of the cylinder must conform to the following:
(1) The calculated wall stress at 750 psi may not exceed 35,000 psi, or one-half of the minimum ultimate strength of the steel as determined in paragraph (l) of this section, whichever value is the smaller. The measured wall thickness may not include galvanizing or other protective coating.
(i) Calculation of wall stress must be made by the formula:
S = [P(1.3D2 + 0.4d2)] / (D2 − d2)
Where:
S = wall stress in pounds psi;
P = 750 psig (minimum test pressure);
D = outside diameter in inches;
d = inside diameter in inches.
(ii) Either D or d must be calculated from the relation D = d + 2t, where t = minimum wall thickness.
(2) Cylinders with a wall thickness less than 0.100 inch, the ratio of straight side wall length to outside diameter may not exceed 3.5.
(3) For cylinders having outside diameter over 5 inches, the minimum wall thickness must be 0.087 inch.
(h) Heat treatment. Each cylinder must be uniformly and properly heat treated, prior to tests, by any suitable method in excess of °F. Heat treatment must be accomplished after all forming and welding operations, except that when brazed joints are used, heat treatment must follow any forming and welding operations but may be done before, during, or after the brazing operations. Liquid quenching is not authorized.
(i) Openings. Standard taper pipe threads required in all openings. The length of the opening may not be less than as specified for American Standard pipe threads; tapped to gauge; clean cut, even, and without checks.
(j) Pressure testing. Each cylinder must successfully withstand a pressure test as follows:
(1) Lot testing.
(i) At least one (1) cylinder selected at random out of each lot of 200 or less must be tested by water-jacket or direct expansion method as prescribed in CGA C-1 (IBR; see § 171.7 of this subchapter). The testing equipment must be calibrated as prescribed in CGA C-1. All testing equipment and pressure indicating devices must be accurate within the parameters defined in CGA C-1.
(ii) The selected cylinder must be tested to a minimum of 750 psig.
(iii) The minimum test pressure must be maintained at least 30 seconds and sufficiently longer to ensure complete expansion. Any internal pressure applied after heat-treatment and prior to the official test may not exceed 90 percent of the test pressure. If, due to failure of the test apparatus or operator error, the test pressure cannot be maintained, the test may be repeated in accordance with CGA C-1, section 5.7.2.
(iv) Permanent volumetric expansion may not exceed 10 percent of the total volumetric expansion at test pressure.
(v) If the selected cylinder passes the volumetric expansion test, each remaining cylinder in the lot must be pressure tested in accordance with paragraph (h)(2) of this section. If the selected cylinder fails, each cylinder in the lot must be tested by water-jacket or direct expansion method as prescribed in CGA C-1 at 750 psig. Each cylinder with a permanent expansion that does not exceed 10% is acceptable.
(2) Pressure testing.
(i) If the selected cylinder passes the water-jacket or direct expansion test, the remaining cylinders in each lot must be pressure tested by the proof pressure water-jacket or direct expansion test method as prescribed in CGA C-1. The minimum test pressure must be maintained for the specific timeframe and the testing equipment must be calibrated as prescribed in CGA C-1. Further, all testing equipment and pressure indicating devices must be accurate within the parameters defined in CGA C-1.
(ii) Each cylinder must be tested between 500 and 600 psig and show no defect. If, due to failure of the test apparatus or operator error, the test pressure cannot be maintained, the test may be repeated in accordance with CGA C-1 section 5.7.2 or 7.1.2, as appropriate. Determination of expansion properties is not required.
(k) Leakage test. Cylinders with bottoms closed in by spinning must be leakage tested by setting the interior air or gas pressure at not less than the service pressure. Any cylinder that leaks must be rejected.
(l) Physical test. A physical test must be conducted as follows;
(1) The test is required on 2 specimens cut longitudinally from 1 cylinder or part thereof taken at random out of each lot of 200 or less, after heat treatment.
(2) Specimens must conform to a gauge length of 8 inches with a width not over 11⁄2 inches, a gauge length 2 inches with a width not over 11⁄2 inches, or a gauge length at least 24 times thickness with a width not over 6 times thickness is authorized when a cylinder wall is not over 3⁄16 inch thick.
(3) The yield strength in tension must be the stress corresponding to a permanent strain of 0.2 percent of the gauge length. The following conditions apply:
(i) The yield strength must be determined by either the “offset” method or the “extension under load” method as prescribed in ASTM E 8 (IBR, see § 171.7 of this subchapter).
(ii) In using the “extension under load” method, the total strain (or “extension under load”) corresponding to the stress at which the 0.2 percent permanent strain occurs may be determined with sufficient accuracy by calculating the elastic extension of the gauge length under appropriate load and adding thereto 0.2 percent of the gauge length. Elastic extension calculations must be based on an elastic modulus of 30,000,000. In the event of controversy, the entire stress-strain diagram must be plotted and the yield strength determined from the 0.2 offset.
(iii) For the purpose of strain measurement, the initial strain must be set while the specimen is under a stress of 12,000 psi, the strain indicator reading being set at the calculated corresponding strain.
(iv) Cross-head speed of the testing machine may not exceed 1⁄8 inch per minute during yield strength determination.
(m) Elongation. Physical test specimens must show at least a 40 percent elongation for a 2 inch gauge length or at least a 20 percent elongation in other cases. Except that these elongation percentages may be reduced numerically by 2 for 2 inch specimens and 1 in other cases for each 7,500 psi increment of tensile strength above 50,000 psi to a maximum of four such increments.
(n) Weld tests. Specimens taken across the circumferentially welded seam must be cut from one cylinder taken at random from each lot of 200 or less cylinders after heat treatment and must pass satisfactorily the following tests:
(1) Tensile test. A specimen must be cut from one cylinder of each lot of 200 or less, or welded test plate. The specimen must be taken from across the major seam and must be prepared and tested in accordance with and must meet the requirements of CGA Pamphlet C-3. Should this specimen fail to meet the requirements, specimens may be taken from two additional cylinders or welded test plates from the same lot and tested. If either of the latter specimens fail to meet the requirements, the entire lot represented must be rejected.
(2) Guided bend test. A root bend test specimen must be cut from the cylinder or welded test plate, used for the tensile test specified in paragraph (n)(1) of this section. Specimens must be prepared and tested in accordance with and must meet the requirements of CGA Pamphlet C-3.
(3) Alternate guided-bend test. This test may be used and must be as required by CGA Pamphlet C-3. The specimen must be bent until the elongation at the outer surface, adjacent to the root of the weld, between the lightly scribed gage lines-a to b, must be at least 20 percent, except that this percentage may be reduced for steels having a tensile strength in excess of 50,000 psi, as provided in paragraph (m) of this section.
(o) Rejected cylinders. Reheat treatment of rejected cylinders is authorized. Subsequent thereto, cylinders must pass all prescribed tests to be acceptable. Repair by welding is authorized.
(p) Porous filling.
(1) Cylinders must be filled with a porous material in accordance with the following:
(i) The porous material may not disintegrate or sag when wet with solvent or when subjected to normal service;
(ii) The filling material must be uniform in quality and free of voids, except that a well drilled into the filling material beneath the valve is authorized if the well is filled with a material of such type that the functions of the filling material are not impaired;
(iii) Overall shrinkage of the filling material is authorized if the total clearance between the cylinder shell and filling material, after solvent has been added, does not exceed 1⁄2 of 1 percent of the respective diameter or length but not to exceed 1⁄8 inch, measured diametrically and longitudinally;
(iv) The clearance may not impair the functions of the filling material;
(v) The installed filling material must meet the requirements of CGA C-12 (IBR, see § 171.7 of this subchapter); and
(vi) Porosity of filling material may not exceed 80 percent except that filling material with a porosity of up to 92 percent may be used when tested with satisfactory results in accordance with CGA Pamphlet C-12.
(2) When the porosity of each cylinder is not known, a cylinder taken at random from a lot of 200 or less must be tested for porosity. If the test cylinder fails, each cylinder in the lot may be tested individually and those cylinders that pass the test are acceptable.
(3) For filling that is molded and dried before insertion in cylinders, porosity test may be made on sample block taken at random from material to be used.
(4) The porosity of the filling material must be determined; the amount of solvent at 70 °F for a cylinder:
(i) Having shell volumetric capacity above 20 pounds water capacity (nominal) may not exceed the following:
Percent porosity of filler Maximum acetone(ii) Having volumetric capacity of 20 pounds or less water capacity (nominal), may not exceed the following:
Percent porosity of filler Maximum acetone(q) Tare weight. The tare weight is the combined weight of the cylinder proper, porous filling, valve, and solvent, but without removable cap.
(r) Duties of inspector. In addition to the requirements of § 178.35, the inspector shall—
(1) Certify chemical analyses of steel used, signed by manufacturer thereof; also verify by check analyses, of samples taken from each heat or from 1 out of each lot of 200 or less plates, shells, or tubes used.
(2) Verify compliance of cylinder shells with all shell requirements, inspect inside before closing in both ends, verify heat treatment as proper; obtain all samples for all tests and for check analyses, witness all tests; verify threads by gauge, report volumetric capacity and minimum thickness of wall noted.
(3) Report percentage of each specified alloying element in the steel. Prepare report on manufacture of steel shells in form prescribed in § 178.35. Furnish one copy to manufacturer and three copies to the company that is to complete the cylinders.
(4) Determine porosity of filling and tare weights; verify compliance of marking with prescribed requirements; obtain necessary copies of steel shell reports prescribed in paragraph (b) of this section; and furnish complete test reports required by this specification to the person who has completed the manufacturer of the cylinders and, upon request, to the purchaser. The test reports must be retained by the inspector for fifteen years from the original test date of the cylinder.
(s) Marking.
(1) Tare weight of cylinder, in pounds and ounces, must be marked on the cylinder.
(2) Cylinders, not completed, when delivered must each be marked for identification of each lot of 200 or less.
(3) Markings must be stamped plainly and permanently in locations in accordance with the following:
(i) On shoulders and top heads not less than 0.087 inch thick; or
(ii) On neck, valve boss, valve protection sleeve, or similar part permanently attached to the top end of cylinder; or
(iii) On a plate of ferrous material attached to the top of the cylinder or permanent part thereof; the plate must be at least 1⁄16 inch thick, and must be attached by welding, or by brazing at a temperature of at least 1,100 °F throughout all edges of the plate. Sufficient space must be left on the plate to provide for stamping at least four (4) retest dates.
[Amdt. 178-114, 61 FR , May 23, , as amended at 66 FR , , Aug. 28, ; 67 FR , Aug. 8, ; 68 FR , , Dec. 31, ; 85 FR , Dec. 28, ]
(a) Type, size, pressure, and application. A DOT 4BW cylinder has a spherical or cylindrical design, a water capacity of 1,000 pounds or less, and a service pressure range of 225 to 500 psig. Closures made by the spinning process are not authorized.
(1) Spherical designs are permitted to have only one circumferentially electric-arc welded seam.
(2) Cylindrical designs must be of circumferentially welded electric-arc construction; longitudinally electric-arc welded seams are permitted.
(b) Steel.
(1) The steel used in the construction of the cylinder must be as specified in table 1 of appendix A to this part. The cylinder manufacturer must maintain a record of intentionally added alloying elements.
(2) Material for heads must meet the requirements of paragraph (b)(1) of this section or be open hearth, electric or basic oxygen carbon steel of uniform quality. Content percent may not exceed the following: Carbon 0.25, Manganese 0.60, Phosphorus 0.045, Sulfur 0.050. Heads must be hemispherical or ellipsoidal in shape with a maximum ratio of 2:1. If low carbon steel is used, the thickness of such heads must be determined by using a maximum wall stress of 24,000 psi in the formula described in paragraph (f)(2) of this section.
(c) Identification of material. Pressure-retaining materials must be identified by any suitable method that does not compromise the integrity of the cylinder. Plates and billets for hotdrawn cylinders must be marked with the heat number.
(d) Manufacture. Cylinders must be manufactured using equipment and processes adequate to ensure that each cylinder produced conforms to the requirements of this subpart and the following:
(1) No defect is permitted that is likely to weaken the finished cylinder appreciably. A reasonably smooth and uniform surface is required. Exposed bottom welds on cylinders over 18 inches long must be protected by footrings. Minimum thickness of heads may not be less than 90 percent of the required thickness of the sidewall. Heads must be concave to pressure.
(2) Circumferential seams must be by electric-arc welding. Joints must be butt with one member offset (joggle butt) or with a lap joint. Joints must have a minimum overlap of at least four (4) times nominal sheet thickness.
(3) Longitudinal electric-arc welded seams (in shells) must be of the butt welded type. Welds must be made by a machine process including automatic feed and welding guidance mechanisms. Longitudinal seams must have complete joint penetration, and must be free from undercuts, overlaps or abrupt ridges or valleys. Misalignment of mating butt edges may not exceed 1⁄6 inch of nominal sheet thickness or 1⁄32 inch whichever is less. All joints with nominal sheet thickness up to and including 1⁄8 inch must be tightly butted. When nominal sheet thickness is greater than 1⁄8 inch, the joint must be gapped with maximum distance equal to one-half the nominal sheet thickness or 1⁄32 inch whichever is less. Joint design, preparation, and fit-up must be such that requirements of this paragraph (d) are satisfied.
(4) Welding procedures and operators must be qualified in accordance with CGA C-3 (IBR, see § 171.7 of this subchapter).
(5)
(i) Welds of the cylinders must be subjected to radioscopic or radiographic examination as follows:
(ii) Radioscopy or radiography must be in conformance with CGA C-3 (IBR; see § 171.7 of this subchapter). Maximum joint efficiency will be 1.0 when each longitudinal seam is examined completely. Maximum joint efficiency will be 0.90 when one cylinder from each lot of 50 consecutively welded cylinders is spot examined. In addition, one out of the first five cylinders welded following a shutdown of welding operations exceeding four hours must be spot examined. Spot radiographs, when required, must be made of a finished welded cylinder and must include the circumferential weld for 2 inches in both directions from the intersection of the longitudinal and circumferential welds and include at least 6 inches of the longitudinal weld. Maximum joint efficiency of 0.75 will be permissible without radiography or radioscopy. When fluoroscopic examination is used, permanent film records need not be retained. Circumferential welds need not be examined, except as part of spot examination.
(e) Welding of attachments. The attachment to the tops and bottoms only of cylinders by welding of neckrings, footrings, handles, bosses, pads and valve protection rings is authorized provided that such attachments and the portion of the container to which they are attached are made of weldable steel, the carbon content of which may not exceed 0.25 percent.
(f) Wall thickness.
(1) For outside diameters over 6 inches the minimum wall thickness must be 0.078 inch. In any case, the minimum wall thickness must be such that the wall stress calculated by the formula listed in paragraph (f)(2) of this section may not exceed the lesser value of any of the following:
(i) The value referenced in paragraph (b) of this section for the particular material under consideration.
(ii) One-half of the minimum tensile strength of the material determined as required in paragraph (j) of this section.
(iii) 35,000 psig.
(2) Stress must be calculated by the following formula:
S = [2P(1.3D2 + 0.4d2)]/[E(D2 − d2)]
Where:
S = wall stress, psig;
P = service pressure, psig;
D = outside diameter, inches;
d = inside diameter, inches; and
E = joint efficiency of the longitudinal seam (from paragraph (d) of this section).
(3) For a cylinder with a wall thickness less than 0.100 inch, the ratio of tangential length to outside diameter may not exceed 4 to 1 (4:1).
(g) Heat treatment. Cylinders must be heat treated in accordance with the following requirements:
(1) Each cylinder must be uniformly and properly heat treated prior to test by the applicable method referenced in table 1 of appendix A to this part. Heat treatment must be accomplished after all forming and welding operations, except that when brazed joints are used, heat treatment must follow any forming and welding operations, but may be done before, during or after the brazing operations (see paragraph (n) of this section for weld repairs).
(2) Heat treatment is not required after welding of weldable low-carbon parts to attachments of similar material which have been previously welded to the top or bottom of cylinders and properly heat treated, provided such subsequent welding does not produce a temperature in excess of 400 °F in any part of the top or bottom material.
(h) Openings in cylinders. Openings in cylinders must comply with the following requirements:
(1) All openings must be in heads or bases.
(2) Each opening in a spherical-type cylinder must be provided with a fitting, boss, or pad of weldable steel securely attached to the cylinder by fusion welding.
(3) Each opening in a cylindrical-type cylinder must be provided with a fitting, boss, or pad securely attached to the cylinder by welding.
(4) If threads are used, they must comply with the following:
(i) Threads must be clean cut, even, without checks, and tapped to gauge.
(ii) Taper threads must be of length not less than as specified for American Standard Taper Pipe Threads.
(iii) Straight threads, having at least four (4) engaged threads, must have a tight fit and calculated shear strength at least ten (10) times the test pressure of the cylinder. Gaskets, adequate to prevent leakage, are required.
(iv) A brass fitting may be brazed to the steel boss or flange on cylinders used as component parts of handheld fire extinguishers.
(i) Pressure testing. Each cylinder must successfully withstand a pressure test as follows:
(1) Lot testing.
(i) At least one (1) cylinder randomly selected out of each lot of 200 or fewer must be tested by the water-jacket or direct expansion method as prescribed in CGA C-1 (IBR, see § 171.7 of this subchapter). The testing equipment must be calibrated as prescribed in CGA C-1. All testing equipment and pressure indicating devices must be accurate within the parameters defined in CGA C-1.
(ii) Each selected cylinder must be tested to a minimum of two (2) times service pressure.
(iii) The minimum test pressure must be maintained at least 30 seconds and sufficiently longer to ensure complete expansion. Any internal pressure applied after heat-treatment and prior to the official test may not exceed 90 percent of the test pressure. If, due to failure of the test apparatus or operator error, the test pressure cannot be maintained, the test may be repeated in accordance with CGA C-1, section 5.7.2.
(iv) Permanent volumetric expansion may not exceed 10 percent of the total volumetric expansion at test pressure.
(2) Pressure testing.
(i) The remaining cylinders in each lot must be pressure tested by the proof pressure, water-jacket or direct expansion test method as prescribed in CGA C-1. The minimum test pressure must be maintained for the specific timeframe and the testing equipment must be calibrated as prescribed in CGA C-1. Further, all testing equipment and pressure indicating devices must be accurate within the parameters defined in CGA C-1.
(ii) Each cylinder must be tested to a minimum of two (2) times service pressure and show no defect. If, due to failure of the test apparatus or operator error, the test pressure cannot be maintained, the test may be repeated in accordance with CGA C-1 5.7.2 or 7.1.2, as appropriate. Determination of expansion properties is not required.
(3) Burst testing. One finished cylinder selected at random out of each lot of 500 or less successively produced must be hydrostatically tested to four
(4) times service pressure without bursting. All testing equipment and pressure indicating devices must be accurate within the parameters defined in CGA C-1.
(j) Mechanical tests. Mechanical tests must be conducted to determine yield strength, tensile strength, elongation as a percentage, and reduction of area of material as a percentage, as follows:
(1) Specimens must be taken from one cylinder after heat treatment as illustrated in appendix A to this subpart, chosen at random from each lot of 200 or fewer, as follows:
(i) One specimen must be taken longitudinally from the body section at least 90 degrees away from the weld.
(ii) One specimen must be taken from either head on a cylinder when both heads are made of the same material. However, if the two heads are made of differing materials, a specimen must be taken from each head.
(iii) If due to welded attachments on the top head there is insufficient surface from which to take a specimen, it may be taken from a representative head of the same heat treatment as the test cylinder.
(2) Specimens must conform to the following:
(i) When a cylinder wall is 3⁄16 inch thick or less, one the following gauge lengths is authorized: A gauge length of 8 inches with a width not over 11⁄2 inches, a gauge length of 2 inches with a width not over 11⁄2 inches, or a gauge length at least twenty-four (24) times the thickness with a width not over six (6) times the thickness.
(ii) The specimen, exclusive of grip ends, may not be flattened. Grip ends may be flattened to within 1 inch of each end of the reduced section.
(iii) When size of the cylinder does not permit securing straight specimens, the specimens may be taken in any location or direction and may be straightened or flattened cold, by pressure only, not by blows. When specimens are taken, and prepared in this manner, the inspector's report must show, in connection with the record of physical tests, detailed information in regard to such specimens.
(iv) Heating of a specimen for any purpose is not authorized.
(3) The yield strength in tension must be the stress corresponding to a permanent strain of 0.2 percent of the gauge length. The following conditions apply:
(i) The yield strength must be determined by either the “off-set” method or the “extension under load” method as prescribed in ASTM E 8 (IBR, see § 171.7 of this subchapter).
(ii) In using the “extension under load” method, the total strain (or “extension under load”), corresponding to the stress at which the 0.2-percent permanent strain occurs may be determined with sufficient accuracy by calculating the elastic extension of the gauge length under appropriate load and adding thereto 0.2 percent of the gauge length. Elastic extension calculations must be based on an elastic modulus of 30,000,000. In the event of controversy, the entire stress-strain diagram must be plotted and the yield strength determined from the 0.2-percent offset.
(iii) For strain measurement, the initial strain reference must be set while the specimen is under a stress of 12,000 psig, and the strain indicator reading must be set at the calculated corresponding strain.
(iv) Cross-head speed of the testing machine may not exceed 1⁄8 inch per minute during yield strength determination.
(k) Elongation. Mechanical test specimens must show at least a 40 percent elongation for a 2-inch gauge length or at least 20 percent in other cases. However, elongation percentages may be reduced numerically by 2 percent for 2-inch specimens, and by 1 percent in other cases, for each 7,500 psi increase of tensile strength above 50,000 psig. The tensile strength may be incrementally increased by four increments of 7,500 psig for a maximum total of 30,000 psig.
(l) Tests of welds. Welds must be subjected to the following tests:
(1) Tensile test. A specimen must be removed from one cylinder of each lot of 200 or fewer. The specimen must be taken from across the longitudinal seam and must be prepared and tested in conformance with the requirements of CGA C-3 (IBR, see § 171.7 of this subchapter).
(2) Guided bend test. A root bend test specimen must be removed from the cylinder or welded test plate used for the tensile test specified in paragraph (m)(1) of this section. Specimens must be taken from across the longitudinal seam and must be prepared and tested in conformance with the requirements of CGA C-3. If the specimen fails to meet the requirements, one specimen each must be taken from two additional cylinders or welded test plates from the same lot as the previously tested cylinder or added test plate and tested. If either of these latter two specimens fails to meet the requirements, the entire lot represented must be rejected.
(3) Alternate guided bend test. This test may be used and must be as required by CGA C-3. The specimen must be bent until the elongation at the outer surface, adjacent to the root of the weld, between the lightly scribed gauge lines a to b, must be at least 20 percent, except that this percentage may be reduced for steels having a tensile strength in excess of 50,000 psig, as provided in paragraph (k) of this section. Should this specimen fail to meet the requirements, one additional specimen must be taken from two additional cylinders or welded test plates from the same lot and tested as the previously tested cylinder or added test plate. If either of these latter two specimens fails to meet the requirements, the entire lot represented must be rejected.
(m) Rejected cylinders.
(1) Unless otherwise stated, if a sample cylinder or specimen taken from a lot of cylinders fails the prescribed test, then two additional specimens must be selected from the same lot and subjected to the prescribed test. If either of these fails the test, then the entire lot must be rejected.
(2) Reheat treatment of rejected cylinders. Reheat treatment is authorized for a rejected cylinder in accordance with this paragraph (m)(2). After reheat treatment, a cylinder must pass all prescribed tests in this section to be considered acceptable. Repair of welded seams by welding is authorized. For cylinders less than or equal to an outside diameter of 6 inches, welded seam repairs greater than 1 inch in length shall require reheat treatment of the cylinder. For cylinders greater than an outside diameter of 6 inches, welded seam repairs greater than 3 inches in length shall require reheat treatment.
(n) Markings.
(1) Markings must be as required in § 178.35 and in addition must be stamped plainly and permanently in one of the following locations on the cylinder:
(i) On shoulders and top heads whose wall thickness is not less than 0.087 inch thick.
(ii) On side wall adjacent to top head for side walls not less than 0.090 inch thick.
(iii) On a cylindrical portion of the shell that extends beyond the recessed bottom of the cylinder constituting an integral and non-pressure part of the cylinder.
(iv) On a plate attached to the top of the cylinder or permanent part thereof; sufficient space must be left on the plate to provide for stamping at least six retest dates; the plate must be at least 1⁄16-inch thick and must be attached by welding at a temperature of 1,100 °F, throughout all edges of the plate.
(v) On the neck, neckring, valve boss, valve protection sleeve, or similar part permanently attached to the top of the cylinder.
(vi) On the footring permanently attached to the cylinder, provided the water capacity of the cylinder does not exceed 30 pounds.
(2) Embossing the cylinder head or side wall is not permitted.
(o) Inspector's report. In addition to the information required by § 178.35, the inspector's report must indicate the type and amount of radiography.
[85 FR , Dec. 28, ]
(a) Type, size, service pressure, and test pressure. A DOT 39 cylinder is a seamless, welded, or brazed cylinder with a service pressure not to exceed 80 percent of the test pressure. Spherical pressure vessels are authorized and covered by references to cylinders in this specification.
(1) Size limitation. Maximum water capacity may not exceed: (i) 55 pounds (1,526 cubic inches) for a service pressure of 500 p.s.i.g. or less, and (ii) 10 pounds (277 cubic inches) for a service pressure in excess of 500 p.s.i.g.
(2) Test pressure. The minimum test pressure is the maximum pressure of contents at 130 °F or 180 p.s.i.g. whichever is greater.
(3) Pressure of contents. The term “pressure of contents” as used in this specification means the total pressure of all the materials to be shipped in the cylinder.
(b) Material; steel or aluminum. The cylinder must be constructed of either steel or aluminum conforming to the following requirements:
(1) Steel.
(i) The steel analysis must conform to the following:
Ladle analysis Check analysis Carbon, maximum percent 0.12 0.15 Phosphorus, maximum percent .04 .05 Sulfur, maximum percent .05 .06(ii) For a cylinder made of seamless steel tubing with integrally formed ends, hot drawn, and finished, content percent for the following may not exceed: Carbon, 0.55; phosphorous, 0.045; sulfur, 0.050.
(iii) For non-heat treated welded steel cylinders, adequately killed deep drawing quality steel is required.
(iv) Longitudinal or helical welded cylinders are not authorized for service pressures in excess of 500 p.s.i.g.
(2) Aluminum. Aluminum is not authorized for service pressures in excess of 500 psig. The analysis of the aluminum must conform to the Aluminum Association standard for alloys , , , , , , , , and , as specified in its publication entitled “Aluminum Standards and Data” (IBR, see § 171.7 of this subchapter).
(3) Material with seams, cracks, laminations, or other injurious defects not permitted.
(4) Material used must be identified by any suitable method.
(c) Manufacture.
(1) General manufacturing requirements are as follows:
(i) The surface finish must be uniform and reasonably smooth.
(ii) Inside surfaces must be clean, dry, and free of loose particles.
(iii) No defect of any kind is permitted if it is likely to weaken a finished cylinder.
(2) Requirements for seams:
(i) Brazing is not authorized on aluminum cylinders.
(ii) Brazing material must have a melting point of not lower than 1,000 °F.
(iii) Brazed seams must be assembled with proper fit to ensure complete penetration of the brazing material throughout the brazed joint.
(iv) Minimum width of brazed joints must be at least four times the thickness of the shell wall.
(v) Brazed seams must have design strength equal to or greater than 1.5 times the minimum strength of the shell wall.
(vi) Welded seams must be properly aligned and welded by a method that provides clean, uniform joints with adequate penetration.
(vii) Welded joints must have a strength equal to or greater than the minimum strength of the shell material in the finished cylinder.
(3) Attachments to the cylinder are permitted by any means which will not be detrimental to the integrity of the cylinder. Welding or brazing of attachments to the cylinder must be completed prior to all pressure tests.
(4) Welding procedures and operators must be qualified in accordance with CGA Pamphlet C-3 (IBR, see § 171.7 of this subchapter).
(d) Wall thickness. The minimum wall thickness must be such that the wall stress at test pressure does not exceed the yield strength of the material of the finished cylinder wall. Calculations must be made by the following formulas:
(1) Calculation of the stress for cylinders must be made by the following formula:
S = [P(1.3D2 + 0.4d2)] / (D2 − d2)
Where:
S = Wall stress, in psi;
P = Test pressure in psig;
D = Outside diameter, in inches;
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d = Inside diameter, in inches.
(2) Calculation of the stress for spheres must be made by the following formula:
S = PD / 4t
Where:
S = Wall stress, in psi;
P = Test pressure i psig;
D = Outside diameter, in inches;
t = Minimum wall thickness, in inches.
(e) Openings and attachments. Openings and attachments must conform to the following:
(1) Openings and attachments are permitted on heads only.
(2) All openings and their reinforcements must be within an imaginary circle, concentric to the axis of the cylinder. The diameter of the circle may not exceed 80 percent of the outside diameter of the cylinder. The plane of the circle must be parallel to the plane of a circumferential weld and normal to the long axis of the cylinder.
(3) Unless a head has adequate thickness, each opening must be reinforced by a securely attached fitting, boss, pad, collar, or other suitable means.
(4) Material used for welded openings and attachments must be of weldable quality and compatible with the material of the cylinder.
(f) Pressure testing.
(1) Each cylinder must be proof pressure tested as prescribed in CGA C-1 (IBR, see § 171.7 of this subchapter). The minimum test pressure must be maintained for the specific timeframe and the testing equipment must be calibrated as prescribed in CGA C-1. All testing equipment and pressure indicating devices must be accurate within the parameters defined in CGA C-1.
(i) The leakage test must be conducted by submersion under water or by some other method that will be equally sensitive.
(ii) If the cylinder leaks, evidences visible distortion or evidences any other defect while under test, it must be rejected (see paragraph (h) of this section).
(iii) If, due to failure of the test apparatus or operator error, the test pressure cannot be maintained, the test may be repeated in accordance with CGA, C-1 section 7.1.2.
(2) One cylinder taken from the beginning of each lot, and one from each 1,000 or less successively produced within the lot thereafter, must be hydrostatically tested to destruction. The testing equipment must be calibrated as prescribed in CGA C-1. All testing equipment and pressure indicating devices must be accurate within the parameters defined in CGA C-1. The entire lot must be rejected (see paragraph (h) of this section) if:
(i) A failure occurs at a gage pressure less than 2.0 times the test pressure;
(ii) A failure initiates in a braze or a weld or the heat affected zone thereof;
(iii) A failure is other than in the sidewall of a cylinder longitudinal with its long axis; or
(iv) In a sphere, a failure occurs in any opening, reinforcement, or at a point of attachment.
(3) A “lot” is defined as the quantity of cylinders successively produced per production shift (not exceeding 10 hours) having identical size, design, construction, material, heat treatment, finish, and quality.
(g) Flattening test. One cylinder must be taken from the beginning of production of each lot (as defined in paragraph (f)(3) of this section) and subjected to a flattening test as follows:
(1) The flattening test must be made on a cylinder that has been tested at test pressure.
(2) A ring taken from a cylinder may be flattened as an alternative to a test on a complete cylinder. The test ring may not include the heat affected zone or any weld. However, for a sphere, the test ring may include the circumferential weld if it is located at a 45 degree angle to the ring, ±5 degrees.
(3) The flattening must be between 60 degrees included-angle, wedge shaped knife edges, rounded to a 0.5 inch radius.
(4) Cylinders and test rings may not crack when flattened so that their outer surfaces are not more than six times wall thickness apart when made of steel or not more than ten times wall thickness apart when made of aluminum.
(5) If any cylinder or ring cracks when subjected to the specified flattening test, the lot of cylinders represented by the test must be rejected (see paragraph (h) of this section).
(h) Rejected cylinders. Rejected cylinders must conform to the following requirements:
(1) If the cause for rejection of a lot is determinable, and if by test or inspection defective cylinders are eliminated from the lot, the remaining cylinders must be qualified as a new lot under paragraphs (f) and (g) of this section.
(2) Repairs to welds are permitted. Following repair, a cylinder must pass the pressure test specified in paragraph (f) of this section.
(3) If a cylinder made from seamless steel tubing fails the flattening test described in paragraph (g) of this section, suitable uniform heat treatment must be used on each cylinder in the lot. All prescribed tests must be performed subsequent to this heat treatment.
(i) Markings.
(1) The markings required by this section must be durable and waterproof. The requirements of § 178.35(h) do not apply to this section.
(2) Required markings are as follows:
(i) DOT-39.
(ii) NRC.
(iii) The service pressure.
(iv) The test pressure.
(v) The registration number (M****) of the manufacturer.
(vi) The lot number.
(vii) The date of manufacture if the lot number does not establish the date of manufacture.
(viii) With one of the following statements:
(A) For cylinders manufactured prior to October 1, : “Federal law forbids transportation if refilled-penalty up to $25,000 fine and 5 years imprisonment (49 U.S.C. )” or “Federal law forbids transportation if refilled-penalty up to $500,000 fine and 5 years imprisonment (49 U.S.C. ).”
(B) For cylinders manufactured on or after October 1, : “Federal law forbids transportation if refilled-penalty up to $500,000 fine and 5 years imprisonment (49 U.S.C. ).”
(3) The markings required by paragraphs (i)(2)(i) through (i)(2)(v) of this section must be in numbers and letters at least 1⁄8 inch high and displayed sequentially. For example:
DOT-39 NRC 250/500 M.
(4) No person may mark any cylinder with the specification identification “DOT-39” unless it was manufactured in compliance with the requirements of this section and its manufacturer has a registration number (M****) from the Associate Administrator.
[Amdt. 178-114, 61 FR , May 23, , as amended at 65 FR , Sept. 29, ; 66 FR , Aug. 28, ; 67 FR , Aug. 8, ; 68 FR , , Dec. 31, ; 85 FR , Dec. 28, ]
(a) Type, size and service pressure. A DOT 4E cylinder is a welded aluminum cylinder with a water capacity (nominal) of not over 1,000 pounds and a service pressure of at least 225 to not over 500 psig. The cylinder must be constructed of not more than two seamless drawn shells with no more than one circumferential weld. The circumferential weld may not be closer to the point of tangency of the cylindrical portion with the shoulder than 20 times the cylinder wall thickness. Cylinders or shells closed in by spinning process and cylinders with longitudinal seams are not authorized.
(b) Authorized material.
(1) The cylinder must be constructed of aluminum of uniform quality. The following chemical analyses are authorized:
Table 1 to Paragraph (b)(1)—Authorized Materials
Designation Chemical(2) The aluminum used in the construction of the cylinder must be as specified in Table 1 to paragraph (b)(1) of this section. Analyses must regularly be made only for the elements specifically mentioned in the table. If, however, the presence of other elements is indicated in the course of routine analysis, further analysis should be made to determine conformance with the limits specified for other elements. The cylinder manufacturer must maintain a record of intentionally added alloying elements.
(c) Identification. Material must be identified by any suitable method that will identify the alloy and manufacturer's lot number.
(d) Manufacture. Cylinders must be manufactured using equipment and processes adequate to ensure that each cylinder produced conforms to the requirements of this subpart. No defect is permitted that is likely to weaken the finished cylinder appreciably. A reasonably smooth and uniform surface finish is required. All welding must be by the gas shielded arc process.
(e) Welding. The attachment to the tops and bottoms only of cylinders by welding of neckrings, flanges, footrings, handles, bosses, pads, and valve protection rings is authorized. However, such attachments and the portion of the cylinder to which it is attached must be made of weldable aluminum alloys.
(f) Wall thickness. The wall thickness of the cylinder must conform to the following:
(1) The minimum wall thickness of the cylinder must be 0.140 inch. In any case, the minimum wall thickness must be such that calculated wall stress at twice service pressure may not exceed the lesser value of either of the following:
(i) 20,000 psi.
(ii) One-half of the minimum tensile strength of the material as required in paragraph (j) of this section.
(2) Calculation must be made by the following formula:
S = [P(1.3D2 + 0.4d2)] / (D2 − d2)
Where:
S = wall stress in psi;
P = minimum test pressure prescribed for water jacket test;
D = outside diameter in inches;
d = inside diameter in inches.
(3) Minimum thickness of heads and bottoms may not be less than the minimum required thickness of the side wall.
(g) Opening in cylinder. Openings in cylinders must conform to the following:
(1) All openings must be in the heads or bases.
(2) Each opening in cylinders, except those for safety devices, must be provided with a fitting, boss, or pad, securely attached to cylinder by welding by inert gas shielded arc process or by threads. If threads are used, they must comply with the following:
(i) Threads must be clean-cut, even, without checks and cut to gauge.
(ii) Taper threads to be of length not less than as specified for American Standard taper pipe threads.
(iii) Straight threads, having at least 4 engaged threads, to have tight fit and calculated shear strength at least 10 times the test pressure of the cylinder; gaskets required, adequate to prevent leakage.
(3) Closure of a fitting, boss, or pad must be adequate to prevent leakage.
(h) Pressure testing. Each cylinder must successfully withstand a pressure test as follows:
(1) Pressure test. All cylinders with a wall stress greater than 18,000 psig must be tested by water-jacket or direct expansion method as prescribed in CGA C-1 (IBR, see § 171.7 of this subchapter). The testing equipment must be calibrated as prescribed in CGA C-1. All testing equipment and pressure indicating devices must be accurate within the parameters defined in CGA C-1.
(i) Each cylinder must be tested to a minimum of two (2) times service pressure.
(ii) The minimum test pressure must be maintained at least 30 seconds and sufficiently longer to ensure complete expansion. Any internal pressure applied after heat-treatment and prior to the official test may not exceed 90 percent of the test pressure. If, due to failure of the test apparatus or operator error, the test pressure cannot be maintained, the test may be repeated in accordance with CGA C-1, section 5.7.2.
(iii) Permanent volumetric expansion may not exceed 12 percent of the total volumetric expansion at test pressure.
(2) Lot testing.
(i) Cylinders with a wall stress of 18,000 psig or less may be lot tested. At least one (1) cylinder randomly selected out of each lot of 200 or less must be tested by the water-jacket or direct expansion method as prescribed in CGA C-1. The testing equipment must be calibrated as prescribed in CGA C-1. All testing equipment and pressure indicating devices must be accurate within the parameters defined in CGA C-1. If, due to failure of the test apparatus or operator error, the test pressure cannot be maintained, the test may be repeated in accordance with CGA C-1, section 5.7.2.
(ii) Each selected cylinder must be tested to a minimum of two (2) times service pressure.
(iii) The minimum test pressure must be maintained at least 30 seconds and sufficiently longer to ensure complete expansion. Any internal pressure applied after heat-treatment and prior to the official test may not exceed 90 percent of the test pressure.
(iv) Permanent volumetric expansion may not exceed 12 percent of the total volumetric expansion at test pressure.
(3) Pressure testing.
(i) For cylinders with a wall stress of 18,000 psig or less, the remaining cylinders of the lot must be pressure tested by the proof pressure, water-jacket, or direct expansion test method as defined in CGA C-1. The minimum test pressure must be maintained for the specific timeframe and the testing equipment must be calibrated as prescribed in CGA C-1. Further, all testing equipment and pressure indicating devices must be accurate within the parameters defined in CGA C-1.
(ii) Each cylinder must be tested to a minimum of two (2) times service pressure and show no defect. If, due to failure of the test apparatus or operator error, the test pressure cannot be maintained, the test may be repeated in accordance with CGA C-1 5.7.2 or 7.1.2, as appropriate. Determination of expansion properties is not required.
(4) Burst testing. One (1) finished cylinder selected at random out of each lot of or less must be hydrostatically tested to four (4) times service pressure without bursting. Inability to meet this requirement must result in rejection of the lot. All testing equipment and pressure indicating devices must be accurate within the parameters defined in CGA C-1.
(i) Flattening test. After hydrostatic testing, a flattening test is required on one section of a cylinder, taken at random out of each lot of 200 or less as follows:
(1) If the weld is not at midlength of the cylinder, the test section must be no less in width than 30 times the cylinder wall thickness. The weld must be in the center of the section. Weld reinforcement must be removed by machining or grinding so that the weld is flush with the exterior of the parent metal. There must be no evidence of cracking in the sample when it is flattened between flat plates to no more than 6 times the wall thickness.
(2) If the weld is at midlength of the cylinder, the test may be made as specified in paragraph (i)(1) of this section or must be made between wedge shaped knife edges (60° angle) rounded to a 1⁄2 inch radius. There must be no evidence of cracking in the sample when it is flattened to no more than 6 times the wall thickness.
(j) Mechanical test. A mechanical test must be conducted to determine yield strength, tensile strength, elongation as a percentage, and reduction of area of material as a percentage as follows:
(1) The test is required on two (2) specimens removed from one cylinder or part thereof as illustrated in appendix A to this subpart taken at random out of each lot of 200 or fewer.
(2) Specimens must conform to the following:
(i) A gauge length of 8 inches with a width not over 11⁄2 inches, a gauge length of 2 inches with a width not over 11⁄2 inches.
(ii) The specimen, exclusive of grip ends, may not be flattened. Grip ends may be flattened to within 1 inch of each end of the reduced section.
(iii) When size of cylinder does not permit securing straight specimens, the specimens may be taken in any location or direction and may be straightened or flattened cold, by pressure only, not by blows; when specimens are so taken and prepared, the inspector's report must show in connection with record of physical test detailed information in regard to such specimens.
(iv) Heating of a specimen for any purpose is not authorized.
(3) The yield strength in tension must be the stress corresponding to a permanent strain of 0.2 percent of the gauge length. The following conditions apply:
(i) The yield strength must be determined by the “offset” method as prescribed in ASTM E 8 (IBR, see § 171.7 of this subchapter).
(ii) Cross-head speed of the testing machine may not exceed 1⁄8 inch per minute during yield strength determination.
(k) Acceptable results for mechanical tests. An acceptable result of the mechanical test requires at least 7 percent and yield strength not over 80 percent of tensile strength.
(l) Weld tests. Welds of the cylinder are required to pass the following tests successfully:
(1) Reduced section tensile test. A specimen must be removed from the cylinder used for the mechanical tests specified in paragraph (j) of this section. The specimen must be taken from across the seam; edges must be parallel for a distance of approximately 2 inches on either side of the weld. The specimen must be fractured in tension. The actual breaking stress must be a minimum of 30,000 psi. The apparent breaking stress calculated on the minimum design wall thickness must be a minimum of two (2) times the stress calculated under paragraph (f)(2) of this section. If the specimen fails to meet the requirements, the lot must be rejected except that specimens may be taken from two (2) additional cylinders from the same lot as the previously tested specimens. If either of the latter specimens fails to meet requirements, the entire lot represented must be rejected.
(2) Guided bend test. A bend test specimen must be removed from the cylinder used for the mechanical test specified in paragraph (j) of this section. The specimen must be taken across the circumferential seam, must be a minimum of 11⁄2 inches wide, edges must be parallel and rounded with a file, and back-up strip, if used, must be removed by machining. The specimen must be tested as follows:
(i) Standard guided bend test. The specimen must be bent to refusal in the guided bend test jig as illustrated in CGA C-3 (IBR, see § 171.7 of this subchapter). The root of the weld (inside surface of the cylinder) must be located away from the ram of the jig. The specimen must not show a crack or other open defect exceeding 1⁄8 inch in any direction upon completion of the test. Should this specimen fail to meet the requirements, one additional specimen must be taken from two additional cylinders from the same lot and tested. If either of the latter specimens fails to meet requirements, the entire lot represented must be rejected.
(ii) Alternate guided bend test. This test may be used as an alternate to the guided bend test. The test specimen must be in conformance with The Aluminum Association's “Welding Aluminum: Theory and Practice, Fourth Edition, ” (IBR, see § 171.7 of this subchapter). If the specimen fails to meet the requirements, one additional specimen must be taken from two additional cylinders or welded test plates from the same lot and tested. If any of these latter two specimens fails to meet the requirements, the entire lot must be rejected.
(m) Rejected cylinders. Repair of welded seams is authorized. Acceptable cylinders must pass all prescribed tests.
(n) Markings.
(1) Markings must be as required in § 178.35 and in addition must be stamped plainly and permanently in one of the following locations on the cylinder:
(i) On the neck, neckring, valve boss, valve protection sleeve, or similar part permanently attached to the top of the cylinder.
(ii) On the footring permanently attached to the cylinder, provided the water capacity of the cylinder does not exceed 30 pounds.
(2) Embossing the cylinder head or side wall is not permitted.
(o) Inspector's report. In addition to the information required by § 178.35, the record of chemical analyses must also include applicable information on iron, titanium, zinc, and magnesium used in the construction of the cylinder.
[Amdt. 178-114, 61 FR , May 23, , as amended at 62 FR , Oct. 1, ; 66 FR , Aug. 28, ; 67 FR , Aug. 8, ; 68 FR , Dec. 31, ; 69 FR , Sept. 7, ; 74 FR , Apr. 9, ; 85 FR , Dec. 27, ]
(a) Each manufacturer of a UN pressure receptacle marked with “USA” as a country of approval must comply with the requirements in this section. The manufacturer must maintain a quality system, obtain an approval for each initial pressure receptacle design type, and ensure that all production of UN pressure receptacles meets the applicable requirements.
(1) Quality system. The manufacturer of a UN pressure receptacle must have its quality system approved by the Associate Administrator. The quality system will initially be assessed through an audit by the Associate Administrator or his or her representative to determine whether it meets the requirements of this section. The Associate Administrator will notify the manufacturer in writing of the results of the audit. The notification will contain the conclusions of the audit and any corrective action required. The Associate Administrator may perform periodic audits to ensure that the manufacturer operates in accordance with the quality system. Reports of periodic audits will be provided to the manufacturer. The manufacturer must bear the cost of audits.
(2) Quality system documentation. The manufacturer must be able to demonstrate a documented quality system. Management must review the adequacy of the quality system to assure that it is effective and conforms to the requirements in § 178.70. The quality system records must be in English and must include detailed descriptions of the following:
(i) The organizational structure and responsibilities of personnel with regard to design and product quality;
(ii) The design control and design verification techniques, processes, and procedures used when designing the pressure receptacles;
(iii) The relevant procedures for pressure receptacle manufacturing, quality control, quality assurance, and process operation instructions;
(iv) Inspection and testing methodologies, measuring and testing equipment, and calibration data;
(v) The process for meeting customer requirements;
(vi) The process for document control and document revision;
(vii) The system for controlling non-conforming material and records, including procedures for identification, segregation, and disposition;
(viii) Production, processing and fabrication, including purchased components, in-process and final materials; and
(ix) Training programs for relevant personnel.
(3) Maintenance of quality system. The manufacturer must maintain the quality system as approved by the Associate Administrator. The manufacturer shall notify the Associate Administrator of any intended changes to the approved quality system prior to making the change. The Associate Administrator will evaluate the proposed change to determine whether the amended quality system will satisfy the requirements. The Associate Administrator will notify the manufacturer of the findings.
(b) Design type approvals. The manufacturer must have each pressure receptacle design type reviewed by an IIA and approved by the Associate Administrator in accordance with § 178.70. A cylinder is considered to be of a new design, compared with an existing approved design, as stated in the applicable ISO design, construction and testing standard.
(c) Production inspection and certification. The manufacturer must ensure that each UN pressure receptacle is inspected and certified in accordance with § 178.71.
[71 FR , June 12, ]
(a) Initial design-type approval. The manufacturer of a UN pressure receptacle must obtain an initial design type approval from the Associate Administrator. The initial design type approval must be of the pressure receptacle design as it is intended to be produced. The manufacturer must arrange for an IIA, approved by the Associate Administrator in accordance with subpart I of part 107 of this chapter, to perform a pre-audit of its pressure receptacle manufacturing operation prior to having an audit conducted by the Associate Administrator or his designee.
(b) IIA pre-audit. The manufacturer must submit an application for initial design type approval to the IIA for review. The IIA will examine the manufacturer's application for initial design type approval for completeness. An incomplete application will be returned to the manufacturer with an explanation. If an application is complete, the IIA will review all technical documentation, including drawings and calculations, to verify that the design meets all requirements of the applicable UN pressure receptacle standard and specification requirements. If the technical documentation shows that the pressure receptacle prototype design conforms to the applicable standards and requirements in § 178.70, the manufacturer will fabricate a prototype lot of pressure receptacles in conformance with the technical documentation representative of the design. The IIA will verify that the prototype lot conforms to the applicable requirements by selecting pressure receptacles and witnessing their testing. After prototype testing has been satisfactorily completed, showing the pressure receptacles fully conform to all applicable specification requirements, the certifying IIA must prepare a letter of recommendation and a design type approval certificate. The design type approval certificate must contain the name and address of the manufacturer and the IIA certifying the design type, the test results, chemical analyses, lot identification, and all other supporting data specified in the applicable ISO design, construction and testing standard. The IIA must provide the certificate and documentation to the manufacturer.
(c) Application for initial design type approval. If the pre-audit is found satisfactory by the IIA, the manufacturer will submit the letter of recommendation from the IIA and an application for design type approval to the Associate Administrator. An application for initial design type approval must be submitted for each manufacturing facility. The application must be in English and, at a minimum, contain the following information:
(1) The name and address of the manufacturing facility. If the application is submitted by an authorized representative on behalf of the manufacturer, the application must include the representative's name and address.
(2) The name and title of the individual responsible for the manufacturer's quality system, as required by § 178.69.
(3) The designation of the pressure receptacle and the relevant pressure receptacle standard.
(4) Details of any refusal of approval of a similar application by a designated approval agency of another country.
(5) The name and address of the production IIA that will perform the functions prescribed in paragraph (e) of this section. The IIA must be approved in writing by the Associate Administrator in accordance with subpart I of part 107 of this chapter.
(6) Documentation on the manufacturing facility as specified in § 178.69.
(7) Design specifications and manufacturing drawings, showing components and subassemblies if relevant, design calculations, and material specifications necessary to verify compliance with the applicable pressure receptacle design standard.
(8) Manufacturing procedures and any applicable standards that describe in detail the manufacturing processes and control.
(9) Design type approval test reports detailing the results of examinations and tests conducted in accordance with the relevant pressure receptacle standard, to include any additional data, such as suitability for underwater applications or compatibility with hydrogen embrittlement gases.
(d) Modification of approved pressure receptacle design type. Modification of an approved UN (ISO) pressure receptacle design type is not authorized without the approval of the Associate Administrator. However, modification of an approved UN (ISO) pressure receptacle design type is authorized without an additional approval of the Associate Administrator provided the design modification is covered under the UN (ISO) standard for the design type. A manufacturer seeking modification of an approved UN (ISO) pressure receptacle design type may be required to submit design qualification test data to the Associate Administrator before production. An audit may be required as part of the process to modify an approval.
(e) Responsibilities of the production IIA. The production IIA is responsible for ensuring that each pressure receptacle conforms to the design type approval. The production IIA must perform the following functions:
(1) Witness all inspections and tests specified in the UN pressure receptacle standard to ensure compliance with the standard and that the procedures adopted by the manufacturer meet the requirements of the standard;
(2) Verify that the production inspections were performed in accordance with this section;
(3) Select UN pressure receptacles from a prototype production lot and witness testing as required for the design type approval;
(4) Ensure that the various design type approval examinations and tests are performed accurately;
(5) Verify that each pressure receptacle is marked in accordance with the applicable requirements in § 178.71; and
(6) Furnish complete test reports to the manufacturer and upon request to the purchaser. The test reports and certificate of compliance must be retained by the IIA for at least 20 years from the original test date of the pressure receptacles.
(f) Production inspection audit and certification.
(1) If the application, design drawing and quality control documents are found satisfactory, PHMSA will schedule an on-site audit of the pressure receptacle manufacturer's quality system, manufacturing processes, inspections, and test procedures.
(2) During the audit, the manufacturer will be required to produce pressure receptacles to the technical standards for which approval is sought.
(3) The production IIA must witness the required inspections and verifications on the pressure receptacles during the production run. The IIA selected by the manufacturer for production inspection and testing may be different from the IIA who performed the design type approval verifications.
(4) If the procedures and controls are deemed acceptable, test sample pressure receptacles will be selected at random from the production lot and sent to a laboratory designated by the Associate Administrator for verification testing.
(5) If the pressure receptacle test samples are found to conform to all the applicable requirements, the Associate Administrator will issue approvals to the manufacturer and the production IIA to authorize the manufacture of the pressure receptacles. The approved design type approval certificate will be returned to the manufacturer.
(6) Upon the receipt of the approved design type approval certificate from the Associate Administrator, the pressure receptacle manufacturer must sign the certificate.
(g) Recordkeeping. The production IIA and the manufacturer must retain a copy of the design type approval certificate and certificate of compliance records for at least 20 years.
(h) Denial of design type application. If the design type application is denied, the Associate Administrator will notify the applicant in writing and provide the reason for the denial. The manufacturer may request that the Associate Administrator reconsider the decision. The application request must—
(1) Be written in English and filed within 60 days of receipt of the decision;
(2) State in detail any alleged errors of fact and law; and
(3) Enclose any additional information needed to support the request to reconsider.
(i) Appeal.
(1) A manufacturer whose reconsideration request is denied may appeal to the PHMSA Administrator. The appeal must—
(i) Be written in English and filed within 60 days of receipt of the Associate Administrator's decision on reconsideration;
(ii) State in detail any alleged errors of fact and law;
(iii) Enclose any additional information needed to support the appeal; and
(iv) State in detail the modification of the final decision sought.
(2) The PHMSA Administrator will grant or deny the relief and inform the appellant in writing of the decision. PHMSA Administrator's decision is the final administrative action.
(j) Termination of a design type approval certificate.
(1) The Associate Administrator may terminate an approval certificate issue under this section if it is determined that, because of a change in circumstances, the approval no longer is needed or no longer would be granted if applied for; information upon which the approval was based is fraudulent or substantially erroneous; or termination of the approval is necessary to adequately protect against risks to life and property.
(2) Before an approval is terminated, the Associate Administrator will provide the manufacturer and the approval agency—
(i) Written notice of the facts or conduct believed to warrant the withdrawal;
(ii) Opportunity to submit oral and written evidence, and
(iii) Opportunity to demonstrate or achieve compliance with the application requirement.
(3) If the Associate Administrator determines that a certificate of approval must be withdrawn to preclude a significant and imminent adverse affect on public safety, the procedures in paragraph (j)(2)(ii) and (iii) of this section need not be provided prior to withdrawal of the approval, but shall be provided as soon as practicable thereafter.
[71 FR , June 12, , as amended at 71 FR , Sept. 14, ; 77 FR , Oct. 5, ; 85 FR , Dec. 28, ]
(a) General. Each UN pressure receptacle must meet the requirements of this section. UN pressure receptacles and service equipment constructed according to the standards applicable at the date of manufacture may continue in use subject to the continuing qualification and maintenance provisions of part 180 of this subchapter. Requirements for approval, qualification, maintenance, and testing are contained in § 178.70, and subpart C of part 180 of this subchapter.
(b) Definitions. The following definitions apply for the purposes of design and construction of UN pressure receptacles under this subpart:
Alternative arrangement means an approval granted by the Associate Administrator for a MEGC that has been designed, constructed or tested to the technical requirements or testing methods other than those specified for UN pressure receptacles in part 178 or part 180 of this subchapter.
Bundle of cylinders. See § 171.8 of this subchapter.
Design type means a pressure receptacle design as specified by a particular pressure receptacle standard.
Design type approval means an overall approval of the manufacturer's quality system and design type of each pressure receptacle to be produced within the manufacturer's facility.
UN tube. See § 171.8 of this subchapter.
(c) Following the final heat treatment, all cylinders, except those selected for batch testing must be subjected to a proof pressure or a hydraulic volumetric expansion test.
(d) Service equipment.
(1) Except for pressure relief devices, UN pressure receptacle equipment, including valves, piping, fittings, and other equipment subjected to pressure must be designed and constructed to withstand at least 1.5 times the test pressure of the pressure receptacle.
(2) Service equipment must be configured, or designed, to prevent damage that could result in the release of the pressure receptacle contents during normal conditions of handling and transport. Manifold piping leading to shut-off valves must be sufficiently flexible to protect the valves and the piping from shearing or releasing the pressure receptacle contents. The filling and discharge valves and any protective caps must be secured against unintended opening. The valves must conform to ISO :(E) and ISO :/Amd 1:(E) (IBR, see § 171.7 of this subchapter), or for non-refillable pressure receptacles valves manufactured until December 31, , ISO :(E), and be protected as specified in § 173.301b(f) of this subchapter. Until December 31, , the manufacture of a valve conforming to the requirements of ISO :(E) is authorized. Until December 31, , the manufacture of a valve conforming to the requirements in ISO :(E) (IBR, see § 171.7 of this subchapter) was authorized. Until December 31, , the manufacture of a valve conforming to the requirements in ISO :(E) (IBR, see § 171.7 of this subchapter) was authorized. Additionally, valves must be initially inspected and tested in accordance with ISO :(E) and ISO :/Amd 1:(E), (IBR, see § 171.7 of this subchapter). For self-closing valves with inherent protection, the requirements of ISO :(E) (IBR, see § 171.7 of this subchapter) shall be met until further notice.
(3) UN pressure receptacles that cannot be handled manually or rolled, must be equipped with devices (e.g., skids, rings, straps) ensuring that they can be safely handled by mechanical means and so arranged as not to impair the strength of, nor cause undue stresses, in the pressure receptacle.
(4) Pressure receptacles filled by volume must be equipped with a level indicator.
(e) Bundles of cylinders. UN pressure receptacles assembled in bundles must be structurally supported and held together as a unit and secured in a manner that prevents movement in relation to the structural assembly and movement that would result in the concentration of harmful local stresses. The frame design must ensure stability under normal operating conditions.
(1) The frame must securely retain all the components of the bundle and must protect them from damage during conditions normally incident to transportation. The method of cylinder restraint must prevent any vertical or horizontal movement or rotation of the cylinder that could cause undue strain on the manifold. The total assembly must be able to withstand rough handling, including being dropped or overturned.
(2) The frame must include features designed for the handling and transportation of the bundle. The lifting rings must be designed to withstand a design load of 2 times the maximum gross weight. Bundles with more than one lifting ring must be designed such that a minimum sling angle of 45 degrees to the horizontal can be achieved during lifting using the lifting rings. If four lifting rings are used, their design must be strong enough to allow the bundle to be lifted by two rings. Where two or four lifting rings are used, diametrically opposite lifting rings must be aligned with each other to allow for correct lifting using shackle pins. If the bundle is filled with forklift pockets, it must contain two forklift pockets on each side from which it is to be lifted. The forklift pockets must be positioned symmetrically consistent with the bundle center of gravity.
(3) The frame structural members must be designed for a vertical load of 2 times the maximum gross weight of the bundle. Design stress levels may not exceed 0.9 times the yield strength of the material.
(4) The frame must not contain any protrusions from the exterior frame structure that could cause a hazardous condition.
(5) The frame design must prevent collection of water or other debris that would increase the tare weight of bundles filled by weight.
(6) The floor of the bundle frame must not buckle during normal operating conditions and must allow for the drainage of water and debris from around the base of the cylinders.
(7) If the frame design includes movable doors or covers, they must be capable of being secured with latches or other means that will not become dislodged by operational impact loads. Valves that need to be operated in normal service or in an emergency must be accessible.
(8) For bundles of cylinders, pressure receptacle marking requirements only apply to the individual cylinders of a bundle and not to any assembly structure.
(f) Design and construction requirements for UN refillable welded cylinders and UN pressure drums. In addition to the general requirements of this section, UN refillable welded cylinders and UN pressure drums must conform to the following ISO standards, as applicable:
(1) ISO : Gas cylinders—Refillable welded steel cylinders—Test pressure 60 bar and below (IBR, see § 171.7 of this subchapter).
(2) ISO -1: Gas cylinders—Refillable welded stainless steel cylinders—Part 1: Test pressure 6 MPa and below (IBR, see § 171.7 of this subchapter).
(3) ISO : Gas cylinders—Refillable welded aluminum-alloy cylinders—Design, construction and testing (IBR, see § 171.7 of this subchapter).
(4) ISO -1:(E) Gas cylinders—Welded steel pressure drums up to 3,000 litres capacity for the transport of gases—Design and construction—Part 1: Capacities up-to 1,000 litres (IBR, see § 171.7 of this subchapter) in combination with ISO -1:/Amd 1:(E)—Gas Cylinders—Welded steel pressure drums up to 3,000 litres capacity for the transport of gases—Design and construction—Part 1: Capacities up—to 1,000 litres—Amendment 1 (IBR, see § 171.7 of this subchapter). Until December 31, , the use of ISO -1: (IBR, see § 171.7 of this subchapter) without the supplemental amendment is authorized.
(g) Design and construction requirements for UN refillable seamless steel cylinders. In addition to the general requirements of this section, UN refillable seamless steel cylinders must conform to the following ISO standards, as applicable:
(1) ISO -1:(E), Gas cylinders—Refillable seamless steel gas cylinders—Design, construction, and testing—Part 1: Quenched and tempered steel cylinders with tensile strength less than MPa (IBR, see § 171.7 of this subchapter). Until December 31, , the manufacture of a cylinder conforming to the requirements in ISO -1:(E) (IBR, see § 171.7 of this subchapter) is authorized.
(2) ISO -2:(E), Gas cylinders—Design, construction, and testing of refillable seamless steel gas cylinders and tubes—Part 2: Quenched and tempered steel cylinders and tubes with tensile strength greater than or equal to MPa (IBR, see § 171.7 of this subchapter). Until December 31, , the manufacture of a cylinder conforming to the requirements in ISO -2: (IBR, see § 171.7 of this subchapter) is authorized.
(3) ISO -3:(E), Gas cylinders—Design, construction, and testing of refillable seamless steel gas cylinders and tubes—Part 3: Normalized steel cylinders and tubes. (IBR, see § 171.7 of this subchapter). Until December 31, , a cylinder may instead conform to ISO -3:(E) (IBR, see § 171.7 of this subchapter).
(4) ISO -4:(E), Gas cylinders—Refillable seamless steel gas cylinders—Design, construction, and testing—Part 4: Stainless steel cylinders with an Rm value of less than 1,100 MPa (IBR, see § 171.7 of this subchapter).
(h) Design and construction requirements for UN refillable seamless aluminum alloy cylinders. In addition to the general requirements of this section, UN refillable seamless aluminum cylinders must conform to ISO :(E) as modified by ISO :/Cor.1:(E) (IBR, see § 171.7 of this subchapter). Until December 31, , the manufacture of a cylinder conforming to the requirements in ISO (E) (IBR, see § 171.7 of this subchapter) is authorized. The use of Aluminum alloy -T6 or equivalent is prohibited.
(i) Design and construction requirements for UN non-refillable metal cylinders. In addition to the general requirements of this section, UN non-refillable metal cylinders must conform to ISO :(E) Gas cylinders—Non-refillable metallic gas cylinders—Specification and test methods, in combination with ISO :/Amd 1: Gas cylinders—Non-refillable metallic gas cylinders—Specification and test methods—Amendment 1. (IBR, see § 171.7 of this subchapter). Until December 31, , the use of ISO : (IBR, see § 171.7 of this subchapter) without the supplemental amendment is authorized.
(j) Design and construction requirements for UN refillable seamless steel tubes. In addition to the general requirements of this section, UN refillable seamless steel tubes must conform to ISO :(E) Gas cylinders—Refillable seamless steel tubes of water capacity between 150 L and 3,000 L—Design, construction and testing (IBR, see § 171.7 of this subchapter). Until December 31, , UN refillable seamless steel tubes may be manufactured in accordance with ISO : Gas cylinders—Refillable seamless steel tubes of water capacity between 150 L and 3,000 L—Design, construction and testing (IBR, see § 171.7 of this subchapter)
(k) Design and construction requirements for UN acetylene cylinders. In addition to the general requirements of this section, UN acetylene cylinders must conform to the following ISO standards, as applicable:
(1) For the cylinder shell:
(i) ISO -1:(E) Gas cylinders—Refillable seamless steel gas cylinders—Design, construction, and testing—Part 1: Quenched and tempered steel cylinders with tensile strength less than MPa (IBR, see § 171.7 of this subchapter). Until December 31, , the manufacture of a cylinder conforming to the requirements in ISO -1:(E) (IBR, see § 171.7 of this subchapter) is authorized.
(ii) ISO -3:(E) Gas cylinders—Design, construction, and testing of refillable seamless steel gas cylinders and tubes—Part 3: Normalized steel cylinders and tubes (IBR, see § 171.7 of this subchapter). Until December 31, , the manufacture of a cylinder conforming to the requirements in ISO -3:(E) (IBR, see § 171.7 of this subchapter) is authorized.
(2) The porous mass in an acetylene cylinder must conform to ISO :(E) (IBR, see § 171.7 of this subchapter). Until December 31, , the manufacture of a cylinder conforming to the requirements in ISO -2(E) (IBR, see § 171.7 of this subchapter) is authorized.
(l) Design and construction requirements for UN composite cylinders and tubes.
(1) In addition to the general requirements of this section, UN composite cylinders and tubes must be designed for a design life of not less than 15 years. Composite cylinders and tubes with a design life longer than 15 years must not be filled after 15 years from the date of manufacture, unless the design has successfully passed a service life test program. The service life test program must be part of the initial design type approval and must specify inspections and tests to demonstrate that cylinders manufactured accordingly remain safe to the end of their design life. The service life test program and the results must be approved by the competent authority of the country of approval that is responsible for the initial approval of the cylinder design. The service life of a composite cylinder or tube must not be extended beyond its initial approved design life. Additionally, composite cylinders and tubes must conform to the following ISO standards, as applicable:
(i) ISO -1:(E) (IBR, see § 171.7 of this subchapter). Until December 31, , cylinders conforming to the requirements in ISO -1(E), (IBR, see § 171.7 of this subchapter) are authorized.
(ii) ISO -2:(E) (ISO -2:/Amd.1:(E)) (IBR, see § 171.7 of this subchapter). Until December 31, , cylinders conforming to the requirements in ISO -2(E) (IBR, see § 171.7 of this subchapter) are authorized.
(iii) ISO -3:(E) (IBR, see § 171.7 of this subchapter). Until December 31, , cylinders conforming to the requirements in ISO -3(E) (IBR, see § 171.7 of this subchapter) are authorized.
(iv) ISO -4:(E) (IBR, see § 171.7 of this subchapter).
(2) ISO -2 and ISO -3 gas cylinders of composite construction manufactured in accordance with the requirements for underwater use must bear the “UW” mark.
(m) Design and construction requirements for UN metal hydride storage systems. In addition to the general requirements of this section, metal hydride storage systems must conform to ISO :(E) Transportable gas storage devices—Hydrogen absorbed in reversible metal hydride (IBR, see § 171.7 of this subchapter). Until December 31, , the manufacture of a UN metal hydride storage system conforming to the requirements in ISO : (IBR, see § 171.7 of this subchapter) is authorized.
(n) Design and construction requirements for UN cylinders for the transportation of adsorbed gases. In addition to the general requirements of this section, UN cylinders for the transportation of adsorbed gases must conform to the following ISO standards, as applicable:
(1) ISO :, Gas cylinders—Refillable welded steel cylinders containing materials for sub-atmospheric gas packaging (excluding acetylene)—Design, construction, testing, use and periodic inspection (IBR, see § 171.7 of this subchapter). Until December 31, , the manufacture of a cylinder conforming to the requirements in ISO :(E) (IBR, see § 171.7 of this subchapter) is authorized.
(2) ISO -1:(E): Gas cylinders—Refillable seamless steel gas cylinders—Design, construction, and testing—Part 1: Quenched and tempered steel cylinders with tensile strength less than MPa (IBR, see § 171.7 of this subchapter). Until December 31, , the manufacture of a cylinder conforming to the requirements in ISO -1:(E) (IBR, see § 171.7 of this subchapter is authorized.
(o) Material compatibility. In addition to the material requirements specified in the UN pressure receptacle design and construction ISO standards, and any restrictions specified in part 173 for the gases to be transported, the requirements of the following standards must be applied with respect to material compatibility:
(1) ISO -1:(E) and -1:/Amd 1:(E) (IBR, see § 171.7 of this subchapter).
(2) ISO -2:(E) (IBR, see § 171.7 of this subchapter).
(p) Protection of closures. Closures and their protection must conform to the requirements in § 173.301(f) of this subchapter.
(q) Marking of UN refillable pressure receptacles. UN refillable pressure receptacles must be marked clearly and legibly. The required markings must be permanently affixed by stamping, engraving, or other equivalent method, on the shoulder, top end or neck of the pressure receptacle or on a permanently affixed component of the pressure receptacle, such as a welded collar. Except for the “UN” mark, the minimum size of the marks must be 5 mm for pressure receptacles with a diameter greater than or equal to 140 mm, and 2.5 mm for pressure receptacles with a diameter less than 140 mm. The minimum size of the “UN” mark must be 5 mm for pressure receptacles with a diameter less than 140 mm, and 10 mm for pressure receptacles with a diameter of greater than or equal to 140 mm. The depth of the markings must not create harmful stress concentrations. A refillable pressure receptacle conforming to the UN standard must be marked as follows:
(1) The UN packaging symbol.
(2) The ISO standard, for example ISO -1, used for design, construction and testing. Acetylene cylinders must be marked to indicate the porous mass and the steel shell, for example: “ISO -2/ISO -1.”
(3) The mark of the country where the approval is granted. The letters “USA” must be marked on UN pressure receptacles approved by the United States. The manufacturer must obtain an approval number from the Associate Administrator. The manufacturer approval number must follow the country of approval mark, separated by a slash (for example, USA/MXXXX). Pressure receptacles approved by more than one national authority may contain the mark of each country of approval, separated by a comma.
(4) The identity mark or stamp of the IIA.
(5) The date of the initial inspection, the year (four digits) followed by the month (two digits) separated by a slash, for example “/04”.
(6) The test pressure in bar, preceded by the letters “PH” and followed by the letters “BAR”.
(7) The rated charging pressure of the metal hydride storage system in bar, preceded by the letters “RCP” and followed by the letters “BAR.”
(8) The empty or tare weight. Except for acetylene cylinders, empty weight is the mass of the pressure receptacle in kilograms, including all integral parts (e.g., collar, neck ring, foot ring, etc.), followed by the letters “KG”. The empty weight does not include the mass of the valve, valve cap or valve guard or any coating. The empty weight must be expressed to three significant figures rounded up to the last digit. For cylinders of less than 1 kg, the empty weight must be expressed to two significant figures rounded down to the last digit. For acetylene cylinders, the tare weight must be marked on the cylinders in kilograms. The tare weight is the sum of the empty weight, mass of the valve, any coating and all permanently attached parts (e.g., fittings and accessories) that are not removed during filling. The tare weight must be expressed to two significant figures rounded down to the last digit. The tare weight does not include the cylinder cap or any outlet cap or plug not permanently attached to the cylinder.
(9) The minimum wall thickness of the pressure receptacle in millimeters followed by the letters “MM”. This mark is not required for pressure receptacles with a water capacity less than or equal to 1.0 L or for composite cylinders.
(10) For pressure receptacles intended for the transport of compressed gases and UN acetylene, dissolved, the working pressure in bar, proceeded by the letters “PW”.
(11) For liquefied gases, the water capacity in liters expressed to three significant digits rounded down to the last digit, followed by the letter “L”. If the value of the minimum or nominal water capacity is an integer, the digits after the decimal point may be omitted.
(12) Identification of the cylinder thread type (e.g., 25E). Information on the marks that may be used for identifying threads for cylinders is given in ISO/TR , Gas Cylinders—Compilation of national and international valve stem/gas cylinder neck threads and their identification and marking system (IBR, see § 171.7 of this subchapter).
(13) The country of manufacture. The letters “USA” must be marked on cylinders manufactured in the United States.
(14) The serial number assigned by the manufacturer.
(15) For steel pressure receptacles, the letter “H” showing compatibility of the steel, as specified in ISO -1.
(16) Identification of aluminum alloy, if applicable.
(17) Stamp for nondestructive testing, if applicable.
(18) Stamp for underwater use of composite cylinders, if applicable.
(19) For metal hydride storage systems having a limited life, the date of expiration indicated by the word “FINAL,” followed by the year (four digits), the month (two digits) and separated by a slash.
(20) For composite cylinders and tubes having a limited design life, the letters “FINAL” followed by the design life shown as the year (four digits) followed by the month (two digits) separated by a slash (i.e. “/”).
(21) For composite cylinders and tubes having a limited design life greater than 15 years and for composite cylinders and tubes having non-limited design life, the letters “SERVICE” followed by the date 15 years from the date of manufacture (initial inspection) shown as the year (four digits) followed by the month (two digits) separated by a slash (i.e. “/”).
(r) Marking sequence. The marking required by paragraph (q) of this section must be placed in three groups as shown in the example below:
(1) The top grouping contains manufacturing marks and must appear consecutively in the sequence given in paragraphs (q)(13) through (19) of this section.
(2) The middle grouping contains operational marks described in paragraphs (q)(6) through (11) of this section.
(3) The bottom grouping contains certification marks and must appear consecutively in the sequence given in paragraphs (q)(1) through (5) of this section.
(s) Other markings. Other markings are allowed in areas other than the side wall, provided they are made in low stress areas and are not of a size and depth that will create harmful stress concentrations. Such marks must not conflict with required marks.
(t) Marking of UN non-refillable pressure receptacles. Unless otherwise specified in this paragraph, each UN non-refillable pressure receptacle must be clearly and legibly marked as prescribed in paragraph (q) of this section. In addition, permanent stenciling is authorized. Except when stenciled, the marks must be on the shoulder, top end or neck of the pressure receptacle or on a permanently affixed component of the pressure receptacle (e.g., a welded collar).
(1) The marking requirements and sequence listed in paragraphs (q)(1) through (19) of this section are required, except the markings in paragraphs (q)(8), (9), (12) and (18) are not applicable. The required serial number marking in paragraph (q)(14) may be replaced by the batch number.
(2) Each receptacle must be marked with the words “DO NOT REFILL” in letters of at least 5 mm in height.
(3) A non-refillable pressure receptacle, because of its size, may substitute the marking required by this paragraph with a label. Reduction in marking size is authorized only as prescribed in ISO , Gas cylinders—Precautionary labels. (IBR, see § 171.7 of this subchapter).
(4) Each non-refillable pressure receptacle must also be legibly marked by stenciling the following statement: “Federal law forbids transportation if refilled-penalty up to $500,000 fine and 5 years in imprisonment (49 U.S.C. ).”
(u) Marking of bundles of cylinders.
(1) Individual cylinders in a bundle of cylinders must be marked in accordance with paragraphs (q), (r), (s) and (t) of this section as appropriate.
(2) Refillable UN bundles of cylinders must be marked clearly and legibly with certification, operational, and manufacturing marks. These marks must be permanently affixed (e.g., stamped, engraved, or etched) on a plate permanently attached to the frame of the bundle of cylinders. Except for the “UN” mark, the minimum size of the marks must be 5 mm. The minimum size of the “UN” mark must be 10 mm. A refillable UN bundle of cylinders must be marked with the following:
(i) The UN packaging symbol;
(ii) The ISO standard, for example ISO -1, used for design, construction and testing. Acetylene cylinders must be marked to indicate the porous mass and the steel shell, for example: “ISO -2/ISO -1”;
(iii) The mark of the country where the approval is granted. The letters “USA” must be marked on UN pressure receptacles approved by the United States. The manufacturer must obtain an approval number from the Associate Administrator. The manufacturer approval number must follow the country of approval mark, separated by a slash (for example, USA/MXXXX). Pressure receptacles approved by more than one national authority may contain the mark of each country of approval, separated by a comma;
(iv) The identity mark or stamp of the IIA;
(v) The date of the initial inspection, the year in four digits followed by the two digit month separated by a slash, for example “/04”;
(vi) The test pressure in bar, preceded by the letters “PH” and followed by the letters “BAR”;
(vii) For pressure receptacles intended for the transport of compressed gases and UN acetylene, dissolved, the working pressure in bar, proceeded by the letters “PW”;
(viii) For liquefied gases, the water capacity in liters expressed to three significant digits rounded down to the last digit, followed by the letter “L”. If the value of the minimum or nominal water capacity is an integer, the digits after the decimal point may be omitted;
(ix) The total mass of the frame of the bundle and all permanently attached parts (cylinders, manifolds, fittings and valves). Bundles intended for the carriage of UN acetylene, dissolved must bear the tare mass as specified in clause N.4.2 of ISO :;
(x) The country of manufacture. The letters “USA” must be marked on cylinders manufactured in the United States;
(xi) The serial number assigned by the manufacturer; and
(xii) For steel pressure receptacles, the letter “H” showing compatibility of the steel, as specified in 1SO -1.
(v) Marking sequence. The marking required by paragraph (u) of this section must be placed in three groups as follows:
(1) The top grouping contains manufacturing marks and must appear consecutively in the sequence given in paragraphs (u)(2)(x) through (u)(2)(xii) of this section as applicable.
(2) The middle grouping contains operational marks described in paragraphs (u)(2)(vi) through (u)(2)(ix) of this section as applicable. When the operational mark specified in paragraph (u)(2)(vii) is required, it must immediately precede the operational mark specified in paragraph (u)(2)(vi).
(3) The bottom grouping contains certification marks and must appear consecutively in the sequence given in paragraphs (u)(2)(i) through (u)(2)(v) of this section as applicable.
[76 FR , Jan. 19, , as amended at 76 FR , July 20, ; 77 FR , Oct. 5, ; 78 FR , Jan. 7, ; 80 FR , Jan. 8, ; 80 FR , Nov. 23, ; 82 FR , Mar. 30, ; 85 FR , May 11, ; 87 FR , July 26, ; 89 FR , Apr. 10, ]
(a) Application for design type approval.
(1) Each new MEGC design type must have a design approval certificate. An owner or manufacturer must apply to an approval agency that is approved by the Associate Administrator in accordance with subpart E of part 107 of this chapter + to obtain approval of a new design. When a series of MEGCs is manufactured without change in the design, the certificate is valid for the entire series. The design approval certificate must refer to the prototype test report, the materials of construction of the manifold, the standards to which the pressure receptacles are made and an approval number. The compliance requirements or test methods applicable to MEGCs as specified in this subpart may be varied when the level of safety is determined to be equivalent to or exceed the requirements of this subchapter and is approved in writing by the Associate Administrator. A design approval may serve for the approval of smaller MEGCs made of materials of the same type and thickness, by the same fabrication techniques and with identical supports, equivalent closures and other appurtenances.
(2) Each application for design approval must be in English and contain the following information:
(i) Two complete copies of all engineering drawings, calculations, and test data necessary to ensure that the design meets the relevant specification.
(ii) The manufacturer's serial number that will be assigned to each MEGC.
(iii) A statement as to whether the design type has been examined by any approval agency previously and judged unacceptable. Affirmative statements must be documented with the name of the approval agency, reason for non-acceptance, and the nature of modifications made to the design type.
(b) Actions by the approval agency. The approval agency must review the application for design type approval, including all drawings and calculations, to ensure that the design of the MEGC meets all requirements of the relevant specification and to determine whether it is complete and conforms to the requirements of this section. An incomplete application will be returned to the applicant with the reasons why the application was returned. If the application is complete and all applicable requirements of this section are met, the approval agency must prepare a MEGC design approval certificate containing the manufacturer's name and address, results and conclusions of the examination and necessary data for identification of the design type. If the Associate Administrator approves the Design Type Approval Certificate application, the approval agency and the manufacturer must each maintain a copy of the approved drawings, calculations, and test data for at least 20 years.
(c) Approval agency's responsibilities. The approval agency is responsible for ensuring that the MEGC conforms to the design type approval. The approval agency must:
(1) Witness all tests required for the approval of the MEGC specified in this section and § 178.75.
(2) Ensure, through appropriate inspection, that each MEGC is fabricated in all respects in conformance with the approved drawings, calculations, and test data.
(3) Determine and ensure that the MEGC is suitable for its intended use and that it conforms to the requirements of this subchapter.
(4) Apply its name, identifying mark or identifying number, and the date the approval was issued, to the metal identification marking plate attached to the MEGC upon successful completion of all requirements of this subpart. Any approvals by the Associate Administrator authorizing design or construction alternatives (Alternate Arrangements) of the MEGC (see paragraph (a) of this section) must be indicated on the metal identification plate as specified in § 178.75(j).
(5) Prepare an approval certificate for each MEGC or, in the case of a series of identical MEGCs manufactured to a single design type, for each series of MEGCs. The approval certificate must include all of the following information:
(i) The information displayed on the metal identification plate required by § 178.75(j);
(ii) The results of the applicable framework test specified in ISO -3 (IBR, see § 171.7 of this subchapter);
(iii) The results of the initial inspection and test specified in paragraph (h) of this section;
(iv) The results of the impact test specified in § 178.75(i)(4);
(v) Certification documents verifying that the cylinders and tubes conform to the applicable standards; and
(vi) A statement that the approval agency certifies the MEGC in accordance with the procedures in this section and that the MEGC is suitable for its intended purpose and meets the requirements of this subchapter. When a series of MEGCs is manufactured without change in the design type, the certificate may be valid for the entire series of MEGCs representing a single design type. The approval number must consist of the distinguishing sign or mark of the country (“USA” for the United States of America) where the approval was granted and a registration number.
(6) Retain on file a copy of each approval certificate for at least 20 years.
(d) Manufacturers' responsibilities. The manufacturer is responsible for compliance with the applicable specifications for the design and construction of MEGCs. The manufacturer of a MEGC must:
(1) Comply with all the requirements of the applicable ISO standard specified in § 178.71;
(2) Obtain and use an approval agency to review the design, construction and certification of the MEGC;
(3) Provide a statement in the manufacturers' data report certifying that each MEGC manufactured complies with the relevant specification and all the applicable requirements of this subchapter; and
(4) Retain records for the MEGCs for at least 20 years. When required by the specification, the manufacturer must provide copies of the records to the approval agency, the owner or lessee of the MEGC, and to a representative of DOT, upon request.
(e) Denial of application for approval. If the Associate Administrator finds that the MEGC will not be approved for any reason, the Associate Administrator will notify the applicant in writing and provide the reason for the denial. The manufacturer may request that the Associate Administrator reconsider the decision. The application request must—
(1) Be written in English and filed within 90 days of receipt of the decision;
(2) State in detail any alleged errors of fact and law; and
(3) Enclose any additional information needed to support the request to reconsider.
(f) Appeal.
(1) A manufacturer whose reconsideration request is denied may appeal to the PHMSA Administrator. The appeal must—
(i) Be in writing and filed within 90 days of receipt of the Associate Administrator s decision on reconsideration;
(ii) State in detail any alleged errors of fact and law;
(iii) Enclose any additional information needed to support the appeal; and
(iv) State in detail the modification of the final decision sought.
(2) The Administrator will grant or deny the relief and inform the appellant in writing of the decision. The Administrator's decision is the final administrative action.
(g) Modifications to approved MEGCs.
(1) Prior to modification of any approved MEGC that may affect conformance and safe use, and that may involve a change to the design type or affect its ability to retain the hazardous material in transportation, the MEGC's owner must inform the approval agency that prepared the initial approval certificate for the MEGC or, if the initial approval agency is unavailable, another approval agency, of the nature of the modification and request certification of the modification. The owner must supply the approval agency with all revised drawings, calculations, and test data relative to the intended modification. The MEGC's owner must also provide a statement as to whether the intended modification has been examined and determined to be unacceptable by any approval agency. The written statement must include the name of the approval agency, the reason for non-acceptance, and the nature of changes made to the modification since its original rejection.
(2) The approval agency must review the request for modification. If the approval agency determines that the proposed modification does not conform to the relevant specification, the approval agency must reject the request in accordance with paragraph (d) of this section. If the approval agency determines that the proposed modification conforms fully with the relevant specification, the request is accepted. If modification to an approved MEGC alters any information on the approval certificate, the approval agency must prepare a new approval certificate for the modified MEGC and submit the certificate to the Associate Administrator for approval. After receiving approval from the Associate Administrator, the approval agency must ensure that any necessary changes are made to the metal identification plate. A copy of each newly issued approval certificate must be retained by the approval agency and the MEGC's owner for at least 20 years. The approval agency must perform the following activities:
(i) Retain a set of the approved revised drawings, calculations, and data as specified in § 178.69(b)(4) for at least 20 years;
(ii) Ensure through appropriate inspection that all modifications conform to the revised drawings, calculations, and test data; and
(iii) Determine the extent to which retesting of the modified MEGC is necessary based on the nature of the proposed modification, and ensure that all required retests are satisfactorily performed.
(h) Termination of Approval Certificate.
(1) The Associate Administrator may terminate an approval issued under this section if he or she determines that—
(i) Because of a change in circumstances, the approval no longer is needed or no longer would be granted if applied for;
(ii) Information upon which the approval was based is fraudulent or substantially erroneous;
(iii) Termination of the approval is necessary to adequately protect against risks to life and property; or
(iv) The MEGC does not meet the specification.
(2) Before an approval is terminated, the Associate Administrator will provide the person—
(i) Written notice of the facts or conduct believed to warrant the termination;
(ii) An opportunity to submit oral and written evidence; and
(3) An opportunity to demonstrate or achieve compliance with the applicable requirements.
(i) Imminent Danger. If the Associate Administrator determines that a certificate of approval must be terminated to preclude a significant and imminent adverse effect on public safety, the Associate Administrator may terminate the certificate immediately. In such circumstances, the opportunities of paragraphs (h)(2) and (3) of this section need not be provided prior to termination of the approval, but must be provided as soon as practicable thereafter.
[71 FR , June 12, ]
(a) General. Each MEGC must meet the requirements of this section. In a MEGC that meets the definition of a “container” within the terms of the International Convention for Safe Containers (CSC) must meet the requirements of the CSC as amended and 49 CFR parts 450 through 453, and must have a CSC approval plate.
(b) Alternate Arrangements. The technical requirements applicable to MEGCs may be varied when the level of safety is determined to be equivalent to or exceed the requirements of this subchapter. Such an alternate arrangement must be approved in writing by the Associate Administrator. MEGCs approved to an Alternate Arrangement must be marked as required by paragraph (j) of this section.
(c) Definitions. The following definitions apply:
Leakproofness test means a test using gas subjecting the pressure receptacles and the service equipment of the MEGC to an effective internal pressure of not less than 20% of the test pressure.
Manifold means an assembly of piping and valves connecting the filling and/or discharge openings of the pressure receptacles.
Maximum permissible gross mass or MPGM means the heaviest load authorized for transport (sum of the tare mass of the MEGC, service equipment and pressure receptacle).
Service equipment means manifold system (measuring instruments, piping and safety devices).
Shut-off valve means a valve that stops the flow of gas.
Structural equipment means the reinforcing, fastening, protective and stabilizing members external to the pressure receptacles.
(d) General design and construction requirements.
(1) The MEGC must be capable of being loaded and discharged without the removal of its structural equipment. It must possess stabilizing members external to the pressure receptacles to provide structural integrity for handling and transport. MEGCs must be designed and constructed with supports to provide a secure base during transport and with lifting and tie-down attachments that are adequate for lifting the MEGC including when loaded to its maximum permissible gross mass. The MEGC must be designed to be loaded onto a transport vehicle or vessel and equipped with skids, mountings or accessories to facilitate mechanical handling.
(2) MEGCs must be designed, manufactured and equipped to withstand, without loss of contents, all normal handling and transportation conditions. The design must take into account the effects of dynamic loading and fatigue.
(3) Each pressure receptacle of a MEGC must be of the same design type, seamless steel, or composite, and constructed and tested according to one of the following ISO standards:
(i) ISO -1:(E), Gas cylinders—Refillable seamless steel gas cylinders—Design, construction, and testing—Part 1: Quenched and tempered steel cylinders with tensile strength less than MPa (IBR, see § 171.7 of this subchapter). Until December 31, , the manufacture of a cylinder conforming to the requirements in ISO -1:(E) (IBR, see § 171.7 of this subchapter) is authorized.
(ii) ISO -2:(E), Gas cylinders—Design, construction and testing of refillable seamless steel gas cylinders and tubes—Part 2: Quenched and tempered steel cylinders and tubes with tensile strength greater than or equal to MPa (IBR, see § 171.7 of this subchapter). Until December 31, , the manufacture of a cylinder conforming to the requirements in \ ISO -2:(E) (IBR, see § 171.7 of this subchapter) is authorized.
(iii) ISO -3:(E), Gas cylinders—Design, construction, and testing of refillable seamless steel gas cylinders and tubes—Part 3: Normalized steel cylinders and tubes (IBR, see § 171.7 of this subchapter). Until December 31, , the manufacture of a cylinder conforming to the requirements in ISO -3:(E) (IBR, see § 171.7 of this subchapter) is authorized.
(iv) ISO -4:(E) Gas cylinders—Refillable seamless steel gas cylinders—Design, construction and testing—Part 4: Stainless steel cylinders with an Rm value of less than 1 100 MPa (IBR, see § 171.7 of this subchapter).
(v) ISO :(E) Gas cylinders—Refillable seamless steel tubes of water capacity between 150 L and L—Design, construction and testing (IBR, see § 171.7 of this subchapter). Until December 31, , pressure receptacles of a MEGC may be constructed and tested in accordance with ISO :(E) Gas cylinders—Refillable seamless steel tubes of water capacity between 150 L and L—Design, construction and testing (IBR, see § 171.7 of this subchapter).
(vi) ISO -1:(E), Gas cylinders—Refillable composite gas cylinders and tubes—Design, construction and testing—Part 1: Hoop wrapped fibre reinforced composite gas cylinders and tubes up to 450 l (IBR, see § 171.7 of this subchapter).
(vii) ISO -2:(E) and ISO -2:/Amd.1:(E), Gas cylinders—Refillable composite gas cylinders and tubes—Design, construction and testing—Part 2: Fully wrapped fibre reinforced composite gas cylinders and tubes up to 450 l with load-sharing metal liners (both IBR, see § 171.7 of this subchapter).
(viii) ISO -3:(E) Gas cylinders—Refillable composite gas cylinders and tubes—Design, construction and testing—Part 3: Fully wrapped fibre reinforced composite gas cylinders and tubes up to 450 l with non-load-sharing metallic or non-metallic liners (IBR, see § 171.7 of this subchapter).
(ix) ISO -4:(E) Gas cylinders—Refillable composite gas cylinders—Design, construction and testing—Part 4: Fully wrapped fibre reinforced composite gas cylinders up to 150 l with load-sharing welded metallic liners (IBR, see § 171.7 of this subchapter).
(4) Pressure receptacles of MEGCs, fittings, and pipework must be constructed of a material that is compatible with the hazardous materials intended to be transported, as specified in this subchapter.
(5) Contact between dissimilar metals that could result in damage by galvanic action must be prevented by appropriate means.
(6) The materials of the MEGC, including any devices, gaskets, and accessories, must have no adverse effect on the gases intended for transport in the MEGC.
(7) MEGCs must be designed to withstand, without loss of contents, at least the internal pressure due to the contents, and the static, dynamic and thermal loads during normal conditions of handling and transport. The design must take into account the effects of fatigue, caused by repeated application of these loads through the expected life of the MEGC.
(8) MEGCs and their fastenings must, under the maximum permissible load, be capable of withstanding the following separately applied static forces (for calculation purposes, acceleration due to gravity (g) = 9.81 m/s2):
(i) In the direction of travel: 2g (twice the MPGM multiplied by the acceleration due to gravity);
(ii) Horizontally at right angles to the direction of travel: 1g (the MPGM multiplied by the acceleration due to gravity. When the direction of travel is not clearly determined, the forces must be equal to twice the MPGM);
(iii) Vertically upwards: 1g (the MPGM multiplied by the acceleration due to gravity); and
(iv) Vertically downwards: 2g (twice the MPGM (total loading including the effect of gravity) multiplied by the acceleration due to gravity.
(9) Under each of the forces specified in paragraph (d)(8) of this section, the stress at the most severely stressed point of the pressure receptacles must not exceed the values given in the applicable design specifications (e.g., ISO ).
(10) Under each of the forces specified in paragraph (d)(8) of this section, the safety factor for the framework and fastenings must be as follows:
(i) For steels having a clearly defined yield point, a safety factor of 1.5 in relation to the guaranteed yield strength; or
(ii) For steels with no clearly defined yield point, a safety factor of 1.5 in relation to the guaranteed 0.2 percent proof strength and, for austenitic steels, the 1 percent proof strength.
(11) MEGCs must be capable of being electrically grounded to prevent electrostatic discharge when intended for flammable gases.
(12) The pressure receptacles of a MEGC must be secured in a manner to prevent movement that could result in damage to the structure and concentration of harmful localized stresses.
(e) Service equipment.
(1) Service equipment must be arranged so that it is protected from mechanical damage by external forces during handling and transportation. When the connections between the frame and the pressure receptacles allow relative movement between the subassemblies, the equipment must be fastened to allow movement to prevent damage to any working part. The manifolds, discharge fittings (pipe sockets, shut-off devices), and shut-off valves must be protected from damage by external forces. Manifold piping leading to shut-off valves must be sufficiently flexible to protect the valves and the piping from shearing, or releasing the pressure receptacle contents. The filling and discharge devices, including flanges or threaded plugs, and any protective caps must be capable of being secured against unintended opening.
(2) Each pressure receptacle intended for the transport of Division 2.3 gases must be equipped with an individual shut-off valve. The manifold for Division 2.3 liquefied gases must be designed so that each pressure receptacle can be filled separately and be kept isolated by a valve capable of being closed during transit. For Division 2.1 gases, the pressure receptacles must be isolated by an individual shut-off valve into assemblies of not more than 3,000 L.
(3) For MEGC filling and discharge openings:
(i) Two valves in series must be placed in an accessible position on each discharge and filling pipe. One of the valves may be a backflow prevention valve.
(ii) The filling and discharge devices may be equipped to a manifold.
(iii) For sections of piping which can be closed at both ends and where a liquid product can be trapped, a pressure-relief valve must be provided to prevent excessive pressure build-up.
(iv) The main isolation valves on a MEGC must be clearly marked to indicate their directions of closure. All shutoff valves must close by a clockwise motion of the handwheel.
(v) Each shut-off valve or other means of closure must be designed and constructed to withstand a pressure equal to or greater than 1.5 times the test pressure of the MEGC.
(vi) All shut-off valves with screwed spindles must close by a clockwise motion of the handwheel. For other shut-off valves, the open and closed positions and the direction of closure must be clearly shown.
(vii) All shut-off valves must be designed and positioned to prevent unintentional opening.
(viii) Ductile metals must be used in the construction of valves or accessories.
(4) The piping must be designed, constructed and installed to avoid damage due to expansion and contraction, mechanical shock and vibration. Joints in tubing must be brazed or have an equally strong metal union. The melting point of brazing materials must be no lower than 525 °C (977 °F). The rated pressure of the service equipment and of the manifold must be not less than two-thirds of the test pressure of the pressure receptacles.
(f) Pressure relief devices. Each pressure receptacle must be equipped with one or more pressure relief devices as specified in § 173.301(f) of this subchapter. When pressure relief devices are installed, each pressure receptacle or group of pressure receptacles of a MEGC that can be isolated must be equipped with one or more pressure relief devices. Pressure relief devices must be of a type that will resist dynamic forces including liquid surge and must be designed to prevent the entry of foreign matter, the leakage of gas and the development of any dangerous excess pressure.
(1) The size of the pressure relief devices: CGA S-1.1, excluding paragraph 9.1.1, (IBR, see § 171.7 of this subchapter) must be used to determine the relief capacity of individual pressure receptacles.
(2) Connections to pressure-relief devices: Connections to pressure relief devices must be of sufficient size to enable the required discharge to pass unrestricted to the pressure relief device. A shut-off valve installed between the pressure receptacle and the pressure relief device is prohibited, except where duplicate devices are provided for maintenance or other reasons, and the shut-off valves serving the devices actually in use are locked open, or the shut-off valves are interlocked so that at least one of the duplicate devices is always operable and capable of meeting the requirements of paragraph (f)(1) of this section. No obstruction is permitted in an opening leading to or leaving from a vent or pressure-relief device that might restrict or cut-off the flow from the pressure receptacle to that device. The opening through all piping and fittings must have at least the same flow area as the inlet of the pressure relief device to which it is connected. The nominal size of the discharge piping must be at least as large as that of the pressure relief device.
(3) Location of pressure-relief devices: For liquefied gases, each pressure relief device must, under maximum filling conditions, be in communication with the vapor space of the pressure receptacles. The devices, when installed, must be arranged to ensure the escaping vapor is discharged upwards and unrestrictedly to prevent impingement of escaping gas or liquid upon the MEGC, its pressure receptacles or personnel. For flammable, pyrophoric and oxidizing gases, the escaping gas must be directed away from the pressure receptacle in such a manner that it cannot impinge upon the other pressure receptacles. Heat resistant protective devices that deflect the flow of gas are permissible provided the required pressure relief device capacity is not reduced. Arrangements must be made to prevent access to the pressure relief devices by unauthorized persons and to protect the devices from damage caused by rollover.
(g) Gauging devices. When a MEGC is intended to be filled by mass, it must be equipped with one or more gauging devices. Glass level-gauges and gauges made of other fragile material are prohibited.
(h) MEGC supports, frameworks, lifting and tie-down attachments.
(1) MEGCs must be designed and constructed with a support structure to provide a secure base during transport. MEGCs must be protected against damage to the pressure receptacles and service equipment resulting from lateral and longitudinal impact and overturning. The forces specified in paragraph (d)(8) of this section, and the safety factor specified in paragraph (d)(10) of this section must be considered in this aspect of the design. Skids, frameworks, cradles or other similar structures are acceptable. If the pressure receptacles and service equipment are so constructed as to withstand impact and overturning, additional protective support structure is not required (see paragraph (h)(4) of this section).
(2) The combined stresses caused by pressure receptacle mountings (e.g. cradles, frameworks, etc.) and MEGC lifting and tie-down attachments must not cause excessive stress in any pressure receptacle. Permanent lifting and tie-down attachments must be equipped to all MEGCs. Any welding of mountings or attachments onto the pressure receptacles is prohibited.
(3) The effects of environmental corrosion must be taken into account in the design of supports and frameworks.
(4) When MEGCs are not protected during transport as specified in paragraph (h)(1) of this section, the pressure receptacles and service equipment must be protected against damage resulting from lateral or longitudinal impact or overturning. External fittings must be protected against release of the pressure receptacles' contents upon impact or overturning of the MEGC on its fittings. Particular attention must be paid to the protection of the manifold. Examples of protection include:
(i) Protection against lateral impact, which may consist of longitudinal bars;
(ii) Protection against overturning, which may consist of reinforcement rings or bars fixed across the frame;
(iii) Protection against rear impact, which may consist of a bumper or frame;
(iv) Protection of the pressure receptacles and service equipment against damage from impact or overturning by use of an ISO frame according to the relevant provisions of ISO -3. (IBR, see § 171.7 of this subchapter).
(i) Initial inspection and test. The pressure receptacles and items of equipment of each MEGC must be inspected and tested before being put into service for the first time (initial inspection and test). This initial inspection and test of an MEGC must include the following:
(1) A check of the design characteristics.
(2) An external examination of the MEGC and its fittings, taking into account the hazardous materials to be transported.
(3) A pressure test performed at the test pressures specified in § 173.304b(b)(1) and (2) of this subchapter. The pressure test of the manifold may be performed as a hydraulic test or by using another liquid or gas. A leakproofness test and a test of the satisfactory operation of all service equipment must also be performed before the MEGC is placed into service. When the pressure receptacles and their fittings have been pressure-tested separately, they must be subjected to a leakproof test after assembly.
(4) An MEGC that meets the definition of “container” in the CSC (see 49 CFR 450.3(a)(2)) must be subjected to an impact test using a prototype representing each design type. The prototype MEGC must be shown to be capable of absorbing the forces resulting from an impact not less than 4 times (4 g) the MPGM of the fully loaded MEGC, at a duration typical of the mechanical shocks experienced in rail transport. A listing of acceptable methods for performing the impact test is provided in the UN Recommendations (IBR, see § 171.7 of this subchapter).
(j) Marking.
(1) Each MEGC must be equipped with a corrosion resistant metal plate permanently attached to the MEGC in a conspicuous place readily accessible for inspection. The pressure receptacles must be marked according to this section. Affixing the metal plate to a pressure receptacle is prohibited. At a minimum, the following information must be marked on the plate by stamping or by any other equivalent method:
Country of manufacture
UN
Approval Country
Approval Number
Alternate Arrangements (see § 178.75(b))
MEGC Manufacturer's name or mark
MEGC's serial number
Approval agency (Authorized body for the design approval)
Year of manufacture
Test pressure: ______ bar gauge
Design temperature range ______ °C to ______ °C
Number of pressure receptacles ______
Total water capacity ______ liters
Initial pressure test date and identification of the Approval Agency
Date and type of most recent periodic tests
Year ______ Month______ Type ______
(e.g. -05, AE/UE, where “AE” represents acoustic emission and “UE” represents ultrasonic examination)
Stamp of the approval agency who performed or witnessed the most recent test
(2) The following information must be marked on a metal plate firmly secured to the MEGC:
Name of the operator
Maximum permissible load mass ______ kg
Working pressure at 15 °C: ______ bar gauge
Maximum permissible gross mass (MPGM) ______ kg
Unladen (tare) mass ______ kg
[71 FR , June 12, , as amended at 73 FR , Jan. 28, ; 77 FR , Oct. 5, ; 80 FR , Jan. 8, ; 82 FR , Mar. 30, ; 85 FR , May 11, ; 85 FR , Dec. 27, ; 87 FR , July 26, ; 89 FR , Apr. 10, ]
The following figures illustrate the recommended locations for test specimens taken from welded cylinders:
[67 FR , Aug. 8, ]
29 FR , Dec. 29, , unless otherwise noted. Redesignated at 32 FR , Apr. 5, .
(a) This specification pertains to a container to be used for the transportation of detonators and percussion caps in connection with the transportation of liquid nitroglycerin, desensitized liquid nitroglycerin or diethylene glycol dinitrate, where any or all of such types of caps may be used for the detonation of liquid nitroglycerin, desentitized liquid nitroglycerin or diethylene glycol dinitrate in blasting operations. This specification is not intended to take the place of any shipping or packing requirements of this Department where the caps in question are themselves articles of commerce.
(b) [Reserved]
[29 FR , Dec. 29, . Redesignated at 32 FR , Apr. 5, , and amended by Amdt. 178-60, 44 FR , Dec. 10, ]
(a) Every container for detonators and percussion caps coming within the scope of this specification shall be constructed entirely of hard rubber, phenolresinous or other resinous material, or other nonmetallic, nonsparking material, except that metal parts may be used in such locations as not in any event to come in contact with any of the caps. Space shall be provided so that each detonator of whatever nature may be inserted in an individual cell in the body of the container, into which each such cap shall snugly fit. There shall be provided no more than twenty (20) such cellular spaces. Space may be provided into which a plurality of percussion caps may be carried, provided that such space may be closed with a screw cap, and further provided that each or any such space is entirely separate from any space provided for any detonator. Each cellular space into which a detonator is to be inserted and carried shall be capable of being covered by a rotary cover so arranged as to expose not more than one cell at any time, and capable of rotation to such a place that all cells will be covered at the same time, at which place means shall be provided to lock the cover in place. Means shall be provided to lock in place the cover for the cells provided for the carrying of detonators. The requirement that not more than one cell be exposed at one time need not apply in the case of detonators, although spaces for such caps and detonators shall be separate. Sufficient annular space shall be provided inside the cover for such detonators that, when the cover is closed, there will be sufficient space to accommodate the wires customarily attached to such caps. If the material is of such a nature as to require treatment to prevent the absorption of moisture, such treatment shall be applied as shall be necessary in order to provide against the penetration of water by permeation. A suitable carrying handle shall be provided, except for which handle no part of the container may project beyond the exterior of the body.
(b) Exhibited in plates I and II are line drawings of a container for detonators and percussion caps, illustrative of the requirements set forth in § 178.318-2(a). These plates shall not be construed as a part of this specification.
Each container must be marked as prescribed in § 178.2(b).
[Amdt. 178-40, 41 FR , Sept. 9, , as amended at 66 FR , Aug. 28, ]
(a) Definitions. For the purpose of this subchapter:
Appurtenance means any attachment to a cargo tank that has no lading retention or containment function and provides no structural support to the cargo tank.
Baffle means a non-liquid-tight transverse partition device that deflects, checks or regulates fluid motion in a tank.
Bulkhead means a liquid-tight transverse closure at the ends of or between cargo tanks.
Cargo tank means a bulk packaging that:
(1) Is a tank intended primarily for the carriage of liquids, gases, solids, or semi-solids and includes appurtenances, reinforcements, fittings, and closures (for tank, see §§ 178.337-1, 178.338-1, or 178.345-1, as applicable);
(2) Is permanently attached to or forms a part of a motor vehicle, or is not permanently attached to a motor vehicle but that, by reason of its size, construction, or attachment to a motor vehicle, is loaded or unloaded without being removed from the motor vehicle; and
(3) Is not fabricated under a specification for cylinders, intermediate bulk containers, multi-unit tank car tanks, portable tanks, or tank cars.
Cargo tank motor vehicle means a motor vehicle with one or more cargo tanks permanently attached to or forming an integral part of the motor vehicle.
Cargo tank wall means those parts of the cargo tank that make up the primary lading retention structure, including shell, bulkheads, and fittings and, when closed, yield the minimum volume of a completed cargo tank motor vehicle.
Charging line means a hose, tube, pipe, or a similar device used to pressurize a tank with material other than the lading.
Companion flange means one of two mating flanges where the flange faces are in contact or separated only by a thin leak-sealing gasket and are secured to one another by bolts or clamps.
Connecting structure means the structure joining two cargo tanks.
Constructed and certified in accordance with the ASME Code means a cargo tank is constructed and stamped in accordance with Section VIII of the ASME Code (IBR, see § 171.7 of this subchapter), and is inspected and certified by an Authorized Inspector.
Constructed in accordance with the ASME Code means a cargo tank is constructed in accordance with Section VIII of the ASME Code with authorized exceptions (see §§ 178.346 through 178.348) and is inspected and certified by a Registered Inspector.
Design type means one or more cargo tanks that are made—
(1) To the same specification;
(2) By the same manufacturer;
(3) To the same engineering drawings and calculations, except for minor variations in piping that do not affect the lading retention capability of the cargo tank;
(4) Of the same materials of construction;
(5) To the same cross-sectional dimensions;
(6) To a length varying by no more than 5 percent;
(7) With the volume varying by no more than 5 percent (due to a change in length only); and
(8) For the purposes of § 178.338 only, with the same insulation system.
External self-closing stop valve means a self-closing stop valve designed so that the self-stored energy source is located outside the cargo tank and the welded flange.
Extreme dynamic loading means the maximum loading a cargo tank motor vehicle may experience during its expected life, excluding accident loadings resulting from an accident, such as overturn or collision.
Flange means the structural ring for guiding or attachment of a pipe or fitting with another flange (companion flange), pipe, fitting or other attachment.
Inspection pressure means the pressure used to determine leak tightness of the cargo tank when testing with pneumatic pressure.
Internal self-closing stop valve means a self-closing stop valve designed so that the self-stored energy source is located inside the cargo tank or cargo tank sump, or within the welded flange, and the valve seat is located within the cargo tank or within one inch of the external face of the welded flange or sump of the cargo tank.
Lading means the hazardous material contained in a cargo tank.
Loading/unloading connection means the fitting in the loading/unloading line farthest from the loading/unloading outlet to which the loading/unloading hose, pipe, or device is attached.
Loading/unloading outlet means a cargo tank outlet used for normal loading/unloading operations.
Loading/unloading stop valve means the stop valve farthest from the cargo tank loading/unloading outlet to which the loading/unloading connection is attached.
Manufacturer means any person engaged in the manufacture of a DOT specification cargo tank, cargo tank motor vehicle, or cargo tank equipment that forms part of the cargo tank wall. This term includes attaching a cargo tank to a motor vehicle or to a motor vehicle suspension component that involves welding on the cargo tank wall. A manufacturer must register with the Department in accordance with subpart F of part 107 in subpart A of this chapter.
Maximum allowable working pressure or MAWP means the maximum pressure allowed at the top of the tank in its normal operating position. The MAWP must be calculated as prescribed in Section VIII of the ASME Code. In use, the MAWP must be greater than or equal to the maximum lading pressure conditions prescribed in § 173.33 of this subchapter for each material transported.
Maximum lading pressure. See § 173.33(c).
Minimum thickness means the minimum required shell and head (and baffle and bulkhead when used as tank reinforcement) thickness needed to meet the specification. The minimum thickness is the greatest of the following values:
(1)
(i) For MC 330, MC 331, and MC 338 cargo tanks, the specified minimum thickness found the applicable specification(s); or
(ii) For DOT 406, DOT 407 and DOT 412 cargo tanks, the specified minimum thickness found in Tables I and II of the applicable specification(s); or
(iii) For MC 300, MC 301, MC 302, MC 303, MC 304, MC 305, MC 306, MC 307, MC 310, MC 311, and MC 312 cargo tanks, the in-service minimum thickness prescribed in Tables I and II of § 180.407(i)(5) of this subchapter, for the minimum thickness specified by Tables I and II of the applicable specification(s); or
(2) The thickness necessary to meet with the structural integrity and accident damage requirements of the applicable specification(s); or
(3) The thickness as computed per the ASME Code requirements (if applicable).
Multi-specification cargo tank motor vehicle means a cargo tank motor vehicle equipped with two or more cargo tanks fabricated to more than one cargo tank specification.
Normal operating loading means the loading a cargo tank motor vehicle may be expected to experience routinely in operation.
Nozzle means a subassembly consisting of a pipe or tubular section with or without a welded or forged flange on one end.
Outlet means any opening in the shell or head of a cargo tank, (including the means for attaching a closure), except that the following are not outlets: a threaded opening securely closed during transportation with a threaded plug or a threaded cap, a flanged opening securely closed during transportation with a bolted or welded blank flange, a manhole, a gauging device, a thermometer well, or a pressure relief device.
Outlet stop valve means the stop valve at a cargo tank loading or unloading outlet.
Pipe coupling means a fitting with internal threads on both ends.
Rear bumper means the structure designed to prevent a vehicle or object from under-riding the rear of another motor vehicle. See § 393.86 of this title.
Rear-end tank protection device means the structure designed to protect a cargo tank and any lading retention piping or devices in case of a rear end collision.
Self-closing stop valve means a stop valve held in the closed position by means of self-stored energy, that opens only by application of an external force and that closes when the external force is removed.
Shell means the circumferential portion of a cargo tank defined by the basic design radius or radii excluding the bulkheads.
Stop valve means a valve that stops the flow of lading.
Sump means a protrusion from the bottom of a cargo tank shell designed to facilitate complete loading and unloading of lading.
Tank means a container, consisting of a shell and heads, that forms a pressure tight vessel having openings designed to accept pressure tight fittings or closures, but excludes any appurtenances, reinforcements, fittings, or closures.
Test pressure means the pressure to which a tank is subjected to determine structural integrity.
Toughness of material means the capability of a material to absorb energy represented by the area under a stress strain curve (indicating the energy absorbed per unit volume of the material) up to the point of rupture.
Vacuum cargo tank means a cargo tank that is loaded by reducing the pressure in the cargo tank to below atmospheric pressure.
Variable specification cargo tank means a cargo tank that is constructed in accordance with one specification, but that may be altered to meet another specification by changing relief device, closures, lading discharge devices, and other lading retention devices.
Void means the space between tank heads or bulkheads and a connecting structure.
Welded flange means a flange attached to the tank by a weld joining the tank shell to the cylindrical outer surface of the flange, or by a fillet weld joining the tank shell to a flange shaped to fit the shell contour.
(b) Design certification.
(1) Each cargo tank or cargo tank motor vehicle design type, including its required accident damage protection device, must be certified to conform to the specification requirements by a Design Certifying Engineer who is registered in accordance with subpart F of part 107 of this title. An accident damage protection device is a rear-end protection, overturn protection, or piping protection device.
(2) The Design Certifying Engineer shall furnish to the manufacturer a certificate to indicate compliance with the specification requirements. The certificate must include the sketches, drawings, and calculations used for certification. Each certificate, including sketches, drawings, and calculations, shall be signed by the Design Certifying Engineer.
(3) The manufacturer shall retain the design certificate at his principal place of business for as long as he manufactures DOT specification cargo tanks.
(c) Exceptions to the ASME Code. Unless otherwise specified, when exceptions are provided in this subpart from compliance with certain paragraphs of the ASME Code, compliance with those paragraphs is not prohibited.
[Amdt. 178-89, 55 FR , Sept. 7, , as amended by Amdt. 178-98, 58 FR , June 16, ; Amdt. 178-118, 61 FR , Oct. 1, ; 68 FR , Apr. 18, ; 68 FR , Sept. 3, ; 68 FR , Dec. 31, ; 76 FR , July 20, ]
(a) ASME Code construction. Tanks must be—
(1) Seamless or welded construction, or a combination of both;
(2) Designed, constructed, certified, and stamped in accordance with Section VIII of the ASME Code (IBR, see § 171.7 of this subchapter);
(3) Made of steel or aluminum; however, if aluminum is used, the cargo tank must be insulated and the hazardous material to be transported must be compatible with the aluminum (see §§ 178.337-1(e)(2), 173.315(a) table, and 178.337-2(a)(1) of this subchapter); and
(4) Covered with a steel jacket if the cargo tank is insulated and used to transport a flammable gas (see § 173.315(a) table Note 11 of this subchapter).
(b) Design pressure. The design pressure of a cargo tank authorized under this specification shall be not less than the vapor pressure of the commodity contained therein at 115 °F. or as prescribed for a particular commodity in § 173.315(a) of this subchapter, except that in no case shall the design pressure of any cargo tank be less than 100 p.s.i.g. nor more than 500 p.s.i.g.
Note 1:The term design pressure as used in this specification, is identical to the term MAWP as used in the ASME Code.
(c) Openings.
(1) Excess pressure relief valves shall be located in the top of the cargo tank or heads.
(2) A chlorine cargo tank shall have only one opening. That opening shall be in the top of the cargo tank and shall be fitted with a nozzle that meets the following requirements:
(i) On a cargo tank manufactured on or before December 31, , the nozzle shall be protected by a dome cover plate which conforms to either the standard of The Chlorine Institute, Inc., Dwg. 103-3, dated January 23, , or to the standard specified in paragraph (c) (2) (ii) of this section.
(ii) On a cargo tank manufactured on or after January 1, , the nozzle shall be protected by a manway cover which conforms to the standard of The Chlorine Institute, Inc., Dwg. 103-4, dated September 1, .
(d) Reflective design. Every uninsulated cargo tank permanently attached to a cargo tank motor vehicle shall, unless covered with a jacket made of aluminum, stainless steel, or other bright nontarnishing metal, be painted a white, aluminum or similar reflecting color on the upper two-thirds of area of the cargo tank.
(e) Insulation.
(1) Each cargo tank required to be insulated must conform with the use and performance requirements contained in §§ 173.315(a) table and 178.337-1 (a)(3) and (e)(2) of this subchapter.
(2) Each cargo tank intended for chlorine; carbon dioxide, refrigerated liquid; or nitrous oxide, refrigerated liquid service must have suitable insulation of such thickness that the overall thermal conductance is not more than 0.08 Btu per square foot per °F differential per hour. The conductance must be determined at 60 °F. Insulation material used on cargo tanks for nitrous oxide, refrigerated liquid must be noncombustible. Insulating material used on cargo tanks for chlorine must be corkboard or polyurethane foam, with a minimum thickness of 4 inches, or 2 inches minimum thickness of ceramic fiber/fiberglass of 4 pounds per cubic foot minimum density covered by 2 inches minimum thickness of fiber.
(f) Postweld heat treatment. Postweld heat treatment must be as prescribed in the ASME Code except that each cargo tank constructed in accordance with Part UHT of Section VIII of the ASME Code must be postweld heat treated. Each chlorine cargo tank must be fully radiographed and postweld heat treated in accordance with the provisions in Section VIII of the ASME Code under which it is constructed. Where postweld heat treatment is required, the cargo tank must be treated as a unit after completion of all the welds in and/or to the shells and heads. The method must be as prescribed in Section VIII of the ASME Code. Welded attachments to pads may be made after postweld heat treatment. A cargo tank used for anhydrous ammonia must be postweld heat treated. The postweld heat treatment must be as prescribed in Section VIII of the ASME Code, but in no event at less than 1,050 °F cargo tank metal temperature.
(g) Definitions. The following definitions apply to §§ 178.337-1 through 178.337-18:
Emergency discharge control means the ability to stop a cargo tank unloading operation in the event of an unintentional release. Emergency discharge control can utilize passive or off-truck remote means to stop the unloading operation. A passive means of emergency discharge control automatically shuts off the flow of product without the need for human intervention within 20 seconds of an unintentional release caused by a complete separation of the liquid delivery hose. An off-truck remote means of emergency discharge control permits a qualified person attending the unloading operation to close the cargo tank's internal self-closing stop valve and shut off all motive and auxiliary power equipment at a distance from the cargo tank motor vehicle.
Excess flow valve, integral excess flow valve, or excess flow feature means a component that will close automatically if the flow rate of a gas or liquid through the component reaches or exceeds the rated flow of gas or liquid specified by the original valve manufacturer when piping mounted directly on the valve is sheared off before the first valve, pump, or fitting downstream from the valve.
Internal self-closing stop valve means a primary shut off valve installed in a product discharge outlet of a cargo tank and designed to be kept closed by self-stored energy.
Primary discharge control system means a primary shut-off installed at a product discharge outlet of a cargo tank consisting of an internal self-closing stop valve that may include an integral excess flow valve or an excess flow feature, together with linkages that must be installed between the valve and remote actuator to provide manual and thermal on-truck remote means of closure.
[Order 59-B, 30 FR 579, Jan. 16, . Redesignated at 32 FR , Apr. 5, ]
(a) General.
(1) All material used for construction of the cargo tank and appurtenances must be suitable for use with the commodities to be transported therein and must conform to the requirements in Section II of the ASME Code (IBR, see § 171.7 of this subchapter) and/or requirements of the American Society for Testing and Materials in all respects.
(2) Impact tests are required on steel used in the fabrication of each cargo tank constructed in accordance with part UHT in Section VIII of the ASME Code. The tests must be made on a lot basis. A lot is defined as 100 tons or less of the same heat treatment processing lot having a thickness variation no greater than plus or minus 25 percent. The minimum impact required for full size specimens must be 20 foot-pounds in the longitudinal direction at −30 °F., Charpy V-Notch and 15 foot-pounds in the transverse direction at −30 °F., Charpy V-Notch. The required values for subsize specimens must be reduced in direct proportion to the cross-sectional area of the specimen beneath the notch. If a lot does not meet this requirement, individual plates may be accepted if they individually meet this requirement.
(3) The fabricator shall record the heat, and slab numbers, and the certified Charpy impact values, where required, of each plate used in each cargo tank on a sketch showing the location of each plate in the shell and heads of the cargo tank. Copies of each sketch shall be provided to the owner and retained for at least five years by the fabricator and made available to duly identified representatives of the Department of Transportation.
(4) The direction of final rolling of the shell material shall be the circumferential orientation of the cargo tank shell.
(b) For a chlorine cargo tank. Plates, the manway nozzle, and anchorage shall be made of carbon steel which meets the following requirements:
(1) For a cargo tank manufactured on or before December 31, —
(i) Material shall conform to ASTM A 300, “Steel Plates for Pressure Vessels for Service at Low Temperatures” (IBR, see § 171.7 of this subchapter);
(ii) Material shall be Class 1, Grade A, flange or firebox quality;
(iii) Plate impact test specimens, as required under paragraph (a) of this section, shall be of the Charpy keyhole notch type; and
(iv) Plate impact test specimens shall meet the impact test requirements in paragraph (a) of this section in both the longitudinal and transverse directions of rolling at a temperature of minus 45.5 C. (−50 °F.).
(2) For a cargo tank manufactured on or after January 1, —
(i) Material shall conform to ASTM A 612 (IBR, see § 171.7 of this subchapter), Grade B or A 516/A 516M (IBR, see § 171.7 of this subchapter), Grade 65 or 70;
(ii) Material shall meet the Charpy V-notch test requirements of ASTM A 20/A 20M (IBR, see § 171.7 of this subchapter); and
(iii) Plate impact test specimens shall meet the impact test requirements in paragraph (a) of this section in both the longitudinal and transverse directions of rolling at a temperature of minus 40 °C. (−40 °F.).
(c) A cargo tank in anhydrous ammonia service must be constructed of steel. The use of copper, silver, zinc or their alloys is prohibited. Baffles made from aluminum may be used only if joined to the cargo tank by a process not requiring postweld heat treatment of the cargo tank.
[Order 59-B, 30 FR 579, Jan. 16, . Redesignated at 32 FR , Apr. 5, ]
(a) General requirements and acceptance criteria.
(1) Except as provided in paragraph (d) of this section, the maximum calculated design stress at any point in the cargo tank may not exceed the maximum allowable stress value prescribed in Section VIII of the ASME Code (IBR, see § 171.7 of this subchapter), or 25 percent of the tensile strength of the material used.
(2) The relevant physical properties of the materials used in each cargo tank may be established either by a certified test report from the material manufacturer or by testing in conformance with a recognized national standard. In either case, the ultimate tensile strength of the material used in the design may not exceed 120 percent of the ultimate tensile strength specified in either the ASME Code or the ASTM standard to which the material is manufactured.
(3) The maximum design stress at any point in the cargo tank must be calculated separately for the loading conditions described in paragraphs (b), (c), and (d) of this section. Alternate test or analytical methods, or a combination thereof, may be used in place of the procedures described in paragraphs (b), (c), and (d) of this section, if the methods are accurate and verifiable.
(4) Corrosion allowance material may not be included to satisfy any of the design calculation requirements of this section.
(b) Static design and construction.
(1) The static design and construction of each cargo tank must be in accordance with Section VIII of the ASME Code. The cargo tank design must include calculation of stresses generated by design pressure, the weight of lading, the weight of structure supported by the cargo tank wall, and the effect of temperature gradients resulting from lading and ambient temperature extremes. When dissimilar materials are used, their thermal coefficients must be used in calculation of thermal stresses.
(2) Stress concentrations in tension, bending and torsion which occur at pads, cradles, or other supports must be considered in accordance with appendix G in Section VIII of the ASME Code.
(c) Shell design. Shell stresses resulting from static or dynamic loadings, or combinations thereof, are not uniform throughout the cargo tank motor vehicle. The vertical, longitudinal, and lateral normal operating loadings can occur simultaneously and must be combined. The vertical, longitudinal and lateral extreme dynamic loadings occur separately and need not be combined.
(1) Normal operating loadings. The following procedure addresses stress in the tank shell resulting from normal operating loadings. The effective stress (the maximum principal stress at any point) must be determined by the following formula:
S = 0.5(Sy + Sx) ±[0.25(Sy − Sx)2 + Ss2]0.5
Where:
(i) S = effective stress at any given point under the combination of static and normal operating loadings that can occur at the same time, in psi.
(ii) Sy = circumferential stress generated by the MAWP and external pressure, when applicable, plus static head, in psi.
(iii) Sx = The following net longitudinal stress generated by the following static and normal operating loading conditions, in psi:
(A) The longitudinal stresses resulting from the MAWP and external pressure, when applicable, plus static head, in combination with the bending stress generated by the static weight of the fully loaded cargo tank motor vehicle, all structural elements, equipment and appurtenances supported by the cargo tank wall;
(B) The tensile or compressive stress resulting from normal operating longitudinal acceleration or deceleration. In each case, the forces applied must be 0.35 times the vertical reaction at the suspension assembly, applied at the road surface, and as transmitted to the cargo tank wall through the suspension assembly of a trailer during deceleration; or the horizontal pivot of the truck tractor or converter dolly fifth wheel, or the drawbar hinge on the fixed dolly during acceleration; or anchoring and support members of a truck during acceleration and deceleration, as applicable. The vertical reaction must be calculated based on the static weight of the fully loaded cargo tank motor vehicle, all structural elements, equipment and appurtenances supported by the cargo tank wall. The following loadings must be included:
(1) The axial load generated by a decelerative force;
(2) The bending moment generated by a decelerative force;
(3) The axial load generated by an accelerative force; and
(4) The bending moment generated by an accelerative force; and
(C) The tensile or compressive stress generated by the bending moment resulting from normal operating vertical accelerative force equal to 0.35 times the vertical reaction at the suspension assembly of a trailer; or the horizontal pivot of the upper coupler (fifth wheel) or turntable; or anchoring and support members of a truck, as applicable. The vertical reaction must be calculated based on the static weight of the fully loaded cargo tank motor vehicle, all structural elements, equipment and appurtenances supported by the cargo tank wall.
(iv) Ss = The following shear stresses generated by the following static and normal operating loading conditions, in psi:
(A) The static shear stress resulting from the vertical reaction at the suspension assembly of a trailer, and the horizontal pivot of the upper coupler (fifth wheel) or turntable; or anchoring and support members of a truck, as applicable. The vertical reaction must be calculated based on the static weight of the fully loaded cargo tank motor vehicle, all structural elements, equipment and appurtenances supported by the cargo tank wall;
(B) The vertical shear stress generated by a normal operating accelerative force equal to 0.35 times the vertical reaction at the suspension assembly of a trailer; or the horizontal pivot of the upper coupler (fifth wheel) or turntable; or anchoring and support members of a truck, as applicable. The vertical reaction must be calculated based on the static weight of the fully loaded cargo tank motor vehicle, all structural elements, equipment and appurtenances supported by the cargo tank wall;
(C) The lateral shear stress generated by a normal operating lateral accelerative force equal to 0.2 times the vertical reaction at each suspension assembly of a trailer, applied at the road surface, and as transmitted to the cargo tank wall through the suspension assembly of a trailer, and the horizontal pivot of the upper coupler (fifth wheel) or turntable; or anchoring and support members of a truck, as applicable. The vertical reaction must be calculated based on the static weight of the fully loaded cargo tank motor vehicle, all structural elements, equipment and appurtenances supported by the cargo tank wall; and
(D) The torsional shear stress generated by the same lateral forces as described in paragraph (c)(1)(iv)(C) of this section.
(2) Extreme dynamic loadings. The following procedure addresses stress in the tank shell resulting from extreme dynamic loadings. The effective stress (the maximum principal stress at any point) must be determined by the following formula:
S = 0.5(Sy + Sx) ±[0.25(Sy − Sx)2 + Ss2]0.5
Where:
(i) S = effective stress at any given point under a combination of static and extreme dynamic loadings that can occur at the same time, in psi.
(ii) Sy = circumferential stress generated by MAWP and external pressure, when applicable, plus static head, in psi.
(iii) Sx = the following net longitudinal stress generated by the following static and extreme dynamic loading conditions, in psi:
(A) The longitudinal stresses resulting from the MAWP and external pressure, when applicable, plus static head, in combination with the bending stress generated by the static weight of the fully loaded cargo tank motor vehicle, all structural elements, equipment and appurtenances supported by the tank wall;
(B) The tensile or compressive stress resulting from extreme longitudinal acceleration or deceleration. In each case the forces applied must be 0.7 times the vertical reaction at the suspension assembly, applied at the road surface, and as transmitted to the cargo tank wall through the suspension assembly of a trailer during deceleration; or the horizontal pivot of the truck tractor or converter dolly fifth wheel, or the drawbar hinge on the fixed dolly during acceleration; or the anchoring and support members of a truck during acceleration and deceleration, as applicable. The vertical reaction must be calculated based on the static weight of the fully loaded cargo tank motor vehicle, all structural elements, equipment and appurtenances supported by the cargo tank wall. The following loadings must be included:
(1) The axial load generated by a decelerative force;
(2) The bending moment generated by a decelerative force;
(3) The axial load generated by an accelerative force; and
(4) The bending moment generated by an accelerative force; and
(C) The tensile or compressive stress generated by the bending moment resulting from an extreme vertical accelerative force equal to 0.7 times the vertical reaction at the suspension assembly of a trailer, and the horizontal pivot of the upper coupler (fifth wheel) or turntable; or the anchoring and support members of a truck, as applicable. The vertical reaction must be calculated based on the static weight of the fully loaded cargo tank motor vehicle, all structural elements, equipment and appurtenances supported by the cargo tank wall.
(iv) Ss = The following shear stresses generated by static and extreme dynamic loading conditions, in psi:
(A) The static shear stress resulting from the vertical reaction at the suspension assembly of a trailer, and the horizontal pivot of the upper coupler (fifth wheel) or turntable; or anchoring and support members of a truck, as applicable. The vertical reaction must be calculated based on the static weight of the fully loaded cargo tank motor vehicle, all structural elements, equipment and appurtenances supported by the cargo tank wall;
(B) The vertical shear stress generated by an extreme vertical accelerative force equal to 0.7 times the vertical reaction at the suspension assembly of a trailer, and the horizontal pivot of the upper coupler (fifth wheel) or turntable; or anchoring and support members of a truck, as applicable. The vertical reaction must be calculated based on the static weight of the fully loaded cargo tank motor vehicle, all structural elements, equipment and appurtenances supported by the cargo tank wall;
(C) The lateral shear stress generated by an extreme lateral accelerative force equal to 0.4 times the vertical reaction at the suspension assembly of a trailer, applied at the road surface, and as transmitted to the cargo tank wall through the suspension assembly of a trailer, and the horizontal pivot of the upper coupler (fifth wheel) or turntable; or anchoring and support members of a truck, as applicable. The vertical reaction must be calculated based on the static weight of the fully loaded cargo tank motor vehicle, all structural elements, equipment and appurtenances supported by the cargo tank wall; and
(D) The torsional shear stress generated by the same lateral forces as described in paragraph (c)(2)(iv)(C) of this section.
(d) In order to account for stresses due to impact in an accident, the design calculations for the cargo tank shell and heads must include the load resulting from the design pressure in combination with the dynamic pressure resulting from a longitudinal deceleration of “2g”. For this loading condition the stress value used may not exceed the lesser of the yield strength or 75 percent of the ultimate tensile strength of the material of construction. For cargo tanks constructed of stainless steel the maximum design stress may not exceed 75 percent of the ultimate tensile strength of the type steel used.
(e) The minimum metal thickness for the shell and heads on tanks with a design pressure of 100 psig or more must be 4.75 mm (0.187 inch) for steel and 6.86 mm (0.270 inch) for aluminum, except for chlorine and sulfur dioxide tanks. In all cases, the minimum thickness of the tank shell and head shall be determined using structural design requirements in Section VIII of the ASME Code or 25% of the tensile strength of the material used. For a cargo tank used in chlorine or sulfur dioxide service, the cargo tank must be made of steel. A corrosion allowance of 20 percent or 2.54 mm (0.10 inch), whichever is less, must be added to the thickness otherwise required for sulfur dioxide and chlorine tank material. In chlorine cargo tanks, the wall thickness must be at least 1.59 cm (0.625 inch), including corrosion allowance.
(f) Where a cargo tank support is attached to any part of the cargo tank wall, the stresses imposed on the cargo tank wall must meet the requirements in paragraph (a) of this section.
(g) The design, construction, and installation of an attachment, appurtenance to the cargo tank, structural support member between the cargo tank and the vehicle or suspension component, or accident protection device must conform to the following requirements:
(1) Structural members, the suspension sub-frame, accident protection structures, and external circumferential reinforcement devices must be used as sites for attachment of appurtenances and other accessories to the cargo tank, when practicable.
(2) A lightweight attachment to the cargo tank wall such as a conduit clip, brake line clip, skirting structure, lamp mounting bracket, or placard holder must be of a construction having lesser strength than the cargo tank wall materials and may not be more than 72 percent of the thickness of the material to which it is attached. The lightweight attachment may be secured directly to the cargo tank wall if the device is designed and installed in such a manner that, if damaged, it will not affect the lading retention integrity of the tank. A lightweight attachment must be secured to the cargo tank shell or head by a continuous weld or in such a manner as to preclude formation of pockets which may become sites for corrosion. Attachments meeting the requirements of this paragraph are not authorized for cargo tanks constructed under part UHT in Section VIII of the ASME Code.
(3) Except as prescribed in paragraphs (g)(1) and (g)(2) of this section, the welding of any appurtenance to the cargo tank wall must be made by attachment of a mounting pad so that there will be no adverse effect upon the lading retention integrity of the cargo tank if any force less than that prescribed in paragraph (b)(1) of this section is applied from any direction. The thickness of the mounting pad may not be less than that of the shell wall or head wall to which it is attached, and not more than 1.5 times the shell or head thickness. However, a pad with a minimum thickness of 0.25 inch may be used when the shell or head thickness is over 0.25 inch. If weep holes or tell-tale holes are used, the pad must be drilled or punched at the lowest point before it is welded to the tank. Each pad must—
(i) Be fabricated from material determined to be suitable for welding to both the cargo tank material and the material of the appurtenance or structural support member; a Design Certifying Engineer must make this determination considering chemical and physical properties of the materials and must specify filler material conforming to the requirements in Section VIII of the ASME Code (IBR, see § 171.7 of this subchapter).
(ii) Be preformed to an inside radius no greater than the outside radius of the cargo tank at the attachment location.
(iii) Extend at least 2 inches in each direction from any point of attachment of an appurtenance or structural support member. This dimension may be measured from the center of the attached structural member.
(iv) Have rounded corners, or otherwise be shaped in a manner to minimize stress concentrations on the shell or head.
(v) Be attached by continuous fillet welding. Any fillet weld discontinuity may only be for the purpose of preventing an intersection between the fillet weld and a tank or jacket seam weld.
[Amdt. 178-89, 55 FR , Sept. 7, , as amended by Amdt. 178-104, 59 FR , Sept. 26, ; Amdt. 178-105, 60 FR , Apr. 5, ; Amdt. 178-118, 61 FR , Oct. 1, ; 65 FR , Sept. 29, ; 68 FR , Apr. 18, ; 68 FR , Sept. 3, ; 68 FR , Dec. 31, ]
(a) Joints shall be as required in Section VIII of the ASME Code (IBR, see § 171.7 of this subchapter), with all undercutting in shell and head material repaired as specified therein.
(b) Welding procedure and welder performance must be in accordance with Section IX of the ASME Code. In addition to the essential variables named therein, the following must be considered as essential variables: Number of passes; thickness of plate; heat input per pass; and manufacturer's identification of rod and flux. When fabrication is done in accordance with part UHT in Section VIII of the ASME Code, filler material containing more than 0.08 percent vanadium must not be used. The number of passes, thickness of plate, and heat input per pass may not vary more than 25 percent from the procedure or welder qualifications. Records of the qualifications must be retained for at least 5 years by the cargo tank manufacturer and must be made available to duly identified representatives of the Department and the owner of the cargo tank.
(c) All longitudinal shell welds shall be located in the upper half of the cargo tank.
(d) Edge preparation of shell and head components may be by machine heat processes, provided such surfaces are remelted in the subsequent welding process. Where there will be no subsequent remelting of the prepared surface as in a tapered section, the final 0.050 inch of material shall be removed by mechanical means.
(e) The maximum tolerance for misalignment and butting up shall be in accordance with the requirement in Section VIII of the ASME Code.
(f) Substructures shall be properly fitted before attachment, and the welding sequence shall be such as to minimize stresses due to shrinkage of welds.
[Order 59-B, 30 FR 580, Jan. 16, . Redesignated at 32 FR , Apr. 5, ]
(a) Not a specification requirement.
(b) [Reserved]
[Order 59-B, 30 FR 580, Jan. 16, . Redesignated at 32 FR , Apr. 5, ]
(a) Each cargo tank marked or certified after April 21, , must be provided with a manhole conforming to paragraph UG-46(g)(1) and other applicable requirements in Section VIII of the ASME Code (IBR, see § 171.7 of this subchapter), except that a cargo tank constructed of NQT steel having a capacity of 3,500 water gallons or less may be provided with an inspection opening conforming to paragraph UG-46 and other applicable requirements of the ASME Code instead of a manhole.
(b) The manhole assembly of cargo tanks constructed after June 30, , may not be located on the front head of the cargo tank.
[Amdt. 178-7, 34 FR , Nov. 14, , as amended by Amdt. 178-52, 43 FR , Dec. 18, ; Amdt. 178-89, 54 FR , June 12, ; 55 FR , May 22, ; 56 FR , June 17, ; 58 FR , Mar. 8, ; Amdt. 178-118, 61 FR , Oct. 1, ; 68 FR , Dec. 31, ]
(a) See § 178.337-10.
(b) [Reserved]
[Order 59-B, 30 FR 580, Jan. 16, . Redesignated at 32 FR , Apr. 5, ]
(a) General. The requirements in this paragraph (a) apply to MC 331 cargo tanks except for those used to transport chlorine. The requirements for inlets and outlets on chlorine cargo tanks are in paragraph (b) of this section.
(1) An opening must be provided on each cargo tank used for the transportation of liquefied materials to permit complete drainage.
(2) Except for gauging devices, thermometer wells, pressure relief valves, manhole openings, product inlet openings, and product discharge openings, each opening in a cargo tank must be closed with a plug, cap, or bolted flange.
(3) Except as provided in paragraph (b) of this section, each product inlet opening, including vapor return lines, must be fitted with a back flow check valve or an internal self-closing stop valve located inside the cargo tank or inside a welded nozzle that is an integral part of the cargo tank. The valve seat must be located inside the cargo tank or within 2.54 cm (one inch) of the external face of the welded flange. Damage to parts exterior to the cargo tank or mating flange must not prevent effective seating of the valve. All parts of a valve inside a cargo tank or welded flange must be made of material that will not corrode or deteriorate in the presence of the lading.
(4) Except as provided in paragraphs (a)(5), (b), and (c) of this section, each liquid or vapor discharge outlet must be fitted with a primary discharge control system as defined in § 178.337-1(g). Thermal remote operators must activate at a temperature of 121.11 °C (250 °F) or less. Linkages between closures and remote operators must be corrosion resistant and effective in all types of environmental conditions incident to discharging of product.
(i) On a cargo tank over 13,247.5 L (3,500 gallons) water capacity, thermal and mechanical means of remote closure must be installed at the ends of the cargo tank in at least two diagonally opposite locations. If the loading/unloading connection at the cargo tank is not in the general vicinity of one of the two locations specified in the first sentence of this paragraph (a)(4)(i), additional means of thermal remote closure must be installed so that heat from a fire in the loading/unloading connection area or the discharge pump will activate the primary discharge control system. The loading/unloading connection area is where hoses or hose reels are connected to the permanent metal piping.
(ii) On a cargo tank of 13,247.5 L (3,500 gallons) water capacity or less, a thermal means of remote closure must be installed at or near the internal self-closing stop valve. A mechanical means of remote closure must be installed on the end of the cargo tank furthest away from the loading/unloading connection area. The loading/unloading connection area is where hoses or hose reels are connected to the permanent metal piping. Linkages between closures and remote operators must be corrosion resistant and effective in all types of environmental conditions incident to discharge of product.
(iii) All parts of a valve inside a cargo tank or within a welded flange must be made of material that will not corrode or deteriorate in the presence of the lading.
(iv) An excess flow valve, integral excess flow valve, or excess flow feature must close if the flow reaches the rated flow of a gas or liquid specified by the original valve manufacturer when piping mounted directly on the valve is sheared off before the first valve, pump, or fitting downstream from the excess flow valve, integral excess flow valve, or excess flow feature.
(v) An integral excess flow valve or the excess flow feature of an internal self-closing stop valve may be designed with a bypass, not to exceed 0. cm (0.040 inch) diameter opening, to allow equalization of pressure.
(vi) The internal self-closing stop valve must be designed so that the self-stored energy source and the valve seat are located inside the cargo tank or within 2.54 cm (one inch) of the external face of the welded flange. Damage to parts exterior to the cargo tank or mating flange must not prevent effective seating of the valve.
(5) A primary discharge control system is not required on the following:
(i) A vapor or liquid discharge opening of less than 11⁄4 NPT equipped with an excess flow valve together with a manually operated external stop valve in place of an internal self-closing stop valve.
(ii) An engine fuel line on a truck-mounted cargo tank of not more than 3⁄4 NPT equipped with a valve having an integral excess flow valve or excess flow feature.
(iii) A cargo tank motor vehicle used to transport refrigerated liquids such as argon, carbon dioxide, helium, krypton, neon, nitrogen, and xenon, or mixtures thereof.
(6) In addition to the internal self-closing stop valve, each filling and discharge line must be fitted with a stop valve located in the line between the internal self-closing stop valve and the hose connection. A back flow check valve or excess flow valve may not be used to satisfy this requirement.
(7) An excess flow valve may be designed with a bypass, not to exceed a 0. centimeter (0.040 inch) diameter opening, to allow equalization of pressure.
(b) Inlets and discharge outlets on chlorine tanks. The inlet and discharge outlets on a cargo tank used to transport chlorine must meet the requirements of § 178.337-1(c)(2) and must be fitted with an internal excess flow valve. In addition to the internal excess flow valve, the inlet and discharge outlets must be equipped with an external stop valve (angle valve). Excess flow valves must conform to the standards of The Chlorine Institute, Inc., as follows:
(1) A valve conforming to The Chlorine Institute, Inc., Dwg. 101-7 (IBR, see § 171.7 of this subchapter), must be installed under each liquid angle valve.
(2) A valve conforming to The Chlorine Institute, Inc., Dwg. 106-6 (IBR, see § 171.7 of this subchapter), must be installed under each gas angle valve.
(c) Discharge outlets on carbon dioxide, refrigerated liquid, cargo tanks. A discharge outlet on a cargo tank used to transport carbon dioxide, refrigerated liquid is not required to be fitted with an internal self-closing stop valve.
[64 FR , May 24, , as amended at 66 FR , Aug. 28, ; 68 FR , Apr. 18, ; 68 FR , Dec. 31, ]
(a) Pressure relief devices.
(1) See § 173.315(i) of this subchapter.
(2) On cargo tanks for carbon dioxide or nitrous oxide see § 173.315 (i) (9) and (10) of this subchapter.
(3) Each valve must be designed, constructed, and marked for a rated pressure not less than the cargo tank design pressure at the temperature expected to be encountered.
(b) Piping, valves, hose, and fittings.
(1) The burst pressure of all piping, pipe fittings, hose and other pressure parts, except for pump seals and pressure relief devices, must be at least 4 times the design pressure of the cargo tank. Additionally, the burst pressure may not be less than 4 times any higher pressure to which each pipe, pipe fitting, hose or other pressure part may be subjected to in service. For chlorine service, see paragraph (b)(7) of this section.
(2) Pipe joints must be threaded, welded, or flanged. If threaded pipe is used, the pipe and fittings must be Schedule 80 weight or heavier, except for sacrificial devices. Malleable metal, stainless steel, or ductile iron must be used in the construction of primary valve body parts and fittings used in liquid filling or vapor equalization. Stainless steel may be used for internal components such as shutoff discs and springs except where incompatible with the lading to be transported. Where copper tubing is permitted, joints must be brazed or be of equally strong metal union type. The melting point of the brazing material may not be lower than 538 °C (1,000 °F). The method of joining tubing may not reduce the strength of the tubing.
(3) Each hose coupling must be designed for a pressure of at least 120 percent of the hose design pressure and so that there will be no leakage when connected.
(4) Piping must be protected from damage due to thermal expansion and contraction, jarring, and vibration. Slip joints are not authorized for this purpose.
(5) [Reserved]
(6) Cargo tank manufacturers and fabricators must demonstrate that all piping, valves, and fittings on a cargo tank are free from leaks. To meet this requirement, the piping, valves, and fittings must be tested after installation at not less than 80 percent of the design pressure marked on the cargo tank.
(7) A hose assembler must:
(i) Permanently mark each hose assembly with a unique identification number.
(ii) Demonstrate that each hose assembly is free from leaks by performing the tests and inspections in § 180.416(f) of this subchapter.
(iii) Mark each hose assembly with the month and year of its original pressure test.
(8) Chlorine cargo tanks. Angle valves on cargo tanks intended for chlorine service must conform to the standards of the Chlorine Institute, Inc., Drawing; Dwg. 104-8; or “Section 3, Pamphlet 166, Angle Valve Guidelines for Chlorine Bulk Transportation;” or “Sections 4 through 6, Pamphlet 168, Guidelines for Dual Valve Systems for Bulk Chlorine Transport” (IBR, see § 171.7 of this subchapter). Before installation, each angle valve must be tested for leakage at not less than 225 psig using dry air or inert gas.
(c) Marking inlets and outlets. Except for gauging devices, thermometer wells, and pressure relief valves, each cargo tank inlet and outlet must be marked “liquid” or “vapor” to designate whether it communicates with liquid or vapor when the cargo tank is filled to the maximum permitted filling density. A filling line that communicates with vapor may be marked “spray-fill” instead of “vapor.”
(d) Refrigeration and heating coils.
(1) Refrigeration and heating coils must be securely anchored with provisions for thermal expansion. The coils must be pressure tested externally to at least the cargo tank test pressure, and internally to either the tank test pressure or twice the working pressure of the heating/refrigeration system, whichever is higher. A cargo tank may not be placed in service if any leakage occurs or other evidence of damage is found. The refrigerant or heating medium to be circulated through the coils must not be capable of causing any adverse chemical reaction with the cargo tank lading in the event of leakage. The unit furnishing refrigeration may be mounted on the motor vehicle.
(2) Where any liquid susceptible to freezing, or the vapor of any such liquid, is used for heating or refrigeration, the heating or refrigeration system shall be arranged to permit complete drainage.
[Order 59-B, 30 FR 580, Jan. 16, . Redesignated at 32 FR , Apr. 5, ]
(a) All valves, fittings, pressure relief devices, and other accessories to the tank proper shall be protected in accordance with paragraph (b) of this section against such damage as could be caused by collision with other vehicles or objects, jack-knifing and overturning. In addition, pressure relief valves shall be so protected that in the event of overturn of the vehicle onto a hard surface, their opening will not be prevented and their discharge will not be restricted.
(b) The protective devices or housing must be designed to withstand static loading in any direction equal to twice the weight of the tank and attachments when filled with the lading, using a safety factor of not less than four, based on the ultimate strength of the material to be used, without damage to the fittings protected, and must be made of metal at least 3⁄16-inch thick.
(c) Rear-end tank protection. Rear-end tank protection devices must:
(1) Consist of at least one rear bumper designed to protect the cargo tank and all valves, piping and fittings located at the rear of the cargo tank from damage that could result in loss of lading in the event of a rear end collision. The bumper design must transmit the force of the collision directly to the chassis of the vehicle. The rear bumper and its attachments to the chassis must be designed to withstand a load equal to twice the weight of the loaded cargo tank motor vehicle and attachments, using a safety factor of four based on the tensile strength of the materials used, with such load being applied horizontally and parallel to the major axis of the cargo tank. The rear bumper dimensions must also meet the requirements of § 393.86 of this title; or
(2) Conform to the requirements of § 178.345-8(d).
(d) Chlorine tanks. A chlorine tank must be equipped with a protective housing and a manway cover to permit the use of standard emergency kits for controlling leaks in fittings on the dome cover plate. For tanks manufactured on or after October 1, , the housing and manway cover must conform to the Chlorine Institute, Inc., Dwg. 137-5 (IBR, see § 171.7 of this subchapter).
(e) Piping and fittings. Piping and fittings must be grouped in the smallest practicable space and protected from damage as required in this section.
(f) Shear section. A shear section or sacrificial device is required for the valves specified in the following locations:
(1) A section that will break under strain must be provided adjacent to or outboard of each valve specified in § 178.337-8(a)(3) and (4).
(2) Each internal self-closing stop valve, excess flow valve, and check valve must be protected by a shear section or other sacrificial device. The sacrificial device must be located in the piping system outboard of the stop valve and within the accident damage protection to prevent any accidental loss of lading. The failure of the sacrificial device must leave the protected lading protection device and its attachment to the cargo tank wall intact and capable of retaining product.
[Order 59-B, 30 FR 581, Jan. 16, . Redesignated at 32 FR , Apr. 5, ]
(a) Emergency discharge control equipment. Emergency discharge control equipment must be installed in a liquid discharge line as specified by product and service in § 173.315(n) of this subchapter. The performance and certification requirements for emergency discharge control equipment are specified in § 173.315(n) of this subchapter and are not a part of the cargo tank motor vehicle certification made under this specification.
(b) Engine fuel lines. On a truck-mounted cargo tank, emergency discharge control equipment is not required on an engine fuel line of not more than 3⁄4 NPT equipped with a valve having an integral excess flow valve or excess flow feature.
[64 FR , May 24, ]
(a) A cargo tank that is not permanently attached to or integral with a vehicle chassis must be secured by the use of restraining devices designed to prevent relative motion between the cargo tank and the vehicle chassis when the vehicle is in operation. Such restraining devices must be readily accessible for inspection and maintenance.
(b) On a cargo tank motor vehicle designed and constructed so that the cargo tank constitutes in whole or in part the structural member used in place of a motor vehicle frame, the cargo tank must be supported by external cradles. A cargo tank mounted on a motor vehicle frame must be supported by external cradles or longitudinal members. Where used, the cradles must subtend at least 120 degrees of the shell circumference.
(c) The design calculations of the support elements must satisfy the requirements of § 178.337-3, (a), (b), (c), and (d).
(d) Where any cargo tank support is attached to any part of a cargo tank head, the stresses imposed upon the head must be provided for as required in paragraph (c) of this section.
[68 FR , Apr. 18, ]
(a) Liquid level gauging devices. See § 173.315(h) of this subchapter.
(b) Pressure gauges.
(1) See § 173.315(h) of this subchapter.
(2) Each cargo tank used in carbon dioxide, refrigerated liquid or nitrous oxide, refrigerated liquid service must be provided with a suitable pressure gauge. A shut-off valve must be installed between the pressure gauge and the cargo tank.
(c) Orifices. See § 173.315(h) (3) and (4) of this subchapter.
[Amdt. 178-29, 38 FR , Oct. 5, , as amended by Amdt. 178-89, 54 FR , June 12, ; Amdt. 178-118, 61 FR , Oct. 1, ]
(a) Liquid pumps or gas compressors, if used, must be of suitable design, adequately protected against breakage by collision, and kept in good condition. They may be driven by motor vehicle power take-off or other mechanical, electrical, or hydraulic means. Unless they are of the centrifugal type, they shall be equipped with suitable pressure actuated by-pass valves permitting flow from discharge to suction or to the cargo tank.
(b) A liquid chlorine pump may not be installed on a cargo tank intended for the transportation of chlorine.
[Amdt. 178-89, 54 FR , June 12, , as amended by Amdt. 178-118, 61 FR , Oct. 1, ]
(a) Inspection and tests. Inspection of materials of construction of the cargo tank and its appurtenances and original test and inspection of the finished cargo tank and its appurtenances must be as required by Section VIII of the ASME Code (IBR, see § 171.7 of this subchapter) and as further required by this specification, except that for cargo tanks constructed in accordance with part UHT in Section VIII of the ASME Code the original test pressure must be at least twice the cargo tank design pressure.
(b) Weld testing and inspection.
(1) Each cargo tank constructed in accordance with part UHT in Section VIII of the ASME Code must be subjected, after postweld heat treatment and hydrostatic tests, to a wet fluorescent magnetic particle inspection to be made on all welds in or on the cargo tank shell and heads both inside and out. The method of inspection must conform to appendix 6 in Section VIII of the ASME Code except that permanent magnets shall not be used.
(2) On cargo tanks of over 3,500 gallons water capacity other than those described in paragraph (b)(1) of this section unless fully radiographed, a test must be made of all welds in or on the shell and heads both inside and outside by either the wet fluorescent magnetic particle method conforming to appendix U in Section VIII of the ASME Code, liquid dye penetrant method, or ultrasonic testing in accordance with appendix 12 in Section VIII of the ASME Code. Permanent magnets must not be used to perform the magnetic particle inspection.
(c) All defects found shall be repaired, the cargo tanks shall then again be postweld heat treated, if such heat treatment was previously performed, and the repaired areas shall again be tested.
[Order 59-B, 30 FR 582, Jan. 16, . Redesignated at 32 FR , Apr. 5, , and amended by Amdt. 178-7, 34 FR , Nov. 14, ; Amdt. 178-99, 58 FR , Oct. 1, ; Amdt. 178-118, 61 FR , Oct. 1, ; 68 FR , Dec. 31, ]
(a) General. Each cargo tank certified after October 1, must have a corrosion-resistant metal name plate (ASME Plate); and each cargo tank motor vehicle certified after October 1, must have a specification plate, permanently attached to the cargo tank by brazing, welding, or other suitable means on the left side near the front, in a place accessible for inspection. If the specification plate is attached directly to the cargo tank wall by welding, it must be welded to the tank before the cargo tank is postweld heat treated.
(1) The plates must be legibly marked by stamping, embossing, or other means of forming letters into the metal of the plate, with the information required in paragraphs (b) and (c) of this section, in addition to that required by the ASME Code, in characters at least 3⁄16 inch high (parenthetical abbreviations may be used). All plates must be maintained in a legible condition.
(2) Each insulated cargo tank must have additional plates, as described, attached to the jacket in the location specified unless the specification plate is attached to the chassis and has the information required in paragraphs (b) and (c) of this section.
(3) The information required for both the name and specification plate may be displayed on a single plate. If the information required by this section is displayed on a plate required by the ASME, the information need not be repeated on the name and specification plates.
(4) The specification plate may be attached to the cargo tank motor vehicle chassis rail by brazing, welding, or other suitable means on the left side near the front head, in a place accessible for inspection. If the specification plate is attached to the chassis rail, then the cargo tank serial number assigned by the cargo tank manufacturer must be included on the plate.
(b) Name plate. The following information must be marked on the name plate in accordance with this section:
(1) DOT-specification number MC 331 (DOT MC 331).
(2) Original test date (Orig. Test Date).
(3) MAWP in psig.
(4) Cargo tank design temperature (Design Temp. Range) ______ °F to ______ °F.
(5) Nominal capacity (Water Cap.), in pounds.
(6) Maximum design density of lading (Max. Lading density), in pounds per gallon.
(7) Material specification number—shell (Shell matl, yyy***), where “yyy” is replaced by the alloy designation and “***” is replaced by the alloy type.
(8) Material specification number—heads (Head matl. yyy***), where “yyy” is replaced by the alloy designation and “***” by the alloy type.
(9) Minimum Thickness—shell (Min. Shell-thick), in inches. When minimum shell thicknesses are not the same for different areas, show (top____, side____, bottom____, in inches).
(10) Minimum thickness—heads (Min. heads thick.), in inches.
(11) Manufactured thickness—shell (Mfd. Shell thick.), top____, side____, bottom____, in inches. (Required when additional thickness is provided for corrosion allowance.)
(12) Manufactured thickness—heads (Mfd. Heads thick.), in inches. (Required when additional thickness is provided for corrosion allowance.)
(13) Exposed surface area, in square feet.
Note to paragraph (b):When the shell and head materials are the same thickness, they may be combined, (Shell&head matl, yyy***).
(c) Specification plate. The following information must be marked on the specification plate in accordance with this section:
(1) Cargo tank motor vehicle manufacturer (CTMV mfr.).
(2) Cargo tank motor vehicle certification date (CTMV cert. date).
(3) Cargo tank manufacturer (CT mfr.).
(4) Cargo tank date of manufacture (CT date of mfr.), month and year.
(5) Maximum weight of lading (Max. Payload), in pounds
(6) Lining materials (Lining), if applicable.
(7) Heating system design pressure (Heating sys. press.), in psig, if applicable.
(8) Heating system design temperature (Heating sys. temp.), in °F, if applicable.
(9) Cargo tank serial number, assigned by cargo tank manufacturer (CT serial), if applicable.
Note 1 to paragraph (c):See § 173.315(a) of this chapter regarding water capacity.
Note 2 to paragraph (c):When the shell and head materials are the same thickness, they may be combined (Shell & head matl, yyy***).
(d) The design weight of lading used in determining the loading in §§ 178.337-3(b), 178.337-10(b) and (c), and 178.337-13(a) and (b), must be shown as the maximum weight of lading marking required by paragraph (c) of this section.
[68 FR , Apr. 18, ; 68 FR , Sept. 3, , as amended at 68 FR , Oct. 6, ; 81 FR , June 2, ]
(a) At or before the time of delivery, the cargo tank motor vehicle manufacturer must supply and the owner must obtain, a cargo tank motor vehicle manufacturer's data report as required by Section VIII of the ASME Code (IBR, see § 171.7 of this subchapter), and a certificate stating that the completed cargo tank motor vehicle conforms in all respects to Specification MC 331 and the ASME Code. The registration numbers of the manufacturer, the Design Certifying Engineer, and the Registered Inspector, as appropriate, must appear on the certificates (see subpart F, part 107 in subchapter A of this chapter).
(1) For each design type, the certificate must be signed by a responsible official of the manufacturer and a Design Certifying Engineer; and
(2) For each cargo tank motor vehicle, the certificate must be signed by a responsible official of the manufacturer and a Registered Inspector.
(3) When a cargo tank motor vehicle is manufactured in two or more stages, each manufacturer who performs a manufacturing function or portion thereof on the incomplete cargo tank motor vehicle must provide to the succeeding manufacturer, at or before the time of delivery, a certificate that states the function performed by the manufacturer, including any certificates received from previous manufacturers, Registered Inspectors, and Design Certifying Engineers.
(4) Specification shortages. When a cargo tank motor vehicle is manufactured in two or more stages, the manufacturer of the cargo tank must attach the name plate and specification plate as required by § 178.337-17(a) and (b) without the original date of certification stamped on the specification plate. Prior manufacturers must list the specification requirements that are not completed on the Certificate of Compliance. When the cargo tank motor vehicle is brought into full compliance with the applicable specification, the cargo tank motor vehicle manufacturer must have a Registered Inspector stamp the date of certification on the specification plate and issue a Certificate of Compliance to the owner of the cargo tank motor vehicle. The Certificate of Compliance must list the actions taken to bring the cargo tank motor vehicle into full compliance. In addition, the certificate must include the date of certification and the person (manufacturer, carrier or repair organization) accomplishing compliance.
(5) The certificate must state whether or not it includes certification that all valves, piping, and protective devices conform to the requirements of the specification. If it does not so certify, the installer of any such valve, piping, or device shall supply and the owner shall obtain a certificate asserting complete compliance with these specifications for such devices. The certificate, or certificates, will include sufficient sketches, drawings, and other information to indicate the location, make, model, and size of each valve and the arrangement of all piping associated with the cargo tank.
(6) The certificate must contain a statement indicating whether or not the cargo tank was postweld heat treated for anhydrous ammonia as specified in § 178.337-1(f).
(b) The owner shall retain the copy of the data report and certificates and related papers in his files throughout his ownership of the cargo tank motor vehicle and for at least one year thereafter; and in the event of change in ownership, retention by the prior owner of nonfading photographically reproduced copies will be deemed to satisfy this requirement. Each motor carrier using the cargo tank motor vehicle, if not the owner thereof, shall obtain a copy of the data report and certificate and retain them in his files during the time he uses the cargo tank motor vehicle and for at least one year thereafter.
[Order 59-B, 30 FR 583, Jan. 16, . Redesignated at 32 FR , Apr. 5, ]
(a) For the purposes of this section—
(1) Design pressure means the “MAWP” as used in Section VIII of the ASME Code (IBR, see § 171.7 of this subchapter), and is the gauge pressure at the top of the tank.
(2) Design service temperature means the coldest temperature for which the tank is suitable (see §§ 173.318 (a)(1) and (f) of this subchapter).
(b) Each cargo tank must consist of a suitably supported welded inner vessel enclosed within an outer shell or jacket, with insulation between the inner vessel and outer shell or jacket, and having piping, valves, supports and other appurtenances as specified in this subchapter. For the purpose of this specification, tank means inner vessel and jacket means either the outer shell or insulation cover.
(c) Each tank must be designed, constructed, certified, and stamped in accordance with Section VIII of the ASME Code.
(d) The exterior surface of the tank must be insulated with a material compatible with the lading.
(1) Each cargo tank must have an insulation system that will prevent the tank pressure from exceeding the pressure relief valve set pressure within the specified holding time when the tank is loaded with the specific cryogenic liquid at the design conditions of—
(i) The specified temperature and pressure of the cryogenic liquid, and
(ii) The exposure of the filled cargo tank to an average ambient temperature of 85 °F.
(2) For a cargo tank used to transport oxygen, the insulation may not sustain combustion in a 99.5 percent oxygen atmosphere at atmospheric pressure when contacted with a continuously heated glowing platinum wire. The cargo tank must be marked in accordance with § 178.338-18(b)(7).
(3) Each vacuum-insulated cargo tank must be provided with a connection for a vacuum gauge to indicate the absolute pressure within the insulation space.
(e) The insulation must be completely covered by a metal jacket. The jacket or the insulation must be so constructed and sealed as to prevent moisture from coming into contact with the insulation (see § 173.318(a)(3) of this subchapter). Minimum metal thicknesses are as follows:
Type metal Jacket evacuated Jacket not evacuated Gauge Inches Gauge Inches Stainless steel 18 0. 22 0. Low carbon mild steel 12 0. 14 0. Aluminum 0.125 0.(f) An evacuated jacket must be in compliance with the following requirements:
(1) The jacket must be designed to sustain a minimum critical collapsing pressure of 30 psig.
(2) If the jacket also supports additional loads, such as the weight of the tank and lading, the combined stress, computed according to the formula in § 178.338-3(b), may not exceed 25 percent of the minimum specified tensile strength.
[Amdt. 178-77, 48 FR , June 16, , as amended at 49 FR , June 12, ; Amdt. 178-104, 59 FR , Sept. 26, ; 66 FR , Aug. 28, ; 68 FR , Dec. 31, ]
(a) All material used in the construction of a tank and its appurtenances that may come in contact with the lading must be compatible with the lading to be transported. All material used for tank pressure parts must conform to the requirements in Section II of the ASME Code (IBR, see § 171.7 of this subchapter). All material used for evacuated jacket pressure parts must conform to the chemistry and steelmaking practices of one of the material specifications of Section II of the ASME Code or the following ASTM Specifications (IBR, see § 171.7 of this subchapter): A 242, A 441, A 514, A 572, A 588, A 606, A 633, A 715, A /A M, A /A M.
(b) All tie-rods, mountings, and other appurtenances within the jacket and all piping, fittings and valves must be of material suitable for use at the lowest temperature to be encountered.
(c) Impact tests are required on all tank materials, except materials that are excepted from impact testing by the ASME Code, and must be performed using the procedure prescribed in Section VIII of the ASME Code.
(d) The direction of final rolling of the shell material must be the circumferential orientation of the tank shell.
(e) Each tank constructed in accordance with part UHT in Section VIII of the ASME Code must be postweld heat treated as a unit after completion of all welds to the shell and heads. Other tanks must be postweld heat treated as required in Section VIII of the ASME Code. For all tanks the method must be as prescribed in the ASME Code. Welded attachments to pads may be made after postweld heat treatment.
(f) The fabricator shall record the heat and slab numbers and the certified Charpy impact values of each plate used in the tank on a sketch showing the location of each plate in the shell and heads of the tank. A copy of the sketch must be provided to the owner of the cargo tank and a copy must be retained by the fabricator for at least five years and made available, upon request, to any duly identified representative of the Department.
(Approved by the Office of Management and Budget under control number -)
[Amdt. 178-77, 48 FR , , June 16, , as amended at 49 FR , June 12, ; 68 FR , Apr. 18, ; 68 FR , Dec. 31, ; 70 FR , June 13, ]
(a) General requirements and acceptance criteria.
(1) Except as permitted in paragraph (d) of this section, the maximum calculated design stress at any point in the tank may not exceed the lesser of the maximum allowable stress value prescribed in Section VIII of the ASME Code (IBR, see § 171.7 of this subchapter), or 25 percent of the tensile strength of the material used.
(2) The relevant physical properties of the materials used in each tank may be established either by a certified test report from the material manufacturer or by testing in conformance with a recognized national standard. In either case, the ultimate tensile strength of the material used in the design may not exceed 120 percent of the minimum ultimate tensile strength specified in either the ASME Code or the ASTM standard to which the material is manufactured.
(3) The maximum design stress at any point in the tank must be calculated separately for the loading conditions described in paragraphs (b), (c), and (d) of this section. Alternate test or analytical methods, or a combination thereof, may be used in lieu of the procedures described in paragraphs (b), (c), and (d) of this section, if the methods are accurate and verifiable.
(4) Corrosion allowance material may not be included to satisfy any of the design calculation requirements of this section.
(b) Static design and construction.
(1) The static design and construction of each tank must be in accordance with appendix G in Section VIII of the ASME Code (IBR, see § 171.7 of this subchapter). The tank design must include calculation of stress due to the design pressure, the weight of lading, the weight of structures supported by the tank wall, and the effect of temperature gradients resulting from lading and ambient temperature extremes. When dissimilar materials are used, their thermal coefficients must be used in calculation of the thermal stresses.
(2) Stress concentrations in tension, bending, and torsion which occur at pads, cradles, or other supports must be considered in accordance with appendix G in Section VIII of the ASME Code.
(c) Stresses resulting from static and dynamic loadings, or a combination thereof, are not uniform throughout the cargo tank motor vehicle. The following is a simplified procedure for calculating the effective stress in the tank resulting from static and dynamic loadings. The effective stress (the maximum principal stress at any point) must be determined by the following formula:
S = 0.5 (Sy + Sx) ±(0.25(Sy − Sx)2 + Ss2)0.5
Where:
(1) S = effective stress at any given point under the most severe combination of static and dynamic loadings that can occur at the same time, in psi.
(2) Sy = circumferential stress generated by internal and external pressure when applicable, in psi.
(3) Sx = the net longitudinal stress, in psi, generated by the following loading conditions:
(i) The longitudinal tensile stress generated by internal pressure;
(ii) The tensile or compressive stress generated by the axial load resulting from a decelerative force applied independently to each suspension assembly at the road surface using applicable static loadings specified in § 178.338-13 (b);
(iii) The tensile or compressive stress generated by the bending moment resulting from a decelerative force applied independently to each suspension assembly at the road surface using applicable static loadings specified in § 178.338-13 (b);
(iv) The tensile or compressive stress generated by the axial load resulting from an accelerative force applied to the horizontal pivot of the fifth wheel supporting the vehicle using applicable static loadings specified in § 178.338-13 (b);
(v) The tensile or compressive stress generated by the bending moment resulting from an accelerative force applied to the horizontal pivot of the fifth wheel supporting the vehicle using applicable static loadings specified in § 178.338-13 (b); and
(vi) The tensile or compressive stress generated by a bending moment produced by a vertical force using applicable static loadings specified in § 178.338-13 (b).
(4) Ss = The following shear stresses that apply, in psi,: The vectorial sum of the applicable shear stresses in the plane under consideration, including direct shear generated by the static vertical loading; direct lateral and torsional shear generated by a lateral accelerative force applied at the road surface, using applicable static loads specified in § 178.338-13 (b)
(d) In order to account for stresses due to impact in an accident, the design calculations for the tank shell and heads must include the load resulting from the design pressure in combination with the dynamic pressure resulting from a longitudinal deceleration of “2g”. For this loading condition the stress value used may not exceed the lesser of the yield strength or 75 percent of the ultimate tensile strength of the material of construction. For a cargo tank constructed of stainless steel, the maximum design stress may not exceed 75 percent of the ultimate tensile strength of the type steel used.
(e) The minimum thickness of the shell or heads of the tank must be 0.187 inch for steel and 0.270 inch for aluminum. However, the minimum thickness for steel may be 0.110 inches provided the cargo tank is:
(1) Vacuum insulated, or
(2) Double walled with a load bearing jacket designed to carry a proportionate amount of structural loads prescribed in this section.
(f) Where a tank support is attached to any part of the tank wall, the stresses imposed on the tank wall must meet the requirements in paragraph (a) of this section.
(g) The design, construction and installation of an attachment, appurtenance to the cargo tank or structural support member between the cargo tank and the vehicle or suspension component or accident protection device must conform to the following requirements:
(1) Structural members, the suspension subframe, accident protection structures and external circumferential reinforcement devices must be used as sites for attachment of appurtenances and other accessories to the cargo tank, when practicable.
(2) A lightweight attachment to the cargo tank wall such as a conduit clip, brakeline clip, skirting structure, lamp mounting bracket, or placard holder must be of a construction having lesser strength than the cargo tank wall materials and may not be more than 72 percent of the thickness of the material to which it is attached. The lightweight attachment may be secured directly to the cargo tank wall if the device is designed and installed in such a manner that, if damaged, it will not affect the lading retention integrity of the tank. A lightweight attachment must be secured to the cargo tank shell or head by a continuous weld or in such a manner as to preclude formation of pockets that may become sites for corrosion. Attachments meeting the requirements of this paragraph are not authorized for cargo tanks constructed under part UHT in Section VIII of the ASME Code.
(3) Except as prescribed in paragraphs (g)(1) and (g)(2) of this section, the welding of any appurtenance the cargo tank wall must be made by attachment of a mounting pad so that there will be no adverse effect upon the lading retention integrity of the cargo tank if any force less than that prescribed in paragraph (b)(1) of this section is applied from any direction. The thickness of the mounting pad may not be less than that of the shell or head to which it is attached, and not more than 1.5 times the shell or head thickness. However, a pad with a minimum thickness of 0.187 inch may be used when the shell or head thickness is over 0.187 inch. If weep holes or tell-tale holes are used, the pad must be drilled or punched at the lowest point before it is welded to the tank. Each pad must:
(i) Be fabricated from material determined to be suitable for welding to both the cargo tank material and the material of the appurtenance or structural support member; a Design Certifying Engineer must make this determination considering chemical and physical properties of the materials and must specify filler material conforming to the requirements in Section IX of the ASME Code (IBR, see § 171.7 of this subchapter).
(ii) Be preformed to an inside radius no greater than the outside radius of the cargo tank at the attachment location.
(iii) Extend at least 2 inches in each direction from any point of attachment of an appurtenance or structural support member. This dimension may be measured from the center of the attached structural member.
(iv) Have rounded corners, or otherwise be shaped in a manner to minimize stress concentrations on the shell or head.
(v) Be attached by continuous fillet welding. Any fillet weld discontinuity may only be for the purpose of preventing an intersection between the fillet weld and a tank or jacket seam weld.
[Amdt. 178-89, 55 FR , Sept. 7, , as amended by Amdt. 178-89, 56 FR , June 17, ; 56 FR , Sept. 11, ; 68 FR , Apr. 18, ; 68 FR , Oct. 6, ; 68 FR , Dec. 31, ; 81 FR , Apr. 29, ]
(a) All joints in the tank, and in the jacket if evacuated, must be as prescribed in Section VIII of the ASME Code (IBR, see § 171.7 of this subchapter), except that a butt weld with one plate edge offset is not authorized.
(b) Welding procedure and welder performance tests must be made in accordance with Section IX of the ASME Code. Records of the qualification must be retained by the tank manufacturer for at least five years and must be made available, upon request, to any duly identified representative of the Department, or the owner of the cargo tank.
(c) All longitudinal welds in tanks and load bearing jackets must be located so as not to intersect nozzles or supports other than load rings and stiffening rings.
(d) Substructures must be properly fitted before attachment and the welding sequence must minimize stresses due to shrinkage of welds.
(e) Filler material containing more than 0.05 percent vanadium may not be used with quenched and tempered steel.
(f) All tank nozzle-to-shell and nozzle-to-head welds must be full penetration welds.
(Approved by the Office of Management and Budget under control number -)
[Amdt. 178-77, 48 FR , , June 16, , as amended at 49 FR , June 12, ; 68 FR , Dec. 31, ]
(a) A tank is not required to be provided with stiffening rings, except as prescribed in Section VIII of the ASME Code (IBR, see § 171.7 of this subchapter).
(b) If a jacket is evacuated, it must be constructed in compliance with § 178.338-1(f). Stiffening rings may be used to meet these requirements.
[Amdt. 178-77, 48 FR , June 16, , as amended at 68 FR , Dec. 31, ]
(a) Each tank in oxygen service must be provided with a manhole as prescribed in Section VIII of the ASME Code (IBR, see § 171.7 of this subchapter).
(b) Each tank having a manhole must be provided with a means of entrance and exit through the jacket, or the jacket must be marked to indicate the manway location on the tank.
(c) A manhole with a bolted closure may not be located on the front head of the tank.
[Amdt. 178-77, 48 FR , June 16, , as amended at 49 FR , June 12, ; 68 FR , Dec. 31, ]
(a) The inlet to the liquid product discharge opening of each tank intended for flammable ladings must be at the bottom centerline of the tank.
(b) If the leakage of a single valve, except a pressure relief valve, pressure control valve, full trycock or gas phase manual vent valve, would permit loss of flammable material, an additional closure that is leak tight at the tank design pressure must be provided outboard of such valve.
[Amdt. 178-77, 48 FR , June 16, ]
(a) Pressure relief devices. Each tank pressure relief device must be designed, constructed, and marked in accordance with § 173.318(b) of this subchapter.
(b) Piping, valves, and fittings.
(1) The burst pressure of all piping, pipe fittings, hoses and other pressure parts, except for pump seals and pressure relief devices, must be at least 4 times the design pressure of the tank. Additionally, the burst pressure may not be less than 4 times any higher pressure to which each pipe, pipe fitting, hose or other pressure part may be subjected to in service.
(2) Pipe joints must be threaded, welded or flanged. If threaded pipe is used, the pipe and fittings must be Schedule 80 weight or heavier. Malleable metals must be used in the construction of valves and fittings. Where copper tubing is permitted, joints shall be brazed or be of equally strong metal union type. The melting point of the brazing materials may not be lower than °F. The method of joining tubing may not reduce the strength of the tubing, such as by the cutting of threads.
(3) Each hose coupling must be designed for a pressure of at least 120 percent of the hose design pressure and so that there will be no leakage when connected.
(4) Piping must be protected from damage due to thermal expansion and contraction, jarring, and vibration. Slip joints are not authorized for this purpose.
(5) All piping, valves and fittings on a cargo tank must be proved free from leaks. This requirement is met when such piping, valves, and fittings have been tested after installation with gas or air and proved leak tight at not less than the design pressure marked on the cargo tank. This requirement is applicable to all hoses used in a cargo tank, except that hose may be tested before or after installation on the tank.
(6) Each valve must be suitable for the tank design pressure at the tank design service temperature.
(7) All fittings must be rated for the maximum tank pressure and suitable for the coldest temperature to which they will be subjected in actual service.
(8) All piping, valves, and fittings must be grouped in the smallest practicable space and protected from damage as required by § 178.338-10.
(9) When a pressure-building coil is used on a tank designed to handle oxygen or flammable ladings, the vapor connection to that coil must be provided with a valve or check valve as close to the tank shell as practicable to prevent the loss of vapor from the tank in case of damage to the coil. The liquid connection to that coil must also be provided with a valve.
[Amdt. 178-77, 48 FR , June 16, , as amended by Amdt. 178-89, 54 FR , June 12, ]
(a) “Holding time” is the time, as determined by testing, that will elapse from loading until the pressure of the contents, under equilibrium conditions, reaches the level of the lowest pressure control valve or pressure relief valve setting.
(b) Holding time test.
(1) The test to determine holding time must be performed by charging the tank with a cryogenic liquid having a boiling point, at a pressure of one atmosphere, absolute, no lower than the design service temperature of the tank. The tank must be charged to its maximum permitted filling density with that liquid and stabilized to the lowest practical pressure, which must be equal to or less than the pressure to be used for loading. The cargo tank together with its contents must then be exposed to ambient temperature.
(2) The tank pressure and ambient temperature must be recorded at 3-hour intervals until the pressure level of the contents reaches the set-to-discharge pressure of the pressure control valve or pressure relief valve with the lowest setting. This total time lapse in hours represents the measured holding time at the actual average ambient temperature. This measured holding time for the test cryogenic liquid must be adjusted to an equivalent holding time for each cryogenic liquid that is to be identified on or adjacent to the specification plate, at an average ambient temperature of 85 °F. This is the rated holding time (RHT). The marked rated holding time (MRHT) displayed on or adjacent to the specification plate (see § 178.338-18(c)(10)) may not exceed this RHT.
(c) Optional test regimen.
(1) If more than one cargo tank is made to the same design, only one cargo tank must be subjected to the full holding time test at the time of manufacture. However, each subsequent cargo tank made to the same design must be performance tested during its first trip. The holding time determined in this test may not be less than 90 percent of the marked rated holding time. This test must be performed in accordance with §§ 173.318(g)(3) and 177.840(h) of this subchapter, regardless of the classification of the cryogenic liquid.
(2) Same design. The term “same design” as used in this section means cargo tanks made to the same design type. See § 178.320(a) for definition of “design type”.
(3) For a cargo tank used in nonflammable cryogenic liquid service, in place of the holding time tests prescribed in paragraph (b) of this section, the marked rated holding time (MRHT) may be determined as follows:
(i) While the cargo tank is stationary, the heat transfer rate must be determined by measuring the normal evaporation rate (NER) of the test cryogenic liquid (preferably the lading, where feasible) maintained at approximately one atmosphere. The calculated heat transfer rate must be determined from:
q = [n(Δ h)(85−t1)] / [ts − tf]
Where:
q = calculated heat transfer rate to cargo tank with lading, Btu/hr.
n = normal evaporation rate (NER), which is the rate of evaporation, determined by the test of a test cryogenic liquid in a cargo tank maintained at a pressure of approximately one atmosphere, absolute, lb/hr.
Δ h = latent heat of vaporization of test fluid at test pressure, Btu/lb.
ts = average temperature of outer shell during test, °F.
t1 = equilibrium temperature of lading at maximum loading pressure, °F.
tf = equilibrium temperature of test fluid at one atmosphere, °F.
(ii) The rated holding time (RHT) must be calculated as follows:
RHT = [(U2 − U1) W] / q
Where:
RHT = rated holding time, in hours
U1 and U2 = internal energy for the combined liquid and vapor lading at the pressure offered for transportation, and the set pressure of the applicable pressure control valve or pressure relief valve, respectively, Btu/lb.
W = total weight of the combined liquid and vapor lading in the cargo tank, pounds.
q = calculated heat transfer rate to cargo tank with lading, Btu/hr.
(iii) The MRHT (see § 178.338-18(b)(9) of this subchapter) may not exceed the RHT.
[Amdt. 178-77, 48 FR , June 16, ; 48 FR , Nov. 1, , as amended at 49 FR , June 12, ; 49 FR , Nov. 1, ; 59 FR , Nov. 3, ; Amdt. 178-118, 61 FR , Oct. 1, ; 68 FR , Oct. 6, ; 71 FR , Sept. 14, ]
(a) All valves, fittings, pressure relief devices and other accessories to the tank proper, which are not isolated from the tank by closed intervening shut-off valves or check valves, must be installed within the motor vehicle framework or within a suitable collision resistant guard or housing, and appropriate ventilation must be provided. Each pressure relief device must be protected so that in the event of the upset of the vehicle onto a hard surface, the device's opening will not be prevented and its discharge will not be restricted.
(b) Each protective device or housing, and its attachment to the vehicle structure, must be designed to withstand static loading in any direction that it may be loaded as a result of front, rear, side, or sideswipe collision, or the overturn of the vehicle. The static loading shall equal twice the loaded weight of the tank and attachments. A safety factor of four, based on the tensile strength of the material, shall be used. The protective device or the housing must be made of steel at least 3⁄16-inch thick, or other material of equivalent strength.
(c) Rear-end tank protection. Rear-end tank protections devices must:
(1) Consist of at least one rear bumper designed to protect the cargo tank and piping in the event of a rear-end collision. The rear-end tank protection device design must transmit the force of the collision directly to the chassis of the vehicle. The rear-end tank protection device and its attachments to the chassis must be designed to withstand a load equal to twice the weight of the loaded cargo tank and attachments, using a safety factor of four based on the tensile strength of the materials used, with such load being applied horizontally and parallel to the major axis of the cargo tank. The rear-end tank protection device dimensions must meet the requirements of § 393.86 of this title and extend vertically to a height adequate to protect all valves and fittings located at the rear of the cargo tank from damage that could result in loss of lading; or
(2) Conform to the requirements of § 178.345-8(d).
(d) Every part of the loaded cargo tank, and any associated valve, pipe, enclosure, or protective device or structure (exclusive of wheel assemblies), must be at least 14 inches above level ground.
[Amdt. 178-77, 48 FR , June 16, , as amended at 49 FR , June 12, ; Amdt. 178-99, 58 FR , Oct. 1, ; 68 FR , Apr. 18, ; 68 FR , Sept. 3, ; 85 FR , Dec. 21, ; 87 FR , Dec. 27, ]
(a) Excess-flow valves are not required.
(b) Each liquid filling and liquid discharge line must be provided with a shut-off valve located as close to the tank as practicable. Unless this valve is manually operable at the valve, the line must also have a manual shut-off valve.
(c) Except for a cargo tank that is used to transport argon, carbon dioxide, helium, krypton, neon, nitrogen, xenon, or mixtures thereof, each liquid filling and liquid discharge line must be provided with an on-vehicle remotely controlled self-closing shutoff valve.
(1) If pressure from a reservoir or from an engine-driven pump or compressor is used to open this valve, the control must be of fail-safe design and spring-biased to stop the admission of such pressure into the cargo tank. If the jacket is not evacuated, the seat of the valve must be inside the tank, in the opening nozzle or flange, or in a companion flange bolted to the nozzle. If the jacket is evacuated, the remotely controlled valve must be located as close to the tank as practicable.
(2) Each remotely controlled shut off valve must be provided with on-vehicle remote means of automatic closure, both mechanical and thermal. One means may be used to close more than one remotely controlled valve. Cable linkage between closures and remote operators must be corrosion resistant and effective in all types of environment and weather. The thermal means must consist of fusible elements actuated at a temperature not exceeding 121 °C (250 °F), or equivalent devices. The loading/unloading connection area is where hoses are connected to the permanent metal piping. The number and location of remote operators and thermal devices shall be as follows:
(i) On a cargo tank motor vehicle over 3,500 gallons water capacity, remote means of automatic closure must be installed at the ends of the cargo tank in at least two diagonally opposite locations. If the loading/unloading connection at the cargo tank is not in the general vicinity of one of these locations, at least one additional thermal device must be installed so that heat from a fire in the loading/unloading connection area will activate the emergency control system.
(ii) On a cargo tank motor vehicle of 3,500 gallons water capacity or less, at least one remote means of automatic closure must be installed on the end of the cargo tank farthest away from the loading/unloading connection area. At least one thermal device must be installed so that heat from a fire in the loading/unloading connection area will activate the emergency control system.
[Amdt. 178-77, 48 FR , June 16, , as amended by Amdt. 178-105, 59 FR , Nov. 3, ; 60 FR , Apr. 5, ; 68 FR , Apr. 18, ]
Unless the valve is located in a rear cabinet forward of and protected by the bumper (see § 178.338-10(c)), the design and installation of each valve, damage to which could result in loss of liquid or vapor, must incorporate a shear section or breakage groove adjacent to, and outboard of, the valve. The shear section or breakage groove must yield or break under strain without damage to the valve that would allow the loss of liquid or vapor. The protection specified in § 178.338-10 is not a substitute for a shear section or breakage groove.
[Amdt. 178-77, 49 FR , June 12, ]
(a) On a cargo tank motor vehicle designed and constructed so that the cargo tank constitutes in whole or in part the structural member used in place of a motor vehicle frame, the cargo tank or the jacket must be supported by external cradles or by load rings. For a cargo tank mounted on a motor vehicle frame, the tank or jacket must be supported by external cradles, load rings, or longitudinal members. If cradles are used, they must subtend at least 120 degrees of the cargo tank circumference. The design calculations for the supports and load-bearing tank or jacket, and the support attachments must include beam stress, shear stress, torsion stress, bending moment, and acceleration stress for the loaded vehicle as a unit, using a safety factor of four, based on the tensile strength of the material, and static loading that uses the weight of the cargo tank and its attachments when filled to the design weight of the lading (see appendix G in Section VIII of the ASME Code) (IBR, see § 171.7 of this subchapter), multiplied by the following factors. The effects of fatigue must also be considered in the calculations. Minimum static loadings must be as follows:
(1) For a vacuum-insulated cargo tank—
(i) Vertically downward of 2;
(ii) Vertically upward of 2;
(iii) Longitudinally of 2; and
(iv) Laterally of 2.
(2) For any other insulated cargo tank—
(i) Vertically downward of 3;
(ii) Vertically upward of 2;
(iii) Longitudinally of 2; and
(iv) Laterally of 2.
(b) When a loaded tank is supported within the vacuum jacket by structural members, the design calculations for the tank and its structural members must be based on a safety factor of four and the tensile strength of the material at ambient temperature. The enhanced tensile strength of the material at actual operating temperature may be substituted for the tensile strength at ambient temperature to the extent recognized in the ASME Code for static loadings. Static loadings must take into consideration the weight of the tank and the structural members when the tank is filled to the design weight of lading (see Appendix G of Section VIII, Division 1 of the ASME Code), multiplied by the following factors. Static loadings must take into consideration the weight of the tank and the structural members when the tank is filled to the design weight of lading (see appendix G in Section VIII of the ASME Code), multiplied by the following factors. When load rings in the jacket are used for supporting the tank, they must be designed to carry the fully loaded tank at the specified static loadings, plus external pressure. Minimum static loadings must be as follows:
(1) Vertically downward of 2;
(2) Vertically upward of 11⁄2;
(3) Longitudinally of 11⁄2; and,
(4) Laterally of 11⁄2.
[68 FR , Apr. 18, , as amended at 68 FR , Dec. 31, ]
(a) Liquid level gauging devices.
(1) Unless a cargo tank is intended to be filled by weight, it must be equipped with one or more gauging devices, which accurately indicate the maximum permitted liquid level at the loading pressure, in order to provide a minimum of two percent outage below the inlet of the pressure control valve or pressure relief valve at the condition of incipient opening of that valve. A fixed-length dip tube, a fixed trycock line, or a differential pressure liquid level gauge must be used as the primary control for filling. Other gauging devices, except gauge glasses, may be used, but not as the primary control for filling.
(2) The design pressure of each liquid level gauging device must be at least that of the tank.
(3) If a fixed length dip tube or trycock line gauging device is used, it must consist of a pipe or tube of small diameter equipped with a valve at or near the jacket and extending into the cargo tank to a specified filling height. The fixed height at which the tube ends in the cargo tank must be such that the device will function when the liquid reaches the maximum level permitted in loading.
(4) The liquid level gauging device used as a primary control for filling must be designed and installed to accurately indicate the maximum filling level at the point midway of the tank both longitudinally and laterally.
(b) Pressure gauges. Each cargo tank must be provided with a suitable pressure gauge indicating the lading pressure and located on the front of the jacket so it can be read by the driver in the rear view mirror. Each gauge must have a reference mark at the cargo tank design pressure or the set pressure of the pressure relief valve or pressure control valve, whichever is lowest.
(c) Orifices. All openings for dip tube gauging devices and pressure gauges in flammable cryogenic liquid service must be restricted at or inside the jacket by orifices no larger than 0.060-inch diameter. Trycock lines, if provided, may not be greater than 1⁄2-inch nominal pipe size.
[Amdt. 178-77, 48 FR , June 16, , as amended at 49 FR , June 12, ]
A cargo tank constructed for oxygen service must be thoroughly cleaned to remove all foreign material in accordance with CGA G-4.1 (IBR, see § 171.7 of this subchapter). All loose particles from fabrication, such as weld beads, dirt, grinding wheel debris, and other loose materials, must be removed prior to the final closure of the manhole of the tank. Chemical or solvent cleaning with a material compatible with the intending lading must be performed to remove any contaminants likely to react with the lading.
[68 FR , Dec. 31, ]
(a) General. The material of construction of a tank and its appurtenances must be inspected for conformance to Section VIII of the ASME Code (IBR, see § 171.7 of this subchapter). The tank must be subjected to either a hydrostatic or pneumatic test. The test pressure must be one and one-half times the sum of the design pressure, plus static head of lading, plus 101.3 kPa (14.7 psi) if subjected to external vacuum, except that for tanks constructed in accordance with Part UHT in Section VIII of the ASME Code the test pressure must be twice the design pressure.
(b) Additional requirements for pneumatic test. A pneumatic test may be used in place of the hydrostatic test. Due regard for protection of all personnel should be taken because of the potential hazard involved in a pneumatic test. The pneumatic test pressure in the tank must be reached by gradually increasing the pressure to one-half of the test pressure. Thereafter, the test pressure must be increased in steps of approximately one-tenth of the test pressure until the required test pressure has been reached. Then the pressure must be reduced to a value equal to four-fifths of the test pressure and held for a sufficient time to permit inspection of the cargo tank for leaks.
(c) Weld inspection. All tank shell or head welds subject to pressure shall be radiographed in accordance with Section VIII of the ASME Code. A tank which has been subjected to inspection by the magnetic particle method, the liquid penetrant method, or any method involving a material deposit on the interior tank surface, must be cleaned to remove any such residue by scrubbing or equally effective means, and all such residue and cleaning solution must be removed from the tank prior to final closure of the tank.
(d) Defect repair. All cracks and other defects must be repaired as prescribed in Section VIII of the ASME Code. The welder and the welding procedure must be qualified in accordance with Section IX of the ASME Code (IBR, see § 171.7 of this subchapter). After repair, the tank must again be postweld heat-treated, if such heat treatment was previously performed, and the repaired areas must be retested.
(e) Verification must be made of the interior cleanliness of a tank constructed for oxygen service by means that assure that all contaminants that are likely to react with the lading have been removed as required by § 178.338-15.
[Amdt. 178-77, 48 FR , June 16, , as amended at 49 FR , June 12, ; 49 FR , Oct. 24, ; 68 FR , Dec. 31, ]
(a) Liquid pumps and gas compressors, if used, must be of suitable design, adequately protected against breakage by collision, and kept in good condition. They may be driven by motor vehicle power take-off or other mechanical, electrical, or hydraulic means. Unless they are of the centrifugal type, they shall be equipped with suitable pressure actuated by-pass valves permitting flow from discharge to suction to the tank.
(b) A valve or fitting made of aluminum with internal rubbing or abrading aluminum parts that may come in contact with oxygen (cryogenic liquid) may not be installed on any cargo tank used to transport oxygen (cryogenic liquid) unless the parts are anodized in accordance with ASTM B 580 (IBR, see § 171.7 of this subchapter).
[Amdt. 178-89, 54 FR , June 12, , as amended at 55 FR , Sept. 7, ; 67 FR , Sept. 27, ; 68 FR , Dec. 31, ]
(a) General. Each cargo tank certified after October 1, must have a corrosion-resistant metal name plate (ASME Plate) and specification plate permanently attached to the cargo tank by brazing, welding, or other suitable means on the left side near the front, in a place accessible for inspection. If the specification plate is attached directly to the cargo tank wall by welding, it must be welded to the tank before the cargo tank is postweld heat treated.
(1) The plates must be legibly marked by stamping, embossing, or other means of forming letters into the metal of the plate, with the information required in paragraphs (b) and (c) of this section, in addition to that required by Section VIII of the ASME Code (IBR, see § 171.7 of this subchapter), in characters at least 3⁄16 inch high (parenthetical abbreviations may be used). All plates must be maintained in a legible condition.
(2) Each insulated cargo tank must have additional plates, as described, attached to the jacket in the location specified unless the specification plate is attached to the chassis and has the information required in paragraphs (b) and (c) of this section.
(3) The information required for both the name and specification plate may be displayed on a single plate. If the information required by this section is displayed on a plate required by Section VIII of the ASME Code, the information need not be repeated on the name and specification plates.
(4) The specification plate may be attached to the cargo tank motor vehicle chassis rail by brazing, welding, or other suitable means on the left side near the front head, in a place accessible for inspection. If the specification plate is attached to the chassis rail, then the cargo tank serial number assigned by the cargo tank manufacturer must be included on the plate.
(b) Name plate. The following information must be marked on the name plate in accordance with this section:
(1) DOT-specification number MC 338 (DOT MC 338).
(2) Original test date (Orig, Test Date).
(3) MAWP in psig.
(4) Cargo tank test pressure (Test P), in psig.
(5) Cargo tank design temperature (Design Temp. Range) ____ °F to ____ °F.
(6) Nominal capacity (Water Cap.), in pounds.
(7) Maximum design density of lading (Max. Lading density), in pounds per gallon.
(8) Material specification number—shell (Shell matl, yyy * * *), where “yyy” is replaced by the alloy designation and “* * *” is replaced by the alloy type.
(9) Material specification number—heads (Head matl. yyy * * *), where “yyy” is replaced by the alloy designation and “* * *” by the alloy type.
Note:When the shell and heads materials are the same thickness, they may be combined, (Shell & head matl, yyy * * *).
(10) Weld material (Weld matl.).
(11) Minimum Thickness-shell (Min. Shell-thick), in inches. When minimum shell thicknesses are not the same for different areas, show (top ____, side ____, bottom ____, in inches).
(12) Minimum thickness-heads (Min heads thick.), in inches.
(13) Manufactured thickness-shell (Mfd. Shell thick.), top ____, side ____, bottom ____, in inches. (Required when additional thickness is provided for corrosion allowance.)
(14) Manufactured thickness-heads (Mfd. Heads thick.), in inches. (Required when additional thickness is provided for corrosion allowance.)
(15) Exposed surface area, in square feet.
(c) Specification plate. The following information must be marked on the specification plate in accordance with this section:
(1) Cargo tank motor vehicle manufacturer (CTMV mfr.).
(2) Cargo tank motor vehicle certification date (CTMV cert. date).
(3) Cargo tank manufacturer (CT mfr.).
(4) Cargo tank date of manufacture (CT date of mfr.), month and year.
(5) Maximum weight of lading (Max. Payload), in pounds.
(6) Maximum loading rate in gallons per minute (Max. Load rate, GPM).
(7) Maximum unloading rate in gallons per minute (Max Unload rate).
(8) Lining materials (Lining), if applicable.
(9) “Insulated for oxygen service” or “Not insulated for oxygen service” as appropriate.
(10) Marked rated holding time for at least one cryogenic liquid, in hours, and the name of that cryogenic liquid (MRHT ____ hrs, name of cryogenic liquid). Marked rated holding marking for additional cryogenic liquids may be displayed on or adjacent to the specification plate.
(11) Cargo tank serial number (CT serial), as assigned by cargo tank manufacturer, if applicable.
Note 1 to paragraph (c):See § 173.315(a) of this chapter regarding water capacity.
Note 2 to paragraph (c):When the shell and head materials are the same thickness, they may be combined (Shell & head matl, yyy***).
(d) The design weight of lading used in determining the loading in §§ 178.338-3 (b), 178.338-10 (b) and (c), and 178.338-13 (b), must be shown as the maximum weight of lading marking required by paragraph (c) of this section.
[68 FR , Apr. 18, , as amended at 68 FR , Oct. 6, ; 68 FR , Dec. 31, ]
(a) At or before the time of delivery, the manufacturer of a cargo tank motor vehicle shall furnish to the owner of the completed vehicle the following:
(1) The tank manufacturer's data report as required by the ASME Code (IBR, see § 171.7 of this subchapter), and a certificate bearing the manufacturer's vehicle serial number stating that the completed cargo tank motor vehicle conforms to all applicable requirements of Specification MC 338, including Section VIII of the ASME Code (IBR, see § 171.7 of this subchapter) in effect on the date (month, year) of certification. The registration numbers of the manufacturer, the Design Certifying Engineer, and the Registered Inspector, as appropriate, must appear on the certificates (see subpart F, part 107 in subchapter B of this chapter).
(2) A photograph, pencil rub, or other facsimile of the plates required by paragraphs (a) and (b) of § 178.338-18.
(b) In the case of a cargo tank vehicle manufactured in two or more stages, each manufacturer who performs a manufacturing operation on the incomplete vehicle or portion thereof shall furnish to the succeeding manufacturer, at or before the time of delivery, a certificate covering the particular operation performed by that manufacturer, and any certificates received from previous manufacturers, Registered Inspectors, and Design Certifying Engineers. The certificates must include sufficient sketches, drawings, and other information to indicate the location, make, model and size of each valve and the arrangement of all piping associated with the tank. Each certificate must be signed by an official of the manufacturing firm responsible for the portion of the complete cargo tank vehicle represented thereby, such as basic tank fabrication, insulation, jacket, or piping. The final manufacturer shall furnish the owner with all certificates, as well as the documents required by paragraph (a) of this section.
(c) The owner shall retain the data report, certificates, and related papers throughout his ownership of the cargo tank. In the event of change of ownership, the prior owner shall retain non-fading photographically reproduced copies of these documents for at least one year. Each operator using the cargo tank vehicle, if not the owner thereof, shall obtain a copy of the data report and the certificate or certificates and retain them during the time he uses the cargo tank and for at least one year thereafter.
(Approved by the Office of Management and Budget under control number -)
[Amdt. 178-77, 48 FR , , June 16, , as amended by Amdt. 178-89, 55 FR , Sept. 7, ; Amdt. 178-99, 58 FR , Oct. 1, ; 62 FR , Oct. 1, ; 68 FR , Dec. 31, ]
(a) Specification DOT 406, DOT 407 and DOT 412 cargo tank motor vehicles must conform to the requirements of this section in addition to the requirements of the applicable specification contained in §§ 178.346, 178.347 or 178.348.
(b) All specification requirements are minimum requirements.
(c) Definitions. See § 178.320(a) for the definition of certain terms used in §§ 178.345, 178.346, 178.347, and 178.348. In addition, the following definitions apply to §§ 178.345, 178.346, 178.347, and 178.348:
Appurtenance means any cargo tank accessory attachment that has no lading retention or containment function and provides no structural support to the cargo tank.
Baffle means a non-liquid-tight transverse partition device that deflects, checks or regulates fluid motion in a tank.
Bulkhead means a liquid-tight transverse closure at the ends of or between cargo tanks.
Charging line means a hose, tube, pipe, or similar device used to pressurize a tank with material other than the lading.
Companion flange means one of two mating flanges where the flange faces are in contact or separated only by a thin leak sealing gasket and are secured to one another by bolts or clamps.
Connecting structure means the structure joining two cargo tanks.
Constructed and certified in conformance with the ASME Code means the cargo tank is constructed and stamped in accordance with the ASME Code, and is inspected and certified by an Authorized Inspector.
Constructed in accordance with the ASME Code means the cargo tank is constructed in accordance with the ASME Code with the authorized exceptions (see §§ 178.346, 178.347, and 178.348) and is inspected and certified by a Registered Inspector.
External self-closing stop-valve means a self-closing stop-valve designed so that the self-stored energy source is located outside the cargo tank and the welded flange.
Extreme dynamic loading means the maximum single-acting loading a cargo tank motor vehicle may experience during its expected life, excluding accident loadings.
Flange means the structural ring for guiding or attachment of a pipe or fitting with another flange (companion flange), pipe, fitting or other attachment.
Inspection pressure means the pressure used to determine leak tightness of the cargo tank when testing with pneumatic pressure.
Internal self-closing stop-valve means a self-closing stop-valve designed so that the self-stored energy source is located inside the cargo tank or cargo tank sump, or within the welded flange, and the valve seat is located within the cargo tank or within one inch of the external face of the welded flange or sump of the cargo tank.
Lading means the hazardous material contained in a cargo tank.
Loading/unloading connection means the fitting in the loading/unloading line farthest from the loading/unloading outlet to which the loading/unloading hose or device is attached.
Loading/unloading outlet means the cargo tank outlet used for normal loading/unloading operations.
Loading/unloading stop-valve means the stop valve farthest from the cargo tank loading/unloading outlet to which the loading/unloading connection is attached.
MAWP. See § 178.320(a).
Multi-specification cargo tank motor vehicle means a cargo tank motor vehicle equipped with two or more cargo tanks fabricated to more than one cargo tank specification.
Normal operating loading means the loading a cargo tank motor vehicle may be expected to experience routinely in operation.
Nozzle means the subassembly consisting of a pipe or tubular section with or without a welded or forged flange on one end.
Outlet means any opening in the shell or head of a cargo tank, (including the means for attaching a closure), except that the following are not outlets: A threaded opening securely closed during transportation with a threaded plug or a threaded cap, a flanged opening securely closed during transportation with a bolted or welded blank flange, a manhole, or gauging devices, thermometer wells, and safety relief devices.
Outlet stop-valve means the stop-valve at the cargo tank loading/unloading outlet.
Pipe coupling means a fitting with internal threads on both ends.
Rear bumper means the structure designed to prevent a vehicle or object from under-riding the rear of a motor vehicle. See § 393.86 of this title.
Rear-end tank protection device means the structure designed to protect a cargo tank and any lading retention piping or devices in case of a rear end collision.
Sacrificial device means an element, such as a shear section, designed to fail under a load in order to prevent damage to any lading retention part or device. The device must break under strain at no more than 70 percent of the strength of the weakest piping element between the cargo tank and the sacrificial device. Operation of the sacrificial device must leave the remaining piping and its attachment to the cargo tank intact and capable of retaining lading.
Self-closing stop-valve means a stop-valve held in the closed position by means of self-stored energy, which opens only by application of an external force and which closes when the external force is removed.
Shear section means a sacrificial device fabricated in such a manner as to abruptly reduce the wall thickness of the adjacent piping or valve material by at least 30 percent.
Shell means the circumferential portion of a cargo tank defined by the basic design radius or radii excluding the closing heads.
Stop-valve means a valve that stops the flow of lading.
Sump means a protrusion from the bottom of a cargo tank shell designed to facilitate complete loading and unloading of lading.
Tank means a container, consisting of a shell and heads, that forms a pressure tight vessel having openings designed to accept pressure tight fittings or closures, but excludes any appurtenances, reinforcements, fittings, or closures.
Test pressure means the pressure to which a tank is subjected to determine pressure integrity.
Toughness of material means the capability of a material to absorb the energy represented by the area under the stress strain curve (indicating the energy absorbed per unit volume of the material) up to the point of rupture.
Vacuum cargo tank means a cargo tank that is loaded by reducing the pressure in the cargo tank to below atmospheric pressure.
Variable specification cargo tank means a cargo tank that is constructed in accordance with one specification, but which may be altered to meet another specification by changing relief device, closures, lading discharge devices, and other lading retention devices.
Void means the space between tank heads or bulkheads and a connecting structure.
Welded flange means a flange attached to the tank by a weld joining the tank shell to the cylindrical outer surface of the flange, or by a fillet weld joining the tank shell to a flange shaped to fit the shell contour.
(d) A manufacturer of a cargo tank must hold a current ASME certificate of authorization and must be registered with the Department in accordance with part 107, subpart F of this chapter.
(e) All construction must be certified by an Authorized Inspector or by a Registered Inspector as applicable to the cargo tank.
(f) Each cargo tank must be designed and constructed in conformance with the requirements of the applicable cargo tank specification. Each DOT 412 cargo tank with a “MAWP” greater than 15 psig, and each DOT 407 cargo tank with a maximum allowable working pressure greater than 35 psig must be “constructed and certified in conformance with Section VIII of the ASME Code” (IBR, see § 171.7 of this subchapter) except as limited or modified by the applicable cargo tank specification. Other cargo tanks must be “constructed in accordance with Section VIII of the ASME Code,” except as limited or modified by the applicable cargo tank specification.
(g) Requirements relating to parts and accessories on motor vehicles, which are contained in part 393 of the Federal Motor Carrier Safety Regulations of this title, are incorporated into these specifications.
(h) Any additional requirements prescribed in part 173 of this subchapter that pertain to the transportation of a specific lading are incorporated into these specifications.
(i) Cargo tank motor vehicle composed of multiple cargo tanks.
(1) A cargo tank motor vehicle composed of more than one cargo tank may be constructed with the cargo tanks made to the same specification or to different specifications. Each cargo tank must conform in all respects with the specification for which it is certified.
(2) The strength of the connecting structure joining multiple cargo tanks in a cargo tank motor vehicle must meet the structural design requirements in § 178.345-3. Any void within the connecting structure must be equipped with a drain located on the bottom centerline that is accessible and kept open at all times. For carbon steel, self-supporting cargo tanks, the drain configuration may consist of a single drain of at least 1.0 inch diameter, or two or more drains of at least 0.5 inch diameter, 6.0 inches apart, one of which is located as close to the bottom centerline as practicable. Vapors trapped in a void within the connecting structure must be allowed to escape to the atmosphere either through the drain or a separate vent.
(j) Variable specification cargo tank. A cargo tank that may be physically altered to conform to another cargo tank specification must have the required physical alterations to convert from one specification to another clearly indicated on the variable specification plate.
[Amdt. 178-89, 54 FR , June 12, , as amended at 55 FR , Sept. 7, ; Amdt. 178-105, 59 FR , Nov. 3, ; Amdt. 178-118, 61 FR , Oct. 1, ; 66 FR , , Aug. 28, ; 68 FR , Apr. 18, ; 68 FR , Sept. 3, ; 68 FR , Dec. 31, ; 70 FR , Sept. 23, ; 76 FR , July 20, ]
(a) All material for shell, heads, bulkheads, and baffles must conform to Section II of the ASME Code (IBR, see § 171.7 of this subchapter) except as follows:
(1) The following steels are also authorized for cargo tanks “constructed in accordance with the ASME Code”, Section VIII.
ASTM A 569
ASTM A 570
ASTM A 572
ASTM A 622
ASTM A 656
ASTM A 715
ASTM A / A M, ASTM A /A M
(2) Aluminum alloys suitable for fusion welding and conforming with the 0, H32 or H34 tempers of one of the following ASTM specifications may be used for cargo tanks “constructed in accordance with the ASME Code”:
ASTM B-209 Alloy
ASTM B-209 Alloy
ASTM B-209 Alloy
ASTM B-209 Alloy
ASTM B-209 Alloy
ASTM B-209 Alloy
All heads, bulkheads and baffles must be of 0 temper (annealed) or stronger tempers. All shell materials shall be of H 32 or H 34 tempers except that the lower ultimate strength tempers may be used if the minimum shell thicknesses in the tables are increased in inverse proportion to the lesser ultimate strength.
(b) Minimum thickness. The minimum thickness for the shell and heads (or baffles and bulkheads when used as tank reinforcement) must be no less than that determined under criteria for minimum thickness specified in § 178.320(a).
(c) Corrosion or abrasion protection. When required by 49 CFR part 173 for a particular lading, a cargo tank or a part thereof, subject to thinning by corrosion or mechanical abrasion due to the lading, must be protected by providing the tank or part of the tank with a suitable increase in thickness of material, a lining or some other suitable method of protection.
(1) Corrosion allowance. Material added for corrosion allowance need not be of uniform thickness if different rates of attack can reasonably be expected for various areas of the cargo tank.
(2) Lining. Lining material must consist of a nonporous, homogeneous material not less elastic than the parent metal and substantially immune to attack by the lading. The lining material must be bonded or attached by other appropriate means to the cargo tank wall and must be imperforate when applied. Any joint or seam in the lining must be made by fusing the materials together, or by other satisfactory means.
[Amdt. 178-89, 54 FR , June 12, , as amended at 55 FR , Sept. 7, ; 56 FR , June 17, ; Amdt. 178-97, 57 FR , Oct. 1, ; Amdt. 178-118, 61 FR , Oct. 1, ; 68 FR , Apr. 18, ; 68 FR , Dec. 31, ; 70 FR , June 13, ]
(a) General requirements and acceptance criteria.
(1) The maximum calculated design stress at any point in the cargo tank wall may not exceed the maximum allowable stress value prescribed in Section VIII of the ASME Code (IBR, see § 171.7 of this subchapter), or 25 percent of the tensile strength of the material used at design conditions.
(2) The relevant physical properties of the materials used in each cargo tank may be established either by a certified test report from the material manufacturer or by testing in conformance with a recognized national standard. In either case, the ultimate tensile strength of the material used in the design may not exceed 120 percent of the minimum ultimate tensile strength specified in either the ASME Code or the ASTM standard to which the material is manufactured.
(3) The maximum design stress at any point in the cargo tank must be calculated separately for the loading conditions described in paragraphs (b) and (c) of this section. Alternate test or analytical methods, or a combination thereof, may be used in place of the procedures described in paragraphs (b) and (c) of this section, if the methods are accurate and verifiable. TTMA RP 96-01, Structural Integrity of DOT 406, DOT 407, and DOT 412 Cylindrical Cargo Tanks, may be used as guidance in performing the calculations.
(4) Corrosion allowance material may not be included to satisfy any of the design calculation requirements of this section.
(b) ASME Code design and construction. The static design and construction of each cargo tank must be in accordance with Section VIII of the ASME Code. The cargo tank design must include calculation of stresses generated by the MAWP, the weight of the lading, the weight of structures supported by the cargo tank wall and the effect of temperature gradients resulting from lading and ambient temperature extremes. When dissimilar materials are used, their thermal coefficients must be used in the calculation of thermal stresses.
(1) Stress concentrations in tension, bending and torsion which occur at pads, cradles, or other supports must be considered in accordance with appendix G in Section VIII of the ASME Code.
(2) Longitudinal compressive buckling stress for ASME certified vessels must be calculated using paragraph UG-23(b) in Section VIII of the ASME Code. For cargo tanks not required to be certified in accordance with the ASME Code, compressive buckling stress may be calculated using alternative analysis methods which are accurate and verifiable. When alternative methods are used, calculations must include both the static loads described in this paragraph and the dynamic loads described in paragraph (c) of this section.
(3) Cargo tank designers and manufacturers must consider all of the conditions specified in § 173.33(c) of this subchapter when matching a cargo tank's performance characteristic to the characteristic of each lading transported.
(c) Shell design. Shell stresses resulting from static or dynamic loadings, or combinations thereof, are not uniform throughout the cargo tank motor vehicle. The vertical, longitudinal, and lateral normal operating loadings can occur simultaneously and must be combined. The vertical, longitudinal and lateral extreme dynamic loadings occur separately and need not be combined.
(1) Normal operating loadings. The following procedure addresses stress in the cargo tank shell resulting from normal operating loadings. The effective stress (the maximum principal stress at any point) must be determined by the following formula:
S = 0.5(Sy + SX) ± [0.25(Sy − SX)2 + SS2]0.5
Where:
(i) S = effective stress at any given point under the combination of static and normal operating loadings that can occur at the same time, in psi.
(ii) Sy = circumferential stress generated by the MAWP and external pressure, when applicable, plus static head, in psi.
(iii) Sx = The following net longitudinal stress generated by the following static and normal operating loading conditions, in psi:
(A) The longitudinal stresses resulting from the MAWP and external pressure, when applicable, plus static head, in combination with the bending stress generated by the static weight of the fully loaded cargo tank motor vehicle, all structural elements, equipment and appurtenances supported by the cargo tank wall;
(B) The tensile or compressive stress resulting from normal operating longitudinal acceleration or deceleration. In each case, the forces applied must be 0.35 times the vertical reaction at the suspension assembly, applied at the road surface, and as transmitted to the cargo tank wall through the suspension assembly of a trailer during deceleration; or the horizontal pivot of the truck tractor or converter dolly fifth wheel, or the drawbar hinge on the fixed dolly during acceleration; or anchoring and support members of a truck during acceleration and deceleration, as applicable. The vertical reaction must be calculated based on the static weight of the fully loaded cargo tank motor vehicle, all structural elements, equipment and appurtenances supported by the cargo tank wall. The following loadings must be included:
(1) The axial load generated by a decelerative force;
(2) The bending moment generated by a decelerative force;
(3) The axial load generated by an accelerative force; and
(4) The bending moment generated by an accelerative force; and
(C) The tensile or compressive stress generated by the bending moment resulting from normal operating vertical accelerative force equal to 0.35 times the vertical reaction at the suspension assembly of a trailer; or the horizontal pivot of the upper coupler (fifth wheel) or turntable; or anchoring and support members of a truck, as applicable. The vertical reaction must be calculated based on the static weight of the fully loaded cargo tank motor vehicle, all structural elements, equipment and appurtenances supported by the cargo tank wall.
(iv) SS = The following shear stresses generated by the following static and normal operating loading conditions, in psi:
(A) The static shear stress resulting from the vertical reaction at the suspension assembly of a trailer, and the horizontal pivot of the upper coupler (fifth wheel) or turntable; or anchoring and support members of a truck, as applicable. The vertical reaction must be calculated based on the static weight of the fully loaded cargo tank motor vehicle, all structural elements, equipment and appurtenances supported by the cargo tank wall;
(B) The vertical shear stress generated by a normal operating accelerative force equal to 0.35 times the vertical reaction at the suspension assembly of a trailer; or the horizontal pivot of the upper coupler (fifth wheel) or turntable; or anchoring and support members of a truck, as applicable. The vertical reaction must be calculated based on the static weight of the fully loaded cargo tank motor vehicle, all structural elements, equipment and appurtenances supported by the cargo tank wall;
(C) The lateral shear stress generated by a normal operating lateral accelerative force equal to 0.2 times the vertical reaction at each suspension assembly of a trailer, applied at the road surface, and as transmitted to the cargo tank wall through the suspension assembly of a trailer, and the horizontal pivot of the upper coupler (fifth wheel) or turntable; or anchoring and support members of a truck, as applicable. The vertical reaction must be calculated based on the static weight of the fully loaded cargo tank motor vehicle, all structural elements, equipment and appurtenances supported by the cargo tank wall; and
(D) The torsional shear stress generated by the same lateral forces as described in paragraph (c)(1)(iv)(C) of this section.
(2) Extreme dynamic loadings. The following procedure addresses stress in the cargo tank shell resulting from extreme dynamic loadings. The effective stress (the maximum principal stress at any point) must be determined by the following formula:
S = 0.5(Sy + Sx) ±[0.25(Sy − Sx)2 + SS2]0.5
Where:
(i) S = effective stress at any given point under a combination of static and extreme dynamic loadings that can occur at the same time, in psi.
(ii) Sy = circumferential stress generated by MAWP and external pressure, when applicable, plus static head, in psi.
(iii) Sx = the following net longitudinal stress generated by the following static and extreme dynamic loading conditions, in psi:
(A) The longitudinal stresses resulting from the MAWP and external pressure, when applicable, plus static head, in combination with the bending stress generated by the static weight of the fully loaded cargo tank motor vehicle, all structural elements, equipment and appurtenances supported by the tank wall;
(B) The tensile or compressive stress resulting from extreme longitudinal acceleration or deceleration. In each case the forces applied must be 0.7 times the vertical reaction at the suspension assembly, applied at the road surface, and as transmitted to the cargo tank wall through the suspension assembly of a trailer during deceleration; or the horizontal pivot of the truck tractor or converter dolly fifth wheel, or the drawbar hinge on the fixed dolly during acceleration; or the anchoring and support members of a truck during acceleration and deceleration, as applicable. The vertical reaction must be calculated based on the static weight of the fully loaded cargo tank motor vehicle, all structural elements, equipment and appurtenances supported by the cargo tank wall. The following loadings must be included:
(1) The axial load generated by a decelerative force;
(2) The bending moment generated by a decelerative force;
(3) The axial load generated by an accelerative force; and
(4) The bending moment generated by an accelerative force; and
(C) The tensile or compressive stress generated by the bending moment resulting from an extreme vertical accelerative force equal to 0.7 times the vertical reaction at the suspension assembly of a trailer, and the horizontal pivot of the upper coupler (fifth wheel) or turntable; or the anchoring and support members of a truck, as applicable. The vertical reaction must be calculated based on the static weight of the fully loaded cargo tank motor vehicle, all structural elements, equipment and appurtenances supported by the cargo tank wall.
(iv) SS = The following shear stresses generated by static and extreme dynamic loading conditions, in psi:
(A) The static shear stress resulting from the vertical reaction at the suspension assembly of a trailer, and the horizontal pivot of the upper coupler (fifth wheel) or turntable; or anchoring and support members of a truck, as applicable. The vertical reaction must be calculated based on the static weight of the fully loaded cargo tank motor vehicle, all structural elements, equipment and appurtenances supported by the cargo tank wall;
(B) The vertical shear stress generated by an extreme vertical accelerative force equal to 0.7 times the vertical reaction at the suspension assembly of a trailer, and the horizontal pivot of the upper coupler (fifth wheel) or turntable; or anchoring and support members of a truck, as applicable. The vertical reaction must be calculated based on the static weight of the fully loaded cargo tank motor vehicle, all structural elements, equipment and appurtenances supported by the cargo tank wall;
(C) The lateral shear stress generated by an extreme lateral accelerative force equal to 0.4 times the vertical reaction at the suspension assembly of a trailer, applied at the road surface, and as transmitted to the cargo tank wall through the suspension assembly of a trailer, and the horizontal pivot of the upper coupler (fifth wheel) or turntable; or anchoring and support members of a truck, as applicable. The vertical reaction must be calculated based on the static weight of the fully loaded cargo tank motor vehicle, all structural elements, equipment and appurtenances supported by the cargo tank wall; and
(D) The torsional shear stress generated by the same lateral forces as described in paragraph (c)(2)(iv)(C) of this section.
(d) In no case may the minimum thickness of the cargo tank shells and heads be less than that prescribed in § 178.346-2, § 178.347-2, or § 178.348-2, as applicable.
(e) For a cargo tank mounted on a frame or built with integral structural supports, the calculation of effective stresses for the loading conditions in paragraph (c) of this section may include the structural contribution of the frame or the integral structural supports.
(f) The design, construction, and installation of an attachment, appurtenance to a cargo tank, structural support member between the cargo tank and the vehicle or suspension component must conform to the following requirements:
(1) Structural members, the suspension sub-frame, accident protection structures and external circumferential reinforcement devices must be used as sites for attachment of appurtenances and other accessories to the cargo tank, when practicable.
(2) A lightweight attachment to a cargo tank wall such as a conduit clip, brake line clip, skirting structure, lamp mounting bracket, or placard holder must be of a construction having lesser strength than the cargo tank wall materials and may not be more than 72 percent of the thickness of the material to which it is attached. The lightweight attachment may be secured directly to the cargo tank wall if the device is designed and installed in such a manner that, if damaged, it will not affect the lading retention integrity of the tank. A lightweight attachment must be secured to the cargo tank shell or head by continuous weld or in such a manner as to preclude formation of pockets which may become sites for corrosion.
(3) Except as prescribed in paragraphs (f)(1) and (f)(2) of this section, the welding of any appurtenance to the cargo tank wall must be made by attachment of a mounting pad so that there will be no adverse effect upon the lading retention integrity of the cargo tank if any force less than that prescribed in paragraph (b)(1) of this section is applied from any direction. The thickness of the mounting pad may not be less than that of the shell or head to which it is attached, and not more than 1.5 times the shell or head thickness. However, a pad with a minimum thickness of 0.187 inch may be used when the shell or head thickness is over 0.187 inch. If weep holes or tell-tale holes are used, the pad must be drilled or punched at the lowest point before it is welded to the tank. Each pad must:
(i) Be fabricated from material determined to be suitable for welding to both the cargo tank material and the material of the appurtenance or structural support member; a Design Certifying Engineer must make this determination considering chemical and physical properties of the materials and must specify filler material conforming to the requirements of the ASME Code (incorporated by reference; see § 171.7 of this subchapter).
(ii) Be preformed to an inside radius no greater than the outside radius of the cargo tank at the attachment location.
(iii) Extend at least 2 inches in each direction from any point of attachment of an appurtenance or structural support member. This dimension may be measured from the center of the structural member attached.
(iv) Have rounded corners, or otherwise be shaped in a manner to minimize stress concentrations on the shell or head.
(v) Be attached by continuous fillet welding. Any fillet weld discontinuity may only be for the purpose of preventing an intersection between the fillet weld and the tank or jacket seam weld.
[Amdt. 178-89, 55 FR , Sept. 7, , as amended by Amdt. 178-89, 56 FR , June 17, ; Amdt. 178-104, 59 FR , Sept. 26, ; Amdt. 178-105, 59 FR , , , Nov. 3, ; 60 FR , Apr. 5, ; Amdt. 178-118, 61 FR , Oct. 1, ; 65 FR , Sept. 29, ; 68 FR , Apr. 18, ; 68 FR , Dec. 31, ; 74 FR , Apr. 9, ; 78 FR , Oct. 2, ; 81 FR , June 2, ]
(a) All joints between the cargo tank shell, heads, baffles, baffle attaching rings, and bulkheads must be welded in conformance with Section VIII of the ASME Code (IBR, see § 171.7 of this subchapter).
(b) Where practical all welds must be easily accessible for inspection.
[Amdt. 178-89, 54 FR , June 12, , as amended by Amdt. 178-118, 61 FR , Oct. 1, ; 68 FR , Dec. 31, ]
(a) Each cargo tank with capacity greater than 400 gallons must be accessible through a manhole at least 15 inches in diameter.
(b) Each manhole, fill opening and washout assembly must be structurally capable of withstanding, without leakage or permanent deformation that would affect its structural integrity, a static internal fluid pressure of at least 36 psig, or cargo tank test pressure, whichever is greater. The manhole assembly manufacturer shall verify compliance with this requirement by hydrostatically testing at least one percent (or one manhole closure, whichever is greater) of all manhole closures of each type produced each 3 months, as follows:
(1) The manhole, fill opening, or washout assembly must be tested with the venting devices blocked. Any leakage or deformation that would affect the product retention capability of the assembly shall constitute a failure.
(2) If the manhole, fill opening, or washout assembly tested fails, then five more covers from the same lot must be tested. If one of these five covers fails, then all covers in the lot from which the tested covers were selected are to be 100% tested or rejected for service.
(c) Each manhole, filler and washout cover must be fitted with a safety device that prevents the cover from opening fully when internal pressure is present.
(d) Each manhole and fill cover must be secured with fastenings that will prevent opening of the covers as a result of vibration under normal transportation conditions or shock impact due to a rollover accident on the roadway or shoulder where the fill cover is not struck by a substantial obstacle.
(e) On cargo tank motor vehicles manufactured after October 1, , each manhole assembly must be permanently marked on the outside by stamping or other means in a location visible without opening the manhole assembly or fill opening, with:
(1) Manufacturer's name;
(2) Test pressure ____ psig;
(3) A statement certifying that the manhole cover meets the requirements in § 178.345-5.
(f) All components mounted on a manhole cover that form part of the lading retention structure of the cargo tank wall must withstand the same static internal fluid pressure as that required for the manhole cover. The component manufacturer shall verify compliance using the same test procedure and frequency of testing as specified in § 178.345-5(b).
[Amdt. 178-89, 54 FR , June 12, , as amended by Amdt. 178-105, 59 FR , Nov. 3, ; 68 FR , Apr. 18, ; 74 FR , Apr. 9, ]
(a) A cargo tank with a frame not integral to the cargo tank must have the tank secured by restraining devices to eliminate any motion between the tank and frame that may abrade the tank shell due to the stopping, starting, or turning of the cargo tank motor vehicle. The design calculations of the support elements must include the stresses indicated in § 178.345-3(b) and as generated by the loads described in § 178.345-3(c). Such restraining devices must be readily accessible for inspection and maintenance, except that insulation and jacketing are permitted to cover the restraining devices.
(b) A cargo tank designed and constructed so that it constitutes, in whole or in part, the structural member used in lieu of a frame must be supported in such a manner that the resulting stress levels in the cargo tank do not exceed those specified in § 178.345-3(a). The design calculations of the support elements must include the stresses indicated in § 178.345-3(b) and as generated by the loads described in § 178.345-3(c).
[Amdt. 178-89, 54 FR , June 12, , as amended by Amdt. 178-105, 59 FR , Nov. 3, ; Amdt. 178-118, 61 FR , Oct. 1, ]
(a) A cargo tank with a shell thickness of less than 3⁄8 inch must be circumferentially reinforced with bulkheads, baffles, ring stiffeners, or any combination thereof, in addition to the cargo tank heads.
(1) Circumferential reinforcement must be located so that the thickness and tensile strength of the shell material in combination with the frame and reinforcement produces structural integrity at least equal to that prescribed in § 178.345-3 and in such a manner that the maximum unreinforced portion of the shell does not exceed 60 inches. For cargo tanks designed to be loaded by vacuum, spacing of circumferential reinforcement may exceed 60 inches provided the maximum unreinforced portion of the shell conforms with the requirements in Section VIII of the ASME Code (IBR, see § 171.7 of this subchapter).
(2) Where circumferential joints are made between conical shell sections, or between conical and cylindrical shell sections, and the angle between adjacent sections is less than 160 degrees, circumferential reinforcement must be located within one inch of the shell joint, unless otherwise reinforced with structural members capable of maintaining shell stress levels authorized in § 178.345-3. When the joint is formed by the large ends of adjacent conical shell sections, or by the large end of a conical shell and a cylindrical shell section, this angle is measured inside the shell; when the joint is formed by the small end of a conical shell section and a cylindrical shell section, it is measured outside the shell.
(b) Except for doubler plates and knuckle pads, no reinforcement may cover any circumferential joint.
(c) When a baffle or baffle attachment ring is used as a circumferential reinforcement member, it must produce structural integrity at least equal to that prescribed in § 178.345-3 and must be circumferentially welded to the cargo tank shell. The welded portion may not be less than 50 percent of the total circumference of the cargo tank and the length of any unwelded space on the joint may not exceed 40 times the shell thickness unless reinforced external to the cargo tank.
(d) When a ring stiffener is used as a circumferential reinforcement member, whether internal or external, reinforcement must be continuous around the circumference of the cargo tank shell and must be in accordance with the following:
(1) The section modulus about the neutral axis of the ring section parallel to the shell must be at least equal to that derived from the applicable formula:
I/C = 0.WL, for MS, HSLA and SS; or
I/C = 0.WL, for aluminum alloys;
Where:
I/C = Section modulus in inches3
W = Tank width, or diameter, inches
L = Spacing of ring stiffener, inches; i.e., the maximum longitudinal distance from the midpoint of the unsupported shell on one side of the ring stiffener to the midpoint of the unsupported shell on the opposite side of the ring stiffener.
(2) If a ring stiffener is welded to the cargo tank shell, a portion of the shell may be considered as part of the ring section for purposes of computing the ring section modulus. This portion of the shell may be used provided at least 50 percent of the total circumference of the cargo tank is welded and the length of any unwelded space on the joint does not exceed 40 times the shell thickness. The maximum portion of the shell to be used in these calculations is as follows:
Number of circumferential ring stiffener-to-shell welds J 1 Shell section 1 20t 2 Less than 20t 20t + J 2 20t or more 40t 1 where: t = Shell thickness, inches; J = Longitudinal distance between parallel circumferential ring stiffener-to-shell welds.(3) When used to meet the vacuum requirements of this section, ring stiffeners must be as prescribed in Section VIII of the ASME Code.
(4) If configuration of internal or external ring stiffener encloses an air space, this air space must be arranged for venting and be equipped with drainage facilities which must be kept operative at all times.
(5) Hat shaped or open channel ring stiffeners which prevent visual inspection of the cargo tank shell are prohibited on cargo tank motor vehicles constructed of carbon steel.
[Amdt. 178-89, 55 FR , Sept. 7, , as amended by Amdt. 178-89, 56 FR , June 17, ; 56 FR , Sept. 11, ; Amdt. 178-104, 59 FR , Sept. 26, ; Amdt. 178-118, 61 FR , Oct. 1, ; 68 FR , Dec. 31, ]
(a) General. Each cargo tank motor vehicle must be designed and constructed in accordance with the requirements of this section and the applicable individual specification to minimize the potential for the loss of lading due to an accident.
(1) Any dome, sump, or washout cover plate projecting from the cargo tank wall that retains lading in any tank orientation, must be as strong and tough as the cargo tank wall and have a thickness at least equal to that specified by the appropriate cargo tank specification. Any such projection located in the lower 1⁄3 of the tank circumference (or cross section perimeter for non-circular cargo tanks) that extends more than half its diameter at the point of attachment to the tank or more than 4 inches from the cargo tank wall, or located in the upper 2⁄3 of the tank circumference (or cross section perimeter for non-circular cargo tanks) that extends more than 1⁄4 its diameter or more than 2 inches from the point of attachment to the tank must have accident damage protection devices that are:
(i) As specified in this section;
(ii) 125 percent as strong as the otherwise required accident damage protection device; or
(iii) Attached to the cargo tank in accordance with the requirements of paragraph (a)(3) of this section.
(2) Outlets, valves, closures, piping, or any devices that if damaged in an accident could result in a loss of lading from the cargo tank must be protected by accident damage protection devices as specified in this section.
(3) Accident damage protection devices attached to the wall of a cargo tank must be able to withstand or deflect away from the cargo tank the loads specified in this section. They must be designed, constructed and installed so as to maximize the distribution of loads to the cargo tank wall and to minimize the possibility of adversely affecting the lading retention integrity of the cargo tank. Accident induced stresses resulting from the appropriate accident damage protection device requirements in combination with the stresses from the cargo tank operating at the MAWP may not result in a cargo tank wall stress greater than the ultimate strength of the material of construction using a safety factor of 1.3. Deformation of the protection device is acceptable provided the devices being protected are not damaged when loads specified in this section are applied.
(4) Any piping that extends beyond an accident damage protection device must be equipped with a stop-valve and a sacrificial device such as a shear section. The sacrificial device must be located in the piping system outboard of the stop-valve and within the accident damage protection device to prevent any accidental loss of lading. The device must break at no more than 70 percent of the load that would be required to cause the failure of the protected lading retention device, part or cargo tank wall. The failure of the sacrificial device must leave the protected lading retention device and its attachment to the cargo tank wall intact and capable of retaining product.
(5) Minimum road clearance. The minimum road clearance of any cargo tank motor vehicle component or protection device located between any two adjacent axles on a vehicle or vehicle combination must be at least one-half inch for each foot separating the component or device from the nearest axle of the adjacent pair, but in no case less than twelve (12) inches, except that the minimum road clearance for landing gear or other attachments within ten (10) feet of an axle must be no less than ten (10) inches. These measurements must be calculated at the gross vehicle weight rating of the cargo tank motor vehicle.
(b) Each outlet, projection or piping located in the lower 1⁄3 of the cargo tank circumference (or cross section perimeter for non-circular cargo tanks) that could be damaged in an accident that may result in the loss of lading must be protected by a bottom damage protection device, except as provided by paragraph (a)(1) of this section and § 173.33(e) of this subchapter. Outlets, projections and piping may be grouped or clustered together and protected by a single protection device.
(1) Any bottom damage protection device must be able to withstand a force of 155,000 pounds (based on the ultimate strength of the material), from the front, side, and rear uniformly distributed, applied in each direction of the device, over an area not to exceed 6 square feet, and a width not to exceed 6 feet. Suspension components and structural mounting members may be used to provide all, or part, of this protection. The device must extend no less than 6 inches beyond any component that may contain lading in transit.
(2) A lading discharge opening equipped with an internal self-closing stop-valve need not conform to paragraph (b)(1) of this section provided it is protected so as to reasonably assure against the accidental loss of lading. This protection must be provided by a sacrificial device located outboard of each internal self-closing stop-valve and within 4 inches of the major radius of the cargo tank shell or within 4 inches of a sump, but in no case more than 8 inches from the major radius of the tank shell. The device must break at no more than 70 percent of the load that would be required to cause the failure of the protected lading retention device, part or cargo tank wall. The failure of the sacrificial device must leave the protected lading retention device or part and its attachment to the cargo tank wall intact and capable of retaining product.
(c) Each closure for openings, including but not limited to the manhole, filling or inspection openings, and each valve, fitting, pressure relief device, vapor recovery stop valve or lading retaining fitting located in the upper 2⁄3 of a cargo tank circumference (or cross section perimeter for non-circular tanks) must be protected by being located within or between adjacent rollover damage protection devices, or by being 125 percent of the strength that would be provided by the otherwise required damage protection device.
(1) A rollover damage protection device on a cargo tank motor vehicle must be designed and installed to withstand loads equal to twice the weight of the loaded cargo tank motor vehicle applied as follows: normal to the cargo tank shell (perpendicular to the cargo tank surface); and tangential (perpendicular to the normal load) from any direction. The stresses shall not exceed the ultimate strength of the material of construction. These design loads may be considered to be uniformly distributed and independently applied. If more than one rollover protection device is used, each device must be capable of carrying its proportionate share of the required loads and in each case at least one-fourth the total tangential load. The design must be proven capable of carrying the required loads by calculations, tests or a combination of tests and calculations.
(2) A rollover damage protection device that would otherwise allow the accumulation of liquid on the top of the cargo tank, must be provided with a drain that directs the liquid to a safe point of discharge away from any structural component of the cargo tank motor vehicle.
(d) Rear-end tank protection. Each cargo tank motor vehicle must be provided with a rear-end tank protection device to protect the cargo tank and piping in the event of a rear-end collision and reduce the likelihood of damage that could result in the loss of lading. Nothing in this paragraph relieves the manufacturer of responsibility for complying with the requirements of § 393.86 of this title and, if applicable, paragraph (b) of this section. The rear-end tank protection device must conform to the following requirements:
(1) The rear-end cargo tank protection device must be designed so that it can deflect at least 6 inches horizontally forward with no contact between any part of the cargo tank motor vehicle which contains lading during transit and with any part of the rear-end protection device, or with a vertical plane passing through the outboard surface of the protection device.
(2) The dimensions of the rear-end cargo tank protection device shall conform to the following:
(i) The bottom surface of the rear-end protection device must be at least 4 inches below the lower surface of any part at the rear of the cargo tank motor vehicle which contains lading during transit and not more than 60 inches from the ground when the vehicle is empty.
(ii) The maximum width of a notch, indentation, or separation between sections of a rear-end cargo tank protection device may not exceed 24 inches. A notched, indented, or separated rear-end protection device may be used only when the piping at the rear of the cargo tank is equipped with a sacrificial device outboard of a shut-off valve.
(iii) The widest part of the motor vehicle at the rear may not extend more than 18 inches beyond the outermost ends of the device or (if separated) devices on either side of the vehicle.
(3) The structure of the rear-end protection device and its attachment to the vehicle must be designed to satisfy the conditions specified in paragraph (d)(1) of this section when subjected to an impact of the cargo tank motor vehicle at rated payload, at a deceleration of 2 “g”. Such impact must be considered as being uniformly applied in the horizontal plane at an angle of 10 degrees or less to the longitudinal axis of the vehicle.
(e) Longitudinal deceleration protection. In order to account for stresses due to longitudinal impact in an accident, the cargo tank shell and heads must be able to withstand the load resulting from the design pressure in combination with the dynamic pressure resulting from a longitudinal deceleration of 2 “g”. For this loading condition, the allowable stress value used may not exceed the ultimate strength of the material of construction using a safety factor of 1.3. Performance testing, analytical methods, or a combination thereof, may be used to prove this capability provided the methods are accurate and verifiable. For cargo tanks with internal baffles, the decelerative force may be reduced by 0.25 “g” for each baffle assembly, but in no case may the total reduction in decelerative force exceed 1.0 “g”.
[Amdt. 178-89, 54 FR , June 12, , as amended at 55 FR , Sept. 7, ; Amdt. 178-105, 59 FR , Nov. 3, ; Amdt. 178-118, 61 FR , Oct. 1, ; 68 FR , Apr. 18, ; 85 FR , Dec. 21, ]
(a) Suitable means must be provided during loading or unloading operations to ensure that pressure within a cargo tank does not exceed test pressure.
(b) Each hose, piping, stop-valve, lading retention fitting and closure must be designed for a bursting pressure of the greater of 100 psig or four times the MAWP.
(c) Each hose coupling must be designed for a bursting pressure of the greater of 120 psig or 4.8 times the MAWP of the cargo tank, and must be designed so that there will be no leakage when connected.
(d) Suitable provision must be made to allow for and prevent damage due to expansion, contraction, jarring, and vibration. Slip joints may not be used for this purpose in the lading retention system.
(e) Any heating device, when installed, must be so constructed that the breaking of its external connections will not cause leakage of the cargo tank lading.
(f) Any gauging, loading or charging device, including associated valves, must be provided with an adequate means of secure closure to prevent leakage.
(g) The attachment and construction of each loading/unloading or charging line must be of sufficient strength, or be protected by a sacrificial device, such that any load applied by loading/unloading or charging lines connected to the cargo tank cannot cause damage resulting in loss of lading from the cargo tank.
(h) Use of a nonmetallic pipe, valve or connection that is not as strong and heat resistant as the cargo tank material is authorized only if such attachment is located outboard of the lading retention system.
[Amdt. 178-89, 54 FR , June 12, , as amended at 55 FR , Sept. 7, , Amdt. 178-89, 56 FR , June 17, ; Amdt. 178-118, 61 FR , Oct. 1, ]
(a) Each cargo tank must be equipped to relieve pressure and vacuum conditions in conformance with this section and the applicable individual specification. The pressure and vacuum relief system must be designed to operate and have sufficient capacity to prevent cargo tank rupture or collapse due to over-pressurization or vacuum resulting from loading, unloading, or from heating and cooling of lading. Pressure relief systems are not required to conform to the ASME Code.
(b) Type and construction of relief systems and devices.
(1) Each cargo tank must be provided with a primary pressure relief system consisting of one or more reclosing pressure relief valves. A secondary pressure relief system consisting of another pressure relief valve in parallel with the primary pressure relief system may be used to augment the total venting capacity of the cargo tank. Non-reclosing pressure relief devices are not authorized in any cargo tank except when in series with a reclosing pressure relief device. Gravity actuated reclosing valves are not authorized on any cargo tank.
(2) When provided by § 173.33(c)(1)(iii) of this subchapter, cargo tanks may be equipped with a normal vent. Such vents must be set to open at not less than 1 psig and must be designed to prevent loss of lading through the device in case of vehicle overturn.
(3) Each pressure relief system must be designed to withstand dynamic pressure surges in excess of the design set pressure as specified in paragraphs (b)(3) (i) and (ii) of this section. Set pressure is a function of MAWP as set forth in paragraph (d) of this section.
(i) Each pressure relief device must be able to withstand dynamic pressure surge reaching 30 psig above the design set pressure and sustained above the set pressure for at least 60 milliseconds with a total volume of liquid released not exceeding one gallon before the relief device recloses to a leak-tight condition. This requirement must be met regardless of vehicle orientation. This capability must be demonstrated by testing. An acceptable method is outlined in TTMA RP No. 81-97 “Performance of Spring Loaded Pressure Relief Valves on MC 306, MC 307, MC 312, DOT 406, DOT 407, and DOT 412 Tanks” (incorporated by reference; see § 171.7 of this subchapter).
(ii) After August 31, , each pressure relief device must be able to withstand a dynamic pressure surge reaching 30 psig above the design set pressure and sustained above the design set pressure for at least 60 milliseconds with a total volume of liquid released not exceeding 1 L before the relief valve recloses to a leak-tight condition. This requirement must be met regardless of vehicle orientation. This capability must be demonstrated by testing. TTMA RP No. 81, cited in paragraph (b)(3)(i) of this section, is an acceptable test procedure.
(4) Each reclosing pressure relief valve must be constructed and installed in such a manner as to prevent unauthorized adjustment of the relief valve setting.
(5) No shut-off valve or other device that could prevent venting through the pressure relief system may be installed in a pressure relief system.
(6) The pressure relief system must be mounted, shielded and drainable so as to minimize the accumulation of material that could impair the operation or discharge capability of the system by freezing, corrosion or blockage.
(c) Location of relief devices. Each pressure relief device must communicate with the vapor space above the lading as near as practicable to the center of the vapor space. For example, on a cargo tank designed to operate in a level attitude, the device should be positioned at the horizontal and transverse center of the cargo tank; on cargo tanks sloped to the rear, the device should be located in the forward half of the cargo tank. The discharge from any device must be unrestricted. Protective devices which deflect the flow of vapor are permissible provided the required vent capacity is maintained.
(d) Settings of pressure relief system. The set pressure of the pressure relief system is the pressure at which it starts to open, allowing discharge.
(1) Primary pressure relief system. The set pressure of each primary relief valve must be no less than 120 percent of the MAWP, and no more than 132 percent of the MAWP. The valve must reclose at not less than 108 percent of the MAWP and remain closed at lower pressures.
(2) Secondary pressure relief system. The set pressure of each pressure relief valve used as a secondary relief device must be not less than 120 percent of the MAWP.
(e) Venting capacity of pressure relief systems. The pressure relief system (primary and secondary, including piping) must have sufficient venting capacity to limit the cargo tank internal pressure to not more than the cargo tank test pressure. The total venting capacity, rated at not more than the cargo tank test pressure, must be at least that specified in table I, except as provided in § 178.348-4.
Table I—Minimum Emergency Vent Capacity
[In cubic feet free air/hour at 60 °F and 1 atm.]
Exposed area in square feet Cubic feet free air per hour 20 15,800 30 23,700 40 31,600 50 39,500 60 47,400 70 55,300 80 63,300 90 71,200 100 79,100 120 94,900 140 110,700 160 126,500 180 142,300 200 158,100 225 191,300 250 203,100 275 214,300 300 225,100 350 245,700 400 265,000 450 283,200 500 300,600 550 317,300 600 333,300 650 348,800 700 363,700 750 378,200 800 392,200 850 405,900 900 419,300 950 432,300 1,000 445,000 Note 1: Interpolate for intermediate sizes.(1) Primary pressure relief system. Unless otherwise specified in the applicable individual specification, the primary relief system must have a minimum venting capacity of 12,000 SCFH per 350 square feet of exposed cargo tank area, but in any case at least one fourth the required total venting capacity for the cargo tank.
(2) Secondary pressure relief system. If the primary pressure relief system does not provide the required total venting capacity, additional capacity must be provided by a secondary pressure relief system.
(f) Certification of pressure relief devices. The manufacturer of any pressure relief device, including valves, frangible (rupture) disks, vacuum vents and combination devices must certify that the device model was designed and tested in accordance with this section and the appropriate cargo tank specification. The certificate must contain sufficient information to describe the device and its performance. The certificate must be signed by a responsible official of the manufacturer who approved the flow capacity certification.
(g) Rated flow capacity certification test. Each pressure relief device model must be successfully flow capacity certification tested prior to first use. Devices having one design, size and set pressure are considered to be one model. The testing requirements are as follows:
(1) At least 3 devices of each specific model must be tested for flow capacity at a pressure not greater than the test pressure of the cargo tank. For a device model to be certified, the capacities of the devices tested must fall within a range of plus or minus 5 percent of the average for the devices tested.
(2) The rated flow capacity of a device model may not be greater than 90 percent of the average value for the devices tested.
(3) The rated flow capacity derived for each device model must be certified by a responsible official of the device manufacturer.
(h) Marking of pressure relief devices. Each pressure relief device must be permanently marked with the following:
(1) Manufacturer's name;
(2) Model number;
(3) Set pressure, in psig; and
(4) Rated flow capacity, in SCFH at the rating pressure, in psig.
[Amdt. 178-89, 54 FR , June 12, , as amended at 55 FR , May 22, ; 55 FR , Sept. 7, ; Amdt. 178-89, 56 FR , June 17, ; Amdt. 178-105, 59 FR , Nov. 3, ; Amdt. 178-118, 61 FR , Oct. 1, ; 65 FR , Sept. 29, ; 66 FR , Aug. 28, ; 68 FR , Apr. 18, ]
(a) General. As used in this section, “loading/unloading outlet” means any opening in the cargo tank wall used for loading or unloading of lading, as distinguished from outlets such as manhole covers, vents, vapor recovery devices, and similar closures. Cargo tank outlets, closures and associated piping must be protected in accordance with § 178.345-8.
(b) Each cargo tank loading/unloading outlet must be equipped with an internal self-closing stop-valve, or alternatively, with an external stop-valve located as close as practicable to the cargo tank wall. Each cargo tank loading/unloading outlet must be in accordance with the following provisions:
(1) Each loading/unloading outlet must be fitted with a self-closing system capable of closing all such outlets in an emergency within 30 seconds of actuation. During normal operations the outlets may be closed manually. The self-closing system must be designed according to the following:
(i) Each self-closing system must include a remotely actuated means of closure located more than 10 feet from the loading/unloading outlet where vehicle length allows, or on the end of the cargo tank farthest away from the loading/unloading outlet. The actuating mechanism must be corrosion-resistant and effective in all types of environment and weather.
(ii) If the actuating system is accidentally damaged or sheared off during transportation, each loading/unloading outlet must remain securely closed and capable of retaining lading.
(iii) When required by part 173 of this subchapter for materials which are flammable, pyrophoric, oxidizing, or Division 6.1 (poisonous liquid) materials, the remote means of closure must be capable of thermal activation. The means by which the self-closing system is thermally activated must be located as close as practicable to the primary loading/unloading connection and must actuate the system at a temperature not over 250 °F. In addition, outlets on these cargo tanks must be capable of being remotely closed manually or mechanically.
(2) Bottom loading outlets which discharge lading into the cargo tank through fixed internal piping above the maximum liquid level of the cargo tank need not be equipped with a self-closing system.
(c) Any loading/unloading outlet extending beyond an internal self-closing stop-valve, or beyond the innermost external stop-valve which is part of a self-closing system, must be fitted with another stop-valve or other leak-tight closure at the end of such connection.
(d) Each cargo tank outlet that is not a loading/unloading outlet must be equipped with a stop-valve or other leak-tight closure located as close as practicable to the cargo tank outlet. Any connection extending beyond this closure must be fitted with another stop-valve or other leak-tight closure at the end of such connection.
[Amdt. 178-89, 56 FR , June 17, , as amended by Amdt. 178-97, 57 FR , Oct. 1, ; Amdt. 178-118, 61 FR , Oct. 1, ]
Each cargo tank, except a cargo tank intended to be filled by weight, must be equipped with a gauging device that indicates the maximum permitted liquid level to within 0.5 percent of the nominal capacity as measured by volume or liquid level. Gauge glasses are not permitted.
[Amdt. 178-89, 55 FR , Sept. 7, , as amended by Amdt. 178-118, 61 FR , Oct. 1, ]
(a) Each cargo tank must be pressure and leakage tested in accordance with this section and §§ 178.346-5, 178.347-5, or 178.348-5.
(b) Pressure test. Each cargo tank or cargo tank compartment must be tested hydrostatically or pneumatically. Each cargo tank of a multi-cargo tank motor vehicle must be tested with the adjacent cargo tanks empty and at atmospheric pressure. Each closure, except pressure relief devices and loading/unloading venting devices rated at less than the prescribed test pressure, must be in place during the test. If the venting device is not removed during the test, such device must be rendered inoperative by a clamp, plug or other equally effective restraining device, which may not prevent the detection of leaks, or damage the device. Restraining devices must be removed immediately after the test is completed.
(1) Hydrostatic method. Each cargo tank, including its domes, must be filled with water or other liquid having similar viscosity, the temperature of which may not exceed 100 °F. The cargo tank must then be pressurized as prescribed in the applicable specification. The pressure must be gauged at the top of the cargo tank. The prescribed test pressure must be maintained for at least 10 minutes during which time the cargo tank must be inspected for leakage, bulging, or other defect.
(2) Pneumatic method. A pneumatic test may be used in place of the hydrostatic test. However, pneumatic pressure testing may involve higher risk than hydrostatic testing. Therefore, suitable safeguards must be provided to protect personnel and facilities should failure occur during the test. The cargo tank must be pressurized with air or an inert gas. Test pressure must be reached gradually by increasing the pressure to one half of test pressure. Thereafter, the pressure must be increased in steps of approximately one tenth of the test pressure until test pressure is reached. Test pressure must be held for at least 5 minutes. The pressure must then be reduced to the inspection pressure which must be maintained while the entire cargo tank surface is inspected for leakage and other sign of defects. The inspection method must consist of coating all joints and fittings with a solution of soap and water or other equally sensitive method.
(c) Leakage test. The cargo tank with all its accessories in place and operable must be leak tested at not less than 80 percent of tank's MAWP with the pressure maintained for at least 5 minutes.
(d) Any cargo tank that leaks, bulges or shows any other sign of defect must be rejected. Rejected cargo tanks must be suitably repaired and retested successfully prior to being returned to service. The retest after any repair must use the same method of test under which the cargo tank was originally rejected.
[Amdt. 178-89, 54 FR , June 12, , as amended at 55 FR , Sept. 7, ; Amdt. 178-105, 59 FR , Nov. 3, ; Amdt. 178-118, 61 FR , Oct. 1, ; 65 FR , Sept. 29, ; 68 FR , Apr. 18, ]
(a) General. The manufacturer shall certify that each cargo tank motor vehicle has been designed, constructed and tested in accordance with the applicable Specification DOT 406, DOT 407 or DOT 412 (§§ 178.345, 178.346, 178.347, 178.348) cargo tank requirements and, when applicable, with Section VIII of the ASME Code (IBR, see § 171.7 of this subchapter). The certification shall be accomplished by marking the cargo tank as prescribed in paragraphs (b) and (c) of this section, and by preparing the certificate prescribed in § 178.345-15. Metal plates prescribed by paragraphs (b), (c), (d) and (e) of this section, must be permanently attached to the cargo tank or its integral supporting structure, by brazing, welding or other suitable means. These plates must be affixed on the left side of the vehicle near the front of the cargo tank (or the frontmost cargo tank of a multi-cargo tank motor vehicle), in a place readily accessible for inspection. The plates must be permanently and plainly marked in English by stamping, embossing or other means in characters at least 3⁄16 inch high. The information required by paragraphs (b) and (c) of this section may be combined on one specification plate.
(b) Nameplate. Each cargo tank must have a corrosion resistant nameplate permanently attached to it. The following information, in addition to any applicable information required by the ASME Code, must be marked on the tank nameplate (parenthetical abbreviations may be used):
(1) DOT-specification number DOT XXX (DOT XXX) where “XXX” is replaced with the applicable specification number. For cargo tanks having a variable specification plate, the DOT-specification number is replaced with the words “See variable specification plate.”
(2) Original test date, month and year (Orig. Test Date).
(3) Tank MAWP in psig.
(4) Cargo tank test pressure (Test P), in psig.
(5) Cargo tank design temperature range (Design temp. range),__ °F to __ °F.
(6) Nominal capacity (Water cap.), in gallons.
(7) Maximum design density of lading (Max. lading density), in pounds per gallon.
(8) Material specification number—shell (Shell matl, yyy***), where “yyy” is replaced by the alloy designation and “***” by the alloy type.
(9) Material specification number—heads (Head matl, yyy***), where “yyy” is replaced by the alloy designation and “***” by the alloy type.
Note:When the shell and heads materials are the same thickness, they may be combined, (Shell&head matl, yyy***).
(10) Weld material (Weld matl.).
(11) Minimum thickness—shell (Min. shell-thick), in inches. When minimum shell thicknesses are not the same for different areas, show (top __, side __, bottom __, in inches).
(12) Minimum thickness—heads (Min. heads thick.), in inches.
(13) Manufactured thickness—shell (Mfd. shell thick.), top __, side __, bottom __, in inches. (Required when additional thickness is provided for corrosion allowance.)
(14) Manufactured thickness—heads (Mfd. heads thick.), in inches. (Required when additional thickness is provided for corrosion allowance.)
(15) Exposed surface area, in square feet.
(c) Specification plate. Each cargo tank motor vehicle must have an additional corrosion resistant metal specification plate attached to it. The specification plate must contain the following information (parenthetical abbreviations may be used):
(1) Cargo tank motor vehicle manufacturer (CTMV mfr.).
(2) Cargo tank motor vehicle certification date (CTMV cert. date), if different from the cargo tank certification date.
(3) Cargo tank manufacturer (CT mfr.).
(4) Cargo tank date of manufacture (CT date of mfr.), month and year.
(5) Maximum weight of lading (Max. Payload), in pounds.
(6) Maximum loading rate in gallons per minute (Max. Load rate, GPM).
(7) Maximum unloading rate in gallons per minute (Max. Unload rate).
(8) Lining material (Lining), if applicable.
(9) Heating system design pressure (Heating sys. press.), in psig, if applicable.
(10) Heating system design temperature (Heating sys. temp.), in °F, if applicable.
(d) Multi-cargo tank motor vehicle. For a multi-cargo tank motor vehicle having all its cargo tanks not separated by any void, the information required by paragraphs (b) and (c) of this section may be combined on one specification plate. When separated by a void, each cargo tank must have an individual nameplate as required in paragraph (b) of this section, unless all cargo tanks are made by the same manufacturer with the same materials, manufactured thickness, minimum thickness and to the same specification. The cargo tank motor vehicle may have a combined nameplate and specification plate. When only one plate is used, the plate must be visible and not covered by insulation. The required information must be listed on the plate from front to rear in the order of the corresponding cargo tank location.
(e) Variable specification cargo tank. Each variable specification cargo tank must have a corrosion resistant metal variable specification plate attached to it. The mounting of this variable specification plate must be such that only the plate identifying the applicable specification under which the tank is being operated is legible.
(1) The following information must be included (parenthetical abbreviations are authorized):
Specification DOT XXX (DOT XXX), where “XXX” is replaced with the applicable specification number.
Equipment required Required rating 1 Pressure relief devices: Pressure actuated type ____________ Frangible type ____________ Lading discharge devices ____________ Top ____________ Bottom ____________ Pressure unloading fitting ____________ Closures: Manhole ____________ Fill openings ____________ Discharge openings ____________ 1 Required rating—to meet the applicable specification.(2) If no change of information in the specification plate is required, the letters “NC” must follow the rating required. If the cargo tank is not so equipped, the word “None” must be inserted.
(3) Those parts to be changed or added must be stamped with the appropriate MC or DOT Specification markings.
(4) The alterations that must be made in order for the tank to be modified from one specification to another must be clearly indicated on the manufacturer's certificate and on the variable specification plate.
[Amdt. 178-89, 54 FR , June 12, , as amended at 55 FR , Sept. 7, ; Amdt. 178-99, 58 FR , Oct. 1, ; Amdt. 178-104, 59 FR , Sept. 26, ; Amdt. 178-105, 59 FR , Nov. 3, ; 60 FR , Apr. 5, ; Amdt. 178-118, 61 FR , Oct. 1, ; 66 FR , Aug. 28, ; 68 FR , Apr. 18, ; 68 FR , Sept. 3, ; 68 FR , Dec. 31, ]
(a) At or before the time of delivery, the manufacturer of a cargo tank motor vehicle must provide certification documents to the owner of the cargo tank motor vehicle. The registration numbers of the manufacturer, the Design Certifying Engineer, and the Registered Inspector, as appropriate, must appear on the certificates (see subpart F, part 107 in subchapter A of this chapter).
(b) The manufacturer of a cargo tank motor vehicle made to any of these specifications must provide:
(1) For each design type, a certificate signed by a responsible official of the manufacturer and a Design Certifying Engineer certifying that the cargo tank motor vehicle design meets the applicable specification; and
(2) For each ASME cargo tank, a cargo tank manufacturer's data report as required by Section VIII of the ASME Code (IBR, see § 171.7 of this subchapter). For each cargo tank motor vehicle, a certificate signed by a responsible official of the manufacturer and a Registered Inspector certifying that the cargo tank motor vehicle is constructed, tested and completed in conformance with the applicable specification.
(c) The manufacturer of a variable specification cargo tank motor vehicle must provide:
(1) For each design type, a certificate signed by a responsible official of the manufacturer and a Design Certifying Engineer certifying that the cargo tank motor vehicle design meets the applicable specifications; and
(2) For each variable specification cargo tank motor vehicle, a certificate signed by a responsible official of the manufacturer and a Registered Inspector certifying that the cargo tank motor vehicle is constructed, tested and completed in conformance with the applicable specifications. The certificate must include all the information required and marked on the variable specification plate.
(d) In the case of a cargo tank motor vehicle manufactured in two or more stages, each manufacturer who performs a manufacturing operation on the incomplete vehicle or portion thereof shall provide to the succeeding manufacturer, at or before the time of delivery, a certificate covering the particular operation performed by that manufacturer, including any certificates received from previous manufacturers, Registered Inspectors, and Design Certifying Engineers. Each certificate must indicate the portion of the complete cargo tank motor vehicle represented thereby, such as basic cargo tank fabrication, insulation, jacket, lining, or piping. The final manufacturer shall provide all applicable certificates to the owner.
(e) Specification shortages. If a cargo tank is manufactured which does not meet all applicable specification requirements, thereby requiring subsequent manufacturing involving the installation of additional components, parts, appurtenances or accessories, the cargo tank manufacturer may affix the name plate and specification plate, as required by § 178.345-14 (b) and (c), without the original date of certification stamped on the specification plate. The manufacturer shall state the specification requirements not complied with on the manufacturer's Certificate of Compliance. When the cargo tank is brought into full compliance with the applicable specification, the Registered Inspector shall stamp the date of compliance on the specification plate. The Registered Inspector shall issue a Certificate of Compliance stating details of the particular operations performed on the cargo tank, and the date and person (manufacturer, carrier, or repair organization) accomplishing the compliance.
[Amdt. 178-89, 55 FR , Sept. 7, , as amended by Amdt. 178-98, 58 FR , June 16, ; Amdt. 178-105, 59 FR , Nov. 3, ; Amdt. 178-118, 61 FR , Oct. 1, ; 68 FR , Dec. 31, ]
(a) Each Specification DOT 406 cargo tank motor vehicle must meet the general design and construction requirements in § 178.345, in addition to the specific requirements contained in this section.
(b) MAWP: The MAWP of each cargo tank must be no lower than 2.65 psig and no higher than 4 psig.
(c) Vacuum loaded cargo tanks must not be constructed to this specification.
(d) Each cargo tank must be “constructed in accordance with Section VIII of the ASME Code” (IBR, see § 171.7 of this subchapter) except as modified herein:
(1) The record-keeping requirements contained in the ASME Code Section VIII do not apply. Parts UG-90 through 94 in Section VIII do not apply. Inspection and certification must be made by an inspector registered in accordance with subpart F of part 107.
(2) Loadings must be as prescribed in § 178.345-3.
(3) The knuckle radius of flanged heads must be at least three times the material thickness, and in no case less than 0.5 inch. Stuffed (inserted) heads may be attached to the shell by a fillet weld. The knuckle radius and dish radius versus diameter limitations of UG-32 do not apply. Shell sections of cargo tanks designed with a non-circular cross section need not be given a preliminary curvature, as prescribed in UG-79(b).
(4) Marking, certification, data reports, and nameplates must be as prescribed in §§ 178.345-14 and 178.345-15.
(5) Manhole closure assemblies must conform to §§ 178.345-5 and 178.346-5.
(6) Pressure relief devices must be as prescribed in § 178.346-3.
(7) The hydrostatic or pneumatic test must be as prescribed in § 178.346-5.
(8) The following paragraphs in parts UG and UW in Section VIII of the ASME Code do not apply: UG-11, UG-12, UG-22(g), UG-32(e), UG-34, UG-35, UG-44, UG-76, UG-77, UG-80, UG-81, UG-96, UG-97, UW-13(b)(2), UW-13.1(f) and the dimensional requirements found in Figure UW-13.1.
(9) Single full fillet lap joints without plug welds may be used for arc or gas welded longitudinal seams without radiographic examination under the following conditions:
(i) For a truck-mounted cargo tank, no more than two such joints may be used on the top half of the tank and no more than two joints may be used on the bottom half. They may not be located farther from the top and bottom centerline than 16 percent of the shell's circumference.
(ii) For a self-supporting cargo tank, no more than two such joints may be used on the top of the tank. They may not be located farther from the top centerline than 12.5 percent of the shell's circumference.
(iii) Compliance test. Two test specimens of the material to be used in the manufacture of a cargo tank must be tested to failure in tension. The test specimens must be of the same thicknesses and joint configuration as the cargo tank, and joined by the same welding procedures. The test specimens may represent all the tanks that are made of the same materials and welding procedures, have the same joint configuration, and are made in the same facility within 6 months after the tests are completed. Before welding, the fit-up of the joints on the test specimens must represent production conditions that would result in the least joint strength. Evidence of joint fit-up and test results must be retained at the manufacturers' facility.
(iv) Weld joint efficiency. The lower value of stress at failure attained in the two tensile test specimens shall be used to compute the efficiency of the joint as follows: Determine the failure ratio by dividing the stress at failure by the mechanical properties of the adjacent metal; this value, when multiplied by 0.75, is the design weld joint efficiency.
(10) The requirements of paragraph UW-9(d) in Section VIII of the ASME Code do not apply.
[Amdt. 178-89, 54 FR , June 12, , as amended at 55 FR , Sept. 7, ; Amdt. 178-89, 56 FR , June 17, ; Amdt. 178-105, 59 FR , Nov. 3, ; 65 FR , Sept. 29, ; 66 FR , Aug. 28, ; 68 FR , Apr. 18, ; 68 FR , Dec. 31, ]
The type and thickness of material for DOT 406 specification cargo tanks must conform to § 178.345-2, but in no case may the thickness be less than that determined by the minimum thickness requirements in § 178.320(a). The following Tables I and II identify the specified minimum thickness values to be employed in that determination.
Table I—Specified Minimum Thickness of Heads (or Bulkheads and Baffles When Used as Tank Reinforcement) Using Mild Steel (MS), High Strength Low Alloy Steel (HSLA), Austenitic Stainless Steel (SS), or Aluminum (AL)—Expressed in Decimals of an Inch After Forming
Material Volume capacity in gallons per inch of length 14 or less Over 14 to 23 Over 23 MS HSLA SS AL MS HSLA SS AL MS HSLA SS AL Thickness .100 .100 .160 .115 .115 .173 .129 .129 .187Table II—Specified Minimum Thickness of Shell Using Mild Steel (MS), High Strength Low Alloy Steel (HSLA), Austenitic Stainless Steel (SS), or Aluminum (AL)—Expressed in Decimals of an Inch After Forming 1
Cargo tank motor vehicle rated capacity (gallons) MS SS/HSLA AL More than 0 to at least 4,500 0.100 0.100 0.151 More than 4,500 to at least 8,000 0.115 0.100 0.160 More than 8,000 to at least 14,000 0.129 0.129 0.173 More than 14,000 0.143 0.143 0.187 1 Maximum distance between bulkheads, baffles, or ring stiffeners shall not exceed 60 inches.[Amdt. 178-89, 54 FR , June 12, , as amended at 55 FR , Sept. 7, ; Amdt. 178-105, 59 FR , Nov. 3, ; 68 FR , Apr. 18, ]
(a) Each cargo tank must be equipped with a pressure relief system in accordance with § 178.345-10 and this section.
(b) Type and construction. In addition to the pressure relief devices required in § 178.345-10:
(1) Each cargo tank must be equipped with one or more vacuum relief devices;
(2) When intended for use only for lading meeting the requirements of § 173.33(c)(1)(iii) of this subchapter, the cargo tank may be equipped with a normal vent. Such vents must be set to open at not less than 1 psig and must be designed to prevent loss of lading through the device in case of vehicle upset; and
(3) Notwithstanding the requirements in § 178.345-10(b), after August 31, , each pressure relief valve must be able to withstand a dynamic pressure surge reaching 30 psig above the design set pressure and sustained above the set pressure for at least 60 milliseconds with a total volume of liquid released not exceeding 1 L before the relief valve recloses to a leak-tight condition. This requirement must be met regardless of vehicle orientation. This capability must be demonstrated by testing. TTMA RP No. 81 (IBR, see § 171.7 of this subchapter), cited at § 178.345-10(b)(3)(i), is an acceptable test procedure.
(c) Pressure settings of relief valves.
(1) Notwithstanding the requirements in § 178.345-10(d), the set pressure of each primary relief valve must be not less than 110 percent of the MAWP or 3.3 psig, whichever is greater, and not more than 138 percent of the MAWP. The valve must close at not less than the MAWP and remain closed at lower pressures.
(2) Each vacuum relief device must be set to open at no more than 6 ounces vacuum.
(d) Venting capacities.
(1) Notwithstanding the requirements in § 178.345-10 (e) and (g), the primary pressure relief valve must have a venting capacity of at least 6,000 SCFH, rated at not greater than 125 percent of the tank test pressure and not greater than 3 psig above the MAWP. The venting capacity required in § 178.345-10(e) may be rated at these same pressures.
(2) Each vacuum relief system must have sufficient capacity to limit the vacuum to 1 psig.
(3) If pressure loading or unloading devices are provided, the relief system must have adequate vapor and liquid capacity to limit the tank pressure to the cargo tank test pressure at maximum loading or unloading rate. The maximum loading and unloading rates must be included on the metal specification plate.
[Amdt. 178-89, 54 FR , June 12, , as amended at 55 FR , Sept. 7, ; Amdt. 178-105, 59 FR , Nov. 3, . Redesignated by Amdt. 178-112, 61 FR , Apr. 29, ; 66 FR , Aug. 28, ; 68 FR , Dec. 31, ]
(a) All outlets on each tank must conform to § 178.345-11 and this section.
(b) External self-closing stop-valves are not authorized as an alternative to internal self-closing stop-valves on loading/unloading outlets.
[Amdt. 178-89, 54 FR , June 12, . Redesignated by Amdt. 178-112, 61 FR , Apr. 29, ]
(a) Each cargo tank must be tested in accordance with § 178.345-13 and this section.
(b) Pressure test. Test pressure must be as follows:
(1) Using the hydrostatic test method, the test pressure must be the greater of 5.0 psig or 1.5 times the cargo tank MAWP.
(2) Using the pneumatic test method, the test pressure must be the greater of 5.0 psig or 1.5 times the cargo tank MAWP, and the inspection pressure must be the cargo tank MAWP.
(c) Leakage test. A cargo tank used to transport a petroleum distillate fuel that is equipped with vapor recovery equipment may be leakage tested in accordance with 40 CFR 63.425(e). To satisfy the leakage test requirements of this paragraph, the test specified in 40 CFR 63.425(e)(1) must be conducted using air. The hydrostatic test alternative permitted under Appendix A to 40 CFR Part 60 (“Method 27—Determination of Vapor Tightness of Gasoline Delivery Tank Using Pressure-Vacuum Test”) may not be used to satisfy the leakage test requirements of this paragraph. A cargo tank tested in accordance with 40 CFR 63.425(e) may be marked as specified in § 180.415 of this subchapter.
[Amdt. 178-89, 54 FR , June 12, , as amended at 55 FR , Sept. 7, ; Amdt. 178-105, 59 FR , Nov. 3, . Redesignated by Amdt. 178-112, 61 FR , Apr. 29, ; 68 FR , Apr. 18, ]
(a) Each specification DOT 407 cargo tank motor vehicle must conform to the general design and construction requirements in § 178.345 in addition to the specific requirements contained in this section.
(b) Each tank must be of a circular cross-section and have an MAWP of at least 25 psig.
(c) Any cargo tank motor vehicle built to this specification with a MAWP greater than 35 psig or any cargo tank motor vehicle built to this specification designed to be loaded by vacuum must be constructed and certified in accordance with Section VIII of the ASME Code (IBR, see § 171.7 of this subchapter). The external design pressure for a cargo tank loaded by vacuum must be at least 15 psi.
(d) Any cargo tank motor vehicle built to this specification with a MAWP of 35 psig or less or any cargo tank motor vehicle built to this specification designed to withstand full vacuum but not equipped to be loaded by vacuum must be constructed in accordance with Section VIII of the ASME Code.
(1) The record-keeping requirements contained in Section VIII of the ASME Code do not apply. The inspection requirements of parts UG-90 through 94 do not apply. Inspection and certification must be made by an inspector registered in accordance with subpart F of part 107.
(2) Loadings must be as prescribed in § 178.345-3.
(3) The knuckle radius of flanged heads must be at least three times the material thickness, and in no case less than 0.5 inch. Stuffed (inserted) heads may be attached to the shell by a fillet weld. The knuckle radius and dish radius versus diameter limitations of UG-32 do not apply for cargo tank motor vehicles with a MAWP of 35 psig or less.
(4) Marking, certification, data reports and nameplates must be as prescribed in §§ 178.345-14 and 178.345-15.
(5) Manhole closure assemblies must conform to § 178.347-3.
(6) Pressure relief devices must be as prescribed in § 178.347-4.
(7) The hydrostatic or pneumatic test must be as prescribed in § 178.347-5.
(8) The following paragraphs in parts UG and UW in Section VIII the ASME Code do not apply: UG-11, UG-12, UG-22(g), UG-32(e), UG-34, UG-35, UG-44, UG-76, UG-77, UG-80, UG-81, UG-96, UG-97, UW-12, UW-13(b)(2), UW-13.1(f), and the dimensional requirements found in Figure UW-13.1.
(9) UW-12 in Section VIII of the ASME Code does not apply to a weld seam in a bulkhead that has not been radiographically examined, under the following conditions:
(i) The strength of the weld seam is assumed to be 0.85 of the strength of the bulkhead.
(ii) The welded seam must be a full penetration butt weld.
(iii) No more than one seam may be used per bulkhead.
(iv) The welded seam must be completed before forming the dish radius and knuckle radius.
(v) Compliance test: Two test specimens of materials representative of those to be used in the manufacture of a cargo tank bulkhead must be tested to failure in tension. The test specimen must be of the same thickness and joined by the same welding procedure. The test specimens may represent all the tanks that are made in the same facility within 6 months after the tests are completed. Before welding, the fit-up of the joints on the test specimens must represent production conditions that would result in the least joint strength. Evidence of joint fit-up and test results must be retained at the manufacturer's facility for at least 5 years.
(vi) Acceptance criteria: The ratio of the actual tensile stress at failure to the actual tensile strength of the adjacent material of all samples of a test lot must be greater than 0.85.
[Amdt. 178-89, 54 FR , June 12, , as amended at 55 FR , Sept. 7, ; Amdt. 178-89, 56 FR , June 17, ; 65 FR , Sept. 29, ; 66 FR , Aug. 28, ; 68 FR , Apr. 18, ; 68 FR , Dec. 31, ; 76 FR , Jan. 19, ; 76 FR , July 20, ]
(a) The type and thickness of material for DOT 407 specification cargo tanks must conform to § 178.345-2, but in no case may the thickness be less than that determined by the minimum thickness requirements in § 178.320(a). Tables I and II identify the specified minimum thickness values to be employed in that the determination:
Table I—Specified Minimum Thickness of Heads (or Bulkheads and Baffles When Used as Tank Reinforcement) Using Mild Steel (MS), High Strength Low Alloy Steel (HSLA), Austenitic Stainless Steel (SS), or Aluminum (AL)—Expressed in Decimals of an Inch After Forming
Volume capacity in gallons per inch 10 or less Over 10 to 14 Over 14 to 18 Over 18 to 22 Over 22 to 26 Over 26 to 30 Over 30 Thickness (MS) 0.100 0.100 0.115 0.129 0.129 0.143 0.156 Thickness (HSLA) 0.100 0.100 0.115 0.129 0.129 0.143 0.156 Thickness (SS) 0.100 0.100 0.115 0.129 0.129 0.143 0.156 Thickness (AL) 0.160 0.160 0.173 0.187 0.194 0.216 0.237Table II—Specified Minimum Thickness of Shell Using Mild Steel (MS), High Strength Low Alloy Steel (HSLA), Austenitic Stainless Steel (SS), or Aluminum (AL)—Expressed in Decimals of an Inch After Forming
Volume capacity in gallons per inch 10 or less Over 10 to 14 Over 14 to 18 Over 18 to 22 Over 22 to 26 Over 26 to 30 Over 30 Thickness (MS) 0.100 0.100 0.115 0.129 0.129 0.143 0.156 Thickness (HSLA) 0.100 0.100 0.115 0.129 0.129 0.143 0.156 Thickness (SS) 0.100 0.100 0.115 0.129 0.129 0.143 0.156 Thickness (AL) 0.151 0.151 0.160 0.173 0.194 0.216 0.237(b) [Reserved]
[Amdt. 178-89, 54 FR , June 12, , as amended at 55 FR , Sept. 7, ; Amdt. 178-104, 59 FR , Sept. 26, ; 68 FR , Apr. 18, ]
Each manhole assembly must conform to § 178.345-5, except that each manhole assembly must be capable of withstanding internal fluid pressures of 40 psig or test pressure of the tank, whichever is greater.
[Amdt. 178-89, 54 FR , June 12, . Redesignated by Amdt. 178-112, 61 FR , Apr. 29, ]
(a) Each cargo tank must be equipped with a pressure and vacuum relief system in accordance with § 178.345-10 and this section.
(b) Type and construction. Vacuum relief devices are not required for cargo tank motor vehicles that are designed to be loaded by vacuum in accordance with § 178.347-1(c) or built to withstand full vacuum in accordance with § 178.347-1(d).
(c) Pressure settings of relief valves. The setting of pressure relief valves must be in accordance with § 178.345-10(d).
(d) Venting capacities.
(1) The vacuum relief system must limit the vacuum to less than 80 percent of the design vacuum capability of the cargo tank.
(2) If pressure loading or unloading devices are provided, the relief system must have adequate vapor and liquid capacity to limit the tank pressure to the cargo tank test pressure at maximum loading or unloading rate. The maximum loading or unloading rate must be included on the metal specification plate.
[Amdt. 178-89, 54 FR , June 12, , as amended at 55 FR , Sept. 7, . Redesignated by Amdt. 178-112, 61 FR , Apr. 29, ; 76 FR , July 20, ]
(a) Each cargo tank must be tested in accordance with § 178.345-13 and this section.
(b) Pressure test. Test pressure must be as follows:
(1) Using the hydrostatic test method, the test pressure must be at least 40 psig or 1.5 times tank MAWP, whichever is greater.
(2) Using the pneumatic test method, the test pressure must be 40 psig or 1.5 times tank MAWP, whichever is greater, and the inspection pressure is tank MAWP.
[Amdt. 178-89, 54 FR , June 12, . Redesignated by Amdt. 178-112, 61 FR , Apr. 29, ]
(a) Each specification DOT 412 cargo tank motor vehicle must conform to the general design and construction requirements in § 178.345 in addition to the specific requirements of this section.
(b) The MAWP of each cargo tank must be at least 5 psig.
(c) The MAWP for each cargo tank designed to be loaded by vacuum must be at least 25 psig internal and 15 psig external.
(d) Each cargo tank having a MAWP greater than 15 psig must be of circular cross-section.
(e) Each cargo tank having a—
(1) MAWP greater than 15 psig must be “constructed and certified in conformance with Section VIII of the ASME Code” (IBR, see § 171.7 of this subchapter); or
(2) MAWP of 15 psig or less must be “constructed in accordance with Section VIII of the ASME Code,” except as modified herein:
(i) The recordkeeping requirements contained in Section VIII of the ASME Code do not apply. Parts UG-90 through 94 in Section VIII do not apply. Inspection and certification must be made by an inspector registered in accordance with subpart F of part 107.
(ii) Loadings must be as prescribed in § 178.345-3.
(iii) The knuckle radius of flanged heads must be at least three times the material thickness, and in no case less than 0.5 inch. Stuffed (inserted) heads may be attached to the shell by a fillet weld. The knuckle radius and dish radius versus diameter limitations of UG-32 do not apply for cargo tank motor vehicles with a MAWP of 15 psig or less. Shell sections of cargo tanks designed with a non-circular cross section need not be given a preliminary curvature, as prescribed in UG-79(b).
(iv) Marking, certification, data reports, and nameplates must be as prescribed in §§ 178.345-14 and 178.345-15.
(v) Manhole closure assemblies must conform to §§ 178.345-5.
(vi) Pressure relief devices must be as prescribed in § 178.348-4.
(vii) The hydrostatic or pneumatic test must be as prescribed in § 178.348-5.
(viii) The following paragraphs in parts UG and UW in Section VIII of the ASME Code do not apply: UG-11, UG-12, UG-22(g), UG-32(e), UG-34, UG-35, UG-44, UG-76, UG-77, UG-80, UG-81, UG-96, UG-97, UW-13(b)(2), UW-13.1(f), and the dimensional requirements found in Figure UW-13.1.
[Amdt. 178-89, 54 FR , June 12, , as amended at 55 FR , Sept. 7, ; Amdt. 178-89, 56 FR , June 17, ; 65 FR , Sept. 29, ; 68 FR , Apr. 18, ; 68 fR , Dec. 31, ]
(a) The type and thickness of material for DOT 412 specification cargo tanks must conform to § 178.345-2, but in no case may the thickness be less than that determined by the minimum thickness requirements in § 178.320(a). The following Tables I and II identify the “Specified Minimum Thickness” values to be employed in that determination.
Table I—Specified Minimum Thickness of Heads (or Bulkheads and Baffles When Used as Tank Reinforcement) Using Mild Steel (MS), High Strength Low Alloy Steel (HSLA), Austenitic Stainless Steel (SS), or Aluminum (AL)—Expressed in Decimals of an Inch After Forming
Volume capacity (gallons per inch) 10 or less Over 10 to 14 Over 14 to 18 18 and over Lading density at 60 °F in pounds per gallon 10 lbs and less Over 10 to 13 lbs Over 13 to 16 lbs Over 16 lbs 10 lbs and less Over 10 to 13 lbs Over 13 to 16 lbs Over 16 lbs 10 lbs and less Over 10 to 13 lbs Over 13 to 16 lbs 10 lbs and less Over 10 to 13 lbs Over 13 to 16 lbs Thickness (inch), steel .100 .129 .157 .187 .129 .157 .187 .250 .157 .250 .250 .157 .250 .312 Thickness (inch), aluminum .144 .187 .227 .270 .187 .227 .270 .360 .227 .360 .360 .227 .360 .450Table II—Specified Minimum Thickness of Shell Using Mild Steel (MS), High Strength Low Alloy Steel (HSLA), Austenitic Stainless Steel (SS), or Aluminum (AL)—Expressed in Decimals of an Inch After Forming
Volume capacity in gallons per inch 10 or less Over 10 to 14 Over 14 to 18 18 and over Lading density at 60 °F in pounds per gallon 10 lbs and less Over 10 to 13 lbs Over 13 to 16 lbs Over 16 lbs 10 lbs and less Over 10 to 13 lbs Over 13 to 16 lbs Over 16 lbs 10 lbs and less Over 10 to 13 lbs Over 13 to 16 lbs 10 lbs and less Over 10 to 13 lbs Over 13 to 16 lbs Thickness (steel): Distances between heads (and bulkheads baffles and ring stiffeners when used as tank reinforcement): 36 in. or less .100 .129 .157 .187 .100 .129 .157 .187 .100 .129 .157 .129 .157 .187 Over 36 in. to 54 inches .100 .129 .157 .187 .100 .129 .157 .187 .129 .157 .187 .157 .250 .250 Over 54 in. to 60 inches .100 .129 .157 .187 .129 .157 .187 .250 .157 .250 .250 .187 .250 .312 Thickness (aluminum): Distances between heads (and bulkheads baffles and ring stiffeners when used as tank reinforcement): 36 in. or less .144 .187 .227 .270 .144 .187 .227 .270 .144 .187 .227 .187 .227 .270 Over 36 in. to 54 inches .144 .187 .227 .270 .144 .187 .227 .270 .187 .227 .270 .157 .360 .360 Over 54 in. to 60 inches .144 .187 .227 .270 .187 .227 .270 .360 .227 .360 .360 .270 .360 .450(b) [Reserved]
[Amdt. 178-89, 54 FR , June 12, ; 54 FR , July 7, , as amended at 55 FR , Sept. 7, ; 68 FR , Apr. 18, ]
Each pump and all piping, hoses and connections on each cargo tank motor vehicle must conform to § 178.345-9, except that the use of nonmetallic pipes, valves, or connections are authorized on DOT 412 cargo tanks.
[Amdt. 178-89, 55 FR , Sept. 7, . Redesignated by Amdt. 178-112, 61 FR , Apr. 29, ]
(a) Each cargo tank must be equipped with a pressure and vacuum relief system in accordance with § 178.345-10 and this section.
(b) Type and construction. Vacuum relief devices are not required for cargo tanks designed to be loaded by vacuum or built to withstand full vacuum.
(c) Pressure settings of relief valves. The setting of the pressure relief devices must be in accordance with § 178.345-10(d), except as provided in paragraph (d)(3) of this section.
(d) Venting capacities.
(1) The vacuum relief system must limit the vacuum to less than 80 percent of the design vacuum capability of the cargo tank.
(2) If pressure loading or unloading devices are provided, the pressure relief system must have adequate vapor and liquid capacity to limit tank pressure to the cargo tank test pressure at the maximum loading or unloading rate. The maximum loading and unloading rates must be included on the metal specification plate.
(3) Cargo tanks used in dedicated service for materials classed as corrosive material, with no secondary hazard, may have a total venting capacity which is less than required by § 178.345-10(e). The minimum total venting capacity for these cargo tanks must be determined in accordance with the following formula (use of approximate values given for the formula is acceptable):
Formula in Nonmetric Units
Q = 37,980,000 A0.82 (ZT)0.5 / (LC)(M0.5)
Where:
Q = The total required venting capacity, in cubic meters of air per hour at standard conditions of 15.6 °C and 1 atm (cubic feet of air per hour at standard conditions of 60 °F and 14.7 psia);
T = The absolute temperature of the vapor at the venting conditions—degrees Kelvin (°C + 273) [degrees Rankine (°F + 460)];
A = The exposed surface area of tank shell—square meters (square feet);
L = The latent heat of vaporization of the lading—calories per gram (BTU/lb);
Z = The compressibility factor for the vapor (if this factor is unknown, let Z equal 1.0);
M = The molecular weight of vapor;
C = A constant derived from (K), the ratio of specific heats of the vapor. If (K) is unknown, let C = 315.
C = 520[K(2/(K ++ 1))[(K + 1)/(K−1)]]0.5
Where:
K = Cp / Cv
Cp = The specific heat at constant pressure, in -calories per gram degree centigrade (BTU/lb °F.); and
Cv = The specific heat at constant volume, in -calories per gram degree centigrade (BTU/lb °F.).
[Amdt. 178-89, 54 FR , June 12, , as amended at 55 FR , Sept. 7, ; Amdt. 178-104, 59 FR , Sept. 26, . Redesignated by Amdt. 178-112, 61 FR , Apr. 29, ; 72 FR , Oct. 1, ; 72 FR , Oct. 18, ]
(a) Each cargo tank must be tested in accordance with § 178.345-13 and this section.
(b) Pressure test. Test pressure must be as follows:
(1) Using the hydrostatic test method, the test pressure must be at least 1.5 times MAWP.
(2) Using the pneumatic test method, the test pressure must be at least 1.5 times tank MAWP, and the inspection pressure is tank MAWP.
[Amdt. 178-89, 54 FR , June 12, . Redesignated by Amdt. 178-112, 61 FR , Apr. 29, ]
In addition to the method prescribed in § 178.604 of this subchapter, the following leakproofness test methods are authorized:
(1) Helium test. The packaging must be filled with at least 1 L inert helium gas, air tight closed, and placed in a testing chamber. The testing chamber must be evacuated down to a pressure of 5 kPa which equals an over-pressure inside the packaging of 95 kPa. The air in the testing chamber must be analyzed for traces of helium gas by means of a mass spectrograph. The test must be conducted for a period of time sufficient to evacuate the chamber and to determine if there is leakage into or out of the packaging. If helium gas is detected, the leaking packaging must be automatically separated from non-leaking drums and the leaking area determined according to the method prescribed in § 178.604(d) of this subchapter. A packaging passes the test if there is no leakage of helium.
(2) Pressure differential test. The packaging shall be restrained while either pressure or a vacuum is applied internally. The packaging must be pressurized to the pressure required by § 178.604(e) of this subchapter for the appropriate packing group. The method of restraint must not affect the results of the test. The test must be conducted for a period of time sufficient to appropriately pressurize or evacuate the interior of the packaging and to determine if there is leakage into or out of the packaging. A packaging passes the pressure differential test if there is no change in measured internal pressure.
(3) Solution over seams. The packaging must be restrained while an internal air pressure is applied; the method of restraint may not affect the results of the test. The exterior surface of all seams and welds must be coated with a solution of soap suds or a water and oil mixture. The test must be conducted for a period of time sufficient to pressurize the interior of the packaging to the specified air pressure and to determine if there is leakage of air from the packaging. A packaging passes the test if there is no leakage of air from the packaging.
(4) Solution over partial seams test. For other than design qualification testing, the following test may be used for metal drums: The packaging must be restrained while an internal air pressure of 48 kPa (7.0 psig) is applied; the method of restraint may not affect the results of the test. The packaging must be coated with a soap solution over the entire side seam and a distance of not less than eight inches on each side of the side seam along the chime seam(s). The test must be conducted for a period of time sufficient to pressurize the interior of the packaging to the specified air pressure and to determine if there is leakage of air from the packaging. A packaging passes the test if there is no leakage of air from the packaging. Chime cuts must be made on the initial drum at the beginning of each production run and on the initial drum after any adjustment to the chime seamer. Chime cuts must be maintained on file in date order for not less than six months and be made available to a representative of the Department of Transportation on request.
[Amdt. 178-97, 55 FR , Dec. 21, , as amended at 56 FR , Dec. 20, ; 57 FR , Oct. 1, ]
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