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% 2Columbium may not be less than 10C and not more than 1.0%. TABLE 2-CHECK ANALYSIS TOLERANCES Tolerance (percent) over the maximum limit or under the minimum limit Element Limit or maximum specified (percent) Under min- Over maximum limit imum 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 10 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 Rephosphorized steels not subject to check analysis for phosphorus. (c) Identification of material. Materials finished cylinder appreciably, a reasonmust be identified by any suitable ably smooth and uniform surface finish method. is required. No abrupt change in wall (d) Manufacture. Cylinders must be thickness is permitted. Welding procemanufactured using equipment and dures and operators must be qualified processes adequate to ensure that each in accordance with CGA Pamphlet C-3 cylinder produced conforms to the re- (IBR, see $171.7 of this subchapter). All quirements of this subpart. No defect is seams of the sphere or cylinder must be permitted that is likely to weaken the fusion welded. Seams must be of the 857 § 178.47 49 CFR Ch. I (10-1-06 Edition) butt type and means must be provided (2) Attachments to a fitting, boss, or for accomplishing complete penetrapad must be adequate to prevent leaktion of the joint. age. Threads must comply with the fol- (e) Attachments. Attachments to the lowing: container are authorized by fusion (i) Threads must be clean cut, even, welding provided that such attachwithout checks, and tapped to gauge. ments are made of weldable stainless (ii) Taper threads to be of length not steel in accordance with paragraph (b) less than as specified for American of this section. Standard taper pipe threads. (f) Wall thickness. The minimum wall (iii) Straight threads having at least thickness must be such that the wall 4 engaged threads, to have tight fit and stress at the minimum specified test calculated shear strength at least 10 pressure may not be over 60,000 psig. A times the test pressure of the conminimum wall thickness of 0.040 inch is tainer; gaskets required, adequate to required for any diameter container. prevent leakage. Calculations must be made by the fol- (i) Process treatment. Each container lowing formulas: must be hydraulically pressurized in a (1) Calculation for sphere must be water jacket to at least 100 percent, made by the formula: but not more than 110 percent, of the S = PD / 4tE test pressure and maintained at this pressure for a minimum of 3 minutes. Where: Total and permanent expansion must S = Wall stress in psi; be recorded and included in the inspec- P = Test pressure prescribed for water jacket tor's report. test, i.e., at least two times service pressure, in psig: (j) Hydrostatic test. Each cylinder D = Outside diameter in inches; must successfully withstand a hydro- t = Minimum wall thickness in inches; static test as follows: E = 0.85 (provides 85 percent weld efficiency (1) The test must be by water-jacket, factor which must be applied in the girth operated so as to obtain accurate data. weld area and heat zones which zone must The pressure gauge must permit readextend a distance of 6 times wall thickness from center of weld); ing to an accuracy of 1 percent. The ex- E = 1.0 (for all other areas). pansion gauge must permit reading of total expansion to an accuracy either (2) Calculation for a cylinder must be of 1 percent or 0.1 cubic centimeter. made by the formula: (2) Pressure must be maintained for S = [P(1.3D² + 0.4d²)] / (D² - d²) at least 30 seconds and sufficiently longer to ensure complete expansion. Where: If, due to failure of the test apparatus, S = Wall stress in psi: the test pressure cannot be main- P = Test pressure prescribed for water jacket tained, the test may be repeated at a test, i.e., at least two times service pressure, in psig; pressure increased by 10 percent or 100 D = Outside diameter in inches; psig. whichever is the lower. d = Inside diameter in inches. (3) Permanent volumetric expansion (g) Heat treatment. The seamless may not exceed 10 percent of total volhemispheres and cylinders may be umetric expansion at test pressure. stress relieved or annealed for forming. (4) Each container must be tested to Welded container must be stress reat least 2 times service pressure. lieved at a temperature of 775 °F ±25° (5) Container must then be inspected. after process treatment and before hy- Any wall thickness lower than that redrostatic test. quired by paragraph (f) of this section (h) Openings in container. Openings must be cause for rejection. Bulges and must comply with the following: cracks must be cause for rejection. (1) Each opening in the container Welded joint defects exceeding requiremust be provided with a fitting, boss or ments of paragraph (k) of this section pad of weldable stainless steel securely must be cause for rejection. attached to the container by fusion (k) Radiographic inspection. Radiowelding. graphic inspection is required on all 858 Pipeline and Hazardous Materials Safety Admin., DOT § 178.50 welded joints which are subjected to incontainer by means other than soft solternal pressure, except that at the disder. cretion of the disinterested inspector, [Amdt. 178-114, 61 FR 25942. May 23, 1996, as openings less than 25 percent of the amended at 66 FR 45386, 45388, Aug. 28, 2001: container diameter need not be sub- 67 FR 51653, Aug. 8, 2002; 68 FR 75748, Dec. 31, jected to radiographic inspection. Evi- 2003] dence of any defects likely to seriously weaken the container is cause for re- § 178.50 Specification 4B welded or jection. Radiographic inspection must brazed steel cylinders. be performed subsequent to the hydro- (a) Type, size, and service pressure. A static test. DOT 4B is a welded or brazed steel cyl- (1) Burst test. One container taken at inder with longitudinal seams that are random out of 200 or less must be forged lap-welded or brazed and with hydrostatically tested to destruction. water capacity (nominal) not over 1,000 Rupture pressure must be included as pounds and a service pressure of at part of the inspector's report. least 150 but not over 500 psig. Cyl- (m) Flattening test. A flattening test inders closed in by spinning process are must be performed as follows: not authorized. (1) For spheres the test must be at (b) Steel. Open-hearth, electric or the weld between parallel steel plates basic oxygen process steel of uniform on a press with welded seam at right quality must be used. Content percent angles to the plates. Test one sphere may not exceed the following: Carbon, taken at random out of each lot of 200 0.25; phosphorus, 0.045; sulphur, 0.050. (c) Identification of material. Material or less after the hydrostatic test. Any must be identified by any suitable projecting appurtenances may be cut method except that plates and billets off (by mechanical means only) prior to for hotdrawn cylinders must be marked crushing. with the heat number. (2) For cylinders the test must be be- (d) Manufacture. Cylinders must be tween knife edges, wedge shaped, 60° manufactured using equipment and angle, rounded to 1/2-inch radius. Test processes adequate to ensure that each one cylinder taken at random out of cylinder produced conforms to the reeach lot of 200 or less, after the hydroquirements of this subpart. No defect is static test. permitted that is likely to weaken the (n) Acceptable results for flattening and finished cylinder appreciably. A reaburst tests. Acceptable results for flatsonably smooth and uniform surface tening and burst tests are as follows: finish is required. Exposed bottom (1) Flattening required to 50 percent welds on cylinders over 18 inches long of the original outside diameter withmust be protected by footrings. Weldout cracking. ing procedures and operators must be (2) Burst pressure must be at least 3 qualified in accordance with CGA Pamtimes the service pressure. phlet C-3 (IBR, see $171.7 of this sub- (o) Rejected containers. Repair of weldchapter). Seams must be made as follows: ed seams by welding prior to process treatment is authorized. Subsequent (1) Welded or brazed circumferential thereto, containers must be heat treatseams. Heads attached by brazing must have a driving fit with the shell, unless ed and pass all prescribed tests. the shell is crimped, swedged, or curled (p) Duties of inspector. In addition to over the skirt or flange of the head, the requirements of $ 178.35, the inspecand be thoroughly brazed until comtor must verify that all tests are conplete penetration by the brazing mateducted at temperatures between 60 °F rial of the brazed joint is secured. and 90 °F. Depth of brazing from end of shell must (q) Marking. Markings must be be at least four times the thickness of stamped plainly and permanently on a shell metal. permanent attachment or on a metal (2) Longitudinal seams in shells. Longinameplate permanently secured to the tudinal seams must be forged lap welded, by copper brazing, by copper alloy 859 § 178.50 49 CFR Ch. I (10-1-06 Edition) brazing, or by silver alloy brazing. Cop- (g) Heat treatment. Cylinder body and per alloy composition must be: Copper, heads, formed by drawing or pressing. 95 percent minimum; Silicon, 1.5 permust be uniformly and properly heat cent to 3.85 percent; Manganese, 0.25 treated prior to tests. percent to 1.10 percent. The melting (h) Opening in cylinders. Openings in point of the silver alloy brazing matecylinders must conform to the folrial must be in excess of 1000 °F. When lowing: brazed. the plate edge must be lapped (1) Each opening in cylinders, except at least eight times the thickness of those for safety devices, must be proplate, laps being held in position, subvided with a fitting, boss, or pad. sestantially metal to metal, by riveting curely attached to cylinder by brazing or electric spot-welding; brazing must or by welding or by threads. Fitting, be done by using a suitable flux and by boss, or pad must be of steel suitable placing brazing material on one side of for the method of attachment emseam and applying heat until this maployed, and which need not be identiterial shows uniformly along the seam fied or verified as to analysis except of the other side. that if attachment is by welding, car- (e) Welding or brazing. Only the atbon content may not exceed 0.25 pertachment of neckrings, footrings, hancent. If threads are used, they must dles, bosses, pads, and valve protection comply with the following: rings to the tops and bottoms of cyl- (i) Threads must be clean cut, even inders by welding or brazing is authorwithout checks, and tapped to gauge. ized. Such attachments and the portion of the container to which they are at- (ii) Taper threads to be of length not tached must be made of weldable steel, less than as specified for American the carbon content of which may not Standard taper pipe threads. exceed 0.25 percent except in the case (iii) Straight threads, having at least of 4130X steel which may be used with 4 engaged threads, to have tight fit and proper welding procedure. calculated shear strength at least 10 (f) Wall thickness. The wall thickness times the test pressure of the cylinder; of the cylinder must comply with the gaskets required, adequate to prevent following requirements: leakage. (1) For cylinders with outside diame- (iv) A brass fitting may be brazed to ters over 6 inches the minimum wall the steel boss or flange on cylinders thickness must be 0.090 inch. In any used as component parts of hand fire case, the minimum wall thickness extinguishers. must be such that calculated wall (2) The closure of a fitting, boss, or stress at minimum test pressure (parapad must be adequate to prevent leakgraph (i)(4) of this section) may not exage. ceed the following values: (i) Hydrostatic test. Cylinders must (i) 24,000 psi for cylinders without withstand a hydrostatic test as follows: longitudinal seam. (1) The test must be by water-jacket, (ii) 22,800 psig for cylinders having or other suitable method, operated so copper brazed or silver alloy brazed as to obtain accurate data. The preslongitudinal seam. sure gauge must permit reading to an (iii) 18,000 psi for cylinders having accuracy of 1 percent. The expansion forged lapped welded longitudinal gauge must permit reading of total exseam. pansion to an accuracy either of 1 per- (2) Calculation must be made by the cent or 0.1 cubic centimeter. formula: (2) Pressure must be maintained for at least 30 seconds and sufficiently S = [P(1.3D² + 0.4d²)] / (D² - d2) longer to ensure complete expansion. Where: Any internal pressure applied after S = wall stress in psi; heat-treatment and previous to the of- P = minimum test pressure prescribed for ficial test may not exceed 90 percent of water jacket test or 450 psig whichever is the test pressure. If, due to failure of the greater; the test apparatus, the test pressure D = outside diameter in inches; cannot be maintained. the test may be d = inside diameter in inches. repeated at a pressure increased by 10 860 Pipeline and Hazardous Materials Safety Admin., DOT § 178.50 percent or 100 psig, whichever is the may be flattened to within one inch of lower. each end of the reduced section. (3) Permanent volumetric expansion (iii) When size of cylinder does not may not exceed 10 percent of total volpermit securing straight specimens, umetric expansion at test pressure. the specimens may be taken in any lo- (4) Cylinders must be tested as folcation or direction and may be lows: straightened or flattened cold, by pres- (i) At least one cylinder selected at sure only, not by blows. When specirandom out of each lot of 200 or less mens are so taken and prepared, the inmust be tested as outlined in paraspector's report must show in connecgraphs (i)(1), (i)(2), and (1)(3) of this section with record of physical tests detion to at least two times service prestailed information in regard to such sure. specimens. (ii) All cylinders not tested as out- (iv) Heating of a specimen for any lined in paragraph (i)(4) (i) of this secpurpose is not authorized. tion must be examined under pressure (3) The yield strength in tension of at least two times service pressure must be the stress corresponding to a and show no defect. permanent strain of 0.2 percent of the (j) Flattening test. After the hydrogauge length. The following conditions static test, a flattening test must be apply: performed on one cylinder taken at random out or each lot of 200 or less, by (i) The yield strength must be determined by either the "offset" method or placing the cylinder between wedge the "extension under load" method as shaped knife edges having a 60° included angle, rounded to ½-inch radius. prescribed in ASTM E 8 (IBR, see $171.7 The longitudinal axis of the cylinder of this subchapter). must be at a 90-degree angle to knife (ii) In using the "extension under load" method, the total strain (or "exedges during the test. For lots of 30 or less, flattening tests are authorized to tension under load") corresponding to be made on a ring at least 8 inches long the stress at which the 0.2 percent percut from each cylinder and subjected to manent strain occurs may be detersame heat treatment as the finished mined with sufficient accuracy by calculating the elastic extension of the cylinder. (k) Physical test. A physical test must gauge length under appropriate load be conducted to determine yield and adding thereto 0.2 percent of the strength, tensile strength, elongation, gauge length. Elastic extension calculations must be based on an elastic and reduction of area of material as modulus of 30,000,000. In the event of follows: (1) The test is required on 2 specicontroversy, the entire stress-strain mens cut from 1 cylinder, or part diagram must be plotted and the yield thereof heat-treated as required, taken strength determined from the 0.2 percent offset. at random out of each lot of 200 or less. For lots of 30 or less, physical tests are (iii) For the purpose of strain measauthorized to be made on a ring at urement, the initial strain must be set least 8 inches long cut from each cylwhile the specimen is under a stress of inder and subjected to same heat treat- 12,000 psi, and strain indicator reading ment as the finished cylinder. must be set at the calculated cor- (2) Specimens must conform to the responding strain. following: (iv) Cross-head speed of the testing (i) A gauge length of 8 inches with a machine may not exceed 1/8 inch per width of not over 1½ inches, a gauge minute during yield strength deterlength of 2 inches with a width of not mination. over 1½ inches, or a gauge length at (1) Acceptable results for physical and least 24 times the thickness with a flattening tests. Either of the following width not over 6 times the thickness is is an acceptable result: authorized when a cylinder wall is not (1) An elongation of at least 40 perover 3/16 inch thick. cent for a 2-inch gauge length or at (ii) The specimen, exclusive of grip least 20 percent in other cases and ends, may not be flattened. Grip ends yield strength not over 73 percent of 861 § 178.51 49 CFR Ch. I (10-1-06 Edition) tensile strength. In this instance, a § 178.51 Specification 4BA welded or flattening test is not required. brazed steel cylinders. (2) When cylinders are constructed of (a) Type, size, and service pressure. A lap welded pipe, flattening test is re- DOT 4BA cylinder is a cylinder, either quired, without cracking, to 6 times spherical or cylindrical in shape, with the wall thickness. In such case, the a water capacity of 1,000 pounds or less rings (crop ends) cut from each end of and a service pressure of at least 225 pipe, must be tested with the weld 45° and not over 500 psig. Closures made by or less from the point of greatest the spinning process are not authorstress. If a ring fails, another from the ized. same end of pipe may be tested. (1) Spherical type cylinders must be made from two seamless hemispheres (m) Rejected cylinders. Reheat treatment is authorized for rejected cyljoined by the welding of one circumferential seam. inder. Subsequent thereto, cylinders (2) Cylindrical type cylinders must be must pass all prescribed tests to be acof circumferentially welded or brazed ceptable. Repair of brazed seams by construction. brazing and welded seams by welding is (b) Steel. The steel used in the conauthorized. struction of the cylinder must be as (n) Markings. Markings must be specified in table 1 of appendix A to stamped plainly and permanently in this part. any of the following locations on the (c) Identification of material. Material cylinder: must be identified by any suitable (1) On shoulders and top heads when method except that plates and billets they are not less than 0.087-inch thick. for hotdrawn cylinders must be marked (2) On side wall adjacent to top head with the heat number. for side walls which are not less than (d) Manufacture. Cylinders must be 0.090 inch thick. manufactured using equipment and (3) On a cylindrical portion of the processes adequate to ensure that each shell which extends beyond the Γe- cylinder produced conforms to the recessed bottom of the cylinder, constiquirements of this subpart. No defect is permitted that is likely to weaken the tuting an integral and non-pressure finished cylinder appreciably. A reapart of the cylinder. sonably smooth and uniform surface (4) On a metal plate attached to the finish is required. Exposed bottom top of the cylinder or permanent part welds on cylinders over 18 inches long thereof; sufficient space must be left on must be protected by footrings. the plate to provide for stamping at (1) Seams must be made as follows: least six retest dates; the plate must be (i) Minimum thickness of heads and at least 1/16-inch thick and must be atbottoms must be not less than 90 pertached by welding, or by brazing. The cent of the required thickness of the brazing rod must melt at a temperaside wall. ture of 1100 °F. Welding or brazing (ii) Circumferential seams must be must be along all the edges of the made by welding or by brazing. Heads plate. must be attached by brazing and must (5) On the neck, neckring, valve boss, have a driving fit with the shell, unless valve protection sleeve, or similar part the shell is crimped, swedged or curled permanently attached to the top of the over the skirt or flange of the head and must be thoroughly brazed until comcylinder. (6) On the footring permanently atplete penetration by the brazing material of the brazed joint is secured. tached to the cylinder, provided the Depth of brazing from end of the shell water capacity of the cylinder does not must be at least four times the thickexceed 25 pounds. ness of shell metal. [Amdt. 178-114, 61 FR 25942, May 23, 1996, as (iii) Longitudinal seams in shells amended at 62 FR 51561, Oct. 1, 1997; 66 FR must be made by copper brazing, cop- 45385, 45388, Aug. 28, 2001; 67 FR 51653, Aug. 8, per alloy brazing, or by silver alloy 2002; 68 FR 75748, Dec. 31, 2003] brazing. Copper alloy composition must be: Copper 95 percent minimum, 862 Pipeline and Hazardous Materials Safety Admin., DOT $ 178.51 Silicon 1.5 percent to 3.85 percent, Mangalvanizing or other protective coatganese 0.25 percent to 1.10 percent. The ing. melting point of the silver alloy braz- (2) Cylinders that are cylindrical in ing material must be in excess of 1,000 shape must have the wall stress cal- °F. The plate edge must be lapped at culated by the formula: least eight times the thickness of S = [P(1.3D² + 0.4d²)] / (D² - d²) plate, laps being held in position, substantially metal to metal, by riveting Where: or by electric spot-welding. Brazing S = wall stress in psi; must be done by using a suitable flux P - minimum test pressure prescribed for and by placing brazing material on one water jacket test; side of seam and applying heat until D = outside diameter in inches; this material shows uniformly along d = inside diameter in inches. the seam of the other side. Strength of (3) Cylinders that are spherical in longitudinal seam: Copper brazed lonshape must have the wall stress calgitudinal seam must have strength at culated by the formula: least 3/2 times the strength of the steel wall. S = PD / 4tE (2) Welding procedures and operators Where: must be qualified in accordance with CGA Pamphlet C-3 (IBR, see $171.7 of S = wall stress in psi: P = minimum test pressure prescribed for this subchapter). water jacket test: (e) Welding and brazing. Only the D = outside diameter in inches; welding or brazing of neckrings, t = minimum wall thickness in inches; footrings, handles, bosses, pads, and E = 0.85 (provides 85 percent weld efficiency valve protection rings to the tops and factor which must be applied in the girth bottoms of cylinders is authorized. weld area and heat affected zones which Provided that such attachments and zone must extend a distance of 6 times wall the portion of the container to which thickness from center line of weld); they are attached are made of weldable E = 1.0 (for all other areas). steel, the carbon content of which may (4) For a cylinder with a wall thicknot exceed 0.25 percent except in the ness less than 0.100 inch, the ratio of case of 4130x steel which may be used tangential length to outside diameter with proper welding procedure. may not exceed 4.1. (f) Wall thickness. The minimum wall (g) Heat treatment. Cylinders must be thickness of the cylinder must meet heat treated in accordance with the the following conditions: following requirements: (1) For any cylinder with an outside (1) Each cylinder must be uniformly diameter of greater than 6 inches, the and properly heat treated prior to test minimum wall thickness is 0.078 inch. by the applicable method shown in In any case the minimum wall thicktable 1 of appendix A to this part. Heat ness must be such that the calculated treatment must be accomplished after wall stress at the minimum test presall forming and welding operations, exsure may not exceed the lesser value of cept that when brazed joints are used, any of the following: heat treatment must follow any form- (i) The value shown in table 1 of aping and welding operations, but may be pendix A to this part, for the particular done before, during or after the brazing material under consideration; operations. (ii) One-half of the minimum tensile (2) Heat treatment is not required strength of the material determined as after the welding or brazing of weldable required in paragraph (j) of this seclow carbon parts to attachments of tion; similar material which have been pre- (iii) 35,000 psi; or viously welded or brazed to the top or (iv) Further provided that wall stress bottom of cylinders and properly heat for cylinders having copper brazed lontreated, provided such subsequent gitudinal seams may not exceed 95 perwelding or brazing does not produce a cent of any of the above values. Meastemperature in excess of 400 °F in any ured wall thickness may not include part of the top or bottom material. 863 § 178.51 49 CFR Ch. I (10-1-06 Edition) (h) Openings in cylinders. Openings in of at least two times service pressure cylinders must comply with the foland show no defect. lowing requirements: (j) Physical test. A physical test must (1) Any opening must be placed on be conducted to determine yield other than a cylindrical surface. strength, tensile strength, elongation, (2) Each opening in a spherical type and reduction of area of material, as cylinder must be provided with a fitfollows: ting, boss, or pad of weldable steel se- (1) The test is required on 2 specicurely attached to the container by fumens cut from one cylinder or part sion welding. thereof having passed the hydrostatic (3) Each opening in a cylindrical type test and heat-treated as required. cylinder must be provided with a fittaken at random out of each lot of 200 ting, boss, or pad, securely attached to or less. Physical tests for spheres are container by brazing or by welding. required on 2 specimens cut from flat (4) If threads are used, they must representative sample plates of the comply with the following: same heat taken at random from the (i) Threads must be clean-cut, even, steel used to produce the spheres. This without checks and tapped to gauge. flat steel from which 2 specimens are (ii) Taper threads must be of a length to be cut must receive the same heat not less than that specified for Amertreatment as the spheres themselves. ican Standard taper pipe threads. Sample plates must be taken from each (iii) Straight threads, having at least lot of 200 or less spheres. 4 engaged threads, must have a tight (2) Specimens must conform to the fit and a calculated shear strength of following: at least 10 times the test pressure of (i) A gauge length of 8 inches with a the cylinder. Gaskets, adequate to prewidth not over 1½ inches, or a gauge vent leakage. are required. length of 2 inches with a width not (i) Hydrostatic test. Each cylinder over 1½ inches, or a gauge length at must successfully withstand a hydroleast 24 times the thickness with a static test, as follows: width not over 6 times the thickness is (1) The test must be by water jacket, authorized when a cylinder wall is not or other suitable method, operated so over 3/16 inch thick. as to obtain accurate data. A pressure (ii) The specimen, exclusive of grip gauge must permit reading to an accuends, may not be flattened. Grip ends racy of 1 percent. An expansion gauge may be flattened to within one inch of must permit reading of total expansion each end of the reduced section. to an accuracy of either 1 percent or 0.1 (iii) When size of the cylinder does cubic centimeter. not permit securing straight speci- (2) Pressure must be maintained for mens, the specimens may be taken in at least 30 seconds and sufficiently any location or direction and may be longer to ensure complete expansion. straightened or flattened cold, by pres- Any internal pressure applied after sure only, not by blows. When speciheat treatment and previous to the ofmens are so taken and prepared, the inficial test may not exceed 90 percent of spector's report must show in connecthe test pressure. tion with record of physical tests de- (3) Permanent volumetric expansion tailed information in regard to such may not exceed 10 percent of the total specimens. volumetric expansion at test pressure. (iv) Heating of a specimen for any (4) Cylinders must be tested as folpurpose is not authorized. lows: (3) The yield strength in tension (i) At least one cylinder selected at must be the stress corresponding to a random out of each lot of 200 or less permanent strain of 0.2 percent of the must be tested as outlined in paragauge length. The following conditions graphs (i)(1), (i)(2), and (i)(3) of this secapply: tion to at least two times service pres- (i) The yield strength must be detersure. mined by either the "offset" method or (ii) All cylinders not tested as outthe "extension under load" method as lined in paragraph (i)(4)(i) of this secprescribed in ASTM E 8 (IBR, see $171.7 tion must be examined under pressure of this subchapter). 864 Pipeline and Hazardous Materials Safety Admin., DOT $ 178.51 (ii) In using the "extension under may be taken from two additional cylload" method, the total strain (or "exinders or welded test plates from the tension under load"), corresponding to same lot and tested. If either of the latthe stress at which the 0.2 percent perter specimens fail to meet the requiremanent strain occurs may be determents, the entire lot represented must mined with sufficient accuracy by calbe rejected. culating the elastic extension of the (2) Guided bend test. A root bend test gauge length under appropriate load specimen must be cut from the cyland adding thereto 0.2 percent of the inder or welded test plate, used for the gauge length. Elastic extension caltensile test specified in paragraph (f)(1) culations must be based on an elastic of this section. Specimens must be modulus of 30,000,000. In the event of taken from across the major seam and controversy, the entire stress-strain must be prepared and tested in accorddiagram must be plotted and the yield ance with and must meet the requirestrength determined from the 0.2 perments of CGA Pamphlet C-3. cent offset. (3) Alternate guided-bend test. This (iii) For the purpose of strain meastest may be used and must be as reurement, the initial strain reference quired by CGA Pamphlet C-3. The specmust be set while the specimen is imen must be bent until the elongation under a stress of 12,000 psi, and the at the outer surface, adjacent to the strain indicator reading must be set at root of the weld, between the lightly the calculated corresponding strain. scribed gage lines a to b, must be at (iv) Cross-head speed of the testing least 20 percent, except that this permachine may not exceed 1/8 inch per centage may be reduced for steels havminute during yield strength detering a tensile strength in excess of 50,000 mination. psig, as provided in paragraph (k) of (k) Elongation. Physical test specithis section. mens must show at least a 40 percent (m) Rejected cylinders. Reheat treatelongation for a 2-inch gauge length or ment is authorized for rejected cylat least 20 percent in other cases. Exinders. Subsequent thereto, cylinders cept that these elongation percentages must pass all prescribed tests to be acmay be reduced numerically by 2 for 2- ceptable. Repair of brazed seams by inch specimens, and by 1 in other cases, brazing and welded seams by welding is for each 7,500 psi increment of tensile authorized. strength above 50,000 psi to a maximum (n) Markings. Markings must be of four such increments. stamped plainly and permanently in (1) Tests of welds. Except for brazed one of the following locations on the seams, welds must be tested as follows: cylinder: (1) Tensile test. A specimen must be (1) On shoulders and top heads not cut from one cylinder of each lot of 200 less than 0.087 inch thick. or less, or welded test plate. The weld- (2) On side wall adjacent to top head ed test plate must be of one of the for side walls not less than 0.090 inch heats in the lot of 200 or less which it thick. represents, in the same condition and (3) On a cylindrical portion of the approximately the same thickness as shell which extends beyond the rethe cylinder wall except that in no case cessed bottom of the cylinder constimust it be of a lesser thickness than tuting an integral and non-pressure that required for a quarter size Charpy part of the cylinder. impact specimen. The weld must be (4) On a plate attached to the top of made by the same procedures and subthe cylinder or permanent part thereof; jected to the same heat treatment as sufficient space must be left on the the major weld on the cylinder. The plate to provide for stamping at least specimen must be taken from across six retest dates; the plate must be at the major seam and must be prepared least 1/16 inch thick and must be atand tested in accordance with and tached by welding. or by brazing at a must meet the requirements of CGA temperature of at least 1100 °F., Pamphlet C-3 (IBR, see $171.7 of this throughout all edges of the plate. subchapter). Should this specimen fail (5) On the neck, neckring, valve boss, to meet the requirements, specimens valve protection sleeve, or similar part 865 $ 178.53 49 CFR Ch. I (10-1-06 Edition) permanently attached to the top of the 0.045; sulphur, 0.050, except that the folcylinder. lowing steels commercially known as (6) On the footring permanently at- 4130X and Type 304, 316, 321, and 347 tached to the cylinder, provided the stainless steels may be used with propwater capacity of the cylinder does not er welding procedure. A heat of steel exceed 25 pounds. made under table 1 in this paragraph [Amdt. 178-114, 61 FR 25942, May 23. 1996, as (b), check chemical analysis of which is amended at 66 FR 4535, Aug. 28, 2001; 67 FR slightly out of the specified range, is 16015, Sept. 27. 2002; 67 FR 51653, Aug. 8, 2002; acceptable, if satisfactory in all other 68 FR 75748. Dec. 31, 2003] respects, provided the tolerances shown in table 2 in this paragraph (b) are not § 178.53 Specification 4D welded steel exceeded, except as approved by the Ascylinders for aircraft use. sociate Administrator. The following (a) Type, size, and service pressure. A chemical analyses are authorized: DOT 4D cylinder is a welded steel sphere (two seamless hemispheres) or TABLE 1-4130X STEEL circumferentially welded cylinder (two 4130X Percent seamless drawn shells) with a water capacity not over 100 pounds and a serv- Carbon 0.25/0.35. ice pressure of at least 300 but not over Manganese 0.40/0.60. 500 psig. Cylinders closed in by spin- Phosphorus 0.04 max. Sulphur 0.05 max ning process are not authorized. Silicon 0.15/0.35. (b) Steel. Open-hearth or electric steel Chromium 0.80/1.10. of uniform and weldable quality must Molybdenum 0.15/0.25. be used. Content may not exceed the Zirconium None. Nickel None. following: Carbon, 0.25; phosphorus, TABLE 2-AUTHORIZED STAINLESS STEELS Stainless steels 304 316 321 347 (percent) (percent) (percent) (percent) Carbon (max) 0.08 0.08 0.08 0.08 Manganese (max) 2.00 2.00 2.00