(a) By competent inspector; chemical analyses and tests, as specified, to be made within limits of the United States. Interested inspectors are authorized. [Order 71, 31 F.R. 9077, July 1, 1966] § 178.61-4 Duties of inspector.

(a) Inspect all material and reject any not complying with requirements of this specification.

(b) Verify chemical analysis of each heat of material by analysis or by obtaining certified analysis: Provided, That a certificate from the manufacturer thereof, giving sufficient data to indicate compliance with requirements is acceptable when verified by check analyses of samples taken from one cylinder out of each lot of 200 or less.

(c) Verify compliance of cylinders with specification requirements including: markings; condition of inside; tests; threads; heat treatment. Obtain samples for all tests, and check chemical analyses, witness all tests; report volumetric capacity, tare weight (see report form), and minimum thickness of wall noted.

(d) Render complete report (§ 178.6121) to purchaser, cylinder maker, and the Bureau of Explosives.

[Order 71, 31 F.R. 9077, July 1, 1966] § 178.61-5 Authorized steel.

(a) Open-hearth steel or at least equivalent of uniform quality. The following chemical analyses are authorized except as provided in paragraph (b) of this section. (See footnote 1 of the following table.)

1 A heat of steel made under any of the above specifications, 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 the following table are not exceeded,
except as approved by the Commission:

2 This designation shall not be restrictive and the commercial steel is limited in
analysis shown in the table.

Any suitable heat treatment in excess of 1,100° F., except that liquid quenching is not permitted.

• Addition of other elements to obtain alloying effect is not authorized. Ferritic grain size 6 or finer, according to ASTM E-112-58T.

• Only fully killed steel authorized.

(b) Heads. Material for heads shall be the same as paragraph (a) of this section or shall be open hearth, electric or basic oxygen carbon steel of uniform quality. Content percent for the following not over: Carbon 0.25, Manganese 0.60, Phosphorus 0.045, Sulfur 0.050.

(1) Heads shall be hemispherical or ellipsoidal in shape with a maximum ratio of 2.1. If low carbon steel is used thickness of such heads shall be determined by using a maximum wall stress of 24,000 p.s.i. in formula (§ 178.61-10(a)). [Order 71, 31 F.R. 9078, July 1, 1966; 31 F.R. 9677, July 16, 1966]

§ 178.61-6 Identification of material. (a) Required; any suitable method. [Order 71, 31 F.R. 9078, July 1, 1966] § 178.61-7

Defects.

(a) Material with seams, cracks, laminations or other injurious defects, not authorized.

[Order 71, 31 F.R. 9078, July 1, 1966]

§ 178.61-8 Manufacture.

(a) By suitable appliances and methods; dirt and scale to be removed as necessary to afford proper inspection; no defect acceptable that is likely to weaken the finished cylinder appreciably; reasonably smooth and uniform surface required. Exposed bottom welds on cylinders over 18 inches long must be protected by footrings. Minimum thick

ness of heads shall be not less than 90 percent of the required thickness of the sidewall. Heads shall be concave to pressure.

seams

(b) Circumferential seams. By electric-arc welding. Joints shall be butt with one member offset (joggle butt) or lap with minimum overlap of at least four times nominal sheet thickness. (c) Longitudinal seams in shells. (1) Longitudinal electric-arc welded shall be of the butt welded type. Welds must be made by a machine process including automatic feed and welding guidance mechanisms. Longitudinal seams shall have complete joint penetration, and shall be free from undercuts, overlaps or abrupt ridges or valleys. Misalignment of mating butt edges shall not exceed % of nominal sheet thickness or 32 inch whichever is less. All joints with nominal sheet thickness up to and including % inch shall be tightly butted. When nominal sheet thickness is greater than 8 inch, the joint shall be gapped for maximum distance equal to one-half the nominal sheet thickness or 32 inch whichever is less. Joint design, preparation and fit-up shall be such that requirements of § 178.61-8(d) are satisfied.

(2) Maximum joint efficiency shall be 1.0 when each seam is radiographed completely. Maximum joint efficiency shall be 0.90 when one cylinder from each lot of 50 consecutively welded cylin

ders in spot radiographed. In addition, one out of the first five cylinders welded following a shut down of welding operations exceeding four hours shall be spot radiographed. Spot radiographs, when required, shall be made of a finished welded cylinder and shall include the girth weld for 2 inches in both directions from the intersection of the longitudinal and girth welds and include at least 6 inches of the longitudinal weld. Maximum joint efficiency of 0.75 shall be permissible without radiography.

(d) Welding procedure and operators must be qualified in accordance with the sections that apply in the Compressed Gas Association's "Standards for Welding and Brazing on Thin Walled Containers" (CGA Pamphlet C-3-1964).1 [Order 71, 31 F.R. 9078, July 1, 1966] § 178.61-8 Welding of attachments.

(a) 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 must not exceed 0.25 percent. [Order 71, 31 F.R. 9078, July 1, 1966] § 178.61-10 Wall thickness.

shall not exceed the lesser value of any of the following:

(1) The value shown in Table I, § 178.61-5(a) for the particular material under consideration.

(2) One-half of the minimum tensile strength of the material determined as required in § 178.61-15.

(3) 35,000 pounds per square inch.
Note 1: In the formula above quoted
S=wall stress, p.s.i.;

P service pressure, p.s.i.;

D=outside diameter, inches;

d=inside diameter, inches;

E=joint efficiency of the longitudinal seam (from § 178.61-8(c) (2)).

1 Available from the Compressed Gas Association, Inc., 500 5th Ave., New York, N.Y.

(b) In any cylinder with wall thickness less than 0.100 inch, the ratio of tangential length to outside diameter shall not exceed 4.0.

[Order 71, 31 F.R. 9079, July 1, 1966]

§ 178.61-11 Heat treatment.

(a) Each cylinder must be uniformly and properly heat treated prior to test by the applicable method shown in § 178.615(a), Table I. Heat treatment must be accomplished after all forming and welding operations.

(b) Heat treatment is not required after welding or brazing 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 or brazing does not produce a temperature in excess of 400° F. in any part of the top or bottom material.

[Order 71, 31 F.R. 9079, July 1, 1966]

§ 178.61-12

Openings in cylinders.

(a) All openings must be in the heads or bases.

(b) Openings in cylinders must be provided with adequate fittings, bosses, or pads, integral with or securely attached to the cylinder by welding.

(c) Threads must comply with the following:

(1) Threads must be clean cut and to gauge.

(2) Taper threads must be of length not less than as specified for American Standard Taper Pipe threads.

(3) 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.

(d) Closure of fittings, boss or pads must be adequate to prevent leakage. [Order 71, 31 F.R. 9079, July 1, 1966] § 178.61-13 Safety relief devices and protection for valves, safety devices and other connections, if applied. (a) Must be as required by the Interstate Commerce Commission's Regulations that apply. (See §§ 173.34(d) and 173.301(g) of this chapter.)

§ 178.61-14 Hydrostatic test.

(a) By water jacket, or other suitable method, operated so as to obtain accurate data. Pressure gauge must permit readings to accuracy of 1 percent. Ex