49 CFR 179.201-5
Postweld heat treatment and corrosion resistance.
(a) Tanks and attachments welded directly thereto must be postweld heat treated as a unit at the proper temperature except as indicated below. Tanks and attachments welded directly thereto fabricated from ASTM Specification A 240 Type 430A, Type 304 and Type 316 materials must be postweld heat treated as a unit and must be tested to demonstrate that they possess the corrosion resistance specified in § 179.200-7(d), Footnote 2. Tanks and attachments welded directly thereto, fabricated from ASTM Specification A 240 Type 304L or Type 316L materials are not required to be postweld heat treated.
(b) Tanks and attachments welded directly thereto, fabricated from ASTM Specification A 240 Type 304L and Type 316 materials must be tested to demonstrate that they possess the corrosion resistance specified in § 179.200-7(d), Footnote 2.
[Amdt. 179-10, 36 FR 21353, Nov. 6, 1971, as amended by Amdt. 179-52, 61 FR 28681, June 5, 1996]