Section 179.100-10 - Postweld heat treatment(a) After welding is complete, steel tanks and all attachments welded thereto must be postweld heat treated as a unit in compliance with the requirements of AAR Specifications for Tank Cars, appendix W (IBR, see §171.7 of this subchapter).(b) For aluminum tanks, postweld heat treatment is prohibited.(c) Tank and welded attachments, fabricated from ASTM A 240/A 240M (IBR, see§171.7 of this subchapter), Type 304L or Type 316L materials do not require postweld heat treatment, but these materials do require a corrosion resistance test as specified in §179.100-7(c)(2).Amdt. 179-10, 36 FR 21345, 11/6/1971, as amended by Amdt. 179-47, 58 FR 50238, 9/24/1993; Amdt. 179-52, 61 FR 28679, 6/5/1996; 67 FR 51660, 8/8/2002; 68 FR 75758 and 75759, 12/31/2003