US lawFederal (United States)RegulationsTitle 49 CFR — TransportationChapter I — PIPELINE AND HAZARDOUS MATERIALS SAFETY ADMINISTRATION, DEPARTMENT OF TRANSPORTATIONPart 179 — SPECIFICATIONS FOR TANK CARSSubpart D — Specifications for Non-Pressure Tank Car Tanks (Classes DOT-111AW, 115AW, and 117AW)179.202-449 C.F.R. § 179.202-4Thickness of plates.Last amended: 2016Year: 2026Length: 38 wordsOfficial source Cite as 49 C.F.R. § 179.202-4 (2026)The wall thickness after the forming of the tank shell and heads must be, at a minimum, 9/16 of an inch AAR TC-128 Grade B, normalized steel, in accordance with § 179.200-7(b). [80 FR 26749, May 8, 2015]Cross-references to the CFR179.200-7Previous49 C.F.R. § 179.202-3Next49 C.F.R. § 179.202-5