49 CFR §179.400-15
Verified against eCFR.gov as of June 20, 2026View official text on eCFR.gov ↗
Each longitudinal and circumferential joint of the inner tank, and each longitudinal and circumferential double welded butt joint of the outer jacket, must be examined along its entire length in accordance with the requirements of AAR Specifications for Tank Cars, appendix W (IBR, see § 171.7 of this subchapter).