49 CFR § 179.400-11 - Welding.
---
identifier: "/us/cfr/t49/s179.400-11"
source: "ecfr"
legal_status: "authoritative_unofficial"
title: "49 CFR § 179.400-11 - Welding."
title_number: 49
title_name: "Transportation"
section_number: "179.400-11"
section_name: "Welding."
chapter_name: "PIPELINE AND HAZARDOUS MATERIALS SAFETY ADMINISTRATION, DEPARTMENT OF TRANSPORTATION"
subchapter_number: "C"
subchapter_name: "HAZARDOUS MATERIALS REGULATIONS"
part_number: "179"
part_name: "SPECIFICATIONS FOR TANK CARS"
positive_law: false
currency: "2026-03-24"
last_updated: "2026-03-24"
format_version: "1.1.0"
generator: "[email protected]"
authority: "49 U.S.C. 5101-5128; 49 CFR 1.81 and 1.97."
regulatory_source: "29 FR 18995, Dec. 29, 1964, unless otherwise noted. Redesignated at 32 FR 5606, Apr. 5, 1967."
cfr_part: "179"
---
# 179.400-11 Welding.
(a) Except for closure of openings and a maximum of two circumferential closing joints in the cylindrical portion of the outer jacket, each joint of an inner tank and the outer jacket must be a fusion double welded butt joint.
(b) The closure for openings and the circumferential closing joints in the cylindrical portion of the outer jacket, including head to shell joints, may be a single welded butt joint using a backing strip on the inside of the joint.
(c) Each joint must be welded in accordance with the requirements of AAR Specifications for Tank Cars, appendix W (IBR, see § 171.7 of this subchapter).
(d) Each welding procedure, welder, and fabricator must be approved.
[Amdt. 179-32, 48 FR 27708, June 16, 1983, as amended at 68 FR 75763, Dec. 31, 2003]