{"data":{"id":"us/49-cfr-179.220-6","jurisdiction":"us","citation":"49 CFR 179.220-6","heading":"-6 Thickness of plates.","body":"(a) The wall thickness, after forming of the inner container shell and 2:1 ellipsoidal heads must be not less than specified in § 179.221-1, or not less than that calculated by the following formula:\nWhere:\nd = Inside diameter in inches;\nE = 0.9 welded joint efficiency; except E = 1.0 for seamless heads;\nP = Minimum required bursting pressure in psig;\nS = Minimum tensile strength of plate material in p.s.i. as prescribed in AAR Specifications for Tank Cars, appendix M, Table M1;\nt = Minimum thickness of plate in inches after forming.\n(b) The wall thickness after forming of the inner container heads, if flanged and dished, must be not less than specified in § 179.221-1, or not less than that calculated by the following formula:\nWhere:\nE = 0.9 welded joint efficiency; except E = 1.0 for seamless heads;\nL = Main inside radius to which head is dished, measured on concave side in inches;\nP = Minimum required bursting pressure in psig;\nS = Minimum tensile strength of plate material in psi as prescribed in AAR Specifications for Tank Cars, appendix M, Table M1 (IBR, see § 171.7 of this subchapter);\nt = Minimum thickness of plate in inches after forming.\n(c) The wall thickness after forming of the cylindrical section and heads of the outer shell must be not less than seven-sixteenths of an inch.\n(d) See § 179.220-9 for plate thickness requirements for inner container when divided into compartments.","path":["Title 49—Transportation","Subtitle B—Other Regulations Relating to Transportation","CHAPTER I—PIPELINE AND HAZARDOUS MATERIALS SAFETY ADMINISTRATION, DEPARTMENT OF TRANSPORTATION","SUBCHAPTER C—HAZARDOUS MATERIALS REGULATIONS","PART 179—SPECIFICATIONS FOR TANK CARS","Subpart D—Specifications for Non-Pressure Tank Car Tanks (Classes DOT-111AW, 115AW, and 117AW)"],"source_url":"https://www.ecfr.gov/api/versioner/v1/full/2026-08-25/title-49.xml","current_through":"2026-08-25","vintage":"","retrieved_at":"2026-08-27T02:26:34Z","sha256":"df540db7b83afae745b93d866af50dd9a431d7f3913445fad5bb9afb682365d5","source_id":"us-cfr","stale":true,"prev":"us/49-cfr-179.220-4","next":"us/49-cfr-179.220-7"},"notice":"GroundRules: Original legal text. Not legal advice."}