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49 CFR 179.100-9 - -9 Welding. | Regulus

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Regulation documentation

49 CFR Part 179

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titleTitle 49 — Transportation subtitleSubtitle B — Other Regulations Relating to Transportation chapterChapter I — Pipeline and Hazardous Materials Safety Administration, Department of Transportation subchapterSubchapter C — Hazardous Materials Regulations partPart 179 subpartSubpart C—Specifications for Pressure Tank Car Tanks (Classes DOT-105, 109, 112, 114 and 120)

31 sections

Subpart A—Introduction, Approvals and Reports8

§ 179.1General.§ 179.2Definitions and abbreviations.§ 179.3Procedure for securing approval.§ 179.4Changes in specifications for tank cars.§ 179.5Certificate of construction.§ 179.6Repairs and alterations.§ 179.7Quality assurance program.§ 179.8Limitation on actions by states, local governments, and Indian tribes.

Subpart B—General Design Requirements11

§ 179.10Tank mounting.§ 179.11Welding certification.§ 179.12Interior heater systems.§ 179.13Tank car capacity and gross weight limitation.§ 179.14Coupler vertical restraint system.§ 179.15Pressure relief devices.§ 179.16Tank-head puncture-resistance systems.§ 179.18Thermal protection systems.§ 179.20Service equipment; protection systems.§ 179.22Marking.§ 179.24Stamping.

Subpart C—Specifications for Pressure Tank Car Tanks (Classes DOT-105, 109, 112, 114 and 120)31

§ 179.100General specifications applicable to pressure tank car tanks.§ 179.100-1-1 Tanks built under these specifications shall comply with the requirements of §§ 179.100, 179.101 and when applicable, §§ 179.102 and 179.103.§ 179.100-3-3 Type.§ 179.100-4-4 Insulation.§ 179.100-6-6 Thickness of plates.§ 179.100-7-7 Materials.§ 179.100-8-8 Tank heads.§ 179.100-9-9 Welding.§ 179.100-10-10 Postweld heat treatment.§ 179.100-12-12 Manway nozzle, cover and protective housing.§ 179.100-13-13 Venting, loading and unloading valves, measuring and sampling devices.§ 179.100-14-14 Bottom outlets.§ 179.100-16-16 Attachments.§ 179.100-17-17 Closures for openings.§ 179.100-18-18 Tests of tanks.§ 179.100-19-19 Tests of safety relief valves.§ 179.100-20-20 Stamping.§ 179.101Individual specification requirements applicable to pressure tank car tanks.§ 179.101-1-1 Individual specification requirements.§ 179.102Special commodity requirements for pressure tank car tanks.§ 179.102-1-1 Carbon dioxide, refrigerated liquid.§ 179.102-2-2 Chlorine.§ 179.102-3-3 Materials poisonous by inhalation.§ 179.102-4-4 Vinyl fluoride, stabilized.§ 179.102-17-17 Hydrogen chloride, refrigerated liquid.§ 179.103Special requirements for class 114A * * * tank car tanks.§ 179.103-1-1 Type.§ 179.103-2-2 Manway cover.§ 179.103-3-3 Venting, loading and unloading valves, measuring and sampling devices.§ 179.103-4-4 Safety relief devices and pressure regulators.§ 179.103-5-5 Bottom outlets.

Subpart D—Specifications for Non-Pressure Tank Car Tanks (Classes DOT-111AW, 115AW, and 117AW)69

§ 179.200General specifications applicable to non-pressure tank car tanks (Class DOT-111, DOT-117).§ 179.200-1-1 Tank built under these specifications must meet the applicable requirements in this part.§ 179.200-3-3 Type.§ 179.200-4-4 Insulation.§ 179.200-6-6 Thickness of plates.§ 179.200-7-7 Materials.§ 179.200-8-8 Tank heads.§ 179.200-9-9 Compartment tanks.§ 179.200-10-10 Welding.§ 179.200-11-11 Postweld heat treatment.§ 179.200-13-13 Manway ring or flange, pressure relief device flange, bottom outlet nozzle flange, bottom washout nozzle flange and other attachments and openings.§ 179.200-14-14 Expansion capacity.§ 179.200-15-15 Closures for manways.§ 179.200-16-16 Gauging devices, top loading and unloading devices, venting and air inlet devices.§ 179.200-17-17 Bottom outlets.§ 179.200-19-19 Reinforcements, when used, and appurtenances not otherwise specified.§ 179.200-21-21 Closures for openings.§ 179.200-22-22 Test of tanks.§ 179.200-23-23 Tests of pressure relief valves.§ 179.200-24-24 Stamping.§ 179.201Individual specification requirements applicable to non-pressure tank car tanks.§ 179.201-1-1 Individual specification requirements.§ 179.201-2-2 [Reserved]§ 179.201-3-3 Lined tanks.§ 179.201-4-4 Material.§ 179.201-5-5 Postweld heat treatment and corrosion resistance.§ 179.201-6-6 Manways and manway closures.§ 179.201-8-8 Sampling device and thermometer well.§ 179.201-9-9 Gauging device.§ 179.201-10-10 Water capacity marking.§ 179.201-11-11 Insulation.§ 179.202Individual specification requirements applicable to DOT-117 tank car tanks.§ 179.202-1-1 Applicability.§ 179.202-2-2 [Reserved]§ 179.202-3-3 Approval to operate at 286,000 gross rail load (GRL).§ 179.202-4-4 Thickness of plates.§ 179.202-5-5 Tank head puncture resistance system.§ 179.202-6-6 Thermal protection system.§ 179.202-7-7 Jackets.§ 179.202-8-8 Bottom outlets.§ 179.202-9-9 Top fittings protection.§ 179.202-11-11 Individual specification requirements.§ 179.202-12-12 Performance standard requirements (DOT-117P).§ 179.202-13-13 Retrofit standard requirements (DOT-117R).§ 179.203-179.202-22§§ 179.203-179.202-22 [Reserved]§ 179.220General specifications applicable to nonpressure tank car tanks consisting of an inner container supported within an outer shell (class DOT-115).§ 179.220-1-1 Tanks built under these specifications must meet the requirements of §§ 179.220 and 179.221.§ 179.220-3-3 Type.§ 179.220-4-4 Insulation.§ 179.220-6-6 Thickness of plates.§ 179.220-7-7 Materials.§ 179.220-8-8 Tank heads.§ 179.220-9-9 Compartment tanks.§ 179.220-10-10 Welding.§ 179.220-11-11 Postweld heat treatment.§ 179.220-13-13 Inner container manway nozzle and cover.§ 179.220-14-14 Openings in the tanks.§ 179.220-15-15 Support system for inner container.§ 179.220-16-16 Expansion capacity.§ 179.220-17-17 Gauging devices, top loading and unloading devices, venting and air inlet devices.§ 179.220-18-18 Bottom outlets.§ 179.220-20-20 Reinforcements, when used, and appurtenances not otherwise specified.§ 179.220-22-22 Closure for openings.§ 179.220-23-23 Test of tanks.§ 179.220-24-24 Tests of pressure relief valves.§ 179.220-25-25 Stamping.§ 179.220-26-26 Stenciling.§ 179.221Individual specification requirements applicable to tank car tanks consisting of an inner container supported within an outer shell.§ 179.221-1-1 Individual specification requirements.

Subpart E—Specifications for Multi-Unit Tank Car Tanks (Classes DOT-106A and 110AW)20

§ 179.300General specifications applicable to multi-unit tank car tanks designed to be removed from car structure for filling and emptying (Classes DOT-106A and 110AW).§ 179.300-1-1 Tanks built under these specifications shall meet the requirements of §§ 179.300 and 179.301.§ 179.300-3-3 Type and general requirements.§ 179.300-4-4 Insulation.§ 179.300-6-6 Thickness of plates.§ 179.300-7-7 Materials.§ 179.300-8-8 Tank heads.§ 179.300-9-9 Welding.§ 179.300-10-10 Postweld heat treatment.§ 179.300-12-12 Protection of fittings.§ 179.300-13-13 Venting, loading and unloading valves.§ 179.300-14-14 Attachments not otherwise specified.§ 179.300-15-15 Pressure relief devices.§ 179.300-16-16 Tests of tanks.§ 179.300-17-17 Tests of pressure relief devices.§ 179.300-18-18 Stamping.§ 179.300-19-19 Inspection.§ 179.300-20-20 Reports.§ 179.301Individual specification requirements for multi-unit tank car tanks.§ 179.302[Reserved]

Subpart F—Specification for Cryogenic Liquid Tank Car Tanks and Seamless Steel Tanks (Classes DOT-113 and 107A)44

§ 179.400General specification applicable to cryogenic liquid tank car tanks.§ 179.400-1-1 General.§ 179.400-3-3 Type.§ 179.400-4-4 Insulation system and performance standard.§ 179.400-5-5 Materials.§ 179.400-6-6 Bursting and buckling pressure.§ 179.400-7-7 Tank heads.§ 179.400-8-8 Thickness of plates.§ 179.400-9-9 Stiffening rings.§ 179.400-10-10 Sump or siphon bowl.§ 179.400-11-11 Welding.§ 179.400-12-12 Postweld heat treatment.§ 179.400-13-13 Support system for inner tank.§ 179.400-14-14 Cleaning of inner tank.§ 179.400-15-15 Radioscopy.§ 179.400-16-16 Access to inner tank.§ 179.400-17-17 Inner tank piping.§ 179.400-18-18 Test of inner tank.§ 179.400-19-19 Valves and gages.§ 179.400-20-20 Pressure relief devices.§ 179.400-21-21 Test of pressure relief valves.§ 179.400-22-22 Protective housings.§ 179.400-23-23 Operating instructions.§ 179.400-24-24 Stamping.§ 179.400-25-25 Stenciling.§ 179.401Individual specification requirements applicable to inner tanks for cryogenic liquid tank car tanks.§ 179.401-1-1 Individual specification requirements.§ 179.500Specification DOT-107A * * * * seamless steel tank car tanks.§ 179.500-1-1 Tanks built under these specifications shall meet the requirements of § 179.500.§ 179.500-3-3 Type and general requirements.§ 179.500-4-4 Thickness of wall.§ 179.500-5-5 Material.§ 179.500-6-6 Heat treatment.§ 179.500-7-7 Physical tests.§ 179.500-8-8 Openings in tanks.§ 179.500-10-10 Protective housing.§ 179.500-11-11 Loading and unloading valves.§ 179.500-12-12 Pressure relief devices.§ 179.500-13-13 Fixtures.§ 179.500-14-14 Test of tanks.§ 179.500-15-15 Handling of tanks failing in tests.§ 179.500-16-16 Tests of pressure relief devices.§ 179.500-17-17 Marking.§ 179.500-18-18 Inspection and reports.

Browse regulation

Subpart A—Introduction, Approvals and Reports8

§ 179.1General.§ 179.2Definitions and abbreviations.§ 179.3Procedure for securing approval.§ 179.4Changes in specifications for tank cars.§ 179.5Certificate of construction.§ 179.6Repairs and alterations.§ 179.7Quality assurance program.§ 179.8Limitation on actions by states, local governments, and Indian tribes.

Subpart B—General Design Requirements11

§ 179.10Tank mounting.§ 179.11Welding certification.§ 179.12Interior heater systems.§ 179.13Tank car capacity and gross weight limitation.§ 179.14Coupler vertical restraint system.§ 179.15Pressure relief devices.§ 179.16Tank-head puncture-resistance systems.§ 179.18Thermal protection systems.§ 179.20Service equipment; protection systems.§ 179.22Marking.§ 179.24Stamping.

Subpart C—Specifications for Pressure Tank Car Tanks (Classes DOT-105, 109, 112, 114 and 120)31

§ 179.100General specifications applicable to pressure tank car tanks.§ 179.100-1-1 Tanks built under these specifications shall comply with the requirements of §§ 179.100, 179.101 and when applicable, §§ 179.102 and 179.103.§ 179.100-3-3 Type.§ 179.100-4-4 Insulation.§ 179.100-6-6 Thickness of plates.§ 179.100-7-7 Materials.§ 179.100-8-8 Tank heads.§ 179.100-9-9 Welding.§ 179.100-10-10 Postweld heat treatment.§ 179.100-12-12 Manway nozzle, cover and protective housing.§ 179.100-13-13 Venting, loading and unloading valves, measuring and sampling devices.§ 179.100-14-14 Bottom outlets.§ 179.100-16-16 Attachments.§ 179.100-17-17 Closures for openings.§ 179.100-18-18 Tests of tanks.§ 179.100-19-19 Tests of safety relief valves.§ 179.100-20-20 Stamping.§ 179.101Individual specification requirements applicable to pressure tank car tanks.§ 179.101-1-1 Individual specification requirements.§ 179.102Special commodity requirements for pressure tank car tanks.§ 179.102-1-1 Carbon dioxide, refrigerated liquid.§ 179.102-2-2 Chlorine.§ 179.102-3-3 Materials poisonous by inhalation.§ 179.102-4-4 Vinyl fluoride, stabilized.§ 179.102-17-17 Hydrogen chloride, refrigerated liquid.§ 179.103Special requirements for class 114A * * * tank car tanks.§ 179.103-1-1 Type.§ 179.103-2-2 Manway cover.§ 179.103-3-3 Venting, loading and unloading valves, measuring and sampling devices.§ 179.103-4-4 Safety relief devices and pressure regulators.§ 179.103-5-5 Bottom outlets.

Subpart D—Specifications for Non-Pressure Tank Car Tanks (Classes DOT-111AW, 115AW, and 117AW)69

§ 179.200General specifications applicable to non-pressure tank car tanks (Class DOT-111, DOT-117).§ 179.200-1-1 Tank built under these specifications must meet the applicable requirements in this part.§ 179.200-3-3 Type.§ 179.200-4-4 Insulation.§ 179.200-6-6 Thickness of plates.§ 179.200-7-7 Materials.§ 179.200-8-8 Tank heads.§ 179.200-9-9 Compartment tanks.§ 179.200-10-10 Welding.§ 179.200-11-11 Postweld heat treatment.§ 179.200-13-13 Manway ring or flange, pressure relief device flange, bottom outlet nozzle flange, bottom washout nozzle flange and other attachments and openings.§ 179.200-14-14 Expansion capacity.§ 179.200-15-15 Closures for manways.§ 179.200-16-16 Gauging devices, top loading and unloading devices, venting and air inlet devices.§ 179.200-17-17 Bottom outlets.§ 179.200-19-19 Reinforcements, when used, and appurtenances not otherwise specified.§ 179.200-21-21 Closures for openings.§ 179.200-22-22 Test of tanks.§ 179.200-23-23 Tests of pressure relief valves.§ 179.200-24-24 Stamping.§ 179.201Individual specification requirements applicable to non-pressure tank car tanks.§ 179.201-1-1 Individual specification requirements.§ 179.201-2-2 [Reserved]§ 179.201-3-3 Lined tanks.§ 179.201-4-4 Material.§ 179.201-5-5 Postweld heat treatment and corrosion resistance.§ 179.201-6-6 Manways and manway closures.§ 179.201-8-8 Sampling device and thermometer well.§ 179.201-9-9 Gauging device.§ 179.201-10-10 Water capacity marking.§ 179.201-11-11 Insulation.§ 179.202Individual specification requirements applicable to DOT-117 tank car tanks.§ 179.202-1-1 Applicability.§ 179.202-2-2 [Reserved]§ 179.202-3-3 Approval to operate at 286,000 gross rail load (GRL).§ 179.202-4-4 Thickness of plates.§ 179.202-5-5 Tank head puncture resistance system.§ 179.202-6-6 Thermal protection system.§ 179.202-7-7 Jackets.§ 179.202-8-8 Bottom outlets.§ 179.202-9-9 Top fittings protection.§ 179.202-11-11 Individual specification requirements.§ 179.202-12-12 Performance standard requirements (DOT-117P).§ 179.202-13-13 Retrofit standard requirements (DOT-117R).§ 179.203-179.202-22§§ 179.203-179.202-22 [Reserved]§ 179.220General specifications applicable to nonpressure tank car tanks consisting of an inner container supported within an outer shell (class DOT-115).§ 179.220-1-1 Tanks built under these specifications must meet the requirements of §§ 179.220 and 179.221.§ 179.220-3-3 Type.§ 179.220-4-4 Insulation.§ 179.220-6-6 Thickness of plates.§ 179.220-7-7 Materials.§ 179.220-8-8 Tank heads.§ 179.220-9-9 Compartment tanks.§ 179.220-10-10 Welding.§ 179.220-11-11 Postweld heat treatment.§ 179.220-13-13 Inner container manway nozzle and cover.§ 179.220-14-14 Openings in the tanks.§ 179.220-15-15 Support system for inner container.§ 179.220-16-16 Expansion capacity.§ 179.220-17-17 Gauging devices, top loading and unloading devices, venting and air inlet devices.§ 179.220-18-18 Bottom outlets.§ 179.220-20-20 Reinforcements, when used, and appurtenances not otherwise specified.§ 179.220-22-22 Closure for openings.§ 179.220-23-23 Test of tanks.§ 179.220-24-24 Tests of pressure relief valves.§ 179.220-25-25 Stamping.§ 179.220-26-26 Stenciling.§ 179.221Individual specification requirements applicable to tank car tanks consisting of an inner container supported within an outer shell.§ 179.221-1-1 Individual specification requirements.

Subpart E—Specifications for Multi-Unit Tank Car Tanks (Classes DOT-106A and 110AW)20

§ 179.300General specifications applicable to multi-unit tank car tanks designed to be removed from car structure for filling and emptying (Classes DOT-106A and 110AW).§ 179.300-1-1 Tanks built under these specifications shall meet the requirements of §§ 179.300 and 179.301.§ 179.300-3-3 Type and general requirements.§ 179.300-4-4 Insulation.§ 179.300-6-6 Thickness of plates.§ 179.300-7-7 Materials.§ 179.300-8-8 Tank heads.§ 179.300-9-9 Welding.§ 179.300-10-10 Postweld heat treatment.§ 179.300-12-12 Protection of fittings.§ 179.300-13-13 Venting, loading and unloading valves.§ 179.300-14-14 Attachments not otherwise specified.§ 179.300-15-15 Pressure relief devices.§ 179.300-16-16 Tests of tanks.§ 179.300-17-17 Tests of pressure relief devices.§ 179.300-18-18 Stamping.§ 179.300-19-19 Inspection.§ 179.300-20-20 Reports.§ 179.301Individual specification requirements for multi-unit tank car tanks.§ 179.302[Reserved]

Subpart F—Specification for Cryogenic Liquid Tank Car Tanks and Seamless Steel Tanks (Classes DOT-113 and 107A)44

§ 179.400General specification applicable to cryogenic liquid tank car tanks.§ 179.400-1-1 General.§ 179.400-3-3 Type.§ 179.400-4-4 Insulation system and performance standard.§ 179.400-5-5 Materials.§ 179.400-6-6 Bursting and buckling pressure.§ 179.400-7-7 Tank heads.§ 179.400-8-8 Thickness of plates.§ 179.400-9-9 Stiffening rings.§ 179.400-10-10 Sump or siphon bowl.§ 179.400-11-11 Welding.§ 179.400-12-12 Postweld heat treatment.§ 179.400-13-13 Support system for inner tank.§ 179.400-14-14 Cleaning of inner tank.§ 179.400-15-15 Radioscopy.§ 179.400-16-16 Access to inner tank.§ 179.400-17-17 Inner tank piping.§ 179.400-18-18 Test of inner tank.§ 179.400-19-19 Valves and gages.§ 179.400-20-20 Pressure relief devices.§ 179.400-21-21 Test of pressure relief valves.§ 179.400-22-22 Protective housings.§ 179.400-23-23 Operating instructions.§ 179.400-24-24 Stamping.§ 179.400-25-25 Stenciling.§ 179.401Individual specification requirements applicable to inner tanks for cryogenic liquid tank car tanks.§ 179.401-1-1 Individual specification requirements.§ 179.500Specification DOT-107A * * * * seamless steel tank car tanks.§ 179.500-1-1 Tanks built under these specifications shall meet the requirements of § 179.500.§ 179.500-3-3 Type and general requirements.§ 179.500-4-4 Thickness of wall.§ 179.500-5-5 Material.§ 179.500-6-6 Heat treatment.§ 179.500-7-7 Physical tests.§ 179.500-8-8 Openings in tanks.§ 179.500-10-10 Protective housing.§ 179.500-11-11 Loading and unloading valves.§ 179.500-12-12 Pressure relief devices.§ 179.500-13-13 Fixtures.§ 179.500-14-14 Test of tanks.§ 179.500-15-15 Handling of tanks failing in tests.§ 179.500-16-16 Tests of pressure relief devices.§ 179.500-17-17 Marking.§ 179.500-18-18 Inspection and reports.

Related 0 Definitions History 30 Authority 25

RegulationsTitle 49Subtitle BChapter ISubchapter CPart 179Subpart C—Specifications for Pressure Tank Car Tanks (Classes DOT-105, 109, 112, 114 and 120)49 CFR 179.100-9

Regulationcurrent

49 CFR 179.100-9

-9 Welding.

Snapshot 2026-08-18 Government source

eCFR editorial compilationAuthoritative but unofficial

3 passages

(a) All joints shall be fusion-welded in compliance with the requirements of AAR Specifications for Tank Cars, appendix W (IBR, see § 171.7 of this subchapter). Welding procedures, welders and fabricators shall be approved.

(b) [Reserved]

[29 FR 18995, Dec. 29, 1964, as amended at 65 FR 58632, Sept. 29, 2000; 68 FR 75759, Dec. 31, 2003]

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Related 0 Definitions History 30 Authority 25 Community

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Retrieved: Aug 20, 2026
Version: 2026-08-18

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