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Subpart A—Introduction, Approvals and Reports8

Subpart B—General Design Requirements11

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

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

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

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

Regulationcurrent

49 CFR 179.200-8

-8 Tank heads.

Current as of 2026-08-18 Government source

eCFR editorial compilationAuthoritative but unofficial

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(a)All external tank heads must be an ellipsoid of revolution in which the major axis must equal the diameter of the shell and the minor axis must be one-half the major axis.#

(b)Internal compartment tank heads may be 2:1 ellipsoidal, 3:1 ellipsoidal, or flanged and dished to thicknesses as specified in § 179.200-6. Flanged and dished heads must have main inside radius not exceeding 10 feet, and inside knuckle radius must not be less than 3 3/4 inches for steel, alloy steel, or nickel tanks, and not less than 5 inches for aluminum alloy tanks.#