49 C.F.R. § 179.400-7 Tank heads.
Title 49 - Transportation
(a) Tank heads of the inner tank and outer jacket must be flanged and dished, or ellipsoidal. (b) Flanged and dished heads must have— (1) A main inside dish radius not greater than the outside diameter of the straight flange; (2) An inside knuckle radius of not less than 6 percent of the outside diameter of the straight flange; and (3) An inside knuckle radius of at least three times the head thickness.
Title 49: Transportation
PART 179—SPECIFICATIONS FOR TANK CARS
Subpart F—Specification for Cryogenic Liquid Tank Car Tanks and Seamless Steel Tanks (Classes DOT-113 and 107A)
§ 179.400-7 Tank heads.
