49 C.F.R. § 178.272-2 Minimum thickness of shells and heads.
Title 49 - Transportation
(a) The approval agency may authorize a minimum thickness less than that required by §178.270–5 of this subpart where additional protection against tank puncture provides equal integrity. (b) The shell and head thickness of a tank must be at least: (1) 3.18 mm (0.125 inches) for a tank with a maximum cross-sectional dimension of 1.8 m (5.9 feet) or less; or (2) 4 mm (0.157 inches) for a tank constructed of the reference mild steel having a maximum cross-sectional dimension exceeding 1.8 m (5.9 feet). For tanks having a maximum cross-sectional dimension exceeding 1.8 m (5.9 feet) constructed of other steels, an equivalent head and shell thickness calculated in accordance with §178.270–5(c) of this subpart may be used, subject to an absolute minimum of 3.18 mm (0.125 inches). (c) The following additional puncture protection systems are authorized: (1) An overall external structural protection, such as a jacket, which is rigidly secured to the tank with a layer of cushioning material installed between the external structural protection and the tank; or (2) A complete framework surrounding the tank including both longitudinal and transverse structural members. [Amdt. 178–65, 46 FR 9899, Jan. 29, 1981, as amended at 66 FR 45387, Aug. 28, 2001]
Title 49: Transportation
PART 178—SPECIFICATIONS FOR PACKAGINGS
Subpart H—Specifications for Portable Tanks
§ 178.272-2 Minimum thickness of shells and heads.
