(a) Material used in the tank must be steel of good weldable quality and conform with the requirements in Sections V, VIII, and IX of the ASME Code (IBR, see Sec. 171.7 of this subchapter).
(b) The minimum thickness of metal, exclusive of lining material, for shell and heads of tanks shall be as follows: ------------------------------------------------------------------------
Minimum
Tank capacity thickness
(inch)------------------------------------------------------------------------Not more than 1,200 gallons................................. \1/4\Over 1,200 to 1,800 gallons................................. \5/16\Over 1,800 gallons.......................................... \3/8\------------------------------------------------------------------------ [29 FR 18972, Dec. 29, 1964. Redesignated at 32 FR 5606, Apr. 5, 1967, and amended by Amdt. 178-7, 34 FR 18250, Nov. 14, 1969; 68 FR 75750, Dec. 31, 2003]