Section 178.360-1 - General requirements(a) Each vessel must be made of stainless steel, malleable iron, or brass, or other material having equivalent physical strength and fire resistance.(b) Each vessel must meet all of the applicable requirements of §173.24(c) and (d) of this subchapter. Letters and numerals at least 6 mm ( 1/4 -inch) in height are authorized for the marking of a vessel not exceeding 5 cm (2 inches) inside diameter.Amdt. 178-35, 39 FR 45245, 12/31/1974. Redesignated by Amdt. 178-97, 55 FR 52716, 12/21/1990; 66 FR 45387, 8/28/2001