A phosphoric acid containment system must be:
(a) Lined with natural rubber or neoprene;
(b) Lined with a material approved for phosphoric acid tanks by the Commandant (CG-ENG); or
(c) Made of a stainless steel that resists corrosion by phosphoric acid.
Note: ``Phosphoric acid'', as defined in Sec. 153.2, includes phosphoric acid, superphosphoric acid, and aqueous solutions of phosphoric acid. [CGD 73-96, 42 FR 49027, Sept. 26, 1977, as amended by CGD 82-063b, 48 FR 4782, Feb. 3, 1983; CGD 88-100, 54 FR 40042, Sept. 29, 1989]