Cargo tanks
(1) Cargo tanks. MC 306 and DOT 406 cargo tank motor vehicles must: (i) Meet qualification and maintenance requirements (including periodic testing and inspection) in accordance with subpart E of part 180 of this subchapter; (ii) Conform to the pressure relief system requirements specified in 173.243(b)(1); (iii) For MC 306 cargo tanks, be equipped with stop-valves capable of being remotely closed by manual and mechanical means; and (iv) For DOT 406 cargo tanks, conform to the bottom outlet requirements specified in 173.243(b)(2). (2) Portable tanks. DOT 57 portable tanks must (i) Be constructed of stainless steel; and (ii) Meet qualification and maintenance requirements of subpart G of part 180 of this subchapter.