§178.348-4. Pressure relief. — Inbound Citations

(e) The pressure relief system (primary and secondary, including piping) must have sufficient venting capacity to limit the cargo tank internal pressure to not more than the cargo tank test pressure. The total venting capacity, rated at not more than the cargo tank test pressure, must be at least that specified in table I, except as provided in § 178.348-4.

(1) Unless otherwise specified in the applicable individual specification, the primary relief system must have a minimum venting capacity of 12,000 SCFH per 350 square feet of exposed cargo tank area, but in any case at least one fourth the required total venting capacity for the cargo tank.

(2) If the primary pressure relief system does not provide the required total venting capacity, additional capacity must be provided by a secondary pressure relief system.

(vi) Pressure relief devices must be as prescribed in § 178.348-4.

(v) A Specification MC 310 or MC 311 cargo tank, to conform with a Specification MC 312 or DOT 412 cargo tank (See §§ 178.348-4 and 178.345-11 of this subchapter).

(B) With reclosing pressure relief valves modified as provided in § 180.405(c) to conform with DOT 412 specifications, according to the pressures set forth for a DOT 412 cargo tank in § 178.348-4 of this subchapter.