Section 56.4430 - Storage facilities(a) Storage tanks for flammable or combustible liquids shall be- (1) Capable of withstanding working pressures and stresses and compatible with the type of liquid stored;(2) Maintained in a manner that prevents leakage;(3) Isolated or separated from ignition sources to prevent fire or explosion; and(4) Vented or otherwise constructed to prevent development of pressure or vacuum as a result of filling, emptying, or atmospheric temperature changes. Vents for storage of Class I, II, or IIIA liquids shall be isolated or separated from ignition sources. These pressure relief requirements do not apply to tanks used for storage of Class IIIB liquids that are larger than 12,000 gallons in capacity.(b) All piping, valves, and fittings shall be-(1) Capable of withstanding working pressures and stresses;(2) Compatible with the type of liquid stored; and(3) Maintained in a manner that prevents leakage.(c) Fixed, unburied tanks located where escaping liquid could present a hazard to persons shall be provided with-(1) Containment for the entire capacity of the largest tank; or(2) Drainage of a remote impoundment area that does not endanger persons. However, storage of only Class IIIB liquids does not require containment or drainage to remote impoundment.