Intermediate Bulk Containers (IBCs) with a classification of 31A may be used on a vessel to which this part applies and must meet at a minimum the following constructional requirements:

(a) The shell thickness must be a minimum 6.36 mm (0.25 inches) in reference steel.

(b) There must be a self-closing relief valve set to open at no less than 5 psig.

(c) Closures used on fill openings, in excess of 20 square inches, must be equipped with a device to prevent them from fully opening without first relieving internal pressure.

(d) All venting requirements must be followed in accordance with 49 CFR 178.345-10, Table 1.