49 CFR 176.172 - Structural serviceability of freight containers and vehicles carrying Class 1 (explosive) materials on ships.
(a) Except for Division 1.4 materials, a freight container may not be offered for the carriage of Class 1 (explosive) materials, unless the container is structurally serviceable as evidenced by a current CSC (International Convention for Safe Containers) approval plate and verified by a detailed visual examination as follows:
(1) Before a freight container or transport vehicle is packed with Class 1 (explosive) materials, it must be visually examined by the shipper to ensure it is structurally serviceable, free of any residue of previous cargo, and its interior walls and floors are free from protrusions.
(2)Structurally serviceable means the freight container or the vehicle cannot have major defects in its structural components, such as top and bottom side rails, top and bottom end rails, door sill and header, floor cross members, corner posts, and corner fittings in a freight container. Major defects include -
(i) Dents or bends in the structural members greater than 19 mm (0.75 inch) in depth, regardless of length;
(ii) Cracks or breaks in structural members;
(iii) More than one splice or an improper splice (such as a lapped splice) in top or bottom end rails or door headers;
(iv) More than two splices in any one top or bottom side rail;
(v) Any splice in a door sill or corner post;
(vi) Door hinges and hardware that are seized, twisted, broken, missing, or otherwise inoperative;
(vii) Gaskets and seals that do not seal; or
(viii) For freight containers, any distortion of the overall configuration great enough to prevent proper alignment of handling equipment, mounting and securing chassis or vehicle, or insertion into ships' cells.
(3) In addition, deterioration of any component of the freight container or vehicle, regardless of the material of construction, such as rusted-out metal in sidewalls or disintegrated fiberglass, is prohibited. Normal wear, however, including oxidation (rust), slight dents and scratches, and other damage that does not affect serviceability or the weather-tight integrity of the units, is not prohibited.
(c) All shipments of Class 1 (explosive) materials except those in Division 1.4 (explosive) must be accompanied by a statement, which may appear on the shipping paper, certifying that the freight container or the vehicle is structurally serviceable as defined in paragraph (a)(2) of this section.