49 CFR §176.137

1. (a)Each portable magazine used for the stowage of Class 1 (explosive) materials on board vessels must meet the following requirements:
   1. (1)It must be weather-tight, constructed of wood or metal lined with wood at least 2 cm (0.787 inch) thick, and with a capacity of no more than 3.1 cubic m (110 cubic feet).
   2. (2)All inner surfaces must be smooth and free of any protruding nails, screws or other projections.
   3. (3)If constructed of wood, a portable magazine must be framed of nominal 5 cm × 10 cm (2 × 4 inch) lumber, and sheathed with nominal 20 mm (0.787 inch) thick boards or plywood.
   4. (4)When constructed of metal, the metal must be not less than 3.2 mm (0.126 inch) thick.
   5. (5)Runners, bearers, or skids must be provided to elevate the magazine at least 10 cm (3.9 inches) from the deck. Padeyes, ring bolts, or other suitable means must be provided for securing.
   6. (6)If the portable magazine has a door or hinged cover, the door or cover must have a strong hasp and padlock or equally effective means of securing.
   7. (7)The portable magazine must be marked on its top and four sides, in letters at least 8 cm (3 inches) high, as follows:
2. (b)A portable magazine which meets the requirements for a type 2 or type 3 magazine under 27 CFR part 555 subpart K may be used for the stowage of Class 1 (explosive) materials on board vessels.
3. (c)A portable magazine with a capacity exceeding 3.1 m 3 (110 cubic feet) may be used for the stowage of Class 1 (explosive) materials under such construction, handling, and stowage requirements as the COTP approves.