46 C.F.R. § 194.10-20 – Magazine chest construction.

(a) Magazine chests shall be of watertight metal construction with flush interior. The body and lid shall have a minimum thickness of 1/8 inch.
(b) Permanent sun shields shall be provided for sides and top including the lid. These shall have a minimum thickness of 1/8-inch aluminum or 16-gage steel. Side shields shall be offset from the body a distance of 1 inch. The top shield shall be offset a distance of 1 1/2 inches. Sun shields may be omitted when chests are installed “on deck protected,” shielded from direct exposure to the sun.
(c) Chests shall be limited to a gross capacity of 100 cubic feet.
(d) Chests shall be secured to the vessel's structure by means of permanently installed foundation clips or bolts or a combination thereof. Lashings will not be acceptable.
(e) Chests shall be provided with substantial hasps and staples for locking purposes.