49 CFR 176.200 - General stowage requirements.
(a) Each package of Class 2 (compressed gas) material being transported by vessel must be prevented from making direct contact with the vessel's deck, side, or bulwark by dunnage, shoring, or other effective means.
(b) When cylinders of Class 2 (compressed gas) materials being transported by vessel are stowed in a horizontal position, each tier must be stowed in the cantlines of the tier below it, and the valves on cylinders in adjacent tiers must be at alternate ends of the stow. Each tier may be stepped back and the ends alternated in order to clear the flange. Lashing must be provided to prevent any shifting.
(c) When cylinders of Class 2 (compressed gas) materials being transported by vessel are stowed in a vertical position they must be stowed in a block and cribbed or boxed-in with suitable sound lumber and the box or crib dunnaged to provide clearance from a steel deck at least 10 cm (3.9 inches) off any metal deck. Pressure receptacles in the box or crib must be braced to prevent any shifting of the pressure receptacles. The box or crib (gas rack) must be securely chocked and lashed to prevent movement in any direction.
(f) Class 2 (compressed gas) material must be kept as cool as practicable and be stowed away from all sources of heat and ignition. Any package containing a Division 2.1 (flammable gas) material is restricted from transport in powered refrigerated temperature controlled containers, unless the equipment is capable of preventing ignition of flammable vapors by having non-sparking or explosion-proof electric fittings within the cooling compartment.