(a) The table in § 172.101 of this subchapter specifies generally the locations authorized for stowage of the various hazardous materials on board vessels. This part prescribes additional requirements with respect to the stowage of specific hazardous materials in addition to those authorized in § 172.101 of this subchapter. This section sets forth the basic physical requirements for the authorized locations. Hazardous materials offered for transport as limited quantities are allocated stowage category A and are not subject to any of the specific stowage requirements indicated in column 10B in § 172.101 of this subchapter for the material being transported.

(b) To qualify as “on deck” stowage, the location must be on the weather deck. If the location is in a house on the weather deck, the location must have a permanent structural opening to the atmosphere, such as a door, hatch, companionway or manhole, and must be vented to the atmosphere. The location may not have any structural opening to any living quarters, cargo, or other compartment unless the opening has means for being closed off and secured. Any deck house containing living quarters, a steering engine, a refrigerating unit, a refrigerated stowage box, or a heating unit may not be used unless that area is isolated from the cargo stowage area by a permanent, and tight, metallic bulkhead. Stowage in a shelter or 'tween deck is not considered to be “on deck”. A barge that is vented to the atmosphere and is stowed on deck on a barge-carrying ship is considered to be “on deck”. When an entry in § 172.101 of this subchapter requires “on-deck” stowage and is qualified by the requirement “protected from sources of heat”, the stowage must be protected from the direct rays of the sun by means of structural erections or awnings except that such protection is not required for shipment in portable tanks.

(c) To qualify as “under deck” stowage, the location must be in a hold or compartment below the weather deck capable of being ventilated and allotted entirely to the carriage of cargo. It must be bounded by permanent steel decks and bulkheads or the shell of the vessel. The deck openings must have means for effectively closing the hold or compartment against the weather, and in the case of superimposed holds, for effectively closing off each hold. A hold or compartment containing a crew passage formed by battens or by mesh or wire screen bulkhead may not be used for the stowage of any hazardous material unless a watchman is provided for this area.

(d) To qualify as “under deck away from heat”, the location must be under deck and have built-in means for ventilation. If it is subject to heat from any artificial source, it only qualifies for the stowage of those hazardous materials for which “under deck” stowage is authorized.

(e) Notwithstanding the stowage provisions given in the table in § 172.101 of this subchapter, empty packages containing residue, including IBCs and large packages, may be stowed “on deck” or “under deck” in a mechanically ventilated cargo space. However, empty pressure receptacles containing residue that carry a label of class 2.3 must be stowed “on deck” and waste aerosols must be stowed in accordance with the table in § 172.101 of this subchapter.

(f) Stowage of containers on board hatchless container ships. (1) Containers holding a hazardous material may be stowed in or vertically above a hatchless container hold if the following conditions are met:

(1) All hazardous materials are permitted for under deck stowage as specified in the Table in § 172.101 of this subchapter; and

(2) The hatchless container hold is in full compliance with the provisions of SOLAS, Chapter II-2/Regulation 19 (IBR; see § 171.7 of this subchapter), applicable to enclosed container cargo spaces, as appropriate for the cargo transported.