Regulations 15-1.1 to 15-1.3 apply to cargo ships which are subject to the damage
stability analysis required in part B-1 or other IMO instruments.
Regulation 15-1.1
With regard to air-pipe closing devices, they should be considered weathertight closing
devices (not watertight). This is consistent with their treatment in regulation
7-2.5.2.1. However, in the context of regulation 15-1, "external openings" are not
intended to include air-pipe openings.