(1) Drums, containers, or hollow structures which have contained toxic or flammable substances must, before welding, cutting, or heating is undertaken on them, either be filled with water or thoroughly cleaned of such substances and ventilated and tested.

(2) Before heat is applied to a drum, container, or hollow structure, a vent or opening must be provided for the release of any built-up pressure during the application of heat.

(3) Before welding, cutting, heating or brazing is begun on structural voids such as skegs, bilge keels, fair waters, masts, booms, support stanchions, pipe stanchions or railings, a competent person must inspect the object and, if necessary, test it for the presence of flammable liquids or vapors. If flammable liquids or vapors are present, the object must be made safe.

(4) Objects such as those listed in (3) of this section must also be inspected to determine whether water or other nonflammable liquids are present which, when heated, would build up excessive pressure. If such liquids are determined to be present, the object must be vented, cooled, or otherwise made safe during the application of heat.

(5) Jacketed vessels must be vented before and during welding, cutting or heating operations in order to release any pressure which may build up during the application of heat.