9.3.4(b) Termination on or above freeboard deck. To prevent possible sources of progressive flooding to otherwise intact spaces below the freeboard deck, vent outlets from double bottom and other structural tanks, including void tanks, whose boundaries extend to the shell of the vessel at or below the deepest load waterline, are to be led above the freeboard deck.
9.3.4(c) Termination in machinery space. Vents from tanks other than those stated in 4-6-4/9.3.4(a) and 4-6-4/9.3.4(b) may terminate within the machinery space, provided that their outlets are so located that overflow therefrom will not impinge on electrical equipment, cause a hazardous consequence such as fire, or endanger personnel.
9.3.5 Protection of Vent Outlets
9.3.5(a) Protection from weather and sea water ingress All vents terminating in the weather are to be fitted with return bends (gooseneck), or equivalent, and the vent outlet is to be provided with an automatic means of closure, i.e., close automatically upon submergence (e.g., ball float or equivalent) complying with 4-6-4/9.3.7. 9.3.5(b) Protection for fuel oil tanks. In addition to 4-6-4/9.3.5(a), vents from fuel oil tanks are to comply with the following: