7.5 Ballast Piping and Valves
7.5.1 Ballast Piping arrangements - General
Suctions in ballast tanks are to be so arranged that the tanks can be emptied under all practical conditions. For ballast tanks with flat bottoms and width exceeding half of the vessel’s beam, wing suctions are to be provided. The diameter of ballast piping is to be sized at least as specified for bilge branch pipe in accordance with 4-6-4/5.5.1(d).
7.5.2 Ballast Tank Valves
Valves controlling flow to ballast tanks are to be arranged so that they will remain closed at all times except when ballasting. Where butterfly valves are used, they are to be of a type with positive holding arrangements, or equivalent, that will prevent movement of the valve position due to vibration or flow of fluids.