Section 26(6) in The Merchant Shipping (Prevention of Pollution by Oil from Ships) Rules, 2010
(6)Lines of piping which run through cargo tanks in a position less than tc from the ship's side or less than Vc from the ship's bottom shall be fitted with valves or closing devices at the point at which they open into any cargo tank and these valves shall be kept closed at sea at any time when the tanks contain cargo oil, except that they may be opened only for cargo transfer needed for the purpose of trimming of the ship.
