Section 30(3)(a) in The Merchant Shipping (Cargo Ship Construction And Survey) Rules, 1974
(a)In every ship, every pipe connected to any oil fuel storage, settling or daily service tank, not being a double bottom tank, which, if damaged, would permit discharge of contents so as to cause a fire hazard, shall be fitted with a valve or cock which shall be secured to the tank to which it is connected and be capable of being closed from a readily accessible position outside the space in which the tank is situated :