Section 30(3)(b) in The Merchant Shipping (Cargo Ship Construction And Survey) Rules, 1974
(b)Every such pipe connected to an oil fuel deep-tank transversed by any shaft or pipe tunnel, in addition to the valve to be fitted to the tank under the requirements of Cl. (a), a valve or valves may be fitted on the pipe line or lines outside the tunnel or tunnels to enable control to be exercised in the event of fire.