Section 12A(11)(b) in The Merchant Shipping (Prevention of Pollution by Oil from Ships) Rules, 2010
(b)the following general assumption shall apply when calculating the mean oil outflow parameter, namely:-(i)the ship shall be assumed loaded to the partial load line draught dp without trim or heel;(ii)all oil fuel tanks shall be assumed loaded to 98% of their volumetric capacity;(iii)the nominal density of the oil fuel (pn) shall generally be taken as 1,000 kg/m3 and if the density of the oil fuel is specifically restricted to a lesser value, the lesser value may be applied; and(iv)for the purpose of these outflow calculations, the permeability of each oil fuel tank shall be taken as 0.99, unless proven otherwise;