Section 12(1) in The Merchant Shipping (Prevention of Pollution by Oil from Ships) Rules, 2010
(1)Every ship of four hundred gross tonnage and above shall be provided with a tank or tanks of adequate capacity, having regard to the type of machinery and length of voyage, to receive the oil residues or sludge, such as those resulting from' the purification of fuel and lubric acting oils and oil leakages in the machinery spaces, which cannot be dealt otherwise in accordance with the requirements of these rules.
