Section 28(3)(e) in The Merchant Shipping (Prevention of Pollution by Oil from Ships) Rules, 2010
(e)equalisation arrangements requiring mechanical aids, such as valves or cross-levelling pipes, if fitted, shall not be considered for the purpose of reducing an angle of heel or attaining the minimum range of residual stability to meet the requirements of clauses (a), (b) and (c) above and sufficient residual stability shall be maintained during all stages where equalization is used and spaces which are linked by ducts of a large cross-sectional area may be considered to be common.