Oil tankers of 150 gross tons and above must be provided with slop tanks.
For ships built before 31st December 1979, any cargo tank may be designated as slop tank.
Adequate means shall be provided for cleaning the cargo tanks and transferring the dirty ballast residue and tank washings from the cargo tanks into a slop tank approved by the Administration.
The arrangement of slop tank shall have a capacity necessary to retain the slop generated by tank washings, oil residues or dirty ballast residues and the total capacity shall not be less than 3% of the oil carrying capacity.