Sludge tank

A sludge tank stores the oily residues separated from fuel and lube oil, the drainings from purifiers, filters, and drip trays, and the settled bottoms of the bunker tanks, pending incineration or landing ashore. It is steam-heated to keep the sludge pumpable, sloped to a suction well, and fitted to feed the incinerator burner or a discharge connection to a shore reception facility, with the transfers recorded in the Oil Record Book under MARPOL Annex I. The tank capacity and its piping are set by MARPOL Annex I Reg 12 on oil residue (sludge) tanks, which bars direct overboard discharge.