Crude oil washing
COW
Meaning
Crude oil washing (COW) cleans a crude tanker's cargo tanks during discharge by spraying them with the cargo itself to dislodge residues.
Crude oil washing explained
High-pressure machines spray crude onto tank surfaces, washing sludge and waxy residues down to be pumped ashore with the cargo. That increases the cargo delivered and reduces what remains on board.
COW takes extra time during discharge. Charters usually allow extra hours for it in the pumping warranty and laytime when it is required.
Related terms
Remaining on board
Remaining on board (ROB) is cargo left in a tanker's tanks after discharge; on-board quantity (OBQ) is residue already in the tanks before loading.
Pumping warranty
A pumping warranty is the owner's promise that the ship can discharge its full cargo within a set time or maintain a set pressure at the manifold.
Inert gas system
An inert gas system (IGS) fills a tanker's cargo tanks with low-oxygen gas so the hydrocarbon vapours above the cargo cannot ignite.
Slops
Slops are the oily water mixtures from tank washing and cargo residues, collected in a tanker's slop tanks for disposal or for loading on top.