A tanker that transports crude oil or petrochemical products can be classified into product carriers and crude oil carriers. A product carrier transports different products in each cargo hold, and so each cargo hold must be cleaned for the safe transportation of cargo and the prevention of product pollution. 

For a tanker, cleaning machines clean each cargo hold after SW or FW reaches temperatures higher than 70~80℃ for cleaning the remaining oil and residue in tanks to preserve the different types of oil after unloading the oil.