An oil tanker is a ship designed for the carriage of oil in bulk; its cargo space consists of several or many separate holds. Tankers load their cargo from the shore by gravity or via shore pumps, and discharge using their own pumps. There are many size categories: handy, panamax, aframax, suezmax, VLCC (Very Large Crude Carrier) and ULCC (Ultra Large Crude Carrier).
Although oil tankers are designed to carry crude oil, they are also suitable for other types of cargo, e.g., refined products such as gasoline, aviation fuel, kerosene and paraffin.
Oil tankers are designed with several separate holds to carry their cargo. These vessels are subject to many IMO regulations and all new oil tankers must be double hulled. Typically, ballast tanks and cofferdams surround the cargo holds, offering extra protection. Oil tankers are fitted with inert gas systems in order to create a non-explosive atmosphere inside the holds.
Many factors must be taken into account: navigational scope and zone, type of cargo and dimensions. As refined products occupy less volume than unrefined oil, smaller tankers are usually used to transport refined petrochemicals, while larger tankers carry unrefined crude oil to the refineries.
