An oil tanker, also known as a crude carrier, is a ship designed to carry crude oil or its petroleum products in bulk. There are two main types of oil tankers: crude oil tankers and product tankers. Crude oil tankers carry large volumes of unrefined crude oil from its point of production to refineries. Product tankers, typically much smaller, are designed to carry refined petroleum products from refineries to points near consumer markets.
Oil tankers are often classified by size as well as by type of activity. Size classes range from inland or coastal tankers of a few thousand metric tons deadweight (DWT) to ultra-large crude carriers (ULCCs) of 550,000 DWT. Tankers carry about 2.0 billion metric tons (2.2 billion short tons) of oil each year. Second only to pipelines in efficiency, the average cost of transporting crude oil by tanker is only US$5–8 per cubic metre ($0.02–0.03 per US gallon). Some specialized types of oil tankers have evolved. One is the naval replenishment tanker, a tanker that can refuel a moving ship. Combination ore-tanker-oil carriers and permanently moored floating storage vessels are two other variations on the standard oil tanker design. Oil tankers have been involved in a number of destructive and high-profile oil spills.
