Oil Tanker
As their name suggests, tankers are mammoth floating tanks that transport liquid cargo such as petroleum and natural gas. A tanker has several individual compartments inside the main body, allowing it to carry thousands of tons of petroleum. Under the Oil Pollution Act of 1990, passed by the United States Congress, tankers with single hulls are to be gradually phased out and replaced by double-hulled tankers. Single-hulled tankers have been responsible for devastating oil spills that have polluted beaches and killed marine life. Under the legislation, only tankers with double hulls will be able to enter U.S. waters by the year 2015.
As their name suggests, tankers are mammoth floating tanks that transport liquid cargo such as petroleum and natural gas. A tanker has several individual compartments inside the main body, allowing it to carry thousands of tons of petroleum. Under the Oil Pollution Act of 1990, passed by the United States Congress, tankers with single hulls are to be gradually phased out and replaced by double-hulled tankers. Single-hulled tankers have been responsible for devastating oil spills that have polluted beaches and killed marine life. Under the legislation, only tankers with double hulls will be able to enter U.S. waters by the year 2015.
The increasing global dependence on petroleum products—from gasoline, kerosene, and diesel to plastics and chemicals—has made petroleum tankers the largest ships afloat. The world’s tanker fleet doubled in number and tripled in tonnage between 1939 and 1959. Tankers are essentially giant holding tanks, or sometimes a series of tanks, shaped like ships and powered by engines. They are equipped with sophisticated piping systems for loading and unloading their contents, fire control systems, navigation equipment, control rooms, and crew quarters.
1.Crude Carriers
Crude carriers transport crude oil from oil wells in the Persian Gulf, Alaskan waters, the North Sea, and other oilfields to oil refineries, where it is converted into useful petroleum products. The largest tankers afloat are called ultra large crude carriers (ULCCs). These enormous ships hold more than 300,000 tons and extend well over 300 m (1,000 ft) in length. ULCCs are so large they cannot pass through the Suez and Panama canals, nor can they enter most harbors. Instead, most ULCCs unload into smaller tankers at offshore pumping stations. Comparing the size of a ULCC with the Titanic illustrates the size of these giant ships. The Titanic measured just over 268 m (880 ft) in length and 46,328 tons. The Batillus, a ULCC built in 1976, stretches 414 m (1,358 ft) and holds 275,267 tons, five times more than the Titanic.
2. Product Tankers
Product tankers carry refined petroleum products from oil refineries to ports around the world, where the products are transferred to trucks and rail cars to be distributed to consumers. Product tankers are much smaller than the crude carriers; the most recent are only around 20,000 tons and just short of 180 m (600 ft) long. Besides being smaller than crude carriers, products tankers are more complex. Instead of consisting of a single giant tank, they feature multiple tanks that can carry a variety of refined products.
3. Other Specialized Tankers
Other specialized tankers include chemical tankers, liquefied gas carriers, and ore/bulk/oil carriers. Chemical tankers carry various chemicals from port to port. Liquefied gas carriers transport natural gas and petroleum gas. These products are carried in a liquefied form rather than as gases because liquids take up less space than the same amount of gas. To maintain their cargo in liquid form, liquefied gas carriers hold cargo under pressure and at very low temperatures to prevent it from vaporizing. They are constructed of special types of steel that can withstand the stresses of pressure and cold. Ore/bulk/oil carriers, or OBOs, are versatile ships that can perform as tankers but carry several cargoes at once. The first OBO was put in service in 1985. Most are of panamax size, meaning that they are not too large to pass through the Panama Canal.
4. Tanker Safety
Tankers of all kinds carry potentially dangerous cargo, and a few have caused environmental disasters of tragic proportions. The 1967 wreck of the oil tanker Torrey Canyon devastated the marine environment off the coast of Great Britain. In 1989 the American oil tanker Exxon Valdez ran aground in Prince William Sound, Alaska, eventually coating 1,770 km (1,100 mi) of the Alaskan coastline with deadly crude oil. These and other devastating oil spills have led to international discussions about whether to institute regulations requiring that oil tankers have double hulls. In particularly sensitive areas, regional governments may require that small local pilot boats captained by sailors familiar with underwater topography accompany tankers when they reach coastal waters.
1.Crude Carriers
Crude carriers transport crude oil from oil wells in the Persian Gulf, Alaskan waters, the North Sea, and other oilfields to oil refineries, where it is converted into useful petroleum products. The largest tankers afloat are called ultra large crude carriers (ULCCs). These enormous ships hold more than 300,000 tons and extend well over 300 m (1,000 ft) in length. ULCCs are so large they cannot pass through the Suez and Panama canals, nor can they enter most harbors. Instead, most ULCCs unload into smaller tankers at offshore pumping stations. Comparing the size of a ULCC with the Titanic illustrates the size of these giant ships. The Titanic measured just over 268 m (880 ft) in length and 46,328 tons. The Batillus, a ULCC built in 1976, stretches 414 m (1,358 ft) and holds 275,267 tons, five times more than the Titanic.
2. Product Tankers
Product tankers carry refined petroleum products from oil refineries to ports around the world, where the products are transferred to trucks and rail cars to be distributed to consumers. Product tankers are much smaller than the crude carriers; the most recent are only around 20,000 tons and just short of 180 m (600 ft) long. Besides being smaller than crude carriers, products tankers are more complex. Instead of consisting of a single giant tank, they feature multiple tanks that can carry a variety of refined products.
3. Other Specialized Tankers
Other specialized tankers include chemical tankers, liquefied gas carriers, and ore/bulk/oil carriers. Chemical tankers carry various chemicals from port to port. Liquefied gas carriers transport natural gas and petroleum gas. These products are carried in a liquefied form rather than as gases because liquids take up less space than the same amount of gas. To maintain their cargo in liquid form, liquefied gas carriers hold cargo under pressure and at very low temperatures to prevent it from vaporizing. They are constructed of special types of steel that can withstand the stresses of pressure and cold. Ore/bulk/oil carriers, or OBOs, are versatile ships that can perform as tankers but carry several cargoes at once. The first OBO was put in service in 1985. Most are of panamax size, meaning that they are not too large to pass through the Panama Canal.
4. Tanker Safety
Exxon Valdez Oil Spill Cleanup
Workers wash the shoreline on Latouche Island, Alaska, after the Exxon Valdez oil tanker ran aground in 1989, dumping more than 38 million liters (more than 10 million gallons) of oil into Prince William Sound. The resulting environmental damage prompted the United States Congress to pass federal safety requirements for oil tankers and barges and to assign the principal cost of spill cleanup to oil companies.
Workers wash the shoreline on Latouche Island, Alaska, after the Exxon Valdez oil tanker ran aground in 1989, dumping more than 38 million liters (more than 10 million gallons) of oil into Prince William Sound. The resulting environmental damage prompted the United States Congress to pass federal safety requirements for oil tankers and barges and to assign the principal cost of spill cleanup to oil companies.
Tankers of all kinds carry potentially dangerous cargo, and a few have caused environmental disasters of tragic proportions. The 1967 wreck of the oil tanker Torrey Canyon devastated the marine environment off the coast of Great Britain. In 1989 the American oil tanker Exxon Valdez ran aground in Prince William Sound, Alaska, eventually coating 1,770 km (1,100 mi) of the Alaskan coastline with deadly crude oil. These and other devastating oil spills have led to international discussions about whether to institute regulations requiring that oil tankers have double hulls. In particularly sensitive areas, regional governments may require that small local pilot boats captained by sailors familiar with underwater topography accompany tankers when they reach coastal waters.
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