Oil tanker

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Ship image
Ship caption	The commercial oil tanker AbQaiq, in ballast

Name	Oil tanker
Subclasses	Handysize, Panamax, Aframax, Suezmax, Very Large Crude Carrier (VLCC), Ultra Large Crude Carrier (ULCC)
Built range	c. 1863–present
In service range	4,024 (above ).

Ship class	Tank ship
Ship capacity	up to
Ship notes	Rear house, full hull, midships pipeline

Ship image

|}

An oil tanker, also known as a petroleum tanker, is a ship designed for the bulk transport of oil. There are two basic types of oil tankers: the crude tanker and the product tanker. the average cost of oil transport by tanker amounts to only two or three United States cents per .]] The technology of oil transportation has evolved alongside the oil industry. Although man's use of oil reaches to prehistory, the first modern commercial exploitation dates back to James Young's manufacture of parafin in 1850. In these early days, oil from Upper Burma was moved in earthenware vessels to the river bank where it was then poured into boat holds.

In the 1850s, the Pennsylvania oil fields became a major supplier of oil, and a center of innovation after Edwin Drake had struck oil near Titusville, Pennsylvania. Within two years, the Titusville field was providing 3,000 barrels per day. Other problems with barrels were their expense, their tendency to leak, and the fact that they were generally used only once. The expense was significant, for example, in the early years of the Russian oil industry, barrels accounted for half the cost of petroleum production. These were followed in 1873 by the first oil-tank steamer, the Vaderland, which was built by Palmers Shipbuilding and Iron Company for Belgian owners. By 1871, the Pennsylvania oil fields were making limited use of oil tank barges and cylindrical railroad tank-cars similar to those in use today. Other challenges included allowing for the cargo to expand and contract due to temperature changes, and providing a method to ventilate the tanks.

In 1883, oil tanker design took a large step forward. Working for the Nobel company, Colonel Henry F. Swan designed a set of three Nobel tankers. Instead of one or two large holds, Swan's design used several holds which spanned the width, or beam, of the ship. But this approach of dividing the ship's storage space into smaller tanks virtually eliminated free-surface problems. The first seagoing diesel-powered tanker, 4,500 ton Mysl, was built by Nobel's competitors in Kolomna. Nobel responded with Emanuel Nobel and Karl Hagelin, 4,600 long ton kerosene tankers with engines.

on Fire Island.]]The Glückauf represented a large step forward in tanker design. Another design of Colonel Swan, the ship has been called the "true progenitor of all subsequent tanker tonnage." The idea that led to moving Russian oil to the Far East via the Suez Canal was the brainchild of two men: importer Marcus Samuel and shipowner/broker Fred Lane. A large ship at the time, with a capacity of 14,500  long tons of deadweight, Maumee began refuelling destroyers en route to Britain at the outset of World War I.

During World War I, unrestricted submarine warfare caused a shortage of tankers. The United States ambassador to the United Kingdom, Walter Hines Page, wrote: :The submarines are sinking freight ships faster than freight ships are being built by the whole world. In this way, too, then, the Germans are succeeding. Now if this goes on long enough, the Allies' game is up. For instance, they have lately sunk so many fuel oil ships, that this country may very soon be in a perilous condition—even the Grand Fleet may not have enough fuel.

Georges Clemenceau wrote to US president Wilson :Gasoline is as vital as blood in the coming battles…a failure in the supply of gasoline would cause the immediate paralysis of our armies.

Wilson reacted strongly.

World War II

Oil tankers, particularly the T2 tanker, played an important part in World War II. The T2-SE-A1 with a capacity of 16,613 long tons of deadweight, was the most popular variant with nearly 500 built during the war. After the war, these tankers were used commercially for decades, and many were sold on the international market. A typical T2 tanker of the World War II era was long and had a capacity of . A modern ultra-large crude carrier (ULCC) can be long and have a capacity of . His Universe Apollo displaced 104,500 long tons, a 23% increase from the previous record-holder, Universe Leader which also belonged to Ludwig.

The world's largest supertanker ever was built in 1979 at the Oppama shipyard by Sumitomo Heavy Industries, Ltd. as the Seawise Giant. This ship was built with a capacity of , a length overall of and a draft of . She had 46 tanks, of deck, and was too large to pass through the English Channel. From 1979 to 2004, she was owned by Loki Stream, at which point she was bought by First Olsen Tankers, renamed Knock Nevis, and converted into a permanently moored storage tanker. In 2009, she was sold to an Indian Breaker Company, and renamed Mont. She was subsequently beached and scrapped.

As of 2008, the world's four largest working supertankers are the TI class supertankers, currently known as the TI Asia, TI Europe, TI Oceania, and TI Africa. These ships were built in 2002 and 2003 as the Hellespont Alhambra, Hellespont Metropolis, Hellespont Tara and Fairfax for the Greek Hellespont Steamship Corporation. Hellespont sold these ships to Overseas Shipholding Group and Euronav in 2004.

Each of the four sister ships has a capacity of over , a length overall of and a cargo capacity of . The first ULCC tankers to be built for some 25 years, they were also the first ULCCs to be double-hulled. In February 2008, their owners announced plans to convert TI Africa and the TI Asia into stationary floating storage and offloading units to be placed in the Al Shaheen oilfield near Qatar in late 2009. Worldwide, tankers carry some annually, and the cost of transportation by tanker amounts to only US$0.02 per gallon at the pump. | colspan="4" align="center" | Flexible market scale !Used
price |- |General Purpose tanker |align="right"|10,000–24,999 |Product tanker |align="right"|10,000–60,000 |rowspan="2" valign="center" align="right" |$43M |rowspan="2" valign="center" align="right" |$42.5M |- |Medium Range tanker |align="right"|25,000–44,999 |Panamax |align="right"|60,000–80,000 |- |LR1 (Large Range 1) |align="right"|45,000–79,999 |Aframax |align="right"|80,000–120,000 |rowspan="2" valign="center" align="right" |$58M |rowspan="2" valign="center" align="right" |$60.7M |- |LR2 (Large Range 2) |align="right"|80,000–159,999 |Suezmax |align="right"|120,000–200,000 |- |VLCC (Very Large Crude Carrier) |align="right"|160,000–319,999 |VLCC |align="right"|200,000–320,000 |rowspan="2" valign="center" align="right" |$120M |rowspan="2" valign="center" align="right" |$116M |- |ULCC (Ultra Large Crude Carrier) |align="right"|320,000–549,999 |Ultra Large Crude Carrier |align="right"|320,000–550,000 |} , which are the largest ocean-going ships in the world]] In 1954 Shell Oil developed the average freight rate assessment (AFRA) system which classifies tankers of different sizes. To make it an independent instrument, Shell consulted the London Tanker Brokers’ Panel (LTBP). At first, they divided the groups as General Purpose for tankers under ; Medium Range for ships between 25,000 and and Large Range for the then-enormous ships that were larger than . The ships became larger during the 1970s, which prompted rescaling.

Merchant oil tankers carry a wide range of hydrocarbon liquids ranging from crude oil to refined petroleum products. Their size is measured in deadweight metric tons (DWT). Crude carriers are among the largest, ranging from Panamax-sized vessels to ultra-large crude carriers (ULCCs) of over .

"Supertanker" is an informal term used to describe the largest tankers. Today it is applied to very-large crude carriers (VLCC) and ULCCs with capacity over . These ships can transport two million barrels of oil.

Because of their great size, supertankers often can not enter port fully loaded.

Chartering

, in Rio de Janeiro, Brazil.]] The act of hiring a ship to carry cargo is called chartering. Tankers are hired by four types of charter agreements: the voyage charter, the time charter, the bareboat charter, and contract of affreightment. In a voyage charter, the charterer rents the vessel from the loading port to the discharge port. Finally, in a contract of affreightment, or COA, the charterer specifies a total volume of cargo to be carried in a specific time period and in specific sizes, for example a COA could be specified as "one million barrels of JP-5 in a year's time in 25,000 barrel shipments." A completed chartering contract is known as a charter party. The freight rate of a tanker charter party is specified in one of four ways: by a lump sum rate, by rate per ton, by a time charter equivalent rate, or by Worldscale rate. Rate per ton arrangements are used mostly in chemical tanker chartering, and differ from lump sum rates in that port costs and voyage expenses are generally paid by the charterer. Time charter arrangements specify a daily rate, and port costs and voyage expenses are also generally paid by the charterer. In Worldscale negotiations, operators and charterers will determine a price based on a percentage of the Worldscale rate. |$95,250 |$59,070 |$51,550 |- |Suezmax |Crude |West Africa –
Caribbean or
East Coast of North America |$64,800 |$47,500 |$46,000 |- |Aframax |Crude |Cross-Mediterranean |$43,915 |$39,000 |$31,750 |- |colspan="2"|All product carriers |Caribbean –
East Coast of North America
or Gulf of Mexico It was a good year across all segments of the tanker market segments, but not as good as 2004 and 2005.

Since 2003, the demand for new ships has started to grow, in 2007 resulting in a record breaking order backlog for shipyards, exceeding their capacity with rising newbuilding prices as a result.

Owners of large oil tanker fleets include Teekay Corporation, A P Moller Maersk, DS Torm, Frontline, MOL Tankship Management, Overseas Shipholding Group, and Euronav.

Fleet characteristics

{| class="toccolours" style="float:right; margin-left: 1em; margin-bottom: 1em; font-size: 85%;" |+Largest Tanker Operators The world's total oil tankers deadweight tonnage has increased from in 1970 to in 2005.

Cargo movement

In 2005, 2.42 billion metric tons of oil were shipped by tanker. 76.7% of this was crude oil, and the rest consisted of refined petroleum products.

By comparison, in 1970 1.44 billion metric tons of oil were shipped by tanker. This amounted to 34.1% of all seaborne trade for that year. In terms of amount carried and distance carried, oil tankers moved 6,487 billion metric-ton-miles of oil in 1970. In 2005, for each of oil tankers, 6.7 metric tons of cargo was carried. The main discharge ports were located in North America, Europe, and Japan with 537.7, 438.4, and 215.0 million metric tons of cargo discharged in these regions. A ship's flag state exercises regulatory control over the vessel and is required to inspect it regularly, certify the ship's equipment and crew, and issue safety and pollution prevention documents. As of 2007, the United States Central Intelligence Agency statistics count 4,295 oil tankers of or greater worldwide. Panama was the world's largest flag state for oil tankers, with 528 of the vessels in its registry. By way of comparison, the United States and the United Kingdom only had 59 and 27 registered oil tankers, respectively. Of these, 31.6% were under 4 years old and 14.3% were over 20 years old. In 2005, 475 new oil tankers were built, accounting for . The average size for these new tankers was . Ship-owners and buyers negotiate scrap prices based on factors such as the ship's empty weight (called light ton displacement or LDT) and prices in the scrap metal market. In 1998, almost 700 ships went through the scrapping process at shipbreakers in places like Alang, India and Chittagong, Bangladesh. In this same timeframe, tankers have accounted for between 56.5 and 90.5 of the world's total scrapped tonnage. In 1985, these vessels would have cost $18 million, $22 million, and $47 million respectively. Some representative prices for that year include $42.5M for a tanker, $60.7 million for a , $73 million for a , and $116 million for tanker. Each tank is split into two or three independent compartments by fore-and-aft bulkheads. Tankers generally have cofferdams forward and aft of the cargo tanks, and sometimes between individual tanks. A pumproom houses all the pumps connected to a tanker's cargo lines. Most newer tankers are double-hulled, with an extra space between the hull and the storage tanks.

In 1998, the Marine Board of the National Academy of Science conducted a survey of industry experts regarding the pros and cons of double-hull design. Some of the advantages of the double-hull design that were mentioned include ease of ballasting in emergency situations, reduced practice of saltwater ballasting in cargo tanks decreases corrosion, increased environmental protection, greater operating expenses (e.g. higher canal and port tariffs), and that cleaning ballast tanks is more difficult for double hull ships. The safety benefits are less clear on larger vessels and in cases of high speed impact.

Inert gas system

An oil tanker's inert gas system is one of the most important parts of its design. Fuel oil itself is very difficult to ignite, but its hydrocarbon vapors are explosive when mixed with air in certain concentrations. The purpose of the system is to create an atmosphere inside tanks in which the hydrocarbon oil vapors cannot burn. At the same time it decreases the upper flammable limit or highest concentration at which the vapors can be ignited.

Inert gas systems deliver air with an oxygen concentration of less than 5% by volume. The exception is in cases when the tank must be entered. Cargo can be moved on or off of an oil tanker in several ways. One method is for the ship to moor alongside a pier, connect with cargo hoses or marine loading arms. Another method involves mooring to offshore buoys, such as a single point mooring, and making a cargo connection via underwater cargo hoses. A third method is by ship-to-ship transfer, also known as lightering. In this method, two ships come alongside in open sea and oil is transferred manifold to manifold via flexible hoses. Lightering is sometimes used where a loaded tanker is too large to enter a specific port. The next step before a transfer is the pretransfer conference. The pretransfer conference covers issues such as what products will be moved, the order of movement, names and titles of key people, particulars of shipboard and shore equipment, critical states of the transfer, regulations in effect, emergency and spill-containment procedures, watch and shift arrangements, and shutdown procedures. securing of all connections, The first step in the operation is following the same pretransfer procedures as used in loading. When the transfer begins, it is the ship's cargo pumps that are used to move the product ashore. While pumping, tank levels are carefully watched and key locations, such as the connection at the cargo manifold and the ship's pumproom are constantly monitored.

On most crude-oil tankers, a special crude oil washing (COW) system is part of the cleaning process. After a tank is gas-free, it may be further hand-cleaned in a manual process known as mucking. Mucking requires protocols for entry into confined spaces, protective clothing, designated safety observers, and possibly the use of airline respirators. Prior to underway replenishment, naval vessels had to enter a port or anchor to take on fuel. This design was intended to provide flexibility in two ways. Firstly, an OBO would be able to shift between the dry and wet bulk trades based on market conditions.

In practice, the flexibility which the OBO design allows has gone largely unused, as these ships tend to specialize in either the liquid or dry bulk trade. These floating units reduce oil production costs and offer mobility, large storage capacity, and production versatility. An example of a FSO that used to be an oil tanker is the Knock Nevis. These units are usually moored to the seabed through a spread mooring system.]]

Oil spills have devastating effects on the environment. Crude oil contains polycyclic aromatic hydrocarbons (PAHs) which are very difficult to clean up, and last for years in the sediment and marine environment. Marine species constantly exposed to PAHs can exhibit developmental problems, susceptibility to disease, and abnormal reproductive cycles.

By the sheer amount of oil carried, modern oil tankers must be considered a threat to the environment. As discussed above, a VLCC tanker can carry of crude oil, or 84,000,000 gallons. This is about eight times the amount spilled in the widely known Exxon Valdez incident. In this spill, the ship ran aground and dumped of oil into the ocean in March 1989. Despite efforts of scientists, managers, and volunteers over 400,000 seabirds, about 1,000 sea otters, and immense numbers of fish were killed. On the other hand, only 5% of the actual spills came from oil tankers, while 51.8% came from other kinds of vessels. According to this study, most spills result from routine operations such as loading cargo, discharging cargo, and taking on fuel oil.

Air pollution

Jupiter, a gasoline tanker.]]

Air pollution from normal tanker engines operation and from cargo fires is another serious concern. Large ships are often run on low quality fuel oils, such as bunker oil which are highly polluting and have been shown to be a health risk. Ship fires may not only result in the loss of the ship due to lack of specialized firefighting gear and techniques but the fires sometimes burn for days and require evacuations of nearby residents due to the dangerous smoke.

See also

List of tankers

List of oil spills

List of replenishment ships of the Royal Fleet Auxiliary

List of Type T2 Tanker names

Marine transfer operations

Merchant vessel

Petroleum rapid transit

References

Notes

Bibliography

Further reading

External links

Bill Willis. Supertankers

Intertanko—the society of International Tanker Operators

The International Maritime Organization—Tanker Safety (for double-hulls)

Ship photos of tankers, ULCCs, VLCCs, barges

Information on crude oil tankers and other forms of oil transport

Category:Tankers Category:Ship types Category:American inventions Category:Swedish inventions Category:Russian inventions