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A tanker (or tank ship or tankship) is a
ship A ship is a large watercraft, vessel that travels the world's oceans and other Waterway, navigable waterways, carrying cargo or passengers, or in support of specialized missions, such as defense, research and fishing. Ships are generally disti ...
designed to transport or store
liquids Liquid is a state of matter with a definite volume but no fixed shape. Liquids adapt to the shape of their container and are nearly incompressible, maintaining their volume even under pressure. The density of a liquid is usually close to th ...
or gases in bulk. Major types of tanker ship include the
oil tanker An oil tanker, also known as a petroleum tanker, is a ship designed for the bulk cargo, bulk transport of petroleum, oil or its products. There are two basic types of oil tankers: crude tankers and product tankers. Crude tankers move large quant ...
(or petroleum tanker), the chemical tanker, cargo ships, and a gas carrier. Tankers also carry commodities such as vegetable oils,
molasses Molasses () is a viscous byproduct, principally obtained from the refining of sugarcane or sugar beet juice into sugar. Molasses varies in the amount of sugar, the method of extraction, and the age of the plant. Sugarcane molasses is usuall ...
and wine. In the
United States Navy The United States Navy (USN) is the naval warfare, maritime military branch, service branch of the United States Department of Defense. It is the world's most powerful navy with the largest Displacement (ship), displacement, at 4.5 millio ...
and
Military Sealift Command The Military Sealift Command (MSC) is an organization that controls the replenishment and military transport ships of the United States Navy. Military Sealift Command has the responsibility for providing sealift and ocean transportation for all U ...
, a tanker used to refuel other ships is called an oiler (or
replenishment oiler A replenishment oiler or replenishment tanker is a naval auxiliary ship with fuel tanks and dry cargo holds which can supply both fuel and dry stores during underway replenishment (UNREP) at sea. Many countries have used replenishment oilers. Th ...
if it can also supply dry stores) but many other navies use the terms tanker and replenishment tanker. Tankers were first developed in the late 19th century as iron and steel hulls and pumping systems were developed. As of 2005, there were just over 4,000 tankers and supertankers or greater operating worldwide.


Description

Tankers can range in size of capacity from several hundred tons, which includes vessels for servicing small harbours and coastal settlements, to several hundred thousand tons, for long-range haulage. Besides ocean- or seagoing tankers there are also specialized inland-waterway tankers which operate on rivers and canals with an average
cargo In transportation, cargo refers to goods transported by land, water or air, while freight refers to its conveyance. In economics, freight refers to goods transported at a freight rate for commercial gain. The term cargo is also used in cas ...
capacity up to some thousand tons. A wide range of products are carried by tankers, including: *
Hydrocarbon In organic chemistry, a hydrocarbon is an organic compound consisting entirely of hydrogen and carbon. Hydrocarbons are examples of group 14 hydrides. Hydrocarbons are generally colourless and Hydrophobe, hydrophobic; their odor is usually fain ...
products such as oil,
liquefied petroleum gas Liquefied petroleum gas, also referred to as liquid petroleum gas (LPG or LP gas), is a fuel gas which contains a flammable mixture of hydrocarbon gases, specifically propane, Butane, ''n''-butane and isobutane. It can also contain some ...
(LPG), and
liquefied natural gas Liquefied natural gas (LNG) is natural gas (predominantly methane, CH4, with some mixture of ethane, C2H6) that has been cooled to liquid form for ease and safety of non-pressurized storage or transport. It takes up about 1/600th the volume o ...
(LNG) * Chemicals, such as
ammonia Ammonia is an inorganic chemical compound of nitrogen and hydrogen with the chemical formula, formula . A Binary compounds of hydrogen, stable binary hydride and the simplest pnictogen hydride, ammonia is a colourless gas with a distinctive pu ...
,
chlorine Chlorine is a chemical element; it has Symbol (chemistry), symbol Cl and atomic number 17. The second-lightest of the halogens, it appears between fluorine and bromine in the periodic table and its properties are mostly intermediate between ...
, and styrene monomer *
Fresh water Fresh water or freshwater is any naturally occurring liquid or frozen water containing low concentrations of dissolved salt (chemistry), salts and other total dissolved solids. The term excludes seawater and brackish water, but it does include ...
*
Wine Wine is an alcoholic drink made from Fermentation in winemaking, fermented fruit. Yeast in winemaking, Yeast consumes the sugar in the fruit and converts it to ethanol and carbon dioxide, releasing heat in the process. Wine is most often made f ...
*
Molasses Molasses () is a viscous byproduct, principally obtained from the refining of sugarcane or sugar beet juice into sugar. Molasses varies in the amount of sugar, the method of extraction, and the age of the plant. Sugarcane molasses is usuall ...
* Citrus juice Tankers primarily date from the later years of the 19th century. Before this, technology had simply not supported the idea of carrying bulk liquids. The market was also not geared towards transporting or selling cargo in bulk, therefore most ships carried a wide range of different products in different holds and traded outside fixed routes. Liquids were usually loaded in casks—hence the term "
tonnage Tonnage is a measure of the capacity of a ship, and is commonly used to assess fees on commercial shipping. The term derives from the taxation paid on '' tuns'' or casks of wine. In modern maritime usage, "tonnage" specifically refers to a cal ...
", which refers to the volume of the holds in terms of how many tuns or casks of wine could be carried. Even potable water, vital for the survival of the crew, was stowed in casks. Carrying bulk liquids in earlier ships posed several problems: *The holds: on timber ships the holds were not sufficiently water, oil or air-tight to prevent a liquid cargo from spoiling or leaking. The development of iron and steel hulls solved this problem. *Loading and discharging: Bulk liquids must be pumped - the development of efficient pumps and piping systems was vital to the development of the tanker. Steam engines were developed as prime-movers for early pumping systems. Dedicated cargo handling facilities were now required ashore too - as was a market for receiving a product in that quantity. Casks could be unloaded using ordinary cranes, and the awkward nature of the casks meant that the volume of liquid was always relatively small - therefore keeping the market more stable. * Free surface effect: a large body of liquid carried aboard a ship will affect the ship's stability, particularly when the liquid is flowing around the hold or tank in response to the ship's movements. The effect was negligible in casks, but could cause capsizing if the tank extended the width of the ship; a problem solved by extensive subdivision of the tanks. Tankers were first used by the oil industry to transfer refined fuel in bulk from refineries to customers. This would then be stored in large tanks ashore, and subdivided for delivery to individual locations. The use of tankers caught on because other liquids were also cheaper to transport in bulk, store in dedicated terminals, then subdivide. Even the
Guinness Guinness () is a stout that originated in the brewery of Arthur Guinness at Guinness Brewery, St. James's Gate, Dublin, Ireland, in the 18th century. It is now owned by the British-based Multinational corporation, multinational alcoholic bever ...
brewery used tankers to transport the stout across the
Irish Sea The Irish Sea is a body of water that separates the islands of Ireland and Great Britain. It is linked to the Celtic Sea in the south by St George's Channel and to the Inner Seas off the West Coast of Scotland in the north by the North Ch ...
. Different products require different handling and transport, with specialised variants such as " chemical tankers", "
oil tanker An oil tanker, also known as a petroleum tanker, is a ship designed for the bulk cargo, bulk transport of petroleum, oil or its products. There are two basic types of oil tankers: crude tankers and product tankers. Crude tankers move large quant ...
s", and "
LNG carrier An LNG carrier is a tank ship designed for transporting liquefied natural gas (LNG). Overview The first oceangoing liquified natural gas tanker in the world was '' Methane Pioneer'', which entered service in 1959 with a carrying capacity of ...
s" developed to handle dangerous chemicals, oil and oil-derived products, and
liquefied natural gas Liquefied natural gas (LNG) is natural gas (predominantly methane, CH4, with some mixture of ethane, C2H6) that has been cooled to liquid form for ease and safety of non-pressurized storage or transport. It takes up about 1/600th the volume o ...
respectively. These broad variants may be further differentiated with respect to ability to carry only a single product or simultaneously transport mixed cargoes such as several different chemicals or refined petroleum products. Among oil tankers, supertankers are designed for transporting oil around the
Horn of Africa The Horn of Africa (HoA), also known as the Somali Peninsula, is a large peninsula and geopolitical region in East Africa.Robert Stock, ''Africa South of the Sahara, Second Edition: A Geographical Interpretation'', (The Guilford Press; 2004), ...
from the
Middle East The Middle East (term originally coined in English language) is a geopolitical region encompassing the Arabian Peninsula, the Levant, Turkey, Egypt, Iran, and Iraq. The term came into widespread usage by the United Kingdom and western Eur ...
. The supertanker
Seawise Giant TT ''Seawise Giant''—earlier ''Oppama''; later ''Happy Giant'', ''Jahre Viking'', ''Knock Nevis'', and ''Mont''—was a Oil tanker, ULCC supertanker and the longest self-propelled ship in history. It was built in 1974–1979 by Sumitomo Heavy ...
, scrapped in 2010, was in length and wide. Supertankers are one of the three preferred methods for transporting large quantities of oil, along with
pipeline transport A pipeline is a system of Pipe (fluid conveyance), pipes for long-distance transportation of a liquid or gas, typically to a market area for consumption. The latest data from 2014 gives a total of slightly less than of pipeline in 120 countries ...
and rail.


Regulations

Tighter regulation means that tankers now cause fewer environmental disasters resulting from
oil spill An oil spill is the release of a liquid petroleum hydrocarbon into the environment, especially the marine ecosystem, due to human activity, and is a form of pollution. The term is usually given to marine oil spills, where oil is released into th ...
s than in the 1970s. ''
Amoco Cadiz ''Amoco Cadiz'' was an oil tanker owned by Amoco, Amoco Transport Corp and transporting crude oil for Royal Dutch Shell, Shell Oil. Operating under the Liberian flag, she ran aground on 16 March 1978 on Portsall, Portsall Rocks, from the coast ...
'', , '' Erika'', '' Exxon Valdez'', ''
Prestige Prestige may refer to: Arts, entertainment and media Films *Prestige (film), ''Prestige'' (film), a 1932 American film directed by Tay Garnett: woman travels to French Indochina to meet up with husband *The Prestige (film), ''The Prestige'' (fi ...
'' and were examples of accidents. Oil spills from tankers amounted to around 1,000 tonnes in 2020 from three incidents (an all-time low), down from 636,000 tonnes from 92 incidents in 1979 - a fall of 99.8%. For ships internationally, the regulations of the
International Maritime Organization The International Maritime Organization (IMO; ; ) is a List of specialized agencies of the United Nations, specialized agency of the United Nations responsible for regulating maritime transport. The IMO was established following agreement at a ...
apply, specifically Annex I, prevention of pollution by oil under
MARPOL 73/78 The International Convention for the Prevention of Pollution from Ships, 1973 as modified by the Protocol of 1978, or "MARPOL 73/78" (short for "marine pollution") is one of the most important international marine environmental conventions. It ...
and rules for construction under the SOLAS Convention. These include requirements for
inert gas An inert gas is a gas that does not readily undergo chemical reactions with other chemical substances and therefore does not readily form chemical compounds. Though inert gases have a variety of applications, they are generally used to prevent u ...
systems designed to supply inert gas to cargo tanks to prevent an explosive atmosphere from being present. For tankers that are either operate in
United States The United States of America (USA), also known as the United States (U.S.) or America, is a country primarily located in North America. It is a federal republic of 50 U.S. state, states and a federal capital district, Washington, D.C. The 48 ...
waters or are owned by US based companies, rules govern their design, construction and operation. Specifically under the US
Code of Federal Regulations In the law of the United States, the ''Code of Federal Regulations'' (''CFR'') is the codification of the general and permanent regulatory law, regulations promulgated by the executive departments and agencies of the federal government of the ...
Title 33 - Navigation and Navigable Waters, Title 40 - Protection of Environment, Title 46 - Shipping, Title 47 - Telecommunication and Title 49 - Transportation.


Design and operational considerations

Many modern tankers are designed for a specific cargo and a specific route.
Draft Draft, the draft, or draught may refer to: Watercraft dimensions * Draft (hull), the distance from waterline to keel of a vessel * Draft (sail), degree of curvature in a sail * Air draft, distance from waterline to the highest point on a v ...
is typically limited by the depth of water in loading and unloading harbors; and may be limited by the depth of
strait A strait is a water body connecting two seas or water basins. The surface water is, for the most part, at the same elevation on both sides and flows through the strait in both directions, even though the topography generally constricts the ...
s or
canal Canals or artificial waterways are waterways or engineered channels built for drainage management (e.g. flood control and irrigation) or for conveyancing water transport vehicles (e.g. water taxi). They carry free, calm surface ...
s along the preferred shipping route. Cargoes with high
vapor pressure Vapor pressure or equilibrium vapor pressure is the pressure exerted by a vapor in thermodynamic equilibrium with its condensed phases (solid or liquid) at a given temperature in a closed system. The equilibrium vapor pressure is an indicat ...
at ambient temperatures may require pressurized tanks or vapor recovery systems. Tank heaters may be required to maintain heavy crude oil, residual fuel, asphalt, wax, or
molasses Molasses () is a viscous byproduct, principally obtained from the refining of sugarcane or sugar beet juice into sugar. Molasses varies in the amount of sugar, the method of extraction, and the age of the plant. Sugarcane molasses is usuall ...
in a fluid state for offloading. Designs will vary by the type of tanker. For oil tankers, systems will need to be in place to manage operational hazards, including a means of producing and introducing inert gas into cargo tanks to prevent explosion. Cargo tanks are typically fitted with the ability to monitor levels of liquid within a tank, as well as an overfill or high level alarm function. For Gas carriers, including
LNG carrier An LNG carrier is a tank ship designed for transporting liquefied natural gas (LNG). Overview The first oceangoing liquified natural gas tanker in the world was '' Methane Pioneer'', which entered service in 1959 with a carrying capacity of ...
s, gas design cargo containment systems are required. These should include means to monitor temperature, volume and pressure, as well as pressure relief valves and associated safety systems in accordance with the IGC Code. Tank lids and joints between pipes may need to be bonded to prevent
static electricity Static electricity is an imbalance of electric charges within or on the surface of a material. The charge remains until it can move away by an electric current or electrical discharge. The word "static" is used to differentiate it from electric ...
from causing an explosion. The International Safety Guide for Oil Tankers and Terminals is the industry code of practice that applies to oil tankers globally.


Tanker capacity

Tankers used for liquid fuels are classified according to their capacity. 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'' (later Long Range) for the then-enormous ships that were larger than . The ships became larger during the 1970s, and the list was extended, where the tons are metric tonnes: * Under : Extra small tanker *10,000–: Small tanker *25,000–34,999 DWT: Intermediate tanker *35,000–44,999 DWT: Medium Range 1 (MR1) *45,000–: Medium Range 2 (MR2) *55,000–: Long Range 1 (LR1) *80,000–: Long Range 2 (LR2) *160,000–: Very Large Crude Carrier (VLCC) *320,000–: Ultra Large Crude Carrier (ULCC) *550,000-: Hyper Large Crude Carrier (HLCC) *900,000-: Mega Crude Carrier (MCC) * Over : Giga Crude Carrier (GCC) ; Very Large Crude Carrier size range At nearly 380 vessels in the size range to , these are by far the most popular size range among the larger VLCCs. Only seven vessels are larger than this, and approximately 90 between and .


Fleets of the world

; Flag states As of 2005, the
United States Maritime Administration The United States Maritime Administration (MARAD) is an Government agency#United States, agency of the United States Department of Transportation. MARAD administers financial programs to develop, promote, and operate the United States Maritime ...
's statistics count 4,024 tankers of or greater worldwide. 2,582 of these are double-hulled.
Panama Panama, officially the Republic of Panama, is a country in Latin America at the southern end of Central America, bordering South America. It is bordered by Costa Rica to the west, Colombia to the southeast, the Caribbean Sea to the north, and ...
is the leading flag state of tankers, with 592 registered ships. Five other flag states have more than two hundred registered tankers:
Liberia Liberia, officially the Republic of Liberia, is a country on the West African coast. It is bordered by Sierra Leone to Liberia–Sierra Leone border, its northwest, Guinea to Guinea–Liberia border, its north, Ivory Coast to Ivory Coast–Lib ...
(520), The Marshall Islands (323),
Greece Greece, officially the Hellenic Republic, is a country in Southeast Europe. Located on the southern tip of the Balkan peninsula, it shares land borders with Albania to the northwest, North Macedonia and Bulgaria to the north, and Turkey to th ...
(233),
Singapore Singapore, officially the Republic of Singapore, is an island country and city-state in Southeast Asia. The country's territory comprises one main island, 63 satellite islands and islets, and one outlying islet. It is about one degree ...
(274) and
The Bahamas The Bahamas, officially the Commonwealth of The Bahamas, is an Archipelagic state, archipelagic and island country within the Lucayan Archipelago of the Atlantic Ocean. It contains 97 per cent of the archipelago's land area and 88 per cent of ...
(215). These flag states are also the top six in terms of fleet size in terms of
deadweight tonnage Deadweight tonnage (also known as deadweight; abbreviated to DWT, D.W.T., d.w.t., or dwt) or tons deadweight (DWT) is a measure of how much weight a ship can carry. It is the sum of the weights of cargo, fuel, fresh water Fresh water or ...
. ; Largest fleets Greece, Japan, and the United States are the top three owners of tankers (including those owned but registered to other nations), with 733, 394, and 311 vessels respectively. These three nations account for 1,438 vessels or over 36% of the world's fleet. ; Builders Asian companies dominate the construction of tankers. Of the world's 4,024 tankers, 2,822 (over 70%) were built in South Korea, Japan and China.


Petroleum Tables

''Petroleum Tables'', a book by William Davies, an early tanker captain, was published in 1903, although Davies had printed earlier versions himself. Including his calculations on the expansion and contraction of bulk oil, and other information for tanker officers, it went into multiple editions, and in 1915 ''The Petroleum World'' commented that it was "the standard book for computations and conversions."''The Petroleum World'', Vol. 12 (1915), p. 146 For modern tables, the standard guide for petroleum measurement on oil tankers are those from
ASTM International ASTM International, formerly known as American Society for Testing and Materials, is a standards organization that develops and publishes voluntary consensus technical international standards for a wide range of materials, products, systems and s ...
specifically ASTM D1250-08.


See also

* History of the oil tanker * Hydrogen tanker * List of gas carriers *
List of tankers This is a list of tanker (ship), tankers. The list includes merchant tankers as well as naval tankers that do not fall into more specialized lists such as List of replenishment ships of the Royal Fleet Auxiliary and List of Type T2 Tanker names. ...
* T1 tanker * T2 tanker * T3 Tanker


References


Bibliography

* * * * * * * * * * *


External links


ship-photos.de
Private homepage of categorized ship photos including tankers of all kinds {{DEFAULTSORT:Tanker (Ship) Ship types