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Oil tanker

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An oil tanker, also called a petroleum tanker, is a massive ship designed for the bulk transport of oil. These vessels are essential to the global economy. They move the energy needed for many industries and daily lives. There are two primary types of tankers based on their specific jobs. Crude tankers carry unrefined crude oil from extraction sites to refineries. Product tankers are generally much smaller. They carry refined products from refineries to markets where people consume them.

Maya OBO carrier 3
Maya OBO carrier 3

Tankers are classified by their size and their specific occupation. Sizes range from small inland or coastal tankers to massive ultra-large crude carriers (ULCCs). The scale of these ships is enormous. Tankers move a huge portion of the world's oil every year. Moving crude oil by tanker is very efficient. The average cost of transport is only US$1.50 per barrel. This makes them nearly as efficient as pipelines.

Tanker unloading crude oil
Tanker unloading crude oil

Early methods of moving oil were very difficult and inefficient. In the 1850s, oil from Upper Burma was moved in earthenware vessels. Later, in the 1860s, Pennsylvania oil fields used wooden barrels. These barrels caused several major problems. They were very heavy, with the wood making up 20% of the total weight. Barrels were expensive and often leaked. In the early Russian oil industry, barrels accounted for half the cost of production.

Zoroastr
Zoroastr

Designers eventually moved away from barrels to improve safety and stability. Early ships used makeshift wooden or iron tanks in the hold. This raised the center of gravity and increased fire risks. To fix this, engineers began incorporating fixed iron tanks into the hull. They used bulkheads, which are internal walls, to divide cargo into separate compartments. This prevented the free-surface effect. This effect occurs when liquid sloshes from side to side, which can cause a ship to capsize.

DoubleBottomDoubleHull
DoubleBottomDoubleHull

Modern tanker technology evolved significantly in the late 19th century. In 1876, the Nobel brothers founded Branobel in Baku, Azerbaijan. They worked with builder Sven Alexander Almqvist to create the Zoroaster. The Zoroaster was the first successful oil tanker. It was 150 feet long and carried 1,000 tons of kerosene. It used two iron tanks separated by the engine room.

Zoroastr
Zoroastr

Another major advancement came from British engineer Colonel Henry F. Swan. He designed the Glückauf, which was the first dedicated steam-driven ocean-going tanker. This ship allowed oil to be pumped directly into the hull. It featured cargo valves on the deck and a vapor line. Swan also used longitudinal bulkheads to divide tanks into port and starboard sections. This design virtually eliminated stability problems caused by sloshing oil.

Glückauf
Glückauf

In the 1970s, the industry entered the supertanker era. Shipowners realized that larger tankers were more economical. After the 1956 Suez Crisis, ships had to travel around the Cape of Good Hope. This encouraged the building of much larger vessels. A typical WWII-era T2 tanker held 50,000 tons. In contrast, ULCCs built in the 1970s were much larger.

Comparison of Knock Nevis with other large buildings
Comparison of Knock Nevis with other large buildings

The largest supertanker ever built was the Seawise Giant. It was completed in 1979 at the Oppama shipyard. This ship was 1,504 feet long and held 564,763 barrels of oil. It was so large that it could not navigate the English Channel. Today, the largest working supertankers are the TI Europe and TI Oceania. These are the first ULCCs to feature a double hull for safety.

Hellespont Alhambra-223713 v2
Hellespont Alhambra-223713 v2

Specialized tankers serve many unique roles in the maritime world. Naval replenishment oilers can fuel other moving vessels at sea.

US Navy 050614-N-0120R-050 The conventionally powered aircraft carrier USS Kitty Hawk (CV 63) and the guided missile cruiser USS Cowpens (CG 63) receives fuel during a replenishment at sea
US Navy 050614-N-0120R-050 The conventionally powered aircraft carrier USS Kitty Hawk (CV 63) and the guided missile cruiser USS Cowpens (CG 63) receives fuel during a replenishment at sea

Combination ore-bulk-oil carriers can move different types of cargo. Some tankers are even converted into floating storage and offloading (FSO) units. These units stay in one place to hold oil for other ships.

FPSO diagram
FPSO diagram
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🖼️ Images & Media (18)
File:Fallsofclydehonolulu.jpg
Fallsofclydehonolulu.jpg
File:Zoroastr.jpg
Zoroastr.jpg
File:Glückauf.jpg
Glückauf.jpg
File:COLLECTIE TROPENMUSEUM Afscheepsteiger Tarakan 14 TMnr 10010382.jpg
COLLECTIE TROPENMUSEUM Afscheepsteiger...
File:Comparison of Knock Nevis with other large buildings.svg
Comparison of Knock Nevis with other...
File:Hellespont Alhambra-223713 v2.jpg
Hellespont Alhambra-223713 v2.jpg
File:Two bunkering tankers.jpg
Two bunkering tankers.jpg
File:Bateaux comparaison3.png
Bateaux comparaison3.png
File:AMYNTAS_Donges_1_by_NS.jpg
AMYNTAS_Donges_1_by_NS.jpg
File:Lightering-grain-in-bangladesh.JPG
Lightering-grain-in-bangladesh.JPG
File:DoubleBottomDoubleHull.png
DoubleBottomDoubleHull.png
File:Tanker unloading crude oil.jpg
Tanker unloading crude oil.jpg

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