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The Coulombi egg tanker is a design that is aimed at reducing oil spills. It was approved by the International Maritime Organization (IMO) as an alternative to the double hull concept. The United States Coast Guard does not allow this design to enter US waters, effectively preventing it from being built. [1]
The design is an enhanced mid-deck tanker and consists of a series of centre and wing tanks that are divided by horizontal bulkheads. The upper wing tanks form ballast tanks and act as emergency receiver tanks for cargo should the lower tanks be fractured. The lower tanks are connected to these ballast tanks by non-return valves.
When a lower tank is damaged, the incoming sea water pushes the oil in the damaged tank up into the ballast tank. Because of the hydrostatic pressure, there is an automatic transfer out of the damaged tank.
The double-hull design is aimed at the probability of zero outflow. In low energy collisions where only the outside hull is penetrated, this will be the case. However, in high energy collisions both hulls are penetrated. As the tanks of a double hull tanker are larger than those of MARPOL tankers and pre-MARPOL tankers and the height of the cargo above the water line is higher, the resulting spill can be much larger than these single hull designs. In the Coulombi egg design spillage is greatly reduced, possibly to zero.
Where a double hull VLCC has a ballast tank coated area of about 225,000 m³, in a Coulombi egg tanker this area is reduced to 66,000 m³. This reduces maintenance and corrosion risks, which otherwise may result in structural failure, as was the case with the Erika and Prestige.
A double-hulled tanker refers to an oil tanker which has a double hull. They reduce the likelihood of leaks occurring compared to single-hulled tankers, and their ability to prevent or reduce oil spills led to double hulls being standardized for oil tankers and other types of ships including by the International Convention for the Prevention of Pollution from Ships or MARPOL Convention. After the Exxon Valdez oil spill disaster in Alaska in 1989, the US government required all new oil tankers built for use between US ports to be equipped with a full double hull.
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 the ocean or coastal waters, but spills may also occur on land. Oil spills may be due to releases of crude oil from tankers, offshore platforms, drilling rigs and wells, as well as spills of refined petroleum products and their by-products, heavier fuels used by large ships such as bunker fuel, or the spill of any oily refuse or waste oil.
MT Petali is an Aframax crude oil tanker. Formerly known as Mastera for almost two decades and briefly as Mikines in early 2022 and Alma until September 2023, she and her sister ship Tempera were the first ships to utilize the double acting tanker (DAT) concept in which the vessel is designed to travel ahead in open water and astern in severe ice conditions. The icebreaking tanker was built to transport crude oil year-round from the Russian oil terminal in Primorsk to Neste Oil refineries in Porvoo and Naantali.
La Noumbi is a floating production storage and offloading (FPSO) unit operated by Perenco. The vessel, converted from the former Finnish Aframax crude oil tanker Tempera by Keppel Corporation, will replace an older FPSO unit in the Yombo field off the Republic of Congo in 2018.
Crude oil washing (COW) is washing out the residue from the oil tanker using the crude oil cargo itself, after the cargo tanks have been emptied. Crude oil is pumped back and preheated in the slop tanks, then sprayed back via high pressure nozzles in the cargo tanks onto the walls of the tank. Due to the sticky nature of the crude oil, the oil clings to the tank walls, and such oil adds to the cargo 'remaining on board'. By COWing the tanks, the amount of ROB is significantly reduced, and with the current high cost of oil, the financial savings are significant, both for the Charterer and the Shipowner. If the cargo ROB is deemed as 'liquid and pumpable' then the charterers can claim from the owner for any cargo loss for normally between 0.3% up to 0.5%. It replaced the load on top and seawater washing systems, both of which involved discharging oil-contaminated water into the sea. MARPOL 73/78 made this mandatory equipment for oil tankers of 20,000 tons or greater deadweight.
A double hull is a ship hull design and construction method where the bottom and sides of the ship have two complete layers of watertight hull surface: one outer layer forming the normal hull of the ship, and a second inner hull which is some distance inboard, typically by a few feet, which forms a redundant barrier to seawater in case the outer hull is damaged and leaks.
A mid-deck oil tanker is a tanker design which includes an additional deck intended to limit spills if the tanker is damaged. The extra deck is placed at about the middle of the draft of the ship. This design is an alternative to the double-hull tanker design, and is superior in terms of spill volume.
An LNG carrier is a tank ship designed for transporting liquefied natural gas (LNG).
An oil tanker, also known as a petroleum tanker, is a ship designed for the bulk transport of oil or its products. There are two basic types of oil tankers: crude tankers and product tankers. Crude tankers move large quantities of unrefined crude oil from its point of extraction to refineries. Product tankers, generally much smaller, are designed to move refined products from refineries to points near consuming markets.
The history of the oil tanker is part of the evolution of the technology of oil transportation alongside the oil industry.
Oil tankers generally have from 8 to 12 tanks. Each tank is split into two or three independent compartments by fore-and-aft bulkheads. The tanks are numbered with tank one being the forwardmost. Individual compartments are referred to by the tank number and the athwartships position, such as "one port", "three starboard", or "six center."
The environmental effects of shipping include air pollution, water pollution, acoustic, and oil pollution. Ships are responsible for more than 18% of nitrogen oxides pollution, and 3% of greenhouse gas emissions.
The 2010 Port Arthur oil spill was the result of a collision between two vessels in the Sabine-Neches Waterway at Port Arthur, Texas on January 23, 2010. The two vessels were the oil tanker Eagle Otome and a barge being pushed by the towboat Dixie Vengeance.
The M/T Burmah Agate was an oil tanker that was involved in a nautical collision and subsequent oil spill near Galveston, Texas in November 1979. 31 crewmen were killed in the collision, and the oil spill damaged the local environment.
The cargo control room, CCR, or cargo office of a tankship is where the person in charge (PIC) can monitor and control the loading and unloading of the ship's liquid cargo. Prevalent on automated vessels, the CCR may be in its own room, or located on the ship's bridge. Among other things, the equipment in the CCR may allow the person in charge to control cargo and stripping pumps, control and monitor valve positions, and monitor cargo tank liquid levels.
All cargo vessels where MARPOL Convention is applicable must have an oil record book in which the officer responsible will record all oil or sludge transfers and discharges within the vessel. This is necessary for authorities to be able to monitor if a vessel's crew has properly disposed of their oil discharges at sea.
The Venpet–Venoil collision was a maritime accident involving sister supertankers; the Liberian-registered Venoil and Venpet, in dense fog off the coast of South Africa on 16 December 1977. The tankers were travelling in opposite directions; the Venoil fully laden with over 250,000 tonnes of crude oil bound for Halifax, Canada, and the Venpet, travelling in ballast, headed for Kharg Island, Iran. The Venoil ploughed into the Venpet, eventually leading to the spilling of approximately 26,600–30,500 tonnes of crude oil. The tankers were sister ships owned and operated by Bethlehem Steel Corporation. Both ships were manned by Taiwanese crews.
Corrosion in Ballast Tanks is the deterioration process where the surface of a ballast tank progresses from microblistering, to hydroscaletric electration, and finally to cracking of the tank steel itself.
MV Stellar Daisy was a South Korean-owned very large ore carrier (VLOC) that sank on March 31, 2017 in the South Atlantic off the coast of Uruguay while on a voyage from Brazil to China. She was the largest ship, by a factor of nearly 2 on gross tonnage, to be lost at sea.
The Sanchioil tanker collision occurred on 6 January 2018 when the Panamanian-flagged, Iranian-owned tanker Sanchi, with a full natural-gas condensate cargo of 136,000 tonnes, sailing from Iran to South Korea, collided with the Hong Kong-flagged cargo ship CF Crystal 160 nautical miles (300 km) off Shanghai, China. Sanchi caught fire shortly after the collision; after burning and drifting for over a week, it sank on 14 January.
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