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' (the ROB). 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.
Although COWing is most notable for actual tankers, the current chairman for Hashimoto Technical Service, Hashimoto Akiyoshi, applied this method in washing refinery plant oil tanks in Japan. Hashimoto is currently using this method in the Kyushu, Chugoku, and Tohouku regions in Japan. [1]
Originally oil tankers used one set of tanks for cargo, and about one third of the same tanks were for water ballast on their empty trips. High-pressure jets of hot seawater were used to clean the tanks, and the mixture of seawater and residue called slops was discharged into the sea, as was the oil-contaminated ballast water. The 1954 OILPOL Convention attempted to reduce the harm by prohibiting such discharges within 50 miles (80 km) of most land and 100 miles (160 km) of certain particularly sensitive areas.
The discharges from seawater washing were still considered a problem, and during the 1960s the load-on-top approach began to be adopted. The mixture of cleaning water and residue was pumped into a slop tank and allowed to separate by their different densities into oil and water during the journey. The water portion was then discharged, leaving only crude oil in the slop tank. This was pumped into the main tanks and the new cargo loaded on top of it, recovering as much as 800 tons of oil which was formerly discarded.
Even with load on top there is still some oil in the discharged water from the slop tank. Starting in the 1970s, equipment capable of using crude oil itself for washing began to replace the water-based washing, leading to the current technique of crude oil washing. This reduces the remaining deliberate discharge of oil-contaminated water and increases the amount of cargo discharged, providing a further benefit to the cargo owner.
Crude oil washing equipment became mandatory for new tankers of 20,000 tons or more deadweight with the 1978 Protocol to the 1973 MARPOL Convention. Revised specifications for the equipment were introduced in 1999.
Modern tankers also use segregated ballast tanks and these remove the problem of discharge of oily ballast water.
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.
The International Convention for the Prevention of Pollution from Ships, 1973 as modified by the Protocol of 1978, or "MARPOL 73/78" is one of the most important international marine environmental conventions. It was developed by the International Maritime Organization with an objective to minimize pollution of the oceans and seas, including dumping, oil and air pollution.
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.
A chemical tanker is a type of tanker ship designed to transport chemicals in bulk. As defined in MARPOL Annex II, chemical tanker means a ship constructed or adapted for carrying in bulk any liquid product listed in chapter 17 of the International Bulk Chemical Code. As well as industrial chemicals and clean petroleum products, such ships also often carry other types of sensitive cargo which require a high standard of tank cleaning, such as palm oil, vegetable oils, tallow, caustic soda, and methanol.
A tanker is a ship designed to transport or store liquids or gases in bulk. Major types of tankship include the oil tanker, the chemical tanker, cargo ships, and a gas carrier. Tankers also carry commodities such as vegetable oils, molasses and wine. In the United States Navy and Military Sealift Command, a tanker used to refuel other ships is called an oiler 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 10,000 LT DWT or greater operating worldwide.
The Aegean Sea tanker oil spill was a spill that occurred on 3 December 1992 when the double-bottomed Greek-flagged oil tanker, Aegean Sea, en route to the Repsol refinery in A Coruña, Spain, suffered an accident off the Galician coast. The ship had successfully passed all required tests and revisions. The accident occurred during extreme weather conditions and affected the Galician coast resulting in ecosystem damage, as well as damage to the fishing and tourist industries in A Coruña.
The Whiddy Island disaster, also known as the Betelgeuse incident or Betelgeuse disaster, occurred on 8 January 1979, around 1:00 am, when the oil tanker Betelgeuse exploded in Bantry Bay, at the offshore jetty for the oil terminal at Whiddy Island, Ireland. The explosion was attributed to the failure of the ship's structure during an operation to discharge its cargo of oil. The tanker was owned by Total S.A., and the oil terminal was owned by Gulf Oil.
An LNG carrier is a tank ship designed for transporting liquefied natural gas (LNG).
Slop or SLOP may refer to:
A heavy-lift ship is a vessel designed to move very large loads that cannot be transported by normal ships. They are of two types:
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 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.
Oil discharge monitoring equipment (ODME) is based on a measurement of oil content in the ballast and slop water, to measure conformance with regulations. The apparatus is equipped with a GPS, data recording functionality, an oil content meter and a flow meter. By use of data interpretation, a computing unit will be able to allow the discharge to continue or it will stop it using a valve outside the deck.
A hydraulic tanker is an oil tanker designed to use water as an incompressible fluid for loading and unloading petroleum cargo. Each cargo tank is kept full at all times so oil floating on water will be pressed against the top of the tank. A cargo tank initially filled with water is loaded with the desired quantity of oil by pumping oil into the top of the tank displacing water which overflows through an opening at the bottom of the tank. The cargo tank is unloaded by removing oil from the top of the tank as water is admitted at the bottom.
The Flotta oil terminal is a major crude oil reception, processing, storage and export facility on the island of Flotta, in the south of Scapa Flow in the Orkney Islands. It receives and processes crude oil delivered by a subsea pipeline from the Piper, Claymore, Tartan and Golden Eagle platforms and associated fields. The terminal includes facilities for exporting stabilised crude oil by tanker.
The Teesside oil terminal is a major crude oil reception, processing, storage and export facility at Seal Sands, Middlesbrough. It receives and processes crude oil delivered by the subsea NORPIPE pipeline from the Norwegian Ekofisk field and the UK Fulmar and J-Block fields. The terminal includes facilities for exporting stabilised crude oil and liquefied petroleum gases (LPG) by tanker and pipeline.