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Dec 10 (Reuters) - South Korea was tallying the economic and environmental cost of the worst oil spill in its history on Monday.
About 10,500 tonnes of crude oil spilled from the Hong Kong-registered Hebei Spirit after the tanker’s single hull was damaged in three places when a barge slammed into the carrier on Friday morning.
Here are some facts on how tankers transport oil around the world and safety regulations in place to protect against spills.
HOW MUCH OIL DO TANKERS CARRY?
— Tankers carry roughly two-thirds of oil trade, about 2.4 billion tons in 2005. The remainder travels mostly by pipelines, but also by trains and trucks.
WHAT KIND OF TANKERS ARE THERE?
— Six major categories, based on carrying capacity per deadweight ton (dwt), ply the world’s different sea routes according to port and access restraints. They are:
* Ultra Large Crude Carrier, (ULCC): Larger than 300,000 dwt.
* Very Large Crude Carrier, (VLCC): 200,000 to 300,000 dwt.
* Suezmax and Aframax: Mid-size tankers, between 120,000 and 200,000 dwt.
* Panamax and Handysize: The smallest tankers, they carry between 10,000 and 80,000 dwt, and are just small enough to transit the Panama Canal.
HOW ARE TANKERS DESIGNED?
— The first tankers, built from the 1870s onwards, generally had single hulls divided into a series of tanks.
— Due to environmental and security concerns, modern tankers now have double-hulls, so that if the outer hull is damaged the cargo in the inner hull will be protected.
WHEN WILL SINGLE-HULL TANKERS BE PHASED OUT?
— The 1990 Oil Pollution Act made it mandatory for all tankers calling at U.S. ports to have double hulls. It was passed in reaction to the worst oil spill in U.S. waters, the 1989 Exxon Valdez tanker spill.
— In 1992 the International Maritime Organisation (IMO) recommended making double hulls mandatory for all tankers carrying heavy crudes and fuel. It opted for a staggered phase-out, in recognition of the move’s cost to the industry.
— The massive Erika oil tanker spill, off the coast of France in 1999, led to the timetable for the global phasing out of single-hulls being accelerated to 2010.
WHAT OTHER ANTI-POLLUTION REGULATIONS ARE IN PLACE?
— As well as bringing in newer tankers, and organising better rapid response teams, several outmoded operational techniques have been banned since the potential for oil to pollute was first recognised by the 1954 International Convention for the Prevention of Pollution of the Sea by Oil (OILPOL).
— The convention prohibited the then standard technique of cleaning cargo tanks with water and pumping the resulting oil and water mix into the sea. It also set "prohibited zones" to stop oil or mixtures of more than 100 parts of oil per million being released less than 50 miles (80 km) from land.
— In 1978, oil discharges were banned in sensitive areas such as the Mediterranean Sea, Black Sea, Baltic Sea, Red Sea and the Gulfs area by the International Convention for the Prevention of Pollution from Ships (MARPOL).
ARE THERE OTHER SOURCES OF MARINE OIL POLLUTION?
— Yes. Large accidental tanker spills are actually a relatively minor source of ocean oil pollution.
— There are also natural and land-based sources of marine oil pollution, such as Coal Oil Point on the California coast near Santa Barbara, where about 2,000 to 3,000 gallons of crude oil is released naturally from the ocean bottom every day. (Writing by Gill Murdoch, Singapore Editorial Reference Unit; Editing by Alex Richardson)