missing@ (Recasts, adds details from CCTV)
BEIJING/SEOUL, Jan 8 (Reuters) - Rescue crews scrambled to bring a blaze on an Iranian oil tanker off China's east coast under control on Monday as fire raged for a second day following a collision with a grain ship, while the U.S. Navy joined the search for 32 missing crew.
Concerns were growing that the tanker, which hit a freight ship on Saturday night in the East China Sea, may explode and sink as the inferno grew, the official China Central Television (CCTV) said on Monday, citing experts on the rescue team.
The extent of the environmental harm and size of the oil spill from the ship were not known, but the disaster has the potential to be the worst since 1991 when 260,000 tonnes of oil leaked off the Angolan coast.
The U.S. Navy sent a military aircraft to assist with the search, which spanned an area of about 3,600 square nautical miles (12,350 sq kms), but said in a statement it did not locate any of the tanker's missing crew members.
As of 8 a.m. (0000 GMT), the search team had not found any of the missing mariners, CCTV said at midday on Monday.
The Sanchi tanker (IMO:9356608) run by Iran's top oil shipping operator, collided with the CF Crystal (IMO:9497050) about 160 nautical miles off China's coast near Shanghai and the mouth of the Yangtze River Delta on Saturday evening.
Chinese state media CCTV showed footage on Monday of a flotilla of boats battling flames as plumes of thick dark smoke continued to billow from the tanker.
China sent four rescue ships and three cleaning boats to the site, while South Korea dispatched a ship and a helicopter.
The Panama-registered tanker was sailing from Iran to South Korea, carrying 136,000 tonnes of condensate, an ultra light crude. That is equivalent to just under 1 million barrels, worth about $60 million, based on global crude oil prices.
The freight ship, which was carrying U.S. grain, suffered limited damage and the 21 crew members, all Chinese nationals, were rescued.
South Korea's Hanwha Total Petrochemical Co Ltd, which was due to receive the cargo, said it was looking at ways to replace the lost barrels.
The company may use its own stock, ask Iran for another cargo or seek alternative condensate supplies from Qatar, a spokesman said. The accident was not affecting its operations on Monday, he added.
COLOURLESS, ODORLESS AND HARMFUL
Bad weather on Sunday night made it hard for the rescue crews to get access to the tanker, but toxic gas from the burning oil also posed a major risk.
Trying to contain a spill of condensate, which is extremely low in density, highly toxic and much more explosive than normal crude, may be difficult.
It is only liquid in certain pressure and temperature conditions and often evaporates into air or dilutes into water when exposed to the atmosphere or spills uncontrolled.
When liquid, most condensate is colourless and virtually odourless. Surface spills of condensate are therefore difficult to detect visually, making them hard to manage and contain.
Tankers also carry shipping fuel, known as bunker, which is extremely heavy and toxic, when spilled, though much less explosive.
Shanghai Maritime Bureau's navigation department said the collision did not affect traffic in and out of Shanghai, one of the world's busiest and biggest ports, or ports along the Yangtze river.
(Reporting by Yuna Park and Jane Chung in SEOUL, Henning Gloystein in SINGAPORE, Meng Meng in BEIJING; Writing by Brenda Goh in SHANGHAI and Josephine Mason in BEIJING; editing by Richard Pullin)