China's largest submersible-support vessel was delivered and put into service on Monday in Qingdao, Shandong province, marking a breakthrough in the development of the country's deep-water salvage force, officials said.

Shenqianhao, China's first ship that carries a saturation diving system allowing divers to work at depths of up to 300 meters, is put into operation in Qingdao, Shandong province, on Monday. Yu Fangping / for China Daily

The Shenqianhao is the nation's most advanced submersible-support vessel, capable of completing submarine rescue and lifting missions as well as other underwater projects, according to a statement from the rescue and salvage bureau under the Ministry of Transport.

The ship was built by Wuchang Shipbuilding Industry and will be managed by Shanghai Salvage Co, which is affiliated with the bureau.

The vessel is equipped with a deep-water saturation diving system, which allows 12 divers to work in turns at a depth of 300 meters — 100 meters deeper than in the past, said Shen Hao, director of Shanghai Salvage Co.

The system has living capsules, adapter modules and other life support facilities, the statement said. It allows divers to live in an enclosed pressurized environment before they enter the water.

A diving bell then takes three divers at a time into deep waters to carry out underwater operations, and returns them to the living capsule to change shifts.

The divers can be decompressed to surface pressure only once — at the end of their tour of duty. The process, known as saturation diving, enables divers to work uninterrupted in deep waters for long periods without the risk of decompression sickness.

Saturation diving technology is widely used in underwater operations performed in waters more than 120 meters deep or that require divers to stay in the sea for more than one hour.

The technology is different from that of the Jiaolong, the Chinese manned deep-sea research submersible that can dive to a depth of more than 7,000 meters.

"Divers can work for 28 days straight with the support of the system," Shen said. He said innovations have been made to tackle the technical problems of saturation diving at great depths.

The 13,000-ton ship is 125 meters long — about the length of 28 sedans if placed end to end.

The ship is equipped with a helicopter landing platform and a crane with a lifting capacity of 140 tons, capable of pulling sunken ships and cargo from the sea.

The large submersible carrier fills the vacancy of such ships in the country. It will greatly enhance China's ability to clean up large oil spills, respond to maritime accidents and conduct deep-water, large-tonnage salvage, said Xu Zuyuan, vice-minister of transport.

At Monday's delivery ceremony, Xu also said developed countries have long possessed saturation diving technology, while China's new breakthrough in the field will be further applied to maritime rescue, salvage and ocean resource exploration.

Eight countries have used this technology to allow divers to work 400 meters below sea level, China Central Television reported on Monday.

The ministry's next goal is to develop saturation diving technology that will make it possible for divers to work 500 meters below the sea, the statement said.

Shenqianhao, China's first ship that carries a saturation diving system allowing divers to work at depths of up to 300 meters, is put into operation in Qingdao, Shandong province, on Monday. Yu Fangping / for China Daily

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Xie Chuanjiao in Qingdao

contributed to this story.