Wang Jin, Peng Yonggui, Li Danna

On November 15, China"s first and the world"s largest LNG carry& bunkering vessel, “Offshore Oil 301”, converted by CSSC GSI Guangzhou Wenchong Dockyard Co.,Ltd. for CNOOC Energy Development Co., Ltd., was completed and delivered.The converted Offshore Oil 301 will become an LNG transport/refueling vessel for LNG transport and bunker refueling, providing ship-to-ship refueling services for large LNG fuelpowered ships berthing in domestic coastal ports.

"Offshore Oil 301" has an overall length of 184.7 m, a molded breadth of 28.1 m, and can load 30,000 m3 LNG. It is the first LNG carrier independently designed, independently built, independently managed and independently operated by China. The ship was officially put into operation in September 2015, mainly serving the LNG second carriage between the coastal LNG terminals in China, and taking into account international shortrange LNG transport.

As the first LNG carry& bunkering ship convertion project in China, Wenchong Dockyard acted as the EPC general contractor, jointly realized the first domestic application of many technologies and equipment with quite a few units within CSSC.The project convertion design scheme was provided by CSSC SDARI, the refueling system was developed and manufactered by the CSSC 716 Research Institute, and the GCU(gas combustion unit) was developed and manufactered by the CSSC 711 Research Institute.

The "Offshore Oil 301" convertion project mainly added the LNG refueling system, combustion unit, cryogenic reliquefaction device, mooring winch,crane and related liquid cargo control system. The convertion project requires adding new functions without changing the original ship system, among which 70 km cables and 5 km piping system are added. The project involved large quantities, tight time limit, and very difficult equipment layout and pipeline and cable laying. The project convertion coincided with extreme weather such as high temperature and typhoon, nearly 300 people worked on board the ship at the production peak,which meant ordeal for the project quality management, safety protection and epidemic containing, and posed a great challenge to ensuring the project cycle.

LNG fuel needs to be stored in a liquid state in a low temperature environment of minus 162 degrees Celsius. During the refueling operation, transmission requires double-wall coil of special structure.Requirements for the production and installation accuracy of the doublewall coil are extremely high, and the pass rate of welding flaw detection must reach 100%, which is one of the biggest technical difficulties in the convertion of the "Offshore Oil 301".Wenchong Dockyard gave full play to the advantages of the integration of shipbuilding and repair resources,and applied the technical experience accumulated in the construction of LNG dual fuel ships in batches, to complete the convertion of the new refueling system with high quality.

Wenchong Dockyard vigorously promoted the localization of equipment in the convertion, so it is necessary to solve the compatibility problem of a large number of imported equipment and domestic equipment. For the purpose of ensuring the project nodes,the Wenchong Dockyard organized the inauguration of the "Offshore Oil 301" Refueling Function Convertion Project to coordinate and allocate the resources. For the added refueling system, combustion unit, cryogenic reliquefaction device, mooring winch,hoists and related liquid cargo control systems involved in the convertion project, the project team actively explored new techniques, new processes and new ideas to ensure the construction quality.