A few days ago, the reporter saw at the site of the PipeChina Zhangzhou LNG (liquefied natural gas) project that the project of "Research on Application of Automatic Welding Technology for Vertical Seam of LNG Inner Tank" in the charge of Offshore Oil Engineering Co., Ltd. (hereinafter referred to as "Offshore Oil Engineering" for short), an enterprise in Tianjin Port Free Trade Zone, successfully passed the final acceptance of the CNOOC expert group. This project takes the lead in the R&D and engineering application of automatic welding technology for inner tank vertical seam in the global LNG industry. It not only fills a technical gap in this field, but also lays a solid foundation for the transformation of LNG inner tank welding from manual to automatic operation.

　　It is learned that the welding of 9 nickel steel is a key technical problem in the construction of the whole LNG storage tank. Its technical level directly determines the service life of the storage tank, and its welding quality is one of the important reasons for LNG storage tank failure. The 9 nickel steel is prone to magnetization and has high crack sensitivity, so it is difficult to be welded. Restricted by the technical conditions, the welding of vertical seam of LNG storage tank at home and abroad mainly uses the traditional electrode arc welding process, which has low welding efficiency, high labor intensity and poor operating environment, and seriously restricts the improvement of LNG storage tank building efficiency.