关键词: X65钢级, 海底管道, 直缝埋弧焊管

Abstract: China’s deepwater natural gas project was kicked off in South China Sea in 2009. The project needed X65, φ762mm×28.6/30.2mm undersea SAWL pipe with a designed pressure of 23.9 MPa. The technological requirement is far higher than that of onshore pipeline. Based on the efforts to make a joint technological study with the steel plant, Julong Steel Pipe Co Ltd has solved the bottlenecks of plate strength, toughness and weldability and developed a series of process technology and equipment for dies for forming, welding, expansion and hydrostatic test of thick-wall offshore pipes. It was also possessed of the process technology for production of subsea thick-wall pipe and produced 31.5 thousand tons of steel pipe for subsea pipeline as scheduled. The mechanical properties of developed steel pipe are excellent while the Charpy impact energy of mother material, welding line and location of fusion-line is 450J, 193J and 290J on average. DWTT cutting area is 94 percent on average, with an extremely high precision of appearance size. This project helps localize production of steel pipe used for China’s deepwater high-pressure oil and gas pipeline and accumulates experience for development and production of thick-wall, high strain and anti-corrosion steel pipe used for ultra-deep undersea pipeline.

Key words: X65 steel grade, undersea pipeline, SAWL pipe