Development of X90 submerged-arc helical welded pipe with diameter of 1 524 mm

The use of high pressure, large diameter and high steel grade pipelines for long-distance natural gas transportation have become an important development tendency in the pipeline industry. The application of X90 pipeline steel pipe can raise the pipeline transmission capacity, lower the effective wall thickness of the steel pipe and save the pipeline construction cost. The X90 hot rolled coil, with a wall thickness of 20.3 mm and mainly composed of granular bainite, has been developed by adopting the design of alloying components with low C, high Mn+Nb and high Mo+Cr, as well as technologies such as pure steel smelting and controlled rolling and cooling. The welding technology for X90 pipeline steel pipe with a wall thickness of 20.3 mm was optimized through experimental research on welding technology, and the low residual stress of high strength and large diameter submerged-arc helical welded pipe was controlled by optimizing design of pipe forming parameters. The test results show that all performance indexes of the trial-manufactured X90 submerged-arc helical welded pipe with a wall thickness of 20.3 mm and the diameter of 1 524 mm meet the requirements of relevant technical specifications, and it would make technical reserves for the construction and application of X90 high strength and large diameter steel pipes in China.