The whole length and diameter of LSAW steel pipe are enlarged to improve dimensional accuracy and stress distribution inside the pipe. X-ray inspection of internal and external welds is used in 100% X-ray industrial television inspection image processing system to ensure detection sensitivity. Gas shielded arc welding (MAG) is used for continuous welding of straight seam welded steel pipe after seam forming. Hydraulic test: Expanded root canal test is carried out on the steel pipe hydraulic test machine to ensure that the pressure test tube meets the required standards. The machine has the function of automatic recording and storage. Later, it was used to manufacture large-caliber submerged arc welded straight seam steel pipes and entered the production line. It was the first time that full-plate ultrasonic testing was carried out. Straight pipe joints can be divided into high frequency submerged arc welded pipe and straight pipe joints according to production process. The submerged arc welded straight seam steel pipes are divided into UOE, RBE and JCOE pipes according to their different forming methods.