The production process of large-caliber LSAW steel pipe is mainly described as follows:
1. Plate probe: used to manufacture large diameter submerged arc welded steel pipe joints and enter the production line, the first full-plate ultrasonic testing;


2. Milling: The milling machine passes through the double-sided edge of the milling plate to meet the requirements of the width of the plate, and the shape and degree of the side of the plate parallel to the groove;


3. Pre-bending side: Pre-bending plate edge, the edge of the plate must meet the curvature requirements;


4. Forming: After several pre-bending steps, the first half of JCO forming machine is pressed into "J" shape, and then the other half of the same steel plate is bended into "C" shape, forming the final "O" shape of the opening.


5. Pre-welding: After forming, the straight seam welded steel pipe is used, and the gas weld (MAG) is used for continuous welding.


6. Internal welding: multi-wire submerged arc welding (up to four lines) in series for inner straight seam welded steel pipes;


7. External welding: External LSAW pipe welding series multi-wire submerged arc welding;


8. Ultrasound inspection: 100% inspection of inner and outer welding of straight seam and base material on both sides of welding;


9. X-ray inspection: 100% welding inside and outside X-ray industrial TV inspection by image processing system to ensure detection sensitivity;


10. Expansion: Used for submerged arc welding and straight seam steel pipe length and aperture, to improve the dimensional accuracy of steel pipe, improve the stress distribution of steel pipe;


11. Hydraulic test: Root canal test after steel bar expansion is carried out on the hydraulic test machine to ensure the standard of steel tube test pressure requirements. The machine has the ability of automatic recording and storage.


12. Chamfering: Pipe inspection is carried out to the pipe end groove dimension requirements after the end of processing.