1. plate inspection: after the steel plate enters the production line, the whole plate will be inspected by ultrasonic wave first;
2. edge milling: both edges of the steel plate are milled on both sides by the edge milling machine, so as to achieve the required plate width, parallelism of the plate edges and the shape of the bevel;
3. pre-bending: pre-bending the plate edges with pre-bending machine to make the plate edges have curvature as required;
4. forming: on the JCO forming machine, first half of the pre-bent steel plate is pressed into J-shape through several step stamping, then the other half of the plate is bent in the same way and pressed into C-shape, and finally the open O-shape is formed;
5. pre-welding: to make the formed steel pipe seam and continuous welding by gas-shielded welding (MAG);
6. internal welding: using longitudinal multi-wire submerged arc welding (up to four wires) on the inside of the straight seam steel pipe for welding;
7. external welding: the use of longitudinal multi-wire submerged arc welding on the outside of the spiral submerged arc welded steel pipe for welding;
8. ultrasonic inspection of the spiral steel pipe inside and outside the weld and the parent material on both sides of the weld for 100% inspection;
9. X-ray inspection: 100% X-ray industrial television inspection of internal and external welds, using image processing system to ensure the sensitivity of the flaw detection;
10. Expansion: the full length of the straight seam steel pipe is expanded to improve the dimensional accuracy of the pipe and to improve the distribution of stresses within the pipe;
11. Hydrostatic test: the expanded steel pipe is inspected one by one on the hydrostatic testing machine to ensure that the steel pipe reaches the test pressure required by the standard, and the machine has the function of automatic recording and storage;
12. chamfering: after the inspection of qualified steel pipe end processing, to achieve the required pipe end bevel size;
