1. Plate detection: After the steel plate used to manufacture large-diameter submerged arc welded straight seam steel pipe enters the production line, the whole plate is ultrasonically inspected;
2. Edge milling: double-sided milling of the two edges of the steel plate by an edge milling machine to achieve the required plate width, plate edge parallelism and bevel shape;
3. Pre-bending: Use a pre-bending machine to pre-bend the edge of the board so that the edge of the board has the required curvature;
4. Forming: On the JCO forming machine, half of the pre-bent steel plate is pressed into a "J" shape by multiple stepping and pressing, and then the other half of the steel plate is also bent and pressed into a "C" shape, and then an opening is formed "O" shape;
5. Pre-welding: Join the formed longitudinally welded steel pipe and use gas shielded welding (MAG) for continuous welding;
6. Inner welding: adopt longitudinal multi-wire submerged arc welding (more than four wires) to weld on the inner side of the straight seam steel pipe;
7. External welding: use longitudinal multi-wire submerged arc welding to weld on the outside of the longitudinal submerged arc welded steel pipe;
8. Ultrasonic inspection I: 100% inspection of the inner and outer welds of the longitudinally welded steel pipe and the base materials on both sides of the weld;
9. X-ray inspection Ⅰ: 100% X-ray industrial TV inspection of the inner and outer welds, using an image processing system to ensure the sensitivity of flaw detection;
10. Diameter expansion: expand the total length of the submerged arc welded straight seam steel pipe to improve the dimensional accuracy of the steel pipe and improve the distribution of the internal stress of the steel pipe;
11. Hydrostatic test: The expanded steel pipes are inspected one by one on the hydrostatic testing machine to ensure that the steel pipe meets the test pressure required by the standard. The machine has automatic recording and storage functions;
12. Chamfering: Process the pipe ends of the steel pipes that have passed the inspection to meet the required pipe end groove size;
13. Ultrasonic inspection Ⅱ: Perform ultrasonic inspection again one by one to check the possible defects of the longitudinally welded steel pipe after the diameter expansion and water pressure;
14. X-ray inspection Ⅱ: X-ray industrial television inspection and pipe end weld filming of the steel pipe after the expansion and hydraulic test;
15. Tube end magnetic particle inspection: carry out this inspection to find tube end defects;
16. Anti-corrosion and coating: Qualified steel pipes are anti-corrosion and coating according to user requirements.
