1. Plate probe: after the steel plate used for manufacturing large diameter saw straight seam steel pipe enters the production line, the full plate ultrasonic inspection shall be carried out first;
2. Edge milling: the two edges of the steel plate are milled on both sides by the edge milling machine to achieve the required plate width, plate edge parallelism and groove shape;
3. Pre bending: pre bending machine is used to pre bend the plate edge, so that the plate edge has the required curvature;
4. Forming: on the JCO molding machine, the half of the pre bent steel plate is firstly pressed into "J" shape by multiple step stamping, and then the other half of the steel plate is also bent and pressed into "C" shape, and finally an open "O" shape is formed
5. Pre welding: weld the formed straight seam welded steel pipe and use gas shielded welding (MAG) for continuous welding;
6. Internal welding: longitudinal multi wire submerged arc welding (up to four wires) is used to weld the inside of straight seam steel pipe;
7. External welding: longitudinal multi wire submerged arc welding is used to weld the outside of LSAW steel pipe;
8. Ultrasonic inspection I: 100% inspection of internal and external welds and base metal on both sides of longitudinal welded steel pipe;
9. X-ray inspection I: 100% X-ray industrial TV inspection shall be carried out for the internal and external welds, and the image processing system shall be used to ensure the sensitivity of flaw detection;
10. Expanding: the full length of saw straight seam steel pipe is expanded to improve the dimensional accuracy of the pipe and improve the distribution of internal stress in the pipe;
11. Hydraulic test: the expanded steel pipes are inspected one by one on the hydraulic testing machine to ensure that the steel pipes meet the test pressure required by the standard. The machine has the function of automatic recording and storage;
12. Chamfering: process the qualified steel pipe end to meet the required groove size;
13. Ultrasonic inspection II: ultrasonic inspection shall be conducted one by one again to check the possible defects of longitudinal welded steel pipe after expanding and water pressure;
14. X-ray inspection II: conduct X-ray industrial TV inspection on the steel pipe after expanding and hydrostatic test and film the weld seam at the pipe end;
15. Magnetic particle inspection of pipe end: this inspection is carried out to find defects at pipe end;
16. Anti corrosion and coating: the qualified steel pipe shall be anticorrosive and coated according to the requirements of users.
