Production Technology of Medium and Thick Wall Thin Wall Longitudinal Seam High Frequency Welded Pipe:


1. Sheet metal test: for making large diameter submerged arc welded steel pipe directly into the production line, the first full-plate ultrasonic test;
2. Milling: double-sided milling of the steel plates on both sides of the milling machine to make the required plate width, plate parallelism and groove shape;
3. Pre-bending: Pre-bending edge with pre-bending machine to meet the bending requirements;
4. Forming: In JCO forming machine, the first half of the pre-bending steel plate is stamped several times to form a "J" shape, then the other half of the same bending steel plate is pressed into a "C" shape, and finally an "O" shape opening is formed.
5. Pre-welding: the forming of longitudinal welded steel pipe joints and continuous welding with gas shielded welding (MAG);
6. Internal welding: vertical multi-wire submerged arc welding (up to four wires) is used in the straight seam steel pipe in the weld.
7. External welding: vertical multi-wire submerged arc welding is used to weld straight submerged arc welded pipe.
8. Ultrasound Inspection I: 100% Inspection of Internal and External Welds of Longitudinal Welded Steel Pipe and Welds on Both Sides of Base Material;
9. X-ray inspection I: 100% internal and external welding X-ray industrial television inspection, using image processing system to ensure the sensitivity of the test;
10. Expansion: Full-length submerged arc welded pipe, enlarging pipe diameter, improving dimensional accuracy, and improving stress distribution of steel pipe;
11. Hydraulic test: Hydraulic test machine inspects the diameter of steel pipe to ensure that the steel pipe meets the standard requirements of test pressure. The machine has the function of automatic recording and storage.
12. Chamfering: After processing, the pipe is qualified, and reaches the required pipe end groove size.
13. Ultrasound test II: The expansion of straight seam welded steel pipe is checked again by ultrasonic inspection, and the water pressure may produce defects.
14. X-ray inspection II: X-ray industrial television inspection and expansion and hydrostatic test of steel pipe after welding film on pipe side;
15. Tube side magnetic powder inspection: carry out this inspection to find the defect at the end of the tube;
16. Anti-corrosion and coating: qualified steel pipes are corroded and coated according to user's requirements.