Thick-walled straight seam welded pipe with submerged arc welding process

1. Plate inspection: Upon entering the production line, the steel plate used to manufacture large-diameter submerged arc welding straight seam steel pipes is first subjected to a full plate ultrasonic inspection.

2. Milling Edges: Double-sided milling of the two edges of the steel plate using a milling machine to achieve the required plate width, parallelism of the edges, and bevel shape.

3. Pre-bent Edges: Utilize a pre-bending machine to pre-bend the sheet edges, achieving the required curvature.

4. Forming: On the JCO forming machine, first, half of the pre-bent steel plate is subjected to multiple step-by-step stamping to form an "J" shape. Then, the other half of the steel plate is bent in the same manner to form a "C" shape. Finally, the "O" shape with an opening is formed.

5. Pre-welding: Seam the formed thick-walled straight seam pipes and perform continuous welding using gas shielded welding (MAG).

6. Internal Welding: Utilizing longitudinal multi-wire submerged arc welding (*up to four wires) for welding on the inner side of straight seam steel pipes.

7. External Welding:纵列多丝埋弧焊 is used on the outer surface of straight seam submerged arc welded steel pipes for welding.

8. Ultrasonic Inspection I: Inspection of the inner and outer weld seams and the base materials on both sides of the welds in straight seam welded steel pipes.

9. X-ray Inspection I: Industrial television X-ray examination of internal and external weld seams.