SAWL Steel Pipe

 SAWL Steel Pipe 

SAWL: Tubular product having one or two longitudinal seams produced by submerged-arc welding

SAWL steel pipe Process flow:

1) Plate detection: The whole plate ultrasonic inspection shall be carried out before the steel plate used to manufacture large diameter straight seam Submerged arc welding steel pipe enters the production line.

2) Edge milling: Double sided milling is performed on the two edges of the steel plate using an edge milling machine to achieve the required plate width, edge parallelism, and beveling shape;

3) Pre bending edge: Use a pre bending machine to pre bends the edge of the plate, so that the edge has the required curvature;

4)Forming: On the JCO forming machine, first half of the pre bent steel plate is stamped multiple times to form a "J" shape, then the other half of the steel plate is also bent to form a "C" shape, and finally an open "O" shape is formed;

5) Pre welding: Make the formed straight seam welded steel pipe joint 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 inside the straight seam steel pipe;

7) External welding: Longitudinal multi wire submerged arc welding is used to weld outside the longitudinal submerged arc welding steel pipe;

8) Finishing and rounding

9) Straighten the whole pipes

10) Cold Expanding: Expand the full length of longitudinal submerged arc welding steel pipe to improve the dimensional accuracy of steel pipe and stress released in steel pipe.

11) Ultrasonic inspection II: Conduct ultrasonic inspection one by one again to inspect the defects that may occur in the straight seam welded steel pipe after expansion and hydrostatic testing.

12) Hydrostatic test: Inspect the expanded steel pipes one by one on a hydraulic testing machine to ensure that they meet the required test pressure. The machine has automatic recording and storage functions;

13) Ultrasonic flaw inspection.

14) End finish: Process the qualified steel pipe at the pipe end to meet the required pipe end beveled size.

15) X-ray inspection II: 100% Conduct X-ray industrial television inspection and take photos of pipe end welds on steel pipes after expansion and hydraulic testing;

16) Pipe end magnetic particle inspection: Conduct this inspection to discover pipe end defects.