Production process of straight seam welded steel pipe

The straight seam electric welded steel pipe is a steel pipe whose weld seam is longitudinally parallel to the steel pipe. During the production process, it carries out cold rolling or hot rolling steel plate or strip coil welding, and then carries out straight seam welding on the welding equipment to form a straight seam welded pipe. The welding process of straight seam steel pipe is as follows:

1、Plate detection: ultrasonic inspection shall be carried out first after entering the production line to manufacture steel plates for large-diameter submerged arc welded straight seam steel pipes.

2、Milling: use the edge milling machine to mill the two edges of the steel plate on both sides to achieve the required parallelism, width and groove shape of the plate edge.

3、Pre bending: pre bending the plate edge with the pre bending machine to make the plate edge meet the requirements.

4. Forming: First, on the forming machine, press half of the pre bent steel plate into J shape through multiple step stamping, then press the other half of the steel plate into C shape, and finally form the O shape of the opening

5. Pre welding: seam weld the formed straight seam welded steel pipe and conduct continuous welding with gas shielded welding.

6. Internal welding: weld on the inner side of the straight seam steel pipe, using longitudinal multi wire submerged arc welding, up to four wires.