Key points and main equipment for processing large-diameter straight seam steel pipes

First, the process flow and main equipment for large-diameter straight seam steel pipes

Process the two plate edges into the required form at one time, steel plate milling machine: machine the two sides of the plate material used for pipe making, and make the parallelism of the two plate edges reach the specified tolerance range, in preparation for the manufacture of high-precision steel pipes. Make the steel plate edge have a radius of curvature equal to the radius of the steel plate to be formed, steel plate pre-bending machine: pre-bend the steel plate edge with welding grooves on both sides processed by the milling machine. Prevent the forming machine from producing too long straight edges in the formed steel pipe to ensure the roundness of the steel plate.

1. Fully automatic steel pipe forming machine: complete the bending and forming of various metal sheets. Further 2. Seam and pre-welding, steel pipe pre-welding machine: prepare the open pipe blank formed by the forming machine for internal and external welding.

3. The welding trolley transports the workpiece along the track. The double-wire internal welding machine is used for automatic submerged arc welding of large-diameter straight seam steel pipes and cooperates with the main machine to achieve welding of the workpiece.

4. The welding trolley transports the workpiece along the track. The double-wire external welding machine is used for automatic submerged arc welding of straight seam steel pipes and cooperates with the main machine to achieve welding of the workpiece.

5. To change the roundness of the steel pipe, the steel pipe finishing machine applies strong pressure from the outside to the long round pipe with poor roundness section by section to make it meet the relevant specifications and use requirements.

6. Gantry mobile sensor straightening machine: used for straightening steel cylindrical pipes.

7. Straight seam steel pipe flat head chamfering machine: chamfer the end of the straight seam steel pipe according to the specified blunt edge and groove angle.

8. Improve the dimensional accuracy of the steel pipe. Steel pipe expansion machine: eliminate stress.

9. Check whether there are penetration defects under the specified pressure of the steel pipe, 3000T water pressure testing machine: perform a water pressure test on the welded pipe. Eliminate welding stress and forming stress to ensure the performance of steel pipes.

10. It can detect longitudinal and transverse defects and heat-affected zone layer defects. Line wave detection equipment: 100% line wave non-destructive testing of all welds.

With the continuous improvement of rural environmental protection requirements and the development of my country's petroleum gas industry. In particular, the layout of energy pipelines has led to an increasing demand for straight seam submerged arc welded steel pipes, and the demand for the localization of large-diameter straight seam steel pipes has become increasingly greater. The West-East Gas Transmission Project is a national standard project, requiring 1.82 million tons of large-diameter straight seam steel pipes, of which 820,000 tons are large-diameter straight seam submerged arc welded steel pipes, and only a part of them are domestic steel pipes.

Second, key points of large-diameter straight seam steel pipe processing technology:

Rebar thread processing

① The threaded head, tooth shape, pitch, etc. of the processed steel bar thread are consistent with the tooth shape and pitch of the connecting sleeve and are qualified after the matching gauge inspection.

② When processing steel bar threads, water-soluble cutting lubricant should be used; when the temperature is below 0℃, 15%-20% sodium nitrite should be added. Engine oil should not be used as lubricant or threading should not be done without lubricant.

③ The operator should check the appearance of the steel bar thread heads one by one and make the operator mark.

④ For steel bar thread heads that have passed the self-inspection, 10% of the processing volume of each specification should be randomly inspected, and no less than 10 pieces should be inspected. If there is one unqualified, the entire batch should be inspected, and the unqualified thread heads should be reprocessed and can be used after passing the re-inspection.

⑤ The thread heads that have passed the inspection should be protected and capped, classified and neatly prepared for use according to specifications.