LSAW Steel Pipe, that is, double-sided submerged arc welded straight seam steel pipe, its production process mainly includes the following steps:

1. Plate detection: After the steel plate enters the production line, it is first subjected to full-plate ultrasonic inspection to strictly control the raw materials for producing steel pipes to ensure that the quality of the steel plate meets the requirements and there are no internal defects.

2. Edge milling: The two longitudinal edges of the steel plate are double-sided milled by a fully automatic edge milling machine to achieve the plate width, plate edge parallelism and groove shape required for processing. The edge milling machine has the function of automatic centering of the steel plate, and the milling head has a floating profiling tracking function. It can automatically adjust the position of the milling head according to the flatness of the steel plate to ensure that both sides of the steel plate have the same groove shape and size.

3. Pre-bending: Use a pre-bending machine to pre-bend the plate edge so that the plate edge has a curvature that meets the requirements, ensure the geometric shape of the weld area, and prepare for subsequent forming, welding and expansion processes.

4. Forming

JCO forming: On the JCO forming machine, first half of the pre-bent steel plate is pressed into a "J" shape through multiple step punching, and then the other half of the steel plate is bent in the same way and pressed into a "C" shape, and finally an open "O" shape is formed.

UOE forming: The steel plate is first pressed into a U shape in the forming die, and then pressed into an O shape.

5. Pre-welding: The formed straight seam welded steel pipe is seamed, and gas shielded welding (MAG) is used for continuous welding, laying a good foundation for internal and external welding.

6. Internal welding: The longitudinal multi-wire submerged arc welding (up to four wires) is used to weld on the inside of the straight seam steel pipe, with high production efficiency, low porosity and slag inclusion rate, small crack tendency, good joint mechanical properties, and easy control of weld geometry.

7. External welding: The longitudinal multi-wire submerged arc welding is used to weld on the outside of the straight seam submerged arc welded steel pipe to further ensure the quality and strength of the weld.

8. Ultrasonic inspection I: 100% automatic flaw detection inspection of the internal and external welds of the straight seam welded steel pipe and the parent materials on both sides of the weld to promptly detect possible defects in the welds and parent materials.

9. X-ray inspection I: 100% X-ray industrial television inspection of the internal and external welds, using an image processing system to ensure the sensitivity of flaw detection and the internal quality of the weld.

10. Diameter expansion: The diameter expansion machine is used to expand, round and straighten the entire length of the submerged arc welded straight seam steel pipe to improve the geometric dimensional accuracy of the steel pipe and improve the distribution of stress in the steel pipe.

11. Hydrostatic test: The expanded steel pipes are inspected one by one on the hydrostatic test machine to ensure that the steel pipes meet the test pressure required by the standard. The hydraulic press has the function of automatically recording and storing the test pressure and time.

12. Chamfering: The steel pipes that have passed the inspection are processed at the pipe end, and the pipe end groove size that meets the requirements is processed by the chamfering machine to ensure the quality of the butt welding of the steel pipe.

13. Ultrasonic inspection II: Ultrasonic inspection is performed again on each pipe to check for possible defects after expansion and water pressure test.

14. X-ray inspection II: X-ray industrial television inspection and pipe end weld filming are performed on the steel pipes after expansion and water pressure test to further detect the quality of the steel pipes.

15. Magnetic particle inspection of pipe ends: This inspection is performed to find defects at the pipe ends and ensure the quality of the pipe ends.

16. Anti-corrosion and coating: After passing the inspection, the qualified steel pipes are treated with anti-corrosion and coating according to user requirements, such as spraying anti-corrosion paint, hot-dip galvanizing, etc., to improve the corrosion resistance and service life of the steel pipes.

The production process of LSAW steel pipes is a complex and delicate process involving multiple links and multiple technologies. Each link is crucial to ensure the quality and performance of the final product.