What does the production process of LSAW Steel Pipe include?

LSAW steel pipe is a longitudinal parallel steel pipe. Usually divided into metric welded steel pipes, welded thin-walled pipes, transformer cooling oil pipes, etc. The production process of straight seam welded pipe is simple, the production efficiency is high, the cost is low, and the development is rapid. Straight seam submerged arc welded steel pipes can be divided into high-frequency straight seam steel pipes and submerged arc welded straight seam steel pipes according to the production process. Submerged arc welded straight seam steel pipes are divided into UOE, RBE and JCOE steel pipes according to different forming methods. The following introduces the most common forming processes of high-frequency straight seam steel pipes and submerged arc welded straight seam steel pipes.

1. Proofing: After the steel plates used to manufacture large-diameter submerged arc welded straight seam steel pipes enter the production line, full-plate ultrasonic flaw detection is first performed;

2. Edge milling: Use an edge milling machine to double-side mill the two edges of the steel plate to achieve the required plate width, plate edge parallelism and bevel shape;

3. Pre-bending: The pre-bending machine pre-bends the edge so that the edge of the board has a required curvature;

4. Forming: First, half of the pre-bent steel plate is stamped into a "J" shape on the JCO forming machine. The other half of the steel plate is also bent and pressed into a "C" shape to create the opening. "O" shape

5. Pre-welding: After the straight seam welded steel pipe joint is formed, gas shielded welding (MAG) is used for continuous welding;

6. Internal welding: vertical multi-wire submerged arc welding (up to four wires) is used to weld the inside of the straight seam steel pipe;

7. External welding: Vertical multi-wire submerged arc welding is used for external welding of straight seam submerged arc welded steel pipes;

8. Ultrasonic flaw detection 1: Conduct 100% flaw detection on the internal and external welds of the straight seam welded steel pipe and the base metal on both sides of the weld;

9. X-ray inspection I: 100% X-ray industrial TV is used to inspect internal and external welds, and an image processing system is used to ensure detection sensitivity;

10. Diameter expansion: The entire length of the submerged arc welded straight seam steel pipe is expanded to improve the dimensional accuracy of the steel pipe and improve the stress distribution within the steel pipe;

11. Hydraulic pressure test: The root diameter of the expanded steel pipe is tested on a hydraulic testing machine to ensure that the steel pipe meets the specified test pressure. The machine has automatic recording and storage functions;

12. Chamfering: After passing the inspection, the pipe end of the steel pipe is processed to achieve the required pipe end bevel size;

13. Ultrasonic flaw detection 2: Perform ultrasonic flaw detection again to check for possible defects that may occur after diameter expansion and water pressure of the straight seam welded steel pipe.

14. X-ray inspection 2: The steel pipe after diameter expansion and hydrostatic pressure test undergoes X-ray industrial television inspection and pipe end weld inspection;

15. Magnetic particle inspection of pipe ends: This inspection is performed to find defects at pipe ends;

16. Anti-corrosion and coating: Qualified steel pipes are anti-corrosion and coated according to user requirements.