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The main production process of the straight welded pipe.
May 09, 2018

The main production process of the straight welded pipe.

Straight welded pipe is made of steel plate or steel strip through bending and then welded. The welding seam is divided into straight seam welded pipe and spiral welded pipe. According to the application is divided into general welded pipe, galvanized welded pipe, oxygen blowing metric welded pipe, welded pipe, wire casing, roller tube, deep well pump pipe, auto tube, transformer, electric welding thin wall pipe, welded pipe and spiral welded pipe.

The main production process of the direct seam welded pipe:

1. Board exploration: when the steel plate used to make large-diameter submerged arc welded steel pipe enters the production line, the whole plate ultrasonic inspection shall be carried out first.

2. Milling edge: double-sided milling on the edge of the steel plate through the edge milling machine, so as to achieve the required plate width, edge parallelism and groove shape;

3. Precurving edge: use the prebending machine to prebend the edge of the plate to make the edge of the plate meet the required curvature; 4. Molding: on the JCO forming machine bending of the plate after half after many step punching, pressure into a "J" shape, and the other half of the steel plate bending, same pressure into a "C" shape, eventually forming the opening "O" shape

5. Pre-welding: weld the welded steel pipe after forming and use gas shielded welding (MAG) for continuous welding;

6. Internal welding: using longitudinal multi-wire submerged arc welding (up to four wires) to be welded on the inside of the straight steel tube; 7. External welding: use longitudinal and multi-wire submerged arc welding to weld on the outside of the welded steel pipe with straight seam;

8. Ultrasonic inspection Ⅰ: inside and outside of straight seam welded steel pipe weld and weld on both sides of the base of 100% of the check;

9. X-ray Ⅰ: 100% of inside and outside weld X-ray industrial TV inspection, using image processing system to ensure the sensitivity of detection;

10. Expanding diameter: the length of the submerged arc welded steel pipe is expanded to improve the size precision of the steel pipe and improve the distribution state of the internal stress of the steel tube;

11. Water pressure test: the test pressure on the steel pipe after expanding the diameter of the steel pipe on the hydraulic test machine is carried out to ensure that the steel pipe meets the test pressure required by the standard. The machine has automatic recording and storage function;

12. Chamfering: the pipe end is processed after the qualified steel pipe is inspected to meet the required pipe end size;

13. The ultrasonic inspection Ⅱ: root by ultrasonic inspection to check again after the straight seam welded steel pipe in the hole diameter, water pressure may produce defects;

14. X-ray Ⅱ: for hole enlargement and after water pressure test of tube X-ray industrial TV inspection and pipe weld shooting;

15. Tube end magnetic particle inspection: this inspection is carried out to find defects in the pipe end;

16. Anticorrosion and coating: the qualified steel pipe shall be antiseptic and coated according to the user's requirements.


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