Main production process description of large diameter straight seam welded pipe

Straight seam welded pipe, where the production of straight seam welded pipe, hot expansion pipe, etc., with strip steel as raw material for production, the pipe obtained by straight seam welding on welding equipment is called straight seam welded pipe. (Because the welded portion of the steel pipe is in a straight line, it is named). Among them, according to different uses, and different post-production processes, (substantially can be divided into scaffolding tubes, fluid tubes, wire casings, bracket tubes, guardrail tubes, etc.). Straight seam welded pipe standard GB/T3091-2008 and low pressure fluid welded pipe is a kind of straight seam welded pipe. Generally, water and gas are transported.steel coil manufacturers

Main production process description of large diameter straight seam welded pipe

After welding, more water pressure test is carried out than ordinary welded pipe. The current low pressure fluid pipe is more straight than ordinary straight seam. The price of welded pipe is a little higher (according to the current market price, it is about 80 yuan higher).

Main production process description of large diameter straight seam welded pipe:

  1. Panel inspection: After the steel plate used to manufacture the large-diameter submerged arc welded straight seam steel pipe enters the production line, the whole board ultrasonic inspection is first carried out;
  2. X-ray inspection I: 100% X-ray industrial TV inspection of internal and external welds, using image processing system to ensure the sensitivity of flaw detection;
  3. Expanding diameter: Expanding the full length of the submerged arc welded straight seam steel pipe to improve the dimensional accuracy of the steel pipe and improve the distribution of stress in the steel pipe;
  4. Milling edge: double-sided milling the two edges of the steel plate by the edge milling machine to achieve the required plate width, parallelism of the edge and the shape of the groove;
  5. Pre-bend: use the pre-bending machine to pre-bend the edge of the board so that the edge of the board has the required curvature;
  6. Molding: First, half of the pre-bent steel plate is stepped and stamped on the JCO molding machine, pressed into a “J” shape, and then the other half of the steel plate is also bent, pressed into a “C” shape, and finally an opening is formed. “O” shape
  7. Pre-welding: joints of straight seam welded steel pipes after forming and continuous welding by gas shielded welding (MAG);
  8. Internal welding: welding by longitudinal multi-wire submerged arc welding (up to four wires) on the inside of a straight seam steel pipe;
  9. External welding: welding by longitudinal multi-wire submerged arc welding on the outside of straight seam submerged arc welded steel pipe;
  10. Ultrasonic inspection I: 100% inspection of the inner and outer welds of straight seam welded steel pipes and the base metal on both sides of the weld;
  11. Hydraulic test: On the hydraulic testing machine, the steel pipe after the diameter expansion is tested one by one to ensure that the steel pipe meets the test pressure required by the standard. The machine has automatic recording and storage functions;
  12. Chamfering: The steel pipe after passing the inspection shall be processed at the pipe end to achieve the required pipe end groove size;
  13. Ultrasonic inspection II: Ultrasonic inspection is carried out again and again to check for defects that may occur after straightening and water pressure of straight seam welded steel pipes;
  14. X-ray inspection II: X-ray industrial TV inspection and tube end weld filming of the steel pipe after the expansion and hydrostatic test;
  15. Anti-corrosion and coating: The qualified steel pipe is preserved and coated according to user requirements;
  16. Tube end magnetic particle inspection: Perform this inspection to find the tube end defect.

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