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Production process of welded steel pipe

2020-08-27 11:42:07   COMMENT:0 HITS:
  The welded steel pipe is made of rolled steel plate, often formed by warm extrusion, and welded by automatic double wire double submerged arc welding process

  (1) The raw materials are strip coil, welding wire and flux. Before putting into operation, they should go through strict physical and chemical tests.

  (2) Single wire or double wire submerged arc welding is adopted for butt joint of strip steel head and tail, and automatic submerged arc welding is adopted after rolling steel pipe.

  (3) Before forming, the strip is leveled, trimmed, planed, cleaned, transported and bent.

  (4) The electric contact pressure gauge is used to control the pressure of the cylinder on both sides of the conveyor to ensure the smooth transportation of the strip steel.

  (5) External control or internal control roller molding is adopted.

  (6) The welding gap control device is used to ensure that the weld gap meets the welding requirements, and the pipe diameter, misalignment and weld clearance are strictly controlled.

  (7) Both internal welding and external welding adopt American Lincoln Electric welding machine for single wire or double wire submerged arc welding, so as to obtain stable welding specification.

  (8) All the welded steel pipe are inspected by on-line continuous ultrasonic automatic flaw detector, which ensures 100% coverage of non-destructive testing for spiral weld. If there are defects, it will alarm automatically and spray the mark. The production workers can adjust the process parameters at any time to eliminate the defects in time.

  (9) Air plasma cutting machine is used to cut the welded steel pipe into single pieces.

  (10) After cutting into single welded steel pipes, the first three pipes of each batch shall be subject to strict first inspection system, and the mechanical properties, chemical composition, fusion condition, surface quality of steel pipes and nondestructive testing shall be inspected to ensure that the pipe manufacturing process is qualified before being put into production.

  (11) The parts with continuous acoustic flaw detection mark on the weld shall be rechecked by manual ultrasonic wave and X-ray. If there is any defect, it shall be repaired and then NDT shall be conducted again until the defect is confirmed to be eliminated.

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