Double-sided submerged arc welding straight seam steel pipe production process

Date:2023-06-16View:474Tags:Double-sided submerged arc welding straight seam steel pipe,LSAW Steel Pipe,welded pipe

LSAW steel pipe Production Process

1. Plate detection: After the steel plate enters the production line, the whole plate ultrasonic inspection is first carried out, and the raw materials for the production of steel pipes are strictly checked.

2. Edge milling: use the automatic edge milling machine to perform double-sided milling on the two longitudinal sides of the steel plate to make it reach the required plate width. The edge milling machine has the function of automatic centering of the steel plate, and the milling head has the function of floating profiling tracking, which 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. the
3. Pre-bending: Use the pre-bending machine to pre-bend the edge of the plate. The pre-bending machine will pre-bend the edge of the plate to a suitable curvature to ensure the geometric shape of the weld area and prepare for the subsequent processes of forming, welding and diameter expansion. prepare for.
4. Forming: The JCO forming method is progressive multi-step molding. The steel plate is ideally rounded by the numerical control system. The deformation of each part of the steel plate is uniform, there is no obvious stress concentration, and the residual stress is small and evenly distributed. On the JCO forming machine, firstly, half of the pre-bent steel plate is stamped into a "J" shape by multiple steps, and then the other half of the steel plate is also bent into a "C" shape, and finally an open "O" shape is formed. .
5. Pre-welding: The pre-welding machine performs fast seam pre-welding on open steel pipes, laying the foundation for ensuring the quality of internal and external multi-wire submerged arc welding. At the same time, high-power continuous active gas shielded arc welding (MAG) is used for pre-welding, which ensures the quality of pre-welding and lays a good foundation for internal and external welding.
6. Internal welding: Internal welding adopts tandem multi-wire submerged arc welding on the inner side of the steel pipe. Its characteristics are: high production efficiency, low porosity and slag inclusion rate, small crack tendency, good mechanical properties of joints, and easy weld geometry. control.
7. External welding: external welding adopts tandem multi-wire submerged arc welding to weld the outer side of the straight seam submerged arc welded steel pipe;
8. Ultrasonic flaw detection Ⅰ: Carry out 100% UT automatic flaw detection on the inner and outer welds of longitudinally welded pipes and the base metal on both sides of the welds;
9. X-ray flaw detection Ⅰ: Carry out 100% X-ray industrial TV flaw detection for internal and external welds, and use image processing system to ensure the sensitivity of flaw detection;
10. Diameter expansion: The diameter expansion machine can expand, round and straighten the entire length of the straight seam submerged arc welded steel pipe (LSAW), so as to improve the geometric precision of the steel pipe and improve the distribution of internal stress of the steel pipe.
11. Hydrostatic test: The hydrostatic testing machine carries out hydrostatic inspection on the expanded steel pipes one by one. The hydraulic press has the function of automatically recording and storing the test pressure and time. The supercharger can increase the water pressure in the pipe in a short time to reach the test pressure required by the standard to ensure that the quality of the steel pipe meets the requirements.
12. Chamfering: The chamfering machine performs pipe end bevel processing on the steel pipe to meet the required pipe end bevel size to ensure the butt welding quality of the steel pipe. the
13. Ultrasonic flaw detection II: Carry out UT flaw detection on the weld seam and the base metal on both sides one by one again, and inspect the possible defects of the straight seam welded pipe after diameter expansion and water pressure;
14. X-ray flaw detection Ⅱ: Take pictures of the pipe end welds of steel pipes after diameter expansion and hydrostatic test to ensure the quality of steel pipes leaving the factory
15. Magnetic particle inspection of pipe ends: carry out this inspection to find pipe end defects;

16. Anti-corrosion and coating: According to user requirements, the steel pipes that have passed the inspection are treated for anti-corrosion and coating.

lsaw Welded Pipe process


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