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The production process of Longigudinally Submerged Arc Welding
- Steel probe: After the steel plate is submerged arc welded to the large-diameter pipe joint into a straight line, first, the entire plate will be ultrasonic inspected.
- Side milling: the milling machine is used for double-sided milling on both sides of the steel plate to meet the requirements of plate width, plate edge parallelism and groove shape;
- Pre-bending edge: the pre-bending machine is used to pre-bend the plate edge node, so that the plate edge has the required curvature;
- Forming: On the JCO forming machine, the semi-curved steel plate is pressed into a “J” shape by several steps, and then the other half of the steel plate is bent into a “C” shape, and finally the opening “O” shape is formed.
- Pre-welding: The preparation of straight welded steel pipe, the use of gas welding (MAG) continuous welding;
- Internal welding: longitudinal multi-wire submerged arc welding (no more than four wires) is used to weld the inside of the straight steel pipe.
- External welding: longitudinal multi-wire submerged arc welding is used for the external welding of straight seam submerged arc welded steel pipe.
- Ultrasonic inspection I: 100% check the metal inside and outside of the straight seam welded steel pipe and on both sides of the weld;
- X-ray flaw detection I: 100% X-ray industrial TV inspection of internal and external weld information, using these image data processing management systems can ensure the sensitivity of the flaw detection.
- Diameter expansion: The full length of the submerged arc welded straight seam steel pipe is expanded to improve the dimensional accuracy of the steel pipe and improve the distribution of stress in the steel pipe.
- Hydraulic test: The steel pipe with expanded diameter is checked one by one on the hydraulic test machine to ensure that the steel pipe meets the standard test pressure. The machine has the function of automatic recording and storage.
- Chamfering: The inspected steel pipe is processed at the end of the pipe to meet the required trench size at the end of the pipe.
- Ultrasonic inspection II: Ultrasonic inspection is carried out again to check the possible defects after the diameter expansion and water pressure of the straight seam welded steel pipe.
- X-ray inspection II: X-ray industrial inspection and tube end weld film diameter expansion and water pressure test;
- Magnetic particle test at the end of the pipe: this inspection is to find out the defects at the end of the pipe;
