DSAW pipe process

One. Panel inspection: After entering the production line, steel plates for manufacturing large diameter submerged arc welded steel pipes are firstly subjected to full plate ultrasonic inspection;


2. Milling: Use a milling machine to perform double-sided milling on the two sides of the steel plate to achieve the required board width, side parallelism and groove shape;


three. Pre-bending: pre-bend the edge of the board with a pre-bending machine so that the edge of the board has the required curvature;


four. Forming: Firstly pre-bent half of the steel plate is stepped and stamped on a JCO forming machine to be pressed into a "J" shape, then the other half of the steel plate is also bent and pressed into a "C" shape, and finally an open O-shape


5. Pre-weld: The joints of straight seam welded steel pipes are continuously welded by gas shielded welding (MAG);


6. Internal welding: Longitudinal multi-wire submerged arc welding is used inside the straight seam steel pipe (up to four wires);


Number 7. Outer welding: longitudinal multi-wire submerged arc welding on the outer side of LSAW steel pipe;


8. Ultrasonic flaw detection 1: 100% flaw detection of the inner and outer welds of the straight seam welded steel pipe and the base metal on both sides of the weld;


No.9. X-ray inspection: 100% X-ray industrial television detects internal and external welds, using an image processing system to ensure flaw detection sensitivity;


10. Expansion: Enlarge the full length of LSAW steel pipe, improve the dimensional accuracy of steel pipe, and improve the stress distribution of steel pipe;


number 11. Hydrostatic test: On the hydrostatic testing machine, test the expanded steel pipe one by one to ensure that the steel pipe meets the test pressure required by the standard. With automatic recording and storage functions;


12 years old. Chamfering: The steel pipe qualified for inspection is processed at the pipe end to reach the required pipe end bevel size;


13 years old. Ultrasonic flaw detection II: Perform ultrasonic flaw detection on the straight seam welded pipe again and again, check for possible defects and water pressure after straightening of the straight seam welded pipe;


14 years old. X-ray inspection II: X-ray industrial TV inspection after pipe expansion and hydrostatic test and coating film at the end of the pipe;


15 years old. Tube end magnetic particle inspection: Conduct this inspection and find tube end defects;


16 years old. Anti-corrosion coating: The qualified steel pipes are subjected to anti-corrosion coating according to user requirements.