Matters needing attention in the inspection process of welded steel pipe

　　Welded steel pipe is a spiral seam steel pipe welded by automatic double wire submerged arc welding technology, which is made of steel coil and main raw material and extruded at room temperature. The strength of the Welded steel pipe is relatively high. It can produce large diameter steel pipe with narrow billet, and can also produce Welded steel pipe with different diameters with the same width. Therefore, the use of spiral pipe is also very extensive, but in the process of making Welded steel pipe, we should pay attention to the following problems.

　　1, oiling and marking: check the qualified Welded steel pipe for oil painting operation to prevent corrosion, and mark according to the requirements of customers.

　　2, leveling milling edge: the original curled steel plate is leveled with the press anvil machine, and then the two edge of the steel plate is milled through the milling machine to achieve the required plate width, the parallelism of the edge of the plate and the shape of the bevel.

　　3, shear forming: steel plate along the outer spiral curved pipe.

　　4, butt welding: double face submerged arc welding technology is used for pre welding, internal welding and external welding. 304 Stainless Steel Precision Welded Steel Pipe is cut into standard length by plasma ruler.

　　5, visual inspection: some basic parameters are inspected by professional and technical personnel.

　　6, ultrasonic flaw detection: 100% check for the internal and external weld and the two sides of the weld.

　　7, X ray flaw detection: 100% X ray industrial TV inspection of internal and external welds, image processing system is adopted to ensure the sensitivity of flaw detection.

　　8, pressure test: test the steel pipe by root test on the hydraulic pressure tester to ensure that the steel pipe meets the test pressure required by the standard.

　　9, chamfering flat head: after processing qualified Welded steel pipe for pipe end processing, to achieve the required pipe end groove size.

　　10., final inspection: ultrasonic and X ray detection and tube side magnetic particle inspection are performed again to check whether there are welding problems and pipe end defects.