Production process of large diameter welded pipe
Large-diameter welded pipe is a spiral seam steel pipe, which is made of strip steel coil as raw material, often formed by warm extrusion, and welded by automatic double-wire and double-sided submerged arc welding process. The spiral steel pipe sends the strip steel into the welding pipe unit. After the rolling of multiple rollers, the strip steel gradually rolls up to form a circular tube billet with an open gap. The reduction amount of the extrusion roller is adjusted to control the weld seam gap at 1~3mm and level the welding mouth at both ends.
Following the Large Diameter Steel Pipe manufacturer China would like to share with us.
Production process of large-diameter welded pipe:
(1) raw materials: strip coil, welding wire, flux. Rigorous physical and chemical examination must be carried out before investment.
(2) the end of the strip shall be butt joint by single wire or double wire submerged arc welding. After the steel pipe is rolled, automatic submerged arc welding shall be adopted.
(3) before forming, the strip is smoothed, trimmed and planed, its surface is cleaned and transported, and its edges are bent.
(4) electric contact pressure gauge is adopted to control the pressure of oil cylinder on both sides of the conveyor, ensuring the smooth transportation of the strip.
(5) external control or internal control roll forming.
(6) weld gap control device is adopted to ensure that weld gap meets welding requirements, and pipe diameter, wrong edge quantity and weld gap are strictly controlled.
(7) both internal and external welding are performed by single or double wire submerged arc welding with American Lincoln welding machine, so as to obtain stable welding quality of the Large Diameter Spiral Steel Pipe.
(8) all welded welds are inspected by online continuous ultrasonic automatic flaw tester, ensuring 100% non-destructive testing coverage of spiral welds. If there are defects, automatic alarm and spraying mark, production workers according to this at any time to adjust the process parameters, timely elimination of defects.
(9) use an air plasma cutting machine to cut the steel tube into a single root.
(10) after cutting into a single steel pipe, each batch of steel pipes shall carry out a strict first inspection system to check the mechanical properties of welding seams, chemical composition, dissolution status, surface quality of steel pipes and through nondestructive inspection to ensure that the pipe production process is qualified, before it is officially put into production.
(11) where there is continuous acoustic inspection mark on the welding seam, manual ultrasonic and X-ray reexamination shall be conducted. If there is a defect, it shall be repaired and then nondestructive inspection shall be conducted again until it is confirmed that the defect has been eliminated.
(12) the tube where the butt welding seam of strip steel and the t-joint intersecting spiral welding seam are located shall all be examined by X-ray television or film.
(13) each steel pipe is tested by hydrostatic test, and the pressure is radial sealed. The test pressure and time are strictly controlled by the microcomputer testing device of steel pipe water pressure. Automatic printing record of test parameters.
(14) the pipe end is machined to control the verticality of the end face, groove Angle and blunt edge accurately.