The large diameter spiral pipe is a spiral welded steel pipe made of strip steel coil as raw material, usually formed by warm extrusion, and welded by automatic double-wire double-side submerged arc welding process.
(1) Raw materials namely strip steel coil, welding wire, flux. They must undergo rigorous physical and chemical tests before they are put in.
(2) The butt joint of strip head and tail shall adopt single or double submerged arc welding, and automatic submerged arc welding shall be adopted after the steel pipe is rolled.
(3) Before forming, strip steel goes through flattening, trimming, planing, surface cleaning, transportation and bending treatment.
(4) The electric contact pressure gauge is used to control the pressure of the oil cylinder pressed down on both sides of the conveyor to ensure the smooth transmission of the belt steel.
(5) Adopt external control or internal control roller forming.
(6) The welding seam clearance control device is adopted to ensure that the welding seam clearance meets the welding requirements, and the pipe diameter, the amount of wrong side and the welding seam clearance are strictly controlled.
(7) Both internal and external welding are performed by Lincoln welder for single or double submerged arc welding, so as to obtain stable welding specifications.
(8) The finished welds are inspected by online continuous ultrasonic automatic wound meter, which ensures 100% coverage of non-destructive testing of spiral welds. If there is a defect, it will be automatically alerted and marked by spraying, and the production workers will adjust the process parameters at any time to eliminate the defect in time.
(9) Air plasma cutting machine is used to cut the steel pipe into single pieces.
(10) After being cut into a single steel tube, three steel tubes of each batch shall be subjected to a strict first inspection system to check the mechanical properties, chemical composition, melt condition, surface quality of the steel tubes and non-destructive inspection to ensure that the tube making process is qualified before being put into production.
(11) The parts marked by continuous acoustic inspection shall be reviewed by manual ultrasonic and X-ray. If there is any defect, after being repaired, the parts shall be subjected to non-destructive testing again until the defect is confirmed to have been eliminated.
(12) The strip butt weld and the pipe where the d joint intersects the spiral weld shall all be inspected by X-ray television or film.
(13) Each steel tube shall be subjected to hydrostatic test and pressure shall be sealed radial. The test pressure and time are strictly controlled by the steel pipe hydraulic microcomputer testing device. Test parameters are automatically printed and recorded.
(14) Pipe end machining, so that the perpendicularity, bevel Angle and blunt edge can be accurately controlled.
