1) raw materials, including steel coil, welding wire and flux. Strict physical and chemical tests must be carried out before putting into operation.
2) Butt welding of strip head and tail, single wire or double wire submerged arc welding, automatic submerged arc welding after coiling steel pipe.
3) before forming, strip is leveled, trimming, planing, surface cleaning and conveying and bending.
4) Electric contact pressure gauge is used to control the pressure of the cylinder on both sides of the conveyor to ensure the smooth conveying of strip steel.
5) adopt external control or internal control roller molding.
6) The weld gap control device is used to ensure that the weld gap meets the welding requirements. The pipe diameter, staggered edge and weld gap are strictly controlled.
7) Both internal welding and external welding are carried out by single wire or double wire submerged arc welding with Lincoln welding machine, so as to obtain stable welding specification.
8) The welds are inspected by on-line continuous ultrasonic automatic flaw detector to ensure 100% coverage of spiral welds. If there is a defect, the automatic alarm and spray marking, production workers at any time to adjust the process parameters, timely elimination of defects.
9) use air plasma cutting machine to cut the steel pipe into single root.
10) After cutting into a single steel pipe, each batch of steel pipes must be strictly inspected for mechanical properties, chemical composition, melting condition, surface quality of the pipe and non-destructive testing to ensure that the pipe-making process is qualified before it can be formally put into production.
11) The part with continuous acoustic flaw detection mark on the weld, after manual ultrasonic and X-ray re-examination, if there is a defect, after repair, through non-destructive testing again, until it is confirmed that the defect has been eliminated.
12) The butt weld of strip steel and the tube where the D-joint intersects with the spiral weld are all inspected by X-ray television or photography.
13) each steel pipe is hydrostatic test and the pressure is radial sealed. The test pressure and time are strictly controlled by the microcomputer inspection device for steel pipe water pressure. The test parameters are automatically printed and recorded.
14) pipe end machining, so that the verticality of end face, slope angle and blunt edge can be controlled accurately.