---

　　It is a spiral seam steel pipe made of strip steel coil as raw material, often warm extrusion and welding by automatic double wire double-sided submerged arc welding process

　　(1) Raw materials, i.e. strip steel coil, welding wire and flux. Before being put into operation, it must undergo strict physical and chemical inspection.

　　(2) The butt joint of strip steel head and tail adopts single wire or double wire submerged arc welding, and automatic submerged arc welding is adopted for repair welding after rolling into welded steel pipe.

　　(3) Before forming, the strip steel is leveled, trimmed, planed, cleaned, transported and pre bent.

　　(4) The electric contact pressure gauge is used to control the pressure of the pressing oil cylinder on both sides of the conveyor to ensure the smooth transportation of strip steel.

　　(5) Adopt external control or internal control roll forming.

　　(6) The weld gap control device is used to ensure that the weld gap meets the welding requirements, and the pipe diameter, misalignment and weld gap are strictly controlled.

　　(7) Both internal welding and external welding adopt American Lincoln Electric welding machine for single wire or double wire submerged arc welding, so as to obtain stable welding specifications.

　　(8) All welded welds are inspected by online continuous ultrasonic automatic flaw detector, ensuring 100% coverage of nondestructive testing of spiral welds. If there are defects, it will automatically alarm and spray marks, and the production workers will adjust the process parameters at any time to eliminate the defects in time.

　　(9) The steel pipe is cut into single pieces by air plasma cutting machine.

　　(10) After cutting into a single steel pipe, the first three steel pipes in each batch shall be subject to a strict first inspection system to check the mechanical properties, chemical composition, fusion condition, surface quality of steel pipe and non-destructive flaw detection to ensure that the pipe making process is qualified before it can be officially put into production.

　　(11) The parts with continuous acoustic flaw detection marks on the weld shall be rechecked by manual ultrasonic and X-ray. If there are defects, after repair, they shall be subject to NDT again until it is confirmed that the defects have been eliminated.

---

Previous: Manufacturing process of straight seamless steel pipe
Next: Brief analysis on the production process of welded steel pipes

---