Spiral welded pipe is also a type of welded pipe equipment. Its strength is generally higher than that of straight seam welded pipe. It can use narrower billets to produce welded pipes with larger diameters. It can also use billets of the same width to produce welded pipes with different diameters. However, compared with straight seam pipes of the same length, the weld length is increased by 30~100%, and the production speed is lower. Therefore, smaller diameter welded pipes mostly use straight seam welding, while large diameter welded pipes mostly use spiral welding.
Spiral steel pipe production process: It is a spiral seam steel pipe welded by automatic double-wire double-sided submerged arc welding process using strip steel coil plate as raw material, constant temperature extrusion molding.
1. The raw materials are steel strip coil, welding wire and flux. They must undergo strict physical and chemical inspections before being put into use.
2. The head and tail of the steel strip are butt-jointed using single-wire or double-wire submerged arc welding. After being rolled into a steel pipe, automatic submerged arc welding is used for repair welding.
3. Before forming, the strip steel is leveled, trimmed, planed, surface cleaned, transported and pre-bent.
4. Electric contact pressure gauges are used to control the pressure of the cylinders on both sides of the conveyor, ensuring smooth conveying of the strip.
5. Adopt external control or internal control roller forming.
6. The weld gap control device is used to ensure that the weld gap meets the welding requirements. The pipe diameter, offset amount and weld gap are strictly controlled.
7. Both internal and external welding use American Lincoln welding machines for single-wire or double-wire submerged arc welding to obtain stable welding specifications.
8. All completed welds are inspected by an online continuous ultrasonic automatic flaw detector, ensuring 100% non-destructive testing coverage of spiral welds. If there is a defect, it will automatically alarm and spray mark, so that production workers can adjust the process parameters at any time to eliminate defects in time.
9. Use an air plasma cutting machine to cut the steel pipe into individual pieces.
10. After cutting into individual steel pipes, the first three steel pipes in each batch must undergo a strict first inspection system to check the mechanical properties, chemical composition, fusion status of the welds, the surface quality of the steel pipes, and non-destructive testing to ensure that the pipe making process is qualified. Only then can it be officially put into production. 11. The areas with continuous sonic flaw detection marks on the welds will undergo manual ultrasonic and X-ray re-examination. If there are indeed defects, they will be repaired and then undergo non-destructive inspection again until it is confirmed that the defects have been eliminated.
12. The butt welds of the strip steel and the pipes where the T-shaped joints intersect with the spiral welds are all inspected by X-ray television or film.
13. Each steel pipe has undergone a hydrostatic pressure test, and the pressure is radially sealed. The test pressure and time are strictly controlled by the steel pipe water pressure microcomputer detection device. Test parameters are automatically printed and recorded.
14. The pipe end is machined to accurately control the end face verticality, bevel angle and blunt edge.