Spiral welded pipe is also a type of welded pipe equipment, and its strength is generally higher than that of straight seam welded pipe. It can produce welded pipes with larger diameters using narrower billets, and can also produce welded pipes with different diameters using billets of the same width. However, compared to straight seam pipes of the same length, the weld seam length increases by 30-100%, resulting in a lower production speed. Therefore, smaller diameter welded pipes mostly use straight seam welding, while larger diameter welded pipes mostly use spiral welding.
1、 Spiral steel pipe production process: Spiral seam steel pipe is made of strip steel coil as raw material, extruded at room temperature, and welded by automatic double wire double-sided submerged arc welding.
1. The raw materials are strip steel coils, welding wires, and fluxes, which must undergo strict physical and chemical inspections before they can be put into use.
2. The head and tail of the strip steel are connected using single or double wire submerged arc welding. After the steel pipe is rolled into a steel pipe, automatic submerged arc welding is used for repair welding.
3. Before forming, the strip steel undergoes processes such as leveling, trimming, planing, surface cleaning, conveying, and pre bending.
4. Using an electric contact pressure gauge to control the pressure of the oil cylinders on both sides of the conveyor, ensuring smooth steel strip transportation.
5. Adopting external or internal control roll forming.
6. Adopting a weld seam gap control device to ensure that the weld seam gap meets the welding requirements, and strictly controlling the pipe diameter, misalignment, and weld seam gap.
7. Both internal and external welding are carried out using American Lincoln welding machines for single or double wire submerged arc welding, which can achieve stable welding specifications.
8. The welded seams are inspected using an online continuous ultrasonic automatic flaw detector to ensure a 100% coverage rate of non-destructive testing for spiral welds. If there are defects, automatic alarms and markings are sprayed, and production workers adjust process parameters at any time to eliminate defects in a timely manner.
9. Steel pipes are cut into single pieces using an air plasma cutting machine.
10. After cutting into individual steel pipes, the first three pipes of each batch must undergo strict inspection to check their mechanical properties, chemical composition, fusion condition, surface quality, non-destructive testing of welds, etc., to ensure that the pipe making process is qualified before they can be officially put into production.
11. The parts with continuous ultrasonic inspection marks on the weld seam need to be manually inspected by ultrasonic and X-ray. If there are defects, they need to be repaired, and then non-destructive testing should be carried out again until it is confirmed that the defects have been eliminated.
12. The steel pipe strip butt weld and the T-shaped joint intersecting with the spiral weld are inspected by X-ray television or film.
13. Each steel pipe undergoes a hydrostatic pressure test, with radial sealing used for pressure. The test pressure and time are strictly controlled by a steel pipe hydraulic microcomputer detection device, and the test parameters are automatically printed and recorded.
14. The pipe end is machined to accurately control the perpendicularity, bevel angle, blunt edge, etc. of the end face.
