Spiral steel pipe is a spiral seam steel pipe which is made of steel coiled coil as raw material, which is often heated and extruded, and welded by automatic double wire double-sided submerged arc welding process.
1. The raw materials are strip coils, welding wire, flux. Before the input, it is subject to strict physical and chemical tests (Q345B is taken as the first letter of the Q-type Chinese pinyin of the Q-steel's yield strength; 345—yield strength value, in MPa; B—quality grade is B.) . 1 Q345B chemical composition C: ≤ 0.20%, Si ≤ 0.50%, Mn: ≤ 1.70%, P ≤ 0.035%, S: ≤ 0.035%, Nb ≤ 0.07%, V: ≤ 0.15%, Ti ≤ 0.20%, Cr ≤ 0.30%, Ni: ≤ 0.50%, Cu: ≤ 0.30%, N: ≤ 0.012%, Mo: ≤ 0.10%; 2 Q345B mechanical properties yield strength: ≤16mm: ≤345,16-40mm: ≤335,40-63mm: ≤325,63-80mm:≤315,80-100m:≤305,100-150mm:≤285,150- 200mm: ≤275. Tensile strength: 450-630. Elongation: greater than 17. Impact test: Test temperature: 20 ° C: greater than 34.
2. The strip head and tail butt joint, using monofilament or double wire submerged arc welding, after the rolling into steel pipe, automatic submerged arc welding repair welding.
3. Before forming, the strip is leveled, trimmed, planed, surface cleaned and treated with crimping.
4. The 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 the strip.
5. The use of external control or internal control roll molding.
6. The weld gap control device is used to ensure that the weld gap meets the welding requirements, and the pipe diameter, the amount of misalignment and the weld gap are strictly controlled.
7. Both internal and external welding are performed by American Lincoln welding machine for single or double wire submerged arc welding to obtain stable welding specifications.
8. The welded welds are inspected by online continuous ultrasonic automatic injury inspection to ensure the non-destructive testing coverage of 100% spiral welds. If there is a defect, the alarm is automatically alarmed and sprayed, and the production worker adjusts the process parameters at any time to eliminate defects in time.
9. Cut the steel pipe into a single root using an air plasma cutting machine.
10. After cutting into a single steel pipe, each batch of steel pipe shall undergo a strict first inspection system to check the mechanical properties, chemical composition, fusion condition, surface quality of the steel pipe and non-destructive testing to ensure the pipe-making process is qualified. In order to formally put into production.
11. The part of the weld with continuous sound wave flaw detection marks, after manual ultrasonic and X-ray review, if it is defective, after repairing, it will pass the non-destructive test again until it is confirmed that the defect has been eliminated.
12. The tube of the butt weld of the strip and the joint of the butt joint intersecting the spiral weld are all inspected by X-ray TV or film.
13. Each steel pipe is subjected to hydrostatic pressure test and the pressure is sealed by radial. 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 make the end face verticality, groove angle and blunt edge accurately controlled.
