Heli-coiled pipes are primarily used for the transmission pipelines of oil and natural gas, with their specifications indicated by the outer diameter multiplied by the wall thickness. These pipes come in single-sided and double-sided焊接 options. The welded pipes must ensure that the hydraulic test, tensile strength of the weld, and cold bending properties meet the specified requirements.
1. Raw materials, including steel coils, welding wire, and welding flux, must undergo rigorous physical and chemical testing before being used.
2. Steel strip ends are joined with single or double wire submerged arc welding, followed by automatic submerged arc welding for reinforcement after the steel pipe is coiled.
3. Prior to forming, the strip steel undergoes leveling, trimming, edge dressing, surface cleaning conveyance, and pre-bending treatment.
4. Utilizing an electric contact pressure gauge to control the pressure in the down-pressure cylinders on both sides of the conveyor, ensuring smooth and even steel strip conveyance.
5. Utilize external or internal roll forming.
6. Utilize a weld gap control device to ensure that the weld gap meets welding requirements; strict control is maintained over pipe diameter, offset amount, and weld gap.
7. Both inner and outer welding are performed using Lincoln welding machines for single or double wire submerged arc welding, ensuring a stable welding specification.
8. All weld seams are inspected by an online continuous ultrasonic flaw detector, ensuring full coverage for the spiral welds' non-destructive testing. In case of defects, an automatic alarm is triggered and marked with paint, allowing production workers to adjust process parameters in real-time and promptly eliminate the defects.
9. Cut steel pipes individually using an air plasma cutting machine.
10. After cutting into individual steel pipes, each batch must undergo a rigorous initial inspection process, checking the mechanical properties of the welds, chemical composition, fusion condition, surface quality of the pipes, and undergo non-destructive testing to ensure the pipe-making process is qualified before it can be officially put into production.
11. Areas with continuous ultrasonic flaw detection marks on the welds must undergo manual ultrasonic and X-ray re-inspection. If defects are confirmed, they must be repaired and re-inspected non-destructively until the defects are eliminated.
12. All pipes with butt welds of steel strips or T-joints intersecting spiral welds have been subjected to X-ray television inspection or filming.
13. Each steel pipe undergoes hydrostatic testing with radial sealing. 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. Precision machining at the pipe end to ensure accurate control of the perpendicularity of the end face, bevel angle, and burr.
Helical Steel Pipe Applications: Spiral-welded pipes are primarily used in water supply projects, petrochemical industry, chemical industry, power industry, agricultural irrigation, urban construction, and are among the twenty key products developed in China. For liquid transportation: water supply and drainage. For gas transportation: coal gas, steam. For structural purposes: used as pile pipes, for bridges, wharfs, roads, and building structures. Helical steel pipes are made from strip steel coils, formed through normal temperature extrusion, and welded into spiral seam pipes using the automatic double-sided submerged arc welding process.
Helical tubes, also known as helical cylinders or helical bodies, have an outer diameter of about 30 nanometers and an inner diameter of about 10 nanometers, with adjacent helical spacing of approximately 11 nanometers. Each complete helix is formed by 6 nucleosomes, with the H1 histone located on the inner surface of the helical tube, playing a crucial role in maintaining its structure. The 10-nanometer fiber composed of nucleosomes spirals to form a 30-nanometer thick fiber, further compressing the DNA length by a factor of 6.
The trend of rapid and stable growth in the demand for spiral steel pipes is unlikely to fundamentally change. Whether the spiral steel pipe market can maintain rapid and stable development hinges on changes in demand. Macroeconomic policies will, in the future, bring about a certain slowdown in the growth rate of the market.
