Large-diameter spiral steel pipe and large-diameter straight-seam steel pipe are both welded steel pipes, and they play an important role in national production and life. Large-diameter spiral steel pipe and large-diameter straight-seam steel pipe have many differences due to different production processes.
1. In terms of the welding process: The welding methods of large-diameter spiral steel pipe and large-diameter straight-seam steel pipe are the same. Large-diameter straight-seam steel pipe has T-welds. The welding residual stress at the T-weld is large, and the weld metal is often in a triaxial stress state, which increases the possibility of cracks. The strength of spiral steel pipe is generally higher than that of straight-seam welded steel pipe. The main production process is submerged arc welding. Spiral steel pipe can use the same width of billet to produce welded steel pipes with different diameters, and can also use narrower billets to produce welded steel pipes with larger diameters.
2. The spiral angle of the weld of large-diameter spiral steel pipe is generally degrees, so the synthetic stress at the spiral weld is the principal stress. Under the same working pressure, the wall thickness of spiral steel pipes of the same diameter can be reduced compared with straight seam welded steel pipes.
3. Toughness and fatigue strength: The development trend of pipelines is large diameter and high strength. With the increase of steel pipe diameter and the improvement of steel grade used, the tendency of stable expansion of tough fracture tip is greater. Although spiral steel pipes and straight seam welded steel pipes are of the same grade, spiral steel pipes have higher impact toughness.
4. Compared with straight seam steel pipes of the same length, the weld length of spiral steel pipes is increased by 30~100%, and the production speed is lower. Therefore, most of the smaller diameter welded steel pipes are straight seam welded, while large diameter steel pipes are mostly spiral welded.
Post time: May-15-2025