1, seamless steel pipe
Wall thickness of seamless steel pipe is relatively thick, relatively small diameter thick. But the diameter is restricted, and its applications are limited, and production costs, especially for large diameter seamless steel pipe production costs are relatively high.

2, high-frequency welded steel pipe
High-frequency welded tubular good, uniform thickness, internal and external burrs generated by the welding tool Calibrating the appropriate online through strict control of non-destructive testing of weld quality, high degree of automation, low production costs. But relatively thin wall thickness, diameter is relatively small, usually no more than a wall thickness of 12mm, diameter of not more than 610mm, is particularly suitable for the production of steel tube truss structure.

3, LSAW steel pipe
LSAW pipe using + double submerged arc welding process, welding under static conditions, high weld quality, short weld defects is very small probability. Expanding through full-length steel tubular good, precise size, wide range of pipe wall thickness and diameter range, the diameter range up to 406-1829mm, wall thickness range up 6.0-60mm, high degree of automation, and seamless Compared to steel, lower production costs, for buildings, bridges, dams, offshore platforms and other steel bearing with pillars, large span structures as well as wind and seismic requirements for electrical tower masts structure.

4, Spiral submerged arc welded pipe
SSAW spiral weld line distribution, long welds, especially under dynamic conditions in welding, the weld had a chance to cool down on the left molding point, easy to produce welding hot cracking. Crack direction and parallel to the weld, and pipe axis into a certain angle, usually between 30-70 °. This angle is just consistent with the angle of shear failure, so the flexural, tensile, compressive and torsional performance is far better than LSAW pipe, and because of welding position limit, and fish ridge saddle weld impact of beautiful. In addition, the construction process, intersecting lines spiral welded seam mother pipe at a node separates the spiral, a greater welding stress, thus greatly impair the safety performance of member, and therefore efforts should be strengthened NDT spiral welded seam, ensure the welding quality, otherwise important occasion not to use spiral submerged arc welded steel pipe.