The bearing capacity of spirally welded steel pipe is related to two points. One is the mechanical properties of steel, which are related to the yield point, tensile strength, elongation and impact toughness. Another point is related to the geometric characteristics of its cross section. Generally, circular spirally welded steel pipe has the strongest local buckling resistance, so it is the best component to withstand radial internal pressure and radial external pressure.


Under the same steel number, same area and same support conditions, rectangular oblique steel pipe has strong eccentric compressive bearing capacity, circular and square steel pipe has the strongest compressive bearing capacity, while square and rectangular straight seam steel pipe is not as good as circular steel pipe because of the resistance of roll gap to local buckling. Compared with spirally welded steel pipe, seamless steel pipe has complex production process, high quality, high price and less engineering application. The latter is more applicable.


At present, steel straight-seam steel pipe can combine the advantages of both, so that the straight-seam steel pipe can be compressed horizontally and the compressive strength can be doubled. At the same time, because the rigidity of the straight-seam steel pipe has been improved, the two work together, thus greatly improving the bearing capacity.