The difference between hot-rolled seamless steel tubes and cold-rolled seamless steel tubes is produced by two different technologies. The main differences are: 1. The local buckling of the cold-rolled seamless pipe is allowed in the cross-section so that the buckling bearing capacity of the bar can be fully utilized. However, the hot-rolled seamless pipe does not allow local buckling of the cross-section. 2. The causes of residual stress in hot-rolled seamless pipes and cold-rolled seamless pipes are different, so the distribution on the cross-section is also very different. The residual stress distribution on cold-formed thin-walled steel sections is curved, while the hot-rolling is not. The residual stress distribution on the cross-section of a welded pipe or welded steel pipe is a thin film type. 3. The free torsional stiffness of hot rolled seamless pipe is higher than that of cold rolled seamless pipe, so the torsional performance of hot rolled seamless pipe is better than that of cold rolled seamless pipe.