METHOD FOR PRODUCING STEEL PIPE

摘要

A method for manufacturing a steel pipe includes a first pipe expanding step of expanding a steel pipe within a range of a pipe expanding ratio having a lower limit at a pipe expanding ratio at which a predetermined roundness is obtained and an upper limit at a maximum value of a pipe expanding ratio at which an equipment load of a pipe expanding machine falls in an allowable range when the steel pipe is expanded, and a second pipe expanding step of expanding the steel pipe after the first pipe expanding step at a pipe expanding ratio at which the pipe diameter of the steel pipe reaches a target value. This improves the roundness of the steel pipe without increasing the equipment load of the pipe expanding machine.