FORFARANDE FOR AVLASTNING AV SVETSSPENNINGAR

摘要

A welding machine is used to heat the outer surface of a butt welded joint of pipe sections such that the weld heat input condition q/t2 (where q: heat input and t: the thickness of the wall of a pipe) is higher than approximately 0.01 and the relative heat transfer coefficient ht/ lambda (where h: the heat transfer coefficient between a coolant and the inner surface of a pipe and lambda : the thermal conductivity of a pipe) is higher than approximately 2, whereby the residual stresses at the inner surface of the weld can be relieved by utilizing the temperature difference between the outer and inner surfaces of the pipe.