IN-LINE WELD SEAM HEAT TREATMENT METHOD AND APPARATUS WITH INTERNAL SELECTIVE HEATING OF THE WELDED JOINT

摘要

The present application relates to a method and an apparatus for in a high frequency welding (HFW) or electrical resistance welding (ERW) line to perform in-line seam heat treatment of an established welded joint on a pipe (1) made from roll- formed plate material, the welded joint being heated inductively from the exterior side of the pipe (1) downstream of a welding location. The method provides for selective heating (7) of the welded joint from the interior of the pipe (1) downstream of the welding location at least one heating zone, such heating from the interior, when operative, being performed simultaneously and in addition to the external heating (4, 5, 6). The apparatus comprises in addition to exterior heating means (4, 5, 6) downstream of a welding location also induction heating means (7) located inside the pipe (1) for selective operation to heat the welded joint from the interior of the pipe (1) downstream of the welding location at least one heating zone, said operation when selected being additional and simultaneous with operation of the external heating means (4, 5, 6).