PURPOSE: To improve heating efficiency in the stage of welding with a process for producing pipe by welding both edges of an open pipe-shaped steel strip with high frequency current by specifying the temp. of the steel strip just before the feed point of the high frequency current.

CONSTITUTION: A steel strip 1 is introduced into a preheating furnace 4 in the direction A and is again introduced in the dirction B and is drawn out to preheat the strip and thereafter the strip is introduced into a heating furnace 5 in the direction C, by which the strip is heated. The strip 1 is then fed into a pipe making device 7 by high frequency welding and is formed to an open pipe of which both wedges are welded by high frequency current and the welded beads part is cut to form a blank pipe 2. The pipe 2 is introduced into a heating furnace 6 to eliminate the hardened structure in the weld zone. The heated pipe is fed into a reducing mill 8 for pipe. The temp. of the strip 1 is maintained in the range of the Curie point or above and ≤900°C at the point of the time when the strip 1 comes to the position of an induction coil 7d.