Abstract: Method and apparatus for preparing an edge of a steel plate in a UOE process of making steel pipes, wherein a steel plate edge is positioned between a male die and a female die which have a curvature as desired in the edge, and held substantially horizontally by holding means outside the die, and the female die is moved against the edge and the male die by action of a lever which is pivoted about a fulcrum point which is inward of the plate edge and which has a moving means at the other end of the lever opposite the fulcrum point a predetermined distance from the female die. Advantageously, such method and apparatus enable formation of steel pipes using the UOE method having thicknesses previously difficult to produce without peaking of the produced seams.

Abstract: In continuous induction heat treatment of an elongated metal member, additional local induction heating is applied to an end portion or portions of the metal member, thereby to obtain uniform induction heating temperature distribution over the whole length of the metal member. The additional local heating or preheating the end portion of the metal member is performed by the use of a preliminary induction heating coil which is maintained in predetermined relative relationship with the metal member for a predetermined period of time.