Heat control for electric resistance welding in steel pipe production

A heat control system for electric resistance welding (ERW) for use in pipe manufacturing has been developed. The distinguishing features of the control system are: (1) use of a silicon photodiode array as a heat input sensor, (2) feedback control for steady welding, and (3) open-loop control for transient welding. This control system has been introduced into three ERW mills at Keihin Works, Nippon Kokan Kabushiki Kaisha, and shows excellent performance in production.