Patent ID: 7317177

Claim:
A method of electric induction heat treatment of at least one end region of a tubular material, the method comprising the steps of inserting the at least one end region of the tubular material into an induction coil to an overhang distance from an end of the induction coil and applying ac power to the induction coil, the improvement comprising, locating a flux concentrator in the vicinity of the at least one end region of the tubular material in the induction coil so that an at least one central pole of the flux concentrator extends generally from the central region of a surface of a base of the flux concentrator at least partially into the overhang distance, and a plurality of peripheral poles, radially distributed around the perimeter of the base, generally extend around the exterior of the end of the induction coil for a distance equal to at least a portion of the overhang distance, each of the plurality of peripheral poles terminating in an extended end.