Importance

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Abstract

Induction heating apparatus for use in welding an end of a first length of pipe (26) to the exterior surface of a second length of pipe (28), consists of heating assemblies (20, 24) each comprising at least one electrical induction coil (32, 36) wound on an annular, laminated, magnetic core assembly (30, 34). The lowermost surfaces of said core assembly (30, 34) define a saddle shape adapted to be seated on the exterior surface of said second length of pipe (28). The arrangement of the coils (32, 36) and the core assemblies (30, 34) is such that substantially all of the magnetic flux generated when the apparatus is seated on the pipe (28) and the coil is energised is contained within the core assembly and within the wall of the pipe (28). Advantageously, the core assemblies (30, 34) have E-sections profiles, the ends of the limbs of the E-sections comprising the lowermost surfaces of the core assemblies and the coils being wound about the central limbs of the E-sections. The core assembly is formed from a plurality of part-annular segments, each segment having an individual induction coil associated therewith. The apparatus may comprise first and second heating assemblies, the first extending around the outer periphery of a circular weld zone defined on the exterior surface of said second length of pipe and the second extending around the inner periphery of the weld zone.

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First Claim