Abstract: There is provided an inductor for heating the inner circumference of a hole, by which induction heating of the inner circumference of a hole and so on can be realized rapidly and uniformly in the direction of the circumference, and there is no risk of a short-circuit between a solenoidal coil and transition conductor passing therethrough. According to a configuration in which a magnetic core 12 with a cylindrical shape is arranged inside of a solenoidal coil 11a which forms the inductor 10, and a transition conductor 11c extending from one end of the solenoidal coil 11a to a feeding terminal through the inside of the solenoidal coil is arranged in an inserted manner into a hollow portion of the magnetic core 12, a risk of the short circuit is avoided by using an insulating material for the magnetic core 12, assuming that the magnetic core 12 with a large cross-sectional area is concentrically arranged in the solenoidal coil 11a.

Abstract: There is provided an inductor for heating the inner circumference of a hole, by which induction heating of the inner circumference of a hole and so on can be realized rapidly and uniformly in the direction of the circumference, and there is no risk of a short-circuit between a solenoidal coil and transition conductor passing therethrough. According to a configuration in which a magnetic core 12 with a cylindrical shape is arranged inside of a solenoidal coil 11a which forms the inductor 10, and a transition conductor 11c extending from one end of the solenoidal coil 11a to a feeding terminal through the inside of the solenoidal coil is arranged in an inserted manner into a hollow portion of the magnetic core 12, a risk of the short circuit is avoided by using an insulating material for the magnetic core 12, assuming that the magnetic core 12 with a large cross-sectional area is concentrically arranged in the solenoidal coil 11a.

Abstract: A bonded pipe produced by using the liquid phase diffusion process in which the pipe ends of pipes to be bonded are butted with an insert material lower in melting point than the pipe material against each other, wherein the thickness is increased in such a manner that the outside diameter of the butted portion is expanded and the inside diameter thereof is reduced. A method for bonding pipes in which pipe ends of the pipes are butted through an insert material lower in melting point than the pipe material against each other, and the butted portion is heated to and held at a holding temperature higher than the melting point of the insert material, whereby the insert material is diffused in liquid phase into the pipe material, characterized in that at the time point when the outer pipe face temperature of the above-mentioned butted portion reaches a value which is not less than the A.sub.

Abstract: A high frequency bolt heater is provided which can heat up the inside of a narrow hole much faster than a conventional bolt heater employing a resistance wire. The high frequency bolt heater includes an induction heating coil made of a copper tube bent in a hairpin fashion and whose shape is made approximately circular in section by pinching a magnet between opposed portions thereof. The heater can be inserted into a hole bored in the axial direction of a metallic bolt. A length of the coil is made approximately equal with that of the bored hole, and the magnet is omitted from a region of the heater which corresponds to a screw portion of the bolt for mounting a nut. An adjustable stopper made of a heat resistant electrical insulator is provided for setting a necessary length of the induction heating coil to be inserted into the hole, and a heat resistant insulator is provided on the surface of the induction heating coil.

Abstract: A heating method and heating apparatus for uniformly or substantially uniformly heating a predetermined portion of main and branch pipes including a welded joint therebetween of a main-and-branch-pipe assembly, thereby relieving the residual stress in the welded joint between the main and branch pipes. The defects and problems encountered in the conventional residual-stress-relief treatment processes can be substantially overcome such as complication in winding fabrication at the branch pipe which results in bad control of temperature; a mock-up test being needed for fabrication of an inductor; and existence of a non-heated zone resulting in unbalance of the stresses so that the effects of the residual stress-relief treatment are reduced.

Abstract: A heating method and apparatus for effecting the residual-stress-relief treatment of a welded joint in a pipe line. A welded joint between main pipes, between a main pipe and a branch pipe, between a main pipe and a pipe base or between a branch pipe and a pipe seat and a portion adjacent to the welded point are uniformly or substantially uniformly heated by an inductor which can be varied into configurations according to the performance of the welded joint. The problems encountered in the conventional residual-stress-relief treatment can be substantially overcome.