Brazing apparatus having a dual function heating and eddy current probe

Abstract

A brazing apparatus and process which utilizes a dual function heating and eddy current probe coil is disclosed herein. The apparatus generally includes a radiant heater assembly having a coil which is capable of both generating radiant heat to effect a braze joint between a reinforcing sleeve and a surrounding tube, as well as serving as an eddy current probe which locates the sections of this sleeve to which the brazing heat should be applied to effect the desired joint. A switching means selectively connects the coil to either a relatively high, heat-generating current, or to the aforementioned alternating current which induces eddy currents within the metal forming the reinforcing sleeve. The apparatus further includes eddy current detection circuitry for monitoring changes in the coil impedance which result from these eddy currents while the coil is slid along the longitudinal axis X of the reinforcing sleeve. In the process of the invention, the edges of the sleeve are accurately located by noting the position of the coil when the coil impedance attains its first and last local maximum values. Both the apparatus and process of the invention are particularly useful in effecting high-quality braze joints in reinforcing sleeves which are brazed within damaged or corroded heat exchange tubes in nuclear steam generators.