Westinghouse Electric Corporation

Donald R Stoner

Wenche W Cheng

Harold T Keller, Deceased

William E Pirl

Bruce W Bevilacqua

Robert D Burack

John M Driggers

Robert D Senger

Fredric W Pement

William G Hall

Norman A Planck

Joseph M Gilkison

A process for thermally stress-relieving a stressed portion of a metallic tube is disclosed herein. The process generally comprises the steps of inserting a small diameter radiant heater into the open end of the metallic conduit and then positioning it adjacent to the portion to be stress relieved, and heating this portion to a temperature between about 1150.degree. F. to 1500.degree. F. for a time period of between about four and twelve minutes, depending upon wall thickness. In order to determine the proper amount of electrical power to apply to the radiant heater, the emissivity of the stressed portion of the conduit is first measured by heating a portion of the section to incandescence at a known power level, and then determining the temperature of the incandescent tube by means of a pyrometer which compares the intensity of two selected colors or wavelengths of the transmitted light. This process is particularly useful in thermally stress-relieving the U-bends of heat exchanger tubes formed from Inconel.RTM. 600 that are used in nuclear steam engines. It may also be used to stress-relieve such heat exchanger tubes in regions where the reinforcing sleeves have been welded into their interiors. Such thermal stress relieving renders the tubes less susceptible to intragranular stress corrosion cracking.

Process for thermally stress-relieving a tube

A metal brazing sleeve includes a ceramic flux band formed on the sleeve adjacent an annular recess typically disposed near an open end of the sleeve for receiving a conventional braze preform, by adhering a powder flux to the sleeve by a tacky adhesive and then melting the powder flux in place, by internal heating of the tube. The ceramic flux band is hard and adherent, and resistant to abrasion effects during insertion of the sleeve into a tube, and provides a shadow effect for protecting an optional cemented powder flux band which may be formed on the braze ring.

Brazing sleeve having ceramic flux band and method for applying same

An improved heater assembly and method for applying a brazing heat across a selected longitudinal section of a tube is disclosed herein. The heater assembly generally comprises a heater mandrel having an electrical resistance heating element coiled thereabout, and a support mandrel for supporting and centering this heating element. The heater mandrel further includes a means for directing a flow of inert gas in the space between the coiled heating element and the inner walls of the tube being brazed in order to purge this space of ambient atmospheric oxygen and prevent the heater mandrel from oxidizing. The support mandrel includes a centering means in the form of two roller assemblies, each of which has three spring-loaded rollers equidistantly spaced 120.degree. around its diameter. In the method of the invention, the heater mandrel is inserted into the tube and slid across the longitudinal section to be brazed. The heater then applies a brazing heat while a purging flow of inert gas is directed in the annular space between the coiled heating element and the inner walls of the tube. After the brazing operation has been completed, the flow of purge gas may be increased to cool down the heater assembly. The heater assembly is particularly useful for brazing reinforcing sleeves across sections of corrosion-damaged heat exchange tubes in nuclear steam generators.

Braze heater assembly and method

A vehicle and its control system is disclosed for inspecting or servicing a remote limited access location. The vehicle has a drive frame comprised of first and second opposing legs, and third and fourth opposing legs pivotable connected to the first and second legs to form a parallelogram. A drive mechanism is interconnected between the first and second legs of the parallelogram drive frame for opening and closing the drive frame. First and second attachment devices, illustratively in the form of magnets, are also attached to the first and second legs. The vehicle control system taking the form of a programmable computer in an illustrative embodiment of this invention responds to the opening and closing of the drive frame for alternatively actuating and deactuating the first and second attachment devices, whereby the vehicle is controllably driven.

Controllable vehicle for inspecting limited access areas

Growing community of inventors

Murrysville, PA, United States of America

Donald R Stoner