Westinghouse Electric Corporation

William E Pirl

Charles H Roth, Jr

Thomas E Arzenti

John M Driggers

Annette M Costlow

Rodney A Lutz

Edward H Smith

William G Cole

Francis X Gradich

David A Chizmar

Donald R Stoner

Robert D Senger

Kurt K Lichtenfels

John P Vogeleer

Edward A Ray

Wesley G Pope

John J Anderson

Frank X Ponko

A laser welding apparatus and method are used to weld the inner surface of small diameter tubes such as nuclear heat exchanger tubes. A weld filler metal carried by a rotatable laser weld head is fed into the weld zone to produce deeply penetrating weldments of low profile. The apparatus and method can effectively be used to repair cracks in heat exchanger tubes to thereby provide extended service life.

Apparatus and method for laser welding the inner surface of a tube

System and method for laser welding an inner surface of a tubular member, which tubular member may be a repair sleeve disposed in a nuclear heat exchanger heat transfer tube. The system includes a laser for generating high intensity laser light sufficient to fuse the sleeve to the inside diameter of the heat exchanger tube, the tube being of the type typically found in nuclear heat exchangers. A fiber-optic cable is optically coupled to the laser for conducting the laser light therethrough. The fiber-optic cable has a predetermined configuration to homogenize the laser light so that the laser light obtains the desired spatial coherency as the light is emitted from the fiber-optic cable. A mirror is optically coupled to the fiber-optic cable so as to receive the homogenized light beam emitted from the fiber-optic cable. The mirror is also optically coupled to the inner diameter of the sleeve for reflecting the homogenized light beam onto the inner diameter of the sleeve to weld or fuse the sleeve to of the tube. In this manner, the sleeve is welded to the inside diameter of the tube to sleeve the tube.

System and method for laser welding an inner surface of a tubular member

A frame is coupled to a remotely operable service arm (ROSA), and a rotatable carousel, in turn, is carried by the frame to position several tool modules used in a welding operation adjacent to a damaged tube in a tubesheet of a nuclear steam generator. The arm positions an alignment module directly beneath the damaged tube and the module aligns the carousel. The carousel is rotated to sequentially align and register a laser welding module, a cleaning module, and an inspection module with the damaged tube for a welding operation on a lower portion of the damaged tube in the tubesheet area. One embodiment for the alignment module has a pneumatically operated pin which is operator controlled, and which has an increasing diameter from its distal end to obtain a gross to a vernier alignment of the carousel and, thus, a proper alignment for the remaining modules. A further embodiment provides an alignment pin which is automatically computer controlled without operator intervention. Limit switches and grooves are used as a logic checking device for the proper positioning of a respective module in the frame, and a pneumatically operated radial pin holds the module in the frame.

Apparatus and method for sequentially registering tool modules for a

System and method for laser welding an inner surface of a small diameter tubular member. The system includes a laser for generating laser light and a mirror optically coupled to the laser for reflecting the light onto the inner surface of the tubular member to laser weld the inner surface of the tubular member. A rotator assembly is connected to the mirror for rotating the mirror in order to weld around the inner surface of the tubular member. The mirror and rotator assembly are each sized to be disposed in the tubular member at a location adjacent the portion of the tubular member to be welded. The rotator assembly has a spiral groove formed in the exterior thereof for receiving a cord wrapped around the exterior of the rotator assembly. An end of the cord is connected to a motor located externally to the tubular member, so that the cord is pulled as the motor is operated. As the cord is pulled, the rotator assembly rotates for rotating the mirror. A retainer is also provided for retaining the cord in the groove as the rotator assembly rotates. Therefore, the rotator assembly and the mirror associated therewith are rotated by a motor located externally to the tubular member. Thus, the system and method of the invention are capable of welding small diameter (e.g., diameters equal to or less than 0.313 inch) tubular members because the motor is located externally to the tubular member rather than being disposed in the tubular member.

System and method for laser welding an inner surface of a small diameter

Both a system and method are provided for laser welding the inner walls of conduits, such as the sleeves used to repair the heat exchanger tubes of nuclear steam generators. The system generally comprises an elongated tubular housing, a fiber-optic cable for conducting remotely generated laser light into the tubular housing, a beam deflection mechanism supported within the distal end of the tubular housing and including a rotating mirror for radially reflecting and focusing light received from the fiber-optic cable around the inner wall of the sleeve, and a tracking assembly mounted on the distal end of the tubular housing for maintaining a constant radial distance between the mirror of the beam deflection mechanism and the inner wall of the sleeve despite any irregularities which may be present in the roundness of the sleeve. The tracking assembly includes at least one roller which is resiliently mounted in the tubular housing of the system behind the front portion of the mirror of the beam deflection mechanism. To facilitate mirror replacement, the distal end of the tubular housing is easily removable. To ensure reliable rotation of movement, an electric motor and gear train is mounted in the proximal end of the tubular housing. Finally, the fiber-optic cable that extends through the proximal end of the tubular housing is configured to traverse the electric motor and drive train with a single S bend in order to maintain a high light transmission efficiency through the cable.

System and method for laser welding the inner surface of a tube

A flexible, hose-like delivery system for positioning and rotatably supporting a probe which may be a pancake-type eddy current probe at a desired position along the longitudinal axis of a small-diametered conduit such as the heat exchanger tube in a nuclear steam generator is disclosed. The system comprises a flexible inner shaft formed from a plurality of short segments of Bowden shafting which is connected to a drive train located remotely from the interior of the heat exchanger tube, a flexible outer housing preferably formed from a plastic conduit concentrically disposed around the inner shaft, and a plurality of ball bearing assemblies which interconnect the short shaft segments for minimizing the frictional engagement between the inner shaft and the interior walls of the flexible outer housing. The frictional losses between the inner shaft and the flexible tubular outer housing are small enough to allow rotational motion to be smoothly and reliably conducted over relatively long lengths and around bends, thus allowing such motion to be transmitted by remotely located, standard-sized drive trains and motors. The system eliminates the need for expensive, miniaturized drive trains, motors and slip ring components which, up to now, have accompanied such eddy current probes within such tubes.

Flexible delivery system for a rotatable probe

System for inspecting the interior of tube plugs, particularly tube plugs of the type having expander elements disposed therein. The system includes a probe assembly connectable to the tube plug, the probe assembly having a rotatable and translatable probe carrier housing for housing a sensor probe capable of inspecting the tube plug. The probe assembly also includes a leaf spring extending through the probe carrier housing and attached to the sensor probe for radially outwardly biasing the sensor probe into sensing contact with the interior of the tube plug, particularly the interior of the tube plug located between the top of the tube plug and the expander element. A tangle-free flexible hose is connected at one end thereof to the probe carrier housing for transversely rotating and longitudinally translating the probe carrier housing. The flexible hose is also connected at the other end thereof to a probe driver assembly that rotates the flexible hose which in turn rotates the probe carrier housing. Rotation of the probe carrier housing rotatably translates the probe carrier housing into the tube plug for inspecting the tube plug in a helical scanning pattern.

Tube plug inspection system

Both a system and method for laser welding the inner surface of a metallic tube, which may be a sleeve inside a heat exchanger tube of a nuclear steam generator, is disclosed. The system comprises an elongated tubular housing that is insertable within a reinforcing sleeve disposed within a heat exchanger tube, a laser unit for generating a beam of light, a fiber optical conduit for conducting light from the laser unit through the interior of the tubular housing, a beam deflection assembly including a mirror canted at an angle of 45.degree. that is rotatably mounted on the distal end of the housing and optically connected to the fiber optical cable, and a remotely powered rotary drive assembly for rotating the beam deflection assembly to direct laser light around the inner surface of the tube that includes a transducer for converting linear to rotary motion. The motion transducer includes a tubular driven member concentrically disposed within said housing and connected to the beam deflection assembly, and a tubular drive member concentrically disposed within the driven member and having a spiral groove around its outer diameter that meshes with a follower ball connected to the inner diameter of the driven tube, such that the driven member rotates whenever the drive member is slidably pulled along the longitudinal axis of the housing. The linear-to-rotational motion transducer obviates the need for miniaturized electrical or pneumatic motors, which in turn allows the outer diameter of the housing of the system to be made small enough to service small-diametered heat exchanger tubes.

System and method for laser welding the inner surface of heat exchanger

A system for helically driving an inspection probe within a tube of a nuclear steam generator is provided, wherein the system is particularly useful in driving a combination eddy-current and ultrasonic probe. The system generally includes a head assembly insertable with the tube for inspection, a drive frame assembly to be located external of the steam generator, and a conduit system connecting the head assembly and drive frame assembly. Particularly, the head assembly includes a portion fixable to the tube by a pressure bladder and a movable portion helically movable with a probe to the fixable portion. The drive motor and electrical pick-up are slidably movable on the drive frame assembly to move linearly with the probe during inspection so as not to limit the stroke of the probe, wherein the drive motor and pick-up are connected with the head assembly by way of two flexible coaxial conduits. The two conduits further provide two fluid flow paths to supply fluid to the bladder and couplant fluid for use during ultrasonic testing.

Support equipment for a combination eddy current and ultrasonic testing

An apparatus and method for remotely inserting and positioning a sleeve-loaded mandrel within a damaged tube mounted in the tubesheet of a nuclear steam generator is disclosed herein. The apparatus of the invention generally comprises a frame, a mounting mechanism for detachably and pivotally mounting the frame to the open end of one of a first tube in the tubesheet, an advancing assembly supported by the frame for remotely inserting and advancing the sleeve-loaded mandrel to a position across a damaged section of the selected tube, and a drive train for pivotally positioning the advancing assembly into alignment with the open end of the selected tube. In the preferred embodiment, the advancing means is formed from the pair of hydraulically operated grippers, one of which is reciprocably movable with respect to the other. Additionally, the mounting mechanism inlcudes a double-action hydraulic cylinder that is capable of translating the frame into engagement with the tubesheet after the advancing assembly has been pivoted into alignment with the damaged tube. In the method of the invention, the first tube is chosen so that the advancement assembly may be pivoted into position under two or more tubes that need to be sleeved.

Apparatus and method for simultaneously loading a reinforcing sleeve and

A tool for inserting sleeve blanks in damaged steam-generator tubes of light weight capable of being manipulated by ROSA, a remotely operated service arm. ROSA permits the tool to be attached externally of the channel head of the steam generator. The tool includes a fixed gripper and a moveable gripper. The gripping member of each gripper is a flexible sheet or bladder which conforms readily to the surface being engaged. For insertion, the sleeve blank is mounted on a mandrel. The insertion is carried out by operating the grippers repeatedly through the following cycle until the sleeve blank is inserted into the damaged tube:

Sleeving of steam generators

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 gripper assembly whose gripping member is a thin (0.050' to 0.060') pliable elastometer, typically of a Pelethane compound having high coefficient of friction with respect to the surface to be gripped. The assembly includes a hollow retainer formed of abutting retainer sections. Internally the sections form a circularly cylindrical surface. The gripping member is circularly cylindrical and is mounted on the retainer so that it extends over the internal cylindrical surface. The ends of the gripping member have rings which are sealed pressure-tight in slots in the end surfaces of the retainer. Within the gripping member there is a cage formed of rods joined by rings for centering an object to be gripped by windows and defined between the rods and rings of the cage. The retainer has a port through which a fluid (air) under pressure is injected. The retainer has a slot connected to the port so that the fluid is distributed over the region between the gripping member and the internal surface of the retainer causing the gripping member to exert pressure on the object to be gripped.

Gripper assembly

An improved apparatus and process for rotopeening metallic conduits of limited accessibility, such as the peripherally located heat exchange tubes around the tubesheet of a nuclear steam generator, is disclosed herein. The bowl-like inner wall which lies directly adjacent to such peripherally-located tubes renders it difficult to insert a rotopeening spindle into the open ends of these tubes in order to work-harden these tubes in the tubesheet region. Generally, the apparatus of the invention comprises at least one flexible rotopeening spindle, an advancing mechanism for remotely and incrementally advancing the flexible spindle through an open end of a selected peripheral tube, and a frame for supporting both the flexible spindle and the advancing mechanism. The length of the advancing mechanism is substantially shorter than the length of the flexible spindle so that the spindle and the advancing mechanism may be easily placed into a peening position with respect to the most remotely located tubes. The advancing mechanism includes first and second grippers which utilize expandable bladders for selectively gripping and ungripping the spindle. The first gripper is mounted on the wall-facing side of the frame, and the second gripper is reciprocably movable with respect to the first gripper. Additionally, the second gripper is rotatable and is mechanically linked to a drive means, in order to render it capable of rotating the rotopeening spindle once it is inserted into a selected tube end.

Tool and method for rotopeening the peripheral tubes in a tubesheet

Both an apparatus and a process for accurately applying a correct amount of brazing heat to a conduit are disclosed herein. The apparatus generally comprises a mandrel including an electrical resistance wire heating element and a heat sensor for sensing the temperature of the inside walls of the conduit which were heated. The mandrel is preferably formed from a refractory material, and the heat sensor is located beneath the surface of the mandrel in order to insulate it from heat radiated from the electrical resistance wire wound about the mandrel body. The mandrel further includes an opening in the portion of the mandrel which surrounds the heat sensor in order that the sensor may be selectively exposed to a section of conduit to which heat was applied by sliding the mandrel to a position which aligns the opening with the wall of the heated conduit. The temperature of the conduit may then be determined as a function of the radiant heat received by the heat sensor. The invention is particularly useful in producing high quality braze joints between reinforcing sleeves inserted within damaged heat exchange tubes of a nuclear steam generator since the heat sensor allows the operator to determine whether or not a proper amount of brazing heat was applied to the sleeve/tube configuration.

Growing community of inventors

Levelgreen, PA, United States of America

William E Pirl