Electric Power Research Institute Incorporated

Shane J Findlan

Gregory J Frederick

Artie Gene Peterson, Jr

Wylie J Childs

Michael K Phillips

J Darryl Baucom

David Wayne Gandy

Ramaswamy Viswanathan

Howard Ocken

Jack C Spanner

Ronald E Munson

Gordon H Macshane

Artie G Peterson

A method of repairing a heat exchanger tube in a steam generator includes the step of removing a degraded tube segment from an operative heat exchanger tube in a steam generator. A weld metal ring is then positioned between the operative heat exchanger tube and a new tube segment. The weld metal ring is then welded to the operative heat exchanger tube and the new tube segment to form a linking tube section. The linking tube section is then heat treated. The new tube segment is then expanded toward a steam generator tubesheet. Finally, the new tube segment is welded to the tube sheet.

Method for repairing heat exchanger tubing through partial tube replacement

A method of repairing a substrate includes the step of excavating a well in the substrate with an electrical discharge machining operation. A wire is then delivered to the well. Simultaneously, laser energy is routed to the well such that the laser energy intersects with the wire to produce a reconstruction weld in the well. A tool delivery system with an electrical discharge machining tool head and a reconstruction welding tool head is used to perform the excavation and welding operations.

Apparatus and method for precision excavation and welding of thick-walled components

A method for repairing a shrink-fitted turbine disc without removing the disc from the shaft. The method is composed of two basic steps: (1) depositing one or more weld layers in a vicinity of a defective region of the disc using a temperbead welding process and (2) heat treating the disc using an induction heating process. In a first embodiment of the method, the heat treating step includes heating a heat-affected zone of the disc in a vicinity of the one or more weld layers to a temperature T.sub.h, heating a rim region of the disc to a temperature T.sub.r and heating a bore region of the disc to a temperature T.sub.b, where T.sub.h, T.sub.r &gt;T.sub.b. In a second embodiment of the method, the heat treating step includes heating a region of the disc in a vicinity of the one or more weld layers using the induction heating process and concurrently cooling a bore region of the disc. In a third embodiment of the method, the heat treating step includes heating at least a portion of the disc using the induction heating process and concurrently heating the shaft to maintain a predetermined temperature differential between the bore region of the disc and the shaft. In a fourth embodiment of the method, the heat treating step includes heating at least a portion of the disc using the induction heating process and concurrently heating the shaft to maintain a uniform temperature between the bore region of the disc and the shaft.

Method for repairing a shrink-fitted turbine disc

An apparatus for welding the interior surface of a tube includes a laser welding probe body configured for positioning within an interior surface of a tube. A centering mechanism relying upon fluid pressure is used to substantially center the laser welding probe body within an annular void defined between the laser welding probe body and the interior surface of the tube. In one embodiment, the centering mechanism is implemented with a set of seals. In another embodiment, the centering mechanism is implemented with a set of centering balls that respond to the fluid pressure and thereby operate to center the laser welding probe body within the annular void. The fluid pressure may be created with shielding gas used during the laser welding operation.

Apparatus and method for centering a laser welding probe within a tube

Novel cobalt-free iron-base, wear-resistant and anti-galling, hardfacing alloys are provided. These alloys are capable of being deposited on substrates by welding without preheating the substrate, thus facilitating field applications of cobalt-free alloys.

Cobalt-free hardfacing alloys with improved welding characteristics

A laser beam welding technique which can be utilized to accomplish clad welding and repair of the internal surface of a tube. The technique uses the addition of filler metal to build up the internal surface of the tube. The apparatus includes a laser energy source connected to an elongated weld head by an optical fiber. The elongated weld head is rotatable and contains a mirror canted at a forty-five (45) degree angle. The laser beam generated by the laser source enters the weld head through a rotary joint, passes through focusing lenses, and is reflected to the interior surface of the damaged tube by the canted mirror. Apparatus rotates the weld head which causes the beam to travel circumferentially around the interior of the tube. Metal fill material is fed to the location where the focused beam contacts the interior surface of the tube. The result is a smooth clad welding repair on the inside surface of the tube which restores the strength of the tube and leaves no crevices for future corrosion attack. In addition, the internal diameter of the tube is very close to the original diameter of the tube thus obviating pressure drop associated with the sleeving type repair and allowing for subsequent repair of the tube at positions beyond the first area of repair.

Method and apparatus for repairing damaged tubes by interior laser clad

A laser welding apparatus for clad welding the interior surface of a tube includes a rotating sleeve that encloses a fiber optic cable. A stationary laser generates light energy for the welding operations performed by the rotating sleeve. An optical coupler is positioned between the stationary laser and the rotating sleeve. A fixed optical assembly of the optical coupler receives light energy from the stationary laser and produces collimated and focused light energy. A rotating cable interface assembly of the optical coupler receives the collimated and focused light energy from the fixed optical assembly and applies it to the fiber optic cable of the rotating sleeve, which delivers the light energy to the interior surface of a tube so that it may be used to produce a clad weld. The fixed optical assembly includes axial and concentric alignment devices. The rotating cable interface assembly includes concentric alignment means and a monitoring cavity to provide optical feedback regarding the alignment between the fixed optical assembly and the rotating cable interface assembly. The rotating cable interface assembly may be constructed to include a safety fiber optic with an accompanying safety fiber optic photocell which is used to assess whether excessive light energy from the laser is being used.

Rotating fiber optic coupler for high power laser welding applications

A method of forming a clad weld on the interior surface of a tube includes the step of delivering a rotating filler metal wire to a selected weld location on the interior surface of the tube. The filler metal wire is synchronously rotated with a fiber optic cable which directs laser energy to the selected weld location. This results in the fusing of the filler metal wire to the interior surface of the tube to produce a clad weld within the tube.

Method of forming a clad weld on the interior surface of a tube with a

A laser welding apparatus for clad welding the interior surface of a tube is disclosed. The apparatus includes a rotating sleeve positionable within the tube. Located within the rotating sleeve is a fiber optic cable and a filler passage. The fiber optic cable receives laser energy from a laser. The filler passage receives filler material from a filler metal delivery system that synchronously moves with the rotating sleeve. Positioned at the end of the rotating sleeve is a welding head which includes a head aperture and a laser energy directional modification assembly. The laser energy from the fiber optic cable is transferred through the laser energy directional modification assembly and through the head aperture to a selected weld location on the interior surface of the tube. The filler metal from the filler metal delivery system is also conveyed through the head aperture and intersects with the laser energy at the selected weld location. The filler metal fuses with the interior surface of the tube to produce a clad weld.

Rotating apparatus for repairing damaged tubes

A welding electrode suitable for underwater welding is manufactured from a welding rod with a flux layer thereon by forming a protective coating of a waterproofing material at least over this layer and subjecting it to a pressure at least as great as the pressure at a depth of water at which the welding electrode is intended to be used such that the waterproofing material is driven into pores and interstices of the flux to impregnate it. Waterproofing materials which do not produce organic residues at welding are preferred, such as liquid sealant with metallic aluminum powder, polyurethane, resins and epoxy-based coatings.

Method of manufacturing welding electrode for underwater welding

Disclosed is a laser beam welding technique which can be utilized to accomplish clad welding and repair of the internal surface of a tube. The technique uses the addition of filler metal to build up the internal surface of the tube. The apparatus includes a laser energy source connected to an elongated weld head by an optical fiber. The elongated weld head is rotatable and contains a mirror canted at a forty-five (45) degree angle. The laser beam generated by the laser source enters the weld head through a rotary joint, passes through focusing lenses, and is reflected to the interior surface of the damaged tube by the canted mirror. Means are provided to rotate the weld head which causes the beam to travel circumferentially around the interior of the tube. Means are also provided to feed metal fill material to the location where the focused beam contacts the interior surface of the tube. The result is a smooth clad welding repair on the inside surface of the tube which restores the strength of the tube and leaves no crevices for future corrosion attack. In addition, the internal diameter of the tube is very close to the original diameter of the tube thus obviating pressure drop associated with the sleeving type repair and allowing for subsequent repair of the tube at positions beyond the first area of repair.

Method and apparatus for repairing damaged tubes

A flux formulation particularly suited for underwater wet flux-cored arc welding of nickel-based and austenitic stainless steels, such as internals of reactor pressure vessels, is free of halogen-containing components and has the following composition:

Flux formulation for underwater wet flux-cored arc welding of

A method for repairing drive shafts such that the corrosion stress cracking resistance is increased. More specifically, the drive shaft is removed from the facility in which it is being utilized. After removal, the region of the shaft experiencing cracking is identified and machined to produce a groove having a flat bottom and outwardly tapered edges. Filler material to restore all material removed by machining and provide some excess material is placed in the groove and HIP bonded to the shaft. The excess material is removed from the surface of the shaft to restore the shaft to its original dimension. Due to the filler material having a lower coefficient of thermal expansion than the shaft the repair area is subject to compressive surface stresses.

Hot isostatic bonding process for repairing shafts

Fabrication of the test structure is functionally illustrated in FIG. 9. More specifically, the first step in the process is to machine the cavity 40 in the third body of austenitic material 42, as functionally illustrated at reference numeral 80. After the cavity 40 has been machined, the fault sample 34 is installed into the cavity by heating the third body of austenitic material 42 and cooling the fault sample 34. This process is functionally illustrated at reference numeral 82. After installation of the fault sample 34, the interface is welded to seal the junction and the combined structure HIP bonded, as functionally illustrated at Reference Numerals, 84 and 86. After bonding the test structure is machined into the desired configuration, as functionally illustrated at Reference Numeral 88.

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Harrisburg, NC, United States of America

Shane J Findlan