Westinghouse Electric Corporation

Douglas G Harman

Philip S Brown

Ralph E Lambert

Luciano Veronesi

Bruce W Bevilacqua

Wenche W Cheng

Richard A Green

Andrew Wowczuk

Susanta Sinha

Elbert P Odor

David F Olechovsky

Harold T Keller

George W Gruber

A process for the controlled expansion of a conduit against the walls of a circumscribing structure is disclosed herein. The process generally comprises the steps of applying a radially expansive force to the conduit, while monitoring a variable associated with the elastic and plastic properties of the particular conduit being expanded in order to determine a final swaging force which will complete the expansion process. The process of the invention is particularly useful in eliminating the clearance between heat exchanger tubes and baffle plates in a nuclear reactor, and in sleeving operations wherein an internally inserted sleeve is plastically deformed against a heat exchanger tube in order to affect an interference joint therebetween.

Tube expansion process

Apparatus (10) for imparting protecting compressive stresses to the inside surfaces of a U-shaped heat exchanger tube (12) in order to eliminate or substantially reduce residual tensile stresses within the U-bend region of the U-shaped heat exchanger tube (12) as a result of the fabrication of the U-shaped tube (12) under cold bending techniques comprises a high-speed rotary drive motor (22), flexible drive shafts (28, 30) extending throughout the axial length of the U-bend region of the U-shaped tube (12), and shot-peening flaps (32) having tungsten-carbide shot particles secured thereto. A plurality of epicyclic gear trains (26) are axially spaced along the flexible drive shafts (28, 30) so as to cause the shot-peening flaps (32) to orbit about the interior surface of the U-bend region of the U-shaped tube (12) simultaneously with the high-speed rotary drive of the flexible drive shafts (28, 30).

Device for shot-peening inside surface of U-bend region of heat

A rigid peening spindle for rotopeening the inside wall of a tube is disclosed herein. Generally, the peening spindle comprises a rotatable housing insertable within a tube, a mandrel disposed within the housing and having a plurality of peening flappers connected thereto, and a pair of bearings for rotatably mounting the mandrel within the housing in an off-center orientation relative to the longitudinal axis of the housing so that the peening flappers rotate and orbit within the tube when the mandrel and housing are simultaneously rotated. The housing includes a cage formed from an open section and a ligment, and the mandrel is rotatably mounted within the housing so that the peening flappers may engage the inside wall of the tube through the open section of the cage. Finally, each of the bearings which rotatably mount the mandrel in an off-center manner preferably have an outer diameter slightly larger than the outer diameter of the housing so that they may engage the inside wall of the tube in a running engagement within fairly tight tolerances, and thereby control the stand-off distance between the peening flappers and the inside wall of the tube. The bearings are preferably made from a self-lubricating plastic material. The invention is particularly useful in rotopeening the interior walls of the heat exchange tubes of a nuclear steam generator in order to prevent stress corrosion cracking in the tubes.

Spindle for rotopeening apparatus

A method of uniformly rotopeening the inside walls of metallic tubes to a desired final peening intensity by means of at least one rotatable peening flapper is disclosed herein. The method generally comprises the step of simultaneously rotating and orbiting the flapper within the tube while maintaining a selected stand-off distance between the inner edge of the flapper and the inside wall of the tube. The angular speed of the flapper and the stand-off distance are selected so that the slope of the curve defined by peening intensity over time is substantially flat in the vicinity of the desired final peening intensity. The method is particularly useful in uniformly and accurately peening the inside walls of the heat exchange tubes anchored in the tubesheet of a nuclear steam generator in order to relieve tensile stresses in the walls of these tubes which might otherwise lead to stress corrosion cracking in the tube walls.

Rotopeening method

A method for peening a portion of the inside of a small diameter heat exchanger tube by inserting a rotating shaft having a peening strip affixed thereto, orbiting and reciprocating the shaft as it rotates, and maintaining this operation for a predetermined length of time to relieve residual tensile stresses in a portion of a tube installed in a heat exchanger.

Method of peening the inside of a small diameter tube

A cantilevered leaf spring with strain gages on the top and bottom surfaces and a phonograph needle disposed on the free end is disposed in a split tubular base which fits over a long tube to measure the depth of scratches in the outer surface of a long tube.

Apparatus for measuring surface scratches on a tube

A mandrel that forms an annular space when inserted within a tube and has O rings adjacent each end and a leading end having a tapered portion and a spring cooperatively associated with the O ring to facilitate sliding the mandrel into the tube and forming a fluid-tight seal adjacent the leading end of the mandrel so that pressurized fluid can be introduced into the annular space to expand the tube into engagement with a tube sheet.

Growing community of inventors

Pensacola Beach, FL, United States of America

Douglas G Harman