Westinghouse Electric Corporation

George D Fulmer

Robert F Keating

James W Everett

Lawrence A Nelson

George G Elder

John B Gunter

Ray A Shirey

Frank Sadofsky

Eugene P Ciferno

Mark M Stickel

Roy D Hosley

William Woolfolk

An improved, easily removable plug for plugging the open end of a heat exchanger tube in a nuclear steam generator is disclosed herein. The plug generally comprises a cylindrical shell of Inconel.RTM. having tapered side walls, a closed end, an open end, a cork-shaped expander element disposed within the shell that radially expands the tapered side walls of the shell into sealing engagement with the inner walls of a tube when axially drawn from the closed to the open end of the shell, and a wall section in the interior of the shell between the closed end and the tapered side walls for receiving the expander element when this element is pushed back from the open end of the shell back against the closed end thereof, thereby affording clear mechanical access to the interior of the tapered side walls of the shell. The improved plug is particularly adapted for use with a plug removal system that includes an expander remover that axially pushes the expander element backward against the closed end of the shell, a TIG torch for creating axially oriented weld beads within the interior of the tapered side walls of the shell in order to contract these side walls and to relax the engagement between the plug and the heat exchanger tube, and a plug puller that pulls the plug from the tube.

System for removing a plug from a heat exchanger tube

A method for removing metallic plugs from conduits such as the heat exchanger tubes in a nuclear steam generator is disclosed herein. In such tubes, plugs formed from a cylindrical shell of Inconel are radially expanded in sealing engagement with the open end of an Inconel tube mounted in a tubesheet by pulling down a cork-shaped expander element disposed in wedging engagement with the shell. The method of the invention removes such plugs by pushing the expander element from the open end back to the closed end of the shell, and then heating the shell to a temperature which substantially lessens its tensile yield while applying a tensile force along the longitudinal axis of the plug shell sufficient to elongate it. In the method, an electrically conductive push-rod is utilized which simultaneously conducts a substantial current of electricity through the plug shell while pushing against the closed end thereof.

Method for removing a metallic plug from a tube by simultaneously

An improved system for removing a plug from the open end of a heat exchanger tube in a nuclear steam generator is disclosed herein. It is particularly adapted for removing a plug formed from an elongated, cylindrical shell of Inconel.RTM. having a closed end, an open ends, and an expander element that radially expands the shell when axially drawn from the clossed to the open end of the shell. The system comprises an expander remover for axially pushing the expander element from the open end completely through the closed end of the plug shell, and a TIG torch for creating beads along the longitudinal axis of the plug shell which relax the engagement between the plug shell and the tube after the weld beams harden. Finally, the system includes a plug puller for pulling the loosened plug from the tube. The expander remover and plug puller maybe remotely operated by means of a robotic arm, and a compliance coupling is provided to facilitate alignment between these tools and the plugged end of a selected heat exchanger tube.

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Hempfield Twp., Westmoreland County, PA, United States of America

George D Fulmer