Westinghouse Electric Corporation

George G Elder

Robert F Keating

Lawrence A Nelson

George D Fulmer

James W Everett

Wenche W Cheng

John B Gunter

Frank Sadofsky

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

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.

A process for rapidly and uniformaly heat treating an Inconel.RTM. heat exchanger tube in the vicinity of a heat sink such as a support plate is disclosed herein. The process utilizes a radiant heater assembly capable of directing heat along a zone whose length is less than the length of the section of tubing to be stress relieved, and generally comprises the step of actuating the heater assembly, and oscillating it between the ends of the tube section in order to heat the tube section having nonhomogeneous thermal conductivity to a temperature that is substantially uniform along its length. The specific timing pattern used in the oscillatory movement of the heater assembly results in a substantially uniform heat gradient along the tube axis despite conductive heat losses through the support plate. The process allows heat exchanger tubes to be readily and reliably stress-relieved in the vicinity of the support plates of a nuclear steam generator.

Process for heat treating a heat exchanger tube surrounded by a support

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Monroeville, PA, United States of America

George G Elder