ODonnell Consulting

Development of Pipelock on Stress Corrosion Cracks on Weldments

Pipelock Allows Multi Cycle Operation With Cracked Weldments
We performed the development, design, test, manufacture and installation of a patented device providing permanent repair for intergranular stress corrosion cracks, which develop in the heat affected zones of BWR piping system weldments. OCE personnel performed and verified the operation of the device by three dimensional finite element analyses. Results show changes in pipe stresses from the Pipelock application when subjected to pressure, thermal, bending and seismic loads. These results were confirmed by alternate analysis methods and by tests on abutting pipe segments representing completely cracked weldments up to the maximum anticipated combined loading conditions.

Pipelocks, developed and designed by OCE personnel are presented as a permanent repair method for intergranular stress corrosion cracks which have developed in the heat affected zones of weldments in BWR piping system. The Pipelock will not only provide a Section III closure of the weldment, preventing breaks, but also inhibits or reduces further crack generation by maintaining the weldment under axial and circumferential compression. This service has been performed for Commonwealth Edison and Carolina Power & Light.

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