A water hammer issue had caused a significant crack at a 10X1 welded branch connection. The operating pressure was 350psi- temperature 150F. Operational changes to the pump had eliminated the water hammer, but concern remained that the weld was compromised. If the weld failed completely it would cause an immediate outage. Because of this, our repair had to both seal the leak as well as constrain the connection in the event the water hammer returned and caused a total weld failure. There was no way short of tripping the unit to reduce flow rate or pressure on the connection.
RJ Stacey developed a leak repair enclosure that would solve multiple problems at once. It would create a metal on metal seal against the outside diameter of the 10” main as well as a “crunch teeth” seal against the outside diameter of the 1” branch. The teeth would also bite into and constrain the 1” pipe in the event the branch weld failed completely. Lastly, a set of strongbacks would constrain the entire enclosure to the 10” main. After mounting the enclosure assembly, it was injected to a leak-free condition with RJ720 a Silica free sealant that would remain semi-pliable during vibration and movement.
From start to finish the leak was repaired in less than 36 hours. The seal was 100% successful and held up perfectly until the next scheduled outage. Additionally, the generator operated at full load for the balance of the season and suffered no derate during the emergency repairs. Because the RJ Stacey repair clamp was completely bolted on, removal was simple for the plant maintenance crew during the next scheduled outage.