Place:
700 megawatt Power Generation unit
Challenge:
Seal a pair of globe valves leaking by inside the plant and causing safety concerns. Both the ¾” Source and Guard valves had simultaneously failed and were leaking on a boiler drum blowdown assembly. The boiler drum was operating at 4000psi and 450f. The goal was to seal the Guard valve and stop the flow as it was cutting the valve seats making the leak worse every day. The plant needed this work accomplished without a shutdown in order to continue generating power.
Solution:
The RJ Stacey crew inspected the valves and determined the safest, most effective method would be to use a bolt on the injection saddle placed between the Guard and Source valves on the pipe itself. This eliminated the need to place the injector on the valve where erosion may have compromised wall thickness. With the injection saddle in place the crew completed the tap; drilling into the pressure boundary. Finally, they injected sealant. The entire space between the two valves was injected with RJS560 and thickening solids.
Results/Benefits:
The leak was sealed 100% and held until the next scheduled outage. RJ Stacey’s work was done with the boiler at full load during the entire process. The sealant choice allowed the plant to open the valves at the next outage and still use the blowdown for its intended purpose at shutdown. Once the blowdown was complete, these parts were cut out and replaced.
