Asset Type
Nuclear Plant
Location
Cordova, Illinois USA
Completion Date
May 2025
Item
72" Butterfly Valve. Henry Pratt Model No. R1A
Equipment
Custom-engineered EDM unit
The challenge arose when a 72 inch CW (circulating water) valve was inadvertently closing while the plant was operating at 100% power. Investigation revealed that the pinned connection between the valve stem and disk had failed. The valve stem was angled at approximately the 7 o’clock position and positioned just 9 inches above the concrete floor - an extremely constrained and difficult-to-access location. Mitigation options considered were to take a forced outage to repair the failed joint, operate at reduced power level until next scheduled outage, or develop an alternate temporary repair design to attempt opening the valve.
Hydratight developed an inline valve repair option in collaboration with an engineering firm that would allow a temporary repair to be carried out without taking a forced outage. The Engineering firm has worked with Hydratight previously - using the EDM System with solid success in the nuclear environment.
Development of a Temporary Repair
Hydratight partnered with the engineering firm to develop an innovative temporary repair solution, enabling the plant to remain online and avoid a costly forced outage.
EDM Delivery System
Hydratight developed an Electrical Discharge Machining (EDM) delivery system to fit into the tight location to allow onsite repair.
Solution Developed in Tight Timeline
Engineering development of EDM tank/electrode/electronics for site delivery in a tight timeline.
Testing and Training
Mock-up training to assure proof of concept, work instruction development along with repair timelines.
Partnering with the Engineering Firm, the team leveraged the Hydratight EDM system to develop a custom assembly for spark erosion delivery capable of operating in the extremely confined space. A complete EDM tank, electrode, and electronics package was engineered, fabricated, and validated through mock-up training in under four weeks. However, one week prior to scheduled mobilization, the unit tripped and the plant entered a forced outage, during which the valve was successfully repaired. The client recognized the team's efforts, stating: "We tasked you with a difficult application and timeline. Even though we did not have to perform the work, you had everything ready and tested."
Utilizing proven EDM technology combined with bespoke design to fit the valve location.
Engineering, fabrication and mock-up all completed in less than 4 weeks.
Mock-up training assured proof of concept, work instruction development.
Coordination of teams from the engineering company, Hydratight, and the operator.
Throughout the Asia Pacific region and beyond, Hydratight delivers precise, high-integrity machining and metrology solutions for critical assets, where accuracy, safety, and uptime are essential.
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