IMI improves valve reliability at South Korean power plant under severe flashing conditions

IMI has resolved repeated valve failures within a critical turbine cooling line at the Pocheon Combined Cycle Power Plant (CCPP) in South Korea, significantly improving reliability and reducing maintenance requirements under extreme operating conditions.

Pocheon CCPP is a large-scale combined cycle power plant located in Gyeonggi Province, South Korea. The facility supplies electricity to the national grid and plays an important role in supporting regional power demand through high-efficiency gas-fired generation.

The issue was driven by pressure differentials of approximately 200 bar and temperatures exceeding 300°C, where the system discharged fluid to near atmospheric pressure. These conditions created severe flashing within the valve, generating high-velocity droplets that caused rapid erosion of internal components and damage to surrounding pipework.

For Pocheon CCPP, this resulted in loss of flow control, internal leakage and progressive equipment degradation, leading to frequent shutdowns and ongoing maintenance intervention. Internal trim components required replacement every three to six months, increasing both direct maintenance costs and wider operational disruption.

To resolve the issue, IMI implemented a valve solution specifically engineered for severe service conditions. Drawing on its EroSolve technology, IMI redesigned the valve internals to better manage flashing and extreme pressure drops.

The IMI solution focused on controlling how energy is dissipated within the valve: a multi-stage pressure reduction design was introduced to manage the pressure drop more effectively, while hardened trim materials improved resistance to erosion. The internal flow path was reconfigured to relocate the flashing point away from critical sealing surfaces, reducing damage to the seat and plug.

Further enhancements included a multi-turn plug to gradually dissipate energy and reduce vibration, alongside improved sealing geometry to maintain performance under sustained high-pressure conditions. Together, these changes enabled more stable operation and significantly reduced wear across key components.

Roby Buyung, President for Process Automation at IMI, said: “Applications involving high pressure drops and flashing place extreme stress on conventional valve designs. The key is not simply resisting that environment but controlling how energy is managed within the valve itself.

“At Pocheon, by redesigning the internal flow path and staging the pressure reduction, we’ve been able to significantly reduce erosion and extend operational life, even under these demanding conditions.”

Following installation of the IMI valve solution, Pocheon CCPP has seen a marked improvement in performance. Inspection after one year of operation showed minimal signs of erosion, with no requirement for major maintenance. Maintenance intervals have been extended from three to six months to between 18 and 24 months, reducing downtime and improving overall plant reliability.