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Case Study

Power plant

A Danish power plant was looking to reduce leaks and energy losses, but ended up reducing their maintenance time too.

Customer benefits


A biomass-fired power plant in Denmark was experiencing steam and energy losses until their boiler drain valves were replaced.  During the start-up and warm-up phase, boiler drain valves must remain open. These severe service drain valves have to discharge flashing water at high pressures. Once the start-up is finished and the plant is in normal operation, the valves need to be shut off tightly. The customer was experiencing their Boiler Drain Valves leaking as a result of trim erosion, and this was increasing maintenance time and spare part replacement cost. The leaks meant the customer was also losing "high-value" steam and energy during the process.

Contol valve for servere services


After walking the plant, GESTRA recommended replacing the existing boiler drain valves with GESTRA's ZK 313 control valve as a drain and warm-up valve solution. 

Specially designed for severe services, ZK 313s are equipped with a special multistage trim with a tandem seat for a reliable tight shut-off with zero leakage. They remain wear-resistant at high differential pressure and flashing water levels.

Summary of technical solution

  • Ideal for service applications in steam, condensate and water cycles
  • Handles high differential pressure
  • Zero leakage tight shut-off trim
  • Wear resistance trim parts against flashing water and 2-phase flow


The installed valves had an additional benefit. As well as providing a robust solution for flashing water, the ZK 313's design reduced the amount of time it took to undergo maintenance procedures. This was due in part to the wear resistance on the multistage trim and the ability to dismantle it without removing the valve from the pipeline in order to reduce maintenance and repair time.

The customer was finally able to retain the high-value steam that they had previously been losing and to reduce the costs of maintenance, focusing on other areas of the plant.

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