Wet steam and particles result in erosion on trim parts. If erosion affects sealing surfaces, this might result in leakage and overheating of downstream piping. This is especially common after supercritical pressure drops, where particles and steam have very high velocity. It is also more common when the valve is operating at a small opening degree. The Zero Passing design eliminates the harmful high steam velocity inside the turbine bypass valves. By mitigating the internal steam velocity, BVT will decrease the maintenance costs, and will improve the reliability of the plant. BVT offers the ZP design both as an upgrade to existing bypass valves, and as a completely new unit.

Hard facing

The plug and seat also have stellite 6 hard facing as standard, further improving the sealing surfaces resistant to erosion. The plugs cage decreases the capacity of the valve, so it might be necessary to move to a larger seat size. The seat is not welded to the valve body, and thus does not need to be cut out. Seat removal and trim compression tools are included for quick and easy seat replacement.