We have a PRDS control valve of BTG make. Observed vibration in the pipe line. And after installation, the piston is found broken !!

Can any one tell me the effect of pipeline vibration and straight length ??

 

If it's a plug type valve, any chance that it was in backwards? That will make them hammer like crazy. The plug should seat AGAINST the flow.

Bill Gausman
SmartParts

 

It sounds that you may have had a water hammer problem.
The prds is a unit which desuperheats and reduces pressure within one unit.This means that at some point water mixes with the superheated steam bringing it close to saturation temp.

If due to piping layout,during start up, water enters the pipe ahead of the valve and there arent any condensate traps in this section of pipe when steam enters this pipe it will drag some water into the PRDS.

The sudden change in velocity created by the phase change through the seat area will create a water hammer which may damage the plug stem.

To avoid this you only need to make sure that any water at the valve inlet is out before starting
the steam flow.