PetroStreet

We had a case where a PCV functionality issue caused a PSV lift, unable to control pressure.
What could be the issues with that PCV?

First thing you need to look into is that a PCV that cannot move properly will NOT regulate pressure.
Possible issues here could be:

• Stem seized
  Actuator diaphragm/piston failure
  Packing too tight
  Grit, rust, debris lodged in the trim
  Foreign material from upstream piping
  Erosion of plug/seat causing sticking

In all these issues, the effect would be that PCV stays closed then the pressure rises, and eventually PSV opens.
Instrumentation team should help you identifying what was the issue in this case.

Yeah, need to have that sorted out, and this is what happened before as well.
Means same PCV, and not only one instance.

Multiple issues should trigger some kind of an investigation into this matter as PSV lift itself qualifies to be reported as a Tier-3 incident and as I see the released material must be either HC or hazardous fluid. Look into the preventive maintenance performed, reported corrective maintenance, any other integrity issues reported. Keep that under close check till this issue gets addressed without causing any kind of an escalation.
Delayed PM or PM skipped for PCV could have some contribution as well to all this.

There was a skipped PM identified causing this issue.
PCV was due for maintenance, and could not be handed over by Operations.