Liquid service for Pilot Safety Valve

[Hansac]

Can share on experience with using Pilot SV for liquid service (boiler feed water, operating at 200 barg and 160 degC). Set pressure is 250 barg. During start-up, sometimes there are pressure spikes above 95% set pressure, due to operational issue.

I'd like to hear similar stories (successful or otherwise), in terms of maintenance, inspection, and operation.

 

[georgeverghese]

Can you describe this startup operational situation ?

 

[The Obturator]

What exactly is the valve experiencing? You say that the pressure spikes, but how is the valve responding?
Do you have a specification sheet for the valve?
Moreso, can you advise on the size, rating and model no/manufacturer?
What is the history of the application? When installed, service data - part changeouts, earlier reported issues?
Inlet piping configuration? Photographs.
What is the code of the application (ASME I, VIII? etc.).

 

[LittleInch]

Pilot valves usually get you closer to the set point before discharge.

But if the pressure is spiking above 95-98% of set pressure then you need to solve the problem (the spiking) not the valve.

Otherwise you are normalising failure.

In any well designed and operated plant the Safety Valves ( the key is in their name), should NEVER lift unless their is some sort of operational or mechanical failure ( or a fire). But if this is happening regularly on start-up then something is not right and you need to fix it. I realise this is probably not what you came here looking for, but that's how I look at it.

any lifting of a Safety Relief valve should be treated as a serious failure incident and suitable investigations and recommendations / precautions taken to prevent it happening again. Accepting it as "one of those things" leads you down dark and dangerous paths. IMHO.

 

[gguliye]

Hello,
i checked the spike snubber but it is being mainly used for gas air vapor applications....
remote sensing could be another choice but pulsation at the inlet may cause the valve to leak anyway if the issue is with pulsating at valve inlet only not on the boiler side or whatever.
modulating action valve seems better choice. it is kept sealing at around 98 percent of SP, and between 98 and 100% percent from AG 400 series, only spool inside the pilot is moved. if the pulsation goes further above 100% in this case, valve may leak some.....

 

[The Obturator]

@gguliye Its 250 bar set pressure!

We need the OP to give us more information as has already been requested.

 

[gguliye]

@gguliye Its 250 bar set pressure!

We need the OP to give us more information as has already been requested.

thanks!, 400 is out of option