PRV's

[windseaker1]

Pressure Relief Valve = PRV
Pressure Regulator Valve = PRV
Pressure Reducing Valve =PRV

On Prints sometimes these are confused and not ID correctly. What is the correct way to designate these valves? There is also the same problem with control valves. This is for a boiler plant drawing.

Pressure Control Valve = PCV

 

[TD2K]

By pressure relief valve do you mean essentially a pressure safety valve? I typically see these tagged as PSV-xxx, most clients don't tag them differently if they are a "pressure safety valve" or "pressure relief valve" notwithstanding the differences between the two per API 520 and other codes/standards. It's not universal, one client tags them VR-xxx and no, they aren't for vacuum.

Pressure regulator valve to me would be a self contained regulator with an internal pressure tap or perhaps with external connections but it's not tied into a DCS control loop. I typically see these tagged as PCV. Sometimes they also will vent excessive pressure to the atmosphere in which case they get tagged PCRV

A conventional control valve is usually PV, FV, LV. Some clients want them tagged PCV, FCV, LCV. In the latter you would have a conflict with a self contained regulator but the self contained regulator does not have an external control loop connected to it so I don't really see it as an issue.

Some clients will default to "ISA designations" but that is also subjective compared to the number of arguments I've seen between instrument engineers how "ISA" requires them to depict a loop.

 

[windseaker1]

you got me half way home.
what about pressure reducing valves vs. PRV?
Would a pressure reducing vale in a DCS control loop also be considered a control valve, PCV?
Seems this topic should have be put to bed a long time ago! Someone must have a old standard ID tag system in the basement we just forgot.

Thank you

 

[TD2K]

"Pressure reducing valve in a DCS loop"

I've typically seen these tagged as PV-xxx but I've also seen them, not as commonly, tagged as PCV. I work in the consulting business so what the client wants, the client gets for something like this. One could argue control valves could simply be tagged as CV-xxx, it doesn't matter in terms of the valve if it's a control valve controlling level, flow, temperature, etc. That approach would make the loop numbers not quite as consistent (FE-xx1, FT-xx1, FY-xx1, FV-xx1, etc).

I leave it up to the instrument group to argue whether a control valve controlling the pressure should be tagged as PV-xxx or PCV-xxx.