Thermal Relief Valve on Cooling water lines for Seal Coolers And Seal Pots

[CHoff07]

API 682 3rd and 4th Edition, Section 9.8.3 has a decision point for the inclusion of thermal relief valves (TRV)for components that may be blocked in by isolation valves. We are considering adding TRVs to the cooling water side of all API plan 23, 52 and 53 (A and B) flush plans as a standard design practices.

My question to the forum is:
Does any one else currently do this?
If so, what is your criteria for including them in the design?

Is this something we should just do all the time or only if the seal cooler or seal pot is a U-Stamped pressure vessel? This would then be at the request of our customers since the "standard" offering per API 682 is to manufacture to B31.3 using piping components.
I have not seen TRVs used in the past and though I can see the benefit, I cannot see a major advantage to adding them to our design at this time (on a risk/benefit basis).

I also believe that for an API plan 23 or 53B, the likelihood is much greater than it is for a seal pot, API plan 52/53A, which has a lower heat load and more cooling from the atmosphere.

Any insight into the Thermal Relief Valve (TRV) matter is appreciated.

 

[JJPellin]

We do not install TRV's on any of these systems. Our seal pots are code stamped (most of them), but our seal coolers are not. I cannot see any advantage that would justify the cost. We have not seen failures that could have been prevented by the installation of a TRV. I believe that this is because the streams on the process side of these coolers are not hot enough to cause a failure in the blocked-in case.

Johnny Pellin

 

[georgeverghese]

You could lower the risk by using locked open valves as isolation valves for the CW to each seal cooler if you find the TRV troublesome.

In this case, the TRV merely enables some improvement in asset integrity ( by preventing coil rupture) and not for HSE reasons (since the coil ruptures into another vessel ( the seal pot) which is either open to atmosphere or the seal pot can handle the max CW pressure( ??).