PSV on a Produced Gas Cooler
PSV on a Produced Gas Cooler
(OP)
Hi
By code I need a PSV to protect my Air Cooled heat exchanger where Produced Gas flows in the tubes. I did a Fire Gas Expansion case sizing & determine the results are not credible at Pdesign=1,200 kPag for gas composition 98% methane.
I decided to select a 3/4" x 1" thermal relief PSV with Pset=1,200 kPag & Trelief=100 degC with a 0.11 in2 orifice. I believe this would suffice. Am I correct?
By code I need a PSV to protect my Air Cooled heat exchanger where Produced Gas flows in the tubes. I did a Fire Gas Expansion case sizing & determine the results are not credible at Pdesign=1,200 kPag for gas composition 98% methane.
I decided to select a 3/4" x 1" thermal relief PSV with Pset=1,200 kPag & Trelief=100 degC with a 0.11 in2 orifice. I believe this would suffice. Am I correct?





RE: PSV on a Produced Gas Cooler
Good luck,
Latexman
RE: PSV on a Produced Gas Cooler
RE: PSV on a Produced Gas Cooler
That is correct. The MAWP for the heat exchanger is 1200 kPag. I checked for the scenario where valves are blocked and a fire broke out. In this scenario the tubes will melt before it reaches the MAWP. So I decided to spec only a 3/4"x1" thermal to satisfy code requirement.
There are currently block valves upstream & downstream of the PG Cooler but they are not CSO.
RE: PSV on a Produced Gas Cooler
Good luck,
Latexman
RE: PSV on a Produced Gas Cooler
Cheers
RE: PSV on a Produced Gas Cooler
Good luck,
Latexman
RE: PSV on a Produced Gas Cooler
RE: PSV on a Produced Gas Cooler
RE: PSV on a Produced Gas Cooler
There's the rub. We don't know what the operators are going to do in the future.
Is it reasonable the HX gets blocked in while vented and at atmospheric pressure? Yes.
Is it reasonable the HX gets blocked in while at the normal operating pressure? Probably.
Is it reasonable the HX gets blocked in while at the maximum allowable working pressure? Probably.
Is it reasonable the HX gets blocked in while at the MAWP? Hmmmmmmm . . . not so sure.
Good luck,
Latexman
RE: PSV on a Produced Gas Cooler
Is it reasonable the HX gets blocked in while at the maximum allowable operating pressure? Probably.
Good luck,
Latexman
RE: PSV on a Produced Gas Cooler
Good luck,
Latexman
RE: PSV on a Produced Gas Cooler
RE: PSV on a Produced Gas Cooler
Refer to Appendix M in ASME to see if you really need a PSV.
In some areas you have to apply to the local authority to use Appendix M. So sometimes it may just be easier to put a 3/4" PSV on the cooler.
My preference is to use Appendix M as much as possible.
If it is an air cooler you may be above 25 ft, in which case you don't have a fire case. If you do have a fire case, Latexman is correct, the fact that the tubes will melt or rupture before relief doesn't change anything (it's in one of the code cases).
RE: PSV on a Produced Gas Cooler
Just to conclude I'll work backwards to see what is the highest operating pressure that the Air Cooler can see in the tubes with the HX block in. Then I'll do a Fire Gas Expansion based on this highest operating pressure although I have to be careful I am not protecting for a double jeopardy situation. My current Produce Gas operating pressure is 150 kPag @ 85C.
Our local provincial Boiler's Branch unfortunately requires us to install a PSV on this Air Cooler.
RE: PSV on a Produced Gas Cooler
RE: PSV on a Produced Gas Cooler