PRV inlet line cold insulation

[prq123]

I have noticed on several designs where a PRV is installed in a main line with cold insulation (on the main line), the insulation is only applied on a short section of the PRV inlet line branch. The remainder of the branch line to the PRV is not insulated. Can someone explain why no cold insulation is typically applied near the PRV inlet? Are there any safety issues if the cold insulation is applied all the way up to the PRV inlet flange?

Thanks

 

[dcasto]

Cost/benefit. The amount of heat gained into the system doesn't pay for the cost of the complex insulation sytems at tees and flanges.

 

[Latexman]

Since the PRV is normally closed, that branch is a stagnant zone and the heat gain is low.

Good luck,
Latexman

 

[prq123]

dcasto/Latexman,
Thanks for the responses. I also had the same initial thoughts. However, when I checked the design specifications, it stated that cutting back the insulation only applied to cold insulation. For hot insulation, the insulation is carried all the way to the PRV inlet. So I'm wondering why cutting back the insulation only applies to cold lines??

Thanks.

 

[Latexman]

For hot cases, it's for personnel protection against burns. A really cold line ices up and you can see that, but a hot line looks . . . like a line.

Good luck,
Latexman

 

[JimCasey]

Or, if it is steam, the steam goes all the way to the SRV and any condensate drains back to the header, so it's ALL at least as hot as saturation temp. As Latexman said, it needs to be insulated to protect personnel. ALso, it'll be dumping heat to atmosphere and the condensate will have to be drained thru steam traps. Steam is expensive.