B31.3 relief valve requirements

[tomhyde]

B31.3 appears to require the use of ASME UV-rated relief valves for thermal relief of trapped line segments.

I have an application using 1/4" to 1/2" tubing on a supercritical CO2 application, and would prefer to use non-UV rated reliefs, which are cheaper and readily available. Trapped volumes are on the order of 5-10 ft of tube length or less.

Can anybody advise as to the necessity of the UV reliefs?

 

[1974vet]

In the areas that I have worked (not supercritical C02), the question always boiled down to: will the proposed configuration satisfy the requirements to be a code installation? Since not using the rated valve results in a non-code installation, the question may be: can you have a non-code installation in your facility? You might can assemble the right group to formally perform a risk accessment on the proposed configuration, or keep looking for another solution that meets the code strictly. Hopefully, others will offer better suggestions.
Good Luck. . .