Safe operating conditions for Autorefrigeration potential

[kevlar49]

Hi,

I am drawing up guidelines to avoid brittle fracture in propane spheres. The concern is autorefrigeration can cause brittle fracture.

I think the safe operating condition is between the equillibrium vapor pressure curve and the MDMT curve as determined using the method in ASME UCS 66, if the vapor pressure curve is to the left of the MDMT curve on a temperature vs. pressure plot.

Any thoughts?

 

[metengr]

kevlar49;
Your stated rationale seems logical regarding using UCS-66 curves in ASME Section VIII, Div 1, because the curve hinges on the lowest temperature in service.

However, I would post part of this question in the chemical engineering forum just to make sure that your interpretation of using the VP curve is accurate regarding autorefrigeration in service.