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?

 

[gedomin]

The contingency that governs is any leak of product to the atmosphere. Local temperature could potentially reach product boiling point. For the case of pure propane this is -43.8 degF (minus 43.8), at sea level.