Dear members,

Please let me know if anybody clearly knows about the second notes of definition of “Stress Ratio” in ASME B31.3-2004, Fig.323.2.2.B Reduction in Minimum Design Metal Temperature Without Impact Test.
Note (2) of (a) “for piping pressure components with pressure ratings, the pressure for the condition under consideration divided by the pressure rating at the design minimum temperature”


My question is ;
What’s the definition of “the pressure rating” in Note (2) of (a) ?
-Does it mean flange rating(150, 300,..) or max. working pressure in the B16.5/B16.47 standards ? If operating pressure is 150 psi at -45 oC and flange rating is Class 150 of B16.5, is stress ratio 1.0 ?
-Does it mean rating of fittings(3000#,6000#,…) in B16.11 ?
-how about for cast valves ?

I would like Mr. John Breen or John C. Luf to give a comment.