NFPA 68

[nuche1973]

Section 6.3.1.3.2 of NFPA 68, 2007 ed. states:
"Fu = ratio of ultimate stress of the enclosure to the allowable stress of the enclosure per the ASME Boiler and Pressure Vessel Code."

I am working on a calculation to determine the Pred of a carbon steel dust collector (SA516-70)and my first instinct to this comment was to divide 70ksi by my allowable stress of 20 ksi (the collector is at 300 deg F). Is this correct? Or is there a specific table in the Code? (I am having difficulty finding "Fu" in the ASME B&PV Code Section VIII Div 1.) The same holds for the NFPA definition of Fy.

 

[gr2vessels]

nuche,
Fu = 70 ksi/20 ksi is correct. Tha ASME code would give you only the materials UTS, Yield and allowable stresses at various design tempeartures (refer ASME II, Table D).
You have to calculate the Fu and Fy using the provided stress values.
Cheers,
gr2vessels

 

[nuche1973]

Thanks, I appreicate the clarificaion.