Occassional Unsustained Loading-Flanges
Occassional Unsustained Loading-Flanges
(OP)
As far as ASME B31.3 is concerned could you please advise if the pressure rating of a CLass 150 flange has an allowance for unsustained occassional loading as would occur in a surge situation?
I understand that for hoop and longitudinal stress that this may be incresed for such cases but does it also apply to fiitings such as flange joints?
I understand that for hoop and longitudinal stress that this may be incresed for such cases but does it also apply to fiitings such as flange joints?





RE: Occassional Unsustained Loading-Flanges
The results from Stress Analyses (forces and moments) out of the occasional load case definition should be verified. Acceptability of these forces and moments (actually highest out of all load case definitions!!) on flange connections should be assessed as per ASME VIII if ASME B31.3 is the applicable design code.
As far as I know there are no specific acceptance criteria for higher pressures/temperatures as those specified in ASME B16.5.
Within ASME B31.3 this applies for stresses, and not for loadings.
Regards,
FKE
RE: Occassional Unsustained Loading-Flanges
Subject to the owners approval, B31.3 does have allowances for occasional pressure increases above the flange rating.
See para. 302.2.4 Allowances for Pressure Temperature Variations for the limitations and also refer to para. 302.2.1
NozzleTwister
Houston, Texas