Morts81
Mechanical
- Dec 11, 2009
- 23
ASME PCC-1 Appendix O provides guidance for the determination of an appropriate assembly bolt stress for flanged joints. However, it doesn't explicitly cover blind flanges.
For weld neck flanges bolted to a blind flange (including heat exchanger cover flanges), a basic summary of how I've been attacking this problem in the past is as follows:
1) Determine suitable assembly bolt stress for the weld neck flange as per Appendix O
2) Determine induced assembly stress in blind flange by re-arranging ASME VIII UG-34 Eq 2
3) Compare induced assembly stress to material minimum specified yield and aim for < 90% utilisation (this is an arbitrary value)
The problem with this is that for larger diameter flanges this can severely limit the bolt stress that can be applied.
Another limitation is that this doesn't check the rotation of the blind flange against rotation limits.
Has anyone developed a methodology on how to tackle this problem?
For weld neck flanges bolted to a blind flange (including heat exchanger cover flanges), a basic summary of how I've been attacking this problem in the past is as follows:
1) Determine suitable assembly bolt stress for the weld neck flange as per Appendix O
2) Determine induced assembly stress in blind flange by re-arranging ASME VIII UG-34 Eq 2
Re-arranged UG-34 Eq 2 : S = (C.P.G^3 + 1.9.W.hG) / (E.G.t^2)
3) Compare induced assembly stress to material minimum specified yield and aim for < 90% utilisation (this is an arbitrary value)
The problem with this is that for larger diameter flanges this can severely limit the bolt stress that can be applied.
Another limitation is that this doesn't check the rotation of the blind flange against rotation limits.
Has anyone developed a methodology on how to tackle this problem?
