Derating of ASME Appendix 2 Flanges for External Loads

[htman]

Currently I utilize the "Equivalent Pressure Method" to derate all of my ASME Code Appendix 2 flanges. It is very easy to use but it is also VERY conservative.

I understand that you can also use the "Equivalent Axial Force Method": F = 4M/G
Where:
M = moments acting on the flange
G = mean gasket diameter
F = equivalent axial force

The only problem is I am not completely clear on how to use this method. Does "M" represent the sum of all my external moments? And how do I apply this equivalent axial force to my flange to make sure it can take the loads?

Does anyone utilize this method or should I stick with my current analysis?

Thanks!!

 

[C2it]

The 'Kellogg equivalent pressure' method is very conservative if the combined pressure = P+Peq is compared to ASME B16.5 allowable and similar. A better approach is to use the combined pressure then use it to do an ASME VIII / PD5500 flange stress calculation. This is the method adopted in ASME III.

Your 'equivalent force', seems to be only part of a solution. The equation terms are same as Kellogg, when
4/(pi.G^2) is factored out.