B16.5 Flange
File: Sample 9
Last Updated: June 16, 2010
lb
A B16.5 flange's pressure at temperature ratings are taken straight from the B16.5 standard. But what if this same flange is calculated by VIII-1 Appendix 2 rules? And how does this compare to FEA results?
This standard 12" Class 150 B16.5 flange's rating was compared with Appendix 2 and FEA. Although we would not normally run FEA or Appendix 2 rules on a B16.5 flange, the comparison is interesting...
A common saying in our office is that you cannot run B16.5 flange calculations using VIII-1 Appendix 2 rules, and here is yet another example of a B16.5 flange that does not pass VIII-1 design rules. Going farther the FEA shows interesting stress patterns and vividly illustrates how a standard flange deforms under load.
This report shows how to accurately apply all of the Appendix 2 flange loads - seldom done correctly in FEA analysis. Also shown is how to combine the seating and operating conditions to get higher allowable bolt loads as allowed by VIII-2 Appendix 4 rules - required to get high seating bolt loads to pass.
We would not run Appendix 2 rules or Finite Element Analysis on a standard B16.5 flange, but we use the methods outlined here regularly on custom flanges that can not be run to the rules of Appendix 2.
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