Flange rigidity check is now a mandatory check in Appendix 2. This check was moved from non-mandatory Appendix S to mandatory Appendix 2 in the 2004 Edition A05 Addenda (if I remember correctly).
For designs made to those Editions/Addenda where the rigidity check is contained in Appendix 2 it is not possible to turn off the check (except by using Code Case discussed below); it is possible to do so for earlier Editions/Addenda. Also, flanges with full face gaskets are not governed under Appendix 2, so for these flanges you can turn off the rigidity check for any Edition/Addenda.
A Code Case was issued to allow some flange designs to be "grandfathered" in without the rigidity check. This is Code Case 2547. You can check the Code Case 2547 option on the ASME Code dialog to indicate that flange designs should apply this Code Case.
