The reason for this error is the calculation of Nmin, see below.
This is not mentioned in ASME, but this is a “good practice” which is mentioned in the French CODAP code:
In case of flat gasket, unless tongue and groove facings are used or mechanical provisions (such as crushing limiter spacer or recess) protect the gasket against excessive tightening the force W should fulfil the following relationship: W <= 2 π N G y
The user can disable this checking (see Gasket Tab):
Answer Verified By: Ruediger Gawlick