hello,
I need some explanations about value to be used in the "bolting information"->"bolt diameter" of the flange/leakage/stress calculation module of CaesarII.

It is clear from the help on line of the software that the nominal diameter of the bolts shall be used.
Reading into ASME VIII div1 app2, the "Ab" is "the cross-sectional area of the bolts using the root diameter of the thread or least diameter of unthreaded position, if less"
The root diameter, I think, is the core stressed diameter of the bolt (the minimum diameter in a bolt)

BUT ... WHY CAESARII ASK FOR THE NOMINAL AND NOT THE CORE OF THE THREAD?
How can the software evaluate the core from the nominal?

Please note that I have used "succesfully" the CaesarII ASME VIII module in the past years, each time with the nominal imperial diameter of the bolts converted in mm because I work to SI units files (for example 1" --> 25.4mm). I check that the CTRL-F routine automatically does the same.
Now i have to check an ASME B16.5 flange with metric bolts and I want to follow the same method (for a metric M24 bolt can I input 24mm in the "bolt diameter").