Required Thickness of Reverse Girth Flange with RTJ Gasket

[AbbasEsmati]

Dears

I have a urgent issue about the required thickness of Girth Flange with RTJ Gasket.
regarding to calculation PVElite introduce required thickness according to ASME SECTION VIII Appendix 2.
my question is about this thickness. this required thickness is from to where?
from End of HUB to the face of Flange? End of HUB to the Bottom of RTJ Seat? or from End of HUB to the FACE OF BOLT? (Please see attached file)

Thanks

 

[gr2vessels]

End of HUB to the Bottom of RTJ groove.
Cheers,
gr2vessels

 

[AbbasEsmati]

is there any reference that show your opinion?

regards