Refer to ASME Section VIII, Division 1 - Appendix 2 Figures 2-4(1) and 2-4(2). In the second figure this value is the dimension for the material removed on the flange face the contacts the back of the lap. In the first figure there is a note indicating that the gasket reaction diameter, G, is determined as the mid-point of contact between the flange and the lap. Therefore, this value will result in G being calculated as the (OD Lap Face + 2*Bevel + B)*0.5. For the example below, the G value will come out to 32.8125 in.
