I have been checking the results of a flange calculation done in the Caesar module and have a question regarding the gasket seating bolt stress calculated. It appears that the safety factor calculated is based on the stress due to the minimum initial bolt load for gasket seating Wm2 as per equation 2 ASME VIII Div 1 app2 rather than the flange design bolt load 'W' as per equation 4.

Is this correct? If so why is the design bolt load not used in calculating the bolt stress and safety factor?