ASME Appendix 2 flange calculation

[starrproe]

Hi Everybody,

I just started designing a heat exchanger body flange using App.2 and got stuck up wondering how this formula works -

Minimum initial bolt load for gasker seating,
Wm2 = 3.14*b*G*y

What is baffling me is that the total area of gasket required to yield by bolting in order to make the gasket seat properly and obtain a tight joint should be the total (effective) area of the gasket contact face, given by
3.14*2b*G*y(assuming a case where b=b0).

Can the forum help me have better clarity on the calculation?

 

[SnTMan]

starrproe, according to some of the literature I've seen the gasket seating width is reduced to account for flange rotation. You will notice the same gasket seating width is used for operating calculations as well.

The basis for these calculations go back many years, and primary references for some of the theory is hard to find.

Regards,

Mike