It's a really good book you have started to write, because it explains the underlying theoretical approach which I have missed, then I have tried to understand the basic flange calculations. It's always good to understand the limitations/assumptions of the formulas you use. I'm just one of those guys who are a bit confused about which approach I should go for. So far I have first used the Kellogg method and if the flange leakage check fails (normally I end up with same problems as you describe) then I just go for Blick method. But maybe I should try to learn/understand some other methods like Koves, Tschiersch and Blach? Which approach do you use? I run Caesar II so it doesn't provide any "automatic flange check", I think Caepipe have some flange check built in. Normally I don't check the structural integrity of the flange because our pipe spec normally just use WN-flanges and I think this is the best flange in ASME B16.5. As you also point out the weakest element seems to be the weld between the pipe and the WN-flange so maybe the weld should be investigated as well? Do you normally investigate the capacity of the welds?
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