ANALYSIS FLANGE 1

[juliocesarp]

I'm making an analysis to differents standard flanges in a piping system. When I run the program the radial, longitudinal,tangential an average stresses are ok for operational and seating cases. But the software always indicate failure in bolting stress in the seating case. My question is what is the formula of this bolting stress used for the software, the code doesn´t talk about bolting stress.
All data is stadanrd, for the flange, gasket and bolts.

Thanks for your cooperation.

 

[C2it]

Ref ASME VIII, PD5500, EN13445 etc .. Bolt stress in the seating case would normally be calculated as S(bolt) = Wm2 / Ab, Coade would confirm what they use or you could back calculate it from your results.

It is not uncommon for standard B16.5 type flanges to fail either or both flange or bolt stresses in the bolt-up case but pass in the operating case. The gasket 'y' factor and seating width 'b' are usually the cause, in association with a conservative bolt allowable stress. Remember that whilst allowable bolt stresses in ASME VIII etc are based on approx (yield stress)/4, actual field bolting procedures normally aim for a residual stress closer to (yield stress)/2.