Bolt Loads per Appendix 2
Bolt Loads per Appendix 2
(OP)
Why is it that when I calculate bolt loads for seating and operating conditions, my seating bolt load comes out significantly higher than my operating condition? Is this the load I would use to specify installation torque? Seems awfully high. For instance, a 30" R.F. manway cover with rubber gasket gives a bolt load of ~98,000 lb. (100 psi internal pressure) for my operating condition but ~380,000 lb. for my seating condition. Refer to Section 2-5(e). Seating load seems to account for actual bolt areas whereas operating load only accounts for required bolt areas. Totally confused!





RE: Bolt Loads per Appendix 2
The following is taken form Taylor Forge Bulletin 502 Modern Flange Design 1964 (Fifth) Edition, Section III Basic Design Considerations, Precautions Against Excess Bolting:
"Where excess bolting cannot be avoided, the designer should make some provision against this known overload potential in the bolting. The ASME Code requires that at least 50% of this potential overload be recognized, and built into the design moment."
Note that the portion (Am+Ab)/2, in Formula 4 of App 2-5(e) is the same as Am + (Ab-Am)/2, where the first term is required area & the second term accounts for 50% of the excess bolting area. As noted, W need only be checked "at atmospheric temperature and before application of internal pressure".
RE: Bolt Loads per Appendix 2
RE: Bolt Loads per Appendix 2
RE: Bolt Loads per Appendix 2
Did you say RUBBER gasket? For rubber gaskets, the minimum design seating stress is either 0 psi or 200 psi depending upon the durometer. Double check the value of Y that you used in your calculations. It seams that you used a much higer value.
RE: Bolt Loads per Appendix 2
RE: Bolt Loads per Appendix 2
RE: Bolt Loads per Appendix 2
Per origninal TF Bulletin 502, Nmin=AbSa/2y(pi)G.
We have found the above to provide good field results.
If N < Nmin, consider increasing N, or using stiffer gasket material with larger y gasket seating load factor.