Can you calculate gasket area?

Out of all of the complexities regarding modern gaskets, Gasket Area should not be something that designers are still getting wrong. 

And yet here we are…

I’ve met Owner/Operators who love to order gaskets with a larger outer diameter than the raised face outer diameter so they can “see the gasket”. That’s fine enough but using that outer gasket diameter in ASME Appendix 2 Flange and ASME PCC-1 Appendix O calculations is not. Please be careful not to include the gasket area outside of the raised face diameter. 

Another common calculation mistake arises when the gasket diameter fits within the flange raised face diameter. Many times designers use the gasket raised face diameter instead of the actual gasket diameter. This is usually because the raised face diameter is the “default” value in the spreadsheet they are using. Please be careful to use the actual gasket area when it resides within the flange raised face diameter.

Are the ASME Appendix 2 Flange and ASME PCC-1 Appendix O calculations causing difficulties for your overworked engineering department? Did you know Metalmark Engineering offers on-site training to teach your team how to use modern software solutions?

When I think about phi, g, I think about relaxation. But have we been too relaxed about phi, g? 

ASME PCC-1 Appendix O allows a default Fraction of Gasket Load Remaining after Relaxation (ϕg) of 0.7 if no data is available. I have found that this statement leads designers to use the “default” value for too many gasket types. 0.7 is too high for some PTFE gaskets and other gaskets with high compressibility and can lead to leaky flanges over time. Please consider your gasket material before selecting the Fraction of Gasket Load Remaining after Relaxation (ϕg) needed in the ASME PCC-1 Appendix O calculation. 

Did you know that the Gasket Load Remaining after Relaxation (ϕg) may be lower for thicker gaskets? Please consider the possibility of using a lower Gasket Load Remaining after Relaxation (ϕg) value when increasing compressible gaskets from 1/16” to 1/8” thickness. 

Unsure what “default” Fraction of Gasket Load Remaining after Relaxation (ϕg) your internal spreadsheets are using? Metalmark Engineering offers on-site training to teach your team how to use modern software solutions.