Lens Ring Flange

[marty007]

Hi all,

Has anyone had experience with performing ASME VIII-1 compliant calculations for a lens ring flange with geometry per specification SP-65? Can anyone point be towards a calculation method?

An image of this flange/gasket type is pictured here: Link

I found this thread from a while back, but there were no responses... Link

Thanks!
Marty

 

[marty007]

As a follow-up question, after some searching it looks like the newest edition (4th) of Pressure Vessel Design Manual by Moss and Basic might have included a design basis for these flanges

Does anyone have a copy of the 4th edition of this text and could confirm the contents of pages 513-514 (not available on online previews)? I am not asking for a photocopy, just a confirmation that these pages show a calculation method for lens ring flanges. If so, I'll either buy a copy of the text or run out to the local university library.

Thanks to anyone that can help!
Marty

 

[doct9960]

marty,

From page 505 of the Moss/Basic book:

Design Methods
Lens, delta, double cone and Bridgman gaskets are all exposed to the vessel internal pressure. There are no standard calculations for determining the forces and moment induced into the flange as a result of these loadings. Accordingly, a free-body diagram is required to determine the additional loads put into the flanges and bolting as a result of pressure on the gasket. Detailed procedures are given for determining these effects for the Bridgman gasket. Similar treatments can be developed for the lens and delta types. Because of the small contact areas and yielding gaskets, the gasket seating forces will never govern design of these flanges and thus can be ignored. The bolting forces due to hydrostatic end force will govern these flanges.

If you can get a hold of Structural Analysis and Design of Process Equipment by Jawad & Farr, check out Chapter 10.7.9. In there you will find formulas that you could use in your Appendix 2 calcs.