O-ring versus flat gasket? 1

[HomeMadeSin]

In sealing two parts, say 8" in diameter and smaller, what are the pros and cons of o-rings versus the same for gaskets? I think for chemical compatibility, o-rings would have to win hands down thanks to the variety of materials all the way up to the perfluoro's (Kalrez). I've never seen any guides on either for design purposes, especially as it pertains to pumps (casing to cover, gland to cover, impeller nut, etc).

 

[ccfowler]

HomeMadeSin,

There is no simple answer to your question. Temperature, pressure, chemistry, configuration, stresses, maintenance needs, and who-knows-how-many-other-factors all affect the choice of gasket material and design for a particular application. Sometimes a sealant may be a valid choice insstead.

 

[arto]

O-Rings are &quot;self energizing,&quot; whereas flat gaskets require a seating preload to seal tight. This preload often is the over-riding factor in flange design thickness - more than internal pressure. Oftentimes [Treq'd + o-ring groove depth] < [Treq'd for Bolt-Up stress]. [see ASME Sec. VIII Div 1 Appendix 2]

 

[motorman]

When faced with a similar assignment to design gasket, I learned at lot from :

http://www.sealinfo.com/isiweb/website.nsf

http://www.sealanddesign.com/product.html