elastomer gasket Y factor

[Tmoose]

We may be locked into using an unrestrained elastomeric gasket in a flanged joint to allow some radial lateral shift due to thermal expansion. basic neoprene or viton, maybe .2 inches thick to allow plenty of shear motion. I expected to find all kinds of info on the 'net about surface finishes and accuracy, minimum clamping stress, but have come up empty.

Any suggestions for good sources where I can look ?

 

[tothepoint]

Surface finish will need to be specified as either smooth or fabric finish. I recommend a smooth finish for lower pressures <50 psig and a fabric finish for higher pressures <100 psig. I don't know what you mean by "accuracy". As for clamping stress, 500 psi - 1500 psi is the target value you should shoot for. Higher stresses and you'll extrude an unrestrained elastomer gasket and experience a dramatic loss in bolt load. You're going to be shocked at the low assembly torque that corresponds to 1500 psi gasket stress. The bolt load/stress will be so low that you'll need a secondary means of maintaining bolt load/strain- check out disc spring washers and design/select them to achieve maximum "travel" for the bolt load developed. If possible utilize smaller diameter bolts with extension spacers to allow for increased elastic bolt stretch.

 

[mjcook]

For what it's worth, in past conversations with Garlock, they have recommended 600 PSI minimim clamping stress, and 900 PSI max clamping stress for rubber less than 70 durometer, 1200 PSI max clamping stress for rubber greater than 70 durometer. Although, in agreement with tothepoint, I've seen rubber acieve a liquid-tight seal at much lower clampinbg stresses than 600 PSI.