"Old" vs "New" Gasket dimensions

[Peter Morenc]

When did the dimensions change for ASME B16.21 non-metallic gaskets? We use the old style where gasket ID = Flange ID. I want to reference the correct year of the B16.21 standard in my purchase requisitions.

Peter Morenc, Reliability Engineer Eco-Services.

 

[DSB123]

Review the older versions of ASME B16.21 to see when and if the dimensions changed.

 

[Peter Morenc]

Before buying all the prior versions was hoping someone may know off-hand. I'll go ahead and start at 1978 and work my way back.

 

[Ehzin]

The only thing I could say is that in comparing the 1992 and 2011 versions it appears they show the same gasket ID. Anything before 1992 I wouldn't have any feedback.

Thanks,
Ehzin

 

[racookpe1978]

How much is the difference in ID's that you are trying to correct for with the "old spec"? I seriously doubt you'd get off-the-shelf new gaskets from a vender who has to cut special diameter gaskets from new gasket material.

Old specifications also = old gasket material selection for that specification = hard-to-get = very expensive, if available at all.

It is, after all, that some "old repair period manually cut the gaskets from square rubber sheets, and so you are trying to duplicate hand-cut no-specifications-at-all old gaskets.

 

[gerhardl]

What is the real problem? Is the new/old not interchangeable?

If the new ones fit, but you have to change gaskets often, you should remind yourself of the usual reasons for gasket failures:
Wrong dimensions (as you suspect?) but also wrong/changed material and/or damaged fanges, vibrations, skew mounting of gasket, unlinear mounting of valves and flanges, unsatisfactorily pressure (new ones could be supplied in harder or other material composites and for other temperature limits), etc.

Anyway, it should not be difficult to find a standard gasket that does the job. If not, in my part of the world, (Scandinavia), it is several companies that on short notice can supply gaskets in any feasible soft materials in any size at a reasonable price. The reason is both the demanding offshore oil industry and urgency by shutdowns, and also use of (among other fabrication methods) programmable high-pressure water-cutting machines for soft materials.

PS: Cannot help with year of change.

Good luck!