Gasketing Practices: Ring vs Full Face Gasket 1

[ehbadger]

Hi all, I've got three main questions I am curious about. All are more specific to 'non-metallic' gaskets (Examples being Sigma 533, GYLON 3510, GORE UPG) but I am open to other responses as well. Most of my experience is 150# to 300# service, raised face flanges, <350F temps.

1) Where you have the choice, which style do you prefer: RING or FULL-FACE?
--> We use both currently, but the FULL-FACE are definitely more 'foolproof' to install. I'm curious to what other plants have standardized on and why.
--> If you use RING style gaskets, why?

2) What dimensions do you use: 'OLD' ANSI (smaller ID) or 'NEW' ANSI (larger ID)?
--> See the differences here:

http://www.sealanddesign.com/category/Ring-Gaskets-150-lbs---old-style/536.html

--> We prefer 'OLD' style so an uncompressed portion of gasket can hang inside the pipe ID ever so slightly. Once the joint is torqued, that overhanging inner section "locks" the gasket and helps prevent blowout or radial creep. This is not achieved with the 'new' dimensions. The minor disruptions to fluid flow or contact with process is not a concern.

3) Do you have any training, tips, tricks, etc for installing RING gaskets correctly (centered between the flanges)?
--> The majority of gasketing issues I see are related to misaligned ring gaskets (read: not getting a complete inner ring overhanging in the pipe ID) cold-flowing and eventually pushing out radially until a leak path develops. See attached photo.

We have very good mechanics with torque tables, gasket selection, and all that. Gasket issues are very uncommon. But they do crop up. And I am curious as to what might be "best practice" or how other people handle ring gaskets.

Thanks!
ninja edit: added photo of ring gasket failure mechanism:

http://files.engineering.com/getfil...4bea-4ff0-8ed3-638ad76d2e55&file=IMG_4263.JPG

 

[moltenmetal]

We use ring gaskets exclusively. The reason is pretty straightforward: to replace a gasket, you do not have to remove ALL the studs. That's a huge advantage.

How do you get them centred? No problem: they are made so that their OD is the same as the ID of the bolt circle.

We don't care about the portion of the gasket hanging into or not hanging into the flow path. We only care about that if the gasket is a spiral wound type- then it's a huge problem, as it is when you use these gaskets between pairs of slip-on flanges below 2"- then you need a special dimension spiral wound.

 

[ehbadger]

Thanks for the reply! Great point on removing all studs vs just a few.

How do you get them centred? No problem: they are made so that their OD is the same as the ID of the bolt circle.

Specific to this, we don't see problems centering spiral wounds or other stiff ring gaskets. The trouble comes with the expanded ptfe or "soft" gaskets that even though they are dimensioned on the OD to match the bolt circle, they can still easily sag/form/warp/fold slightly on themselves before or during the torque process - this is the trouble.

 

[curtis2004]

Hello everyone,

I think selection of type of gasket (full face or ring) for !50#-300# is dictated by flange. You always use a "full face" gasket if you have FF ("flat face") flanges, and you always use a "ring" gasket if you have RF (raised face) flanges.

I would recommend gasket manufacturer's selection manual. You can download these from Flexitalic or Gylon or any other's web site.

Regards,
Curtis

 

[ehbadger]

I think selection of type of gasket (full face or ring) for !50#-300# is dictated by flange. You always use a "full face" gasket if you have FF ("flat face") flanges, and you always use a "ring" gasket if you have RF (raised face) flanges.

I agree with the full face gasket being required on a flat face flange. But why couldn't you use a full-face gasket on a raised-face flange? We do all over the place, successfully.

 

[rconner]

I am kind of partial myself to basically "full-faced" design gaskets with "special sealing" features (i.e. employing one or more torus or bulb, designed to improve or make more robust the seal). However, the only specific concern I've seen of ring gaskets is when very strong flanges like steel or ductile iron are joined with very strong bolting to weaker or more brittle materials (like gray cast iron or weaker etc., with the fear that overturning moment on the weaker flange, with nothing but air supporting same outside the ring gasket, might break the weaker flange).

 

[curtis2004]

ehbadger,

I think for non-metallic gaskets you can use full face gaskets in any place as you said. It is because you probably do not need compression force per area to compress rubber (or other non-metallic material). However, in case of metallic gaskets you are required to have smaller area to have a good sealing. You are literally deforming metal ring gasket between two flanges.

My another suspicion is it is easier (and cheaper) to manufacture a ring metallic gasket then full face metallic gasket.

I do not have an information to back it all up. It is my guessing...

Regards,
Kurt

 

[miningman]

I believe that an important consideration here is , what is the material in the pipes and what are the consequences of leaks? I have worked in sour gas plants where obviously leaks are critical and perhaps, totally ignoring code requirements, one question should be is any particular type of gasket more forgiving in terms of poor workmanship / installation procedures. Most of my experience has however been pumping mine water in shafts where the air is 100% saturated , water is leaking out of the rock formation and I really couldn't care less about a few extra gallons per minute falling to the shaft bottom.

 

[LittleInch]

Terminology is a bitch isn't it.

I initially read "Ring" to mean RTJ type flanges, but it's now clear you mean the difference between the two green gaskets below

For me,
1) For RF flanges I prefer the "Ring" type. Smaller, easier to fit ( only need two bolts on the bottom to locate)and you can see the flange type easier / check for any corrosion or leak

2) No opinion

3) Check the OD of the flange matches the bolt holes very well then you can use the bolts to secure.

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[ehbadger]

Yes, the discussion started with non metallic gaskets. I can see the issues re: FF vs Ring for metallic gaskets. Different set of considerations