The functions of inner and outer rings of SWG and Kammproflie gaskets 3

[mechengineer]

Dear Exoerts,
Is there any other functions for the inner/out ring of SWG and Kammproflie gaskets except the gasket positioning?
Thanks,

 

[BJI]

The spiral wound inner and outer rings provide strength, they restrain the windings from extruding. This allows for higher compressive load on typical raised face applications. Alternatively the gasket can be confined by grooves in the mating flanges or tubesheets. The outer ring is sometimes also known as a compression stop, but generally speaking a well made and well proportioned gasket, assembled correctly, shouldn't make contact with the outer ring. For poorly proportioned gaskets in thermal applications, this can lead to joint leakage.

Typically the outer ring on kammprofile gaskets is only used for centering. There are some rare cases where an integral outer ring is required for strength but 99.99% of the time this is not the case.

 

[mechengineer]

@BJI,
Thanks for the input.
The Kammprofile gasket is with the metal core. So, I think the Kammprofile gasket without inner/outer rings and with the confined step at OD of the gasket in the flange may be the better design, the gasket will be cheaper.
But I am not so sure whether the sealing layer material of the gasket will stick the gasket on the flange by the operating gasket stress. So, may the gasket with inner be a help and easy to remove the gasket after service for a long time?

Regards,

 

[SnTMan]

For SW gaskets an outer ring can keep the gasket from unwinding while being handled as well as acting as a compression stop. Good practice, IMO

Regards

Mike

The problem with sloppy work is that the supply FAR EXCEEDS the demand

 

[Christine74]

The outer ring helps with centering and can act as a compression stop to prevent the gasket from being crushed. This article (if you have access) discusses the benefits of including an inner ring on SW gaskets, as it can help prevent the windings from buckling inward or springing:

https://www.hydrocarbonprocessing.c...liability/spiral-wound-or-kammprofile-gaskets

-Christine

 

[SnTMan]

Both inner and outer really is the way to go.

The problem with sloppy work is that the supply FAR EXCEEDS the demand

 

[BJI]

@mechengineer, if you have a recessed face on the OD, then no rings will be required for the kammprofile. If you were to use spiral wound, then you would still need a ring on the ID. A ring on the OD of a spiral wound should not be used on a recessed face.

This application seems pretty typical for a heat exchanger, I don't believe an inner ring would be required for gasket removal.

 

[Krausen]

For kammpro gaskets, the outer ring is only a guide ring. Typically used for pipe flanges only to help install. It is not a compression stop. In fact, the best kammpro gaskets for unconfined flanges/pipe flanges have "loose-fit" outer/guide rings, that allow the metal core to thermally expand out toward the guide ring to prevent damage of the metal core (e.g. LAMONS LP-3 gasket). Kammpro gaskets do not have inner rings typically, as their is no need it with this gasket type.

Spiral wounds, on the other hand, are required to have a inner rings for pipe flanges (per ASME B16.20) to prevent the windings for buckling. Note that spiral-wounds with inner rings can be a problem when using with threaded or slip-on pipe flanges (see B16.20 for more on this). The outer ring for spiral-wounds serves the same purpose as with kammpros, as a guide ring for install.

The kammpro gasket design is deceivingly simple & very effective. They require less bolt load to seat compared to spiral-wounds & will outperform them in many situations (all things being equal with install quality, correct bolt torque, etc.)