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Unique Benefits of Installing Fishbone Gaskets

The unique design of the internationally patented fishbone gaskets produced by AIGI Environmental makes them an innovative and highly effective tool in the limiting of fugitive emissions and increasing equipment reliability across the Australian petrochemical, oil and gas industry.

Strong and resilient, fishbone gaskets (so named because they have a shape similar to a fish skeleton) have several unique design features that mean they are ideal for a variety of sealing applications.

What are the key design features of fishbone gaskets?

Key design elements of fishbone gaskets include the concentric bevelled ribs that make them stronger than spiral wound gaskets. They also have greater resilience and operating life than kammprofile gaskets, and don’t impact or damage flanges due to the rounded contact surface.

Crucially, fishbone gaskets are in one piece (with or without a centring ring), which is why they are able to deliver the strength, resilience and live loading capability required to reduce fugitive emissions, particularly in critical flange applications.

The unique crescent shape and stop-step design (which can incorporate single or double stop-steps, depending on the sealing width) are also central components that help to prevent leakage. This also means that fishbone gaskets are self-energised by fluid pressure and so are capable of delivering significant sealing power without over-compression, ideal for high pressure flanges.

FITT Resources AIGI International Fishbone Gaskets

AIGI International Fishbone Gaskets

Fishbone gasket specifications

Round Edged Beveled Ribs

The graphite or PTFE coated round edged beveled metal ribs create separate sealing chambers when they are compressed, and these break down system pressure across the gasket face. The rib tip is also covered by a sealing element that becomes more densified and so creates an alternating sequence of sealing chambers (plus back up seals) at the point of contact between the rib and flange face.

The thickness and angle of the bevelled ribs produce a bending movement under bolt load that compresses and stresses the graphite, which also results in a self-energising effect that effectively creates an internal live loading system. In addition, all of the surfaces are rounded, and this helps to prevent flange damage.

Patented Stop-step Design

The internal, rounded stop-step provides a positive stop and thus prevents over stressing of the ribs and the graphite sealing element. It also ensures that these remain elastic without being stressed beyond their limit.

These features, which are integral parts of the unique design of fishbone gaskets, combine to produce maximum sealing performance under bolt load. It likewise means that a fishbone gasket can be used to replace both CG and CGI type SWGs, as well as kammprofile gaskets.

Contact FITT Resources to learn more about fishbone gaskets

FITT Resources specialises in fluid sealing and has a long track record of supplying, fitting and maintaining fishbone gaskets for prominent names in Australian petrochemical, oil and gas sectors over a number of years.

To learn more about AIGI Environmental fishbone gaskets and their application in the Australian oil and gas industry, contact our Head of Sealing Division Mathew Howell on 0428 731 732 or [email protected].


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