What graphite material is used for mechanical seals?

Faces and rings are typically machined from carbon-graphite or impregnated graphite for sealing and controlled wear. We complement with GRAFOIL for monoblock gaskets and packing.

Is GRAFOIL suitable for high-temperature gaskets?

Yes. Flexible GRAFOIL graphite withstands high temperatures, sealing flanges and monoblocks where elastomers fail. We cut and supply sheets, rings, and custom gaskets.

Why does a graphite gasket not suffer cold flow?

Because it contains no organic binder or filler that flows under sustained load. The gasket conforms on tightening and holds that shape; what must be watched is that the flange retains its seating stress.

How is a monoblock gasket specified?

With the geometry — outside diameter, inside diameter, bolt holes, or drawing — plus thickness, temperature, pressure, and medium. Those define the appropriate reinforcement type and density.

Can it be made from the used gasket?

Yes. It is the fastest route when no drawing exists: dimensions are taken from the removed gasket and reproduced, stating temperature, pressure, and medium to confirm the material.

Must the flange be retightened after the first cycle?

Retightening practice depends on the joint design and the plant assembly procedure. The gasket keeps its conformation, but bolt tension can change with the first thermal cycle.

Flexible graphite monoblock gaskets and seals

Sealing applications

Sealing monoblock gaskets

They provide hermetic sealing in engines and mechanical systems.

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Static sealing gasket

Also known as: Graphite flange gaskets · Monoblock graphite gaskets · Die-cut flexible graphite gaskets · Graphite gaskets for static joints

[ Technical summary ]

A monoblock gasket is a single piece of flexible graphite, with or without reinforcement, cut to the flange geometry. Being neither layered nor binder-based, it does not show the cold flow and progressive hardening that make other soft gaskets fail after several thermal cycles. It seals by conforming under bolt load, copying the flange face, and holds that conformation as long as the seating stress is maintained.

[ Problem it solves ]

Keep a flange sealed across thermal cycles, without the progressive relaxation and hardening that force retightening or replacement of conventional gaskets.

Processes

Flange sealing
Static sealing

Operating conditions

High temperature and pressure

When it is suitable

The flange runs thermal cycles and the gasket relaxes between them
Temperature exceeds the elastomer and fibre-gasket range
The flange geometry does not match a standard gasket
The process medium chemically degrades conventional gaskets

When it may not be suitable

The process medium is a strong oxidizer and compatibility has not been verified
The seal is exposed to hot air on its outer face without protection
The flange cannot reach or maintain the required seating stress

Process challenges

Flange leaks
Cold flow of soft gaskets
Thermal cycles

Advantages

Thermal stability
Formability
Grades for different media

Limitations

Does not replace metals in high-load structural seals without proper design
Oxidation in air at high temperature
Chemical compatibility of the medium

[ Critical selection variables ]

These variables define the grade and the geometry. Actual values are confirmed against the grade datasheet.

Gasket seating stressDecisive
Operating temperatureDecisive
Fluid or medium in contactDecisive
Differential pressureDecisive
Joint and housing designRelevant
Bolt load and tightening sequenceRelevant
Flatness and surface finishRelevant
Thermal and duty cyclingRelevant

[ Required material properties ]

Properties that guide selection. Numerical values come from each grade's datasheet.

Critical properties

Compressibility
Impermeability
Thermal stability
Chemical resistance

Secondary properties

Compressive strength
Bulk density

[ Related ]

[ Frequently asked questions ]

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Technical content reviewed by ESGRAF — Last reviewed: September 8, 2026

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