Why does a conventional gasket fail when hot?

Because its organic binder degrades and the gasket hardens, losing the ability to follow joint movement. Leakage usually appears after several cycles, not on first heat-up.

Does graphite oxidize in these joints?

The face exposed to hot air can oxidize over time. In practice the outer edge is the critical zone, and the joint design — seating, cover, or adequate compression — determines whether that ever compromises the seal.

What is needed to propose a solution?

The joint type, working temperature and pressure, the medium, dimensions or drawing, and the observed failure mode. The failure mode distinguishes a material problem from a joint design problem.

Sealing applications

High-temperature sealing

Graphite gaskets, packings, and seals for flanges, furnaces, and equipment operating at high temperature.

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High-temperature sealing solution

Also known as: High-temperature graphite sealing · Gaskets for furnaces and boilers · Exhaust gas seals · Thermal sealing of hot flanges

[ Technical summary ]

When service temperature rules out elastomers and binder-based gaskets, sealing is resolved with graphite. This application gathers those hot joints — furnace flanges, ducts, boilers, exhaust gas lines — where the problem is not only peak temperature but cycling: the joint expands and contracts, and the seal must follow that movement without hardening or losing conformation over time.

[ Problem it solves ]

Seal a joint that expands and contracts with the thermal cycle, using a material that neither hardens nor loses conformation because it contains no organic binder.

Processes

Hot flange sealing
Furnace sealing

Operating conditions

High-temperature exhaust gases

When it is suitable

Elastomers and fibre gaskets degrade in the service
The joint expands and contracts with every cycle
Leakage appears at temperature rather than cold
Sealing must hold without frequent retightening

When it may not be suitable

The seal is exposed to hot air on its outer face without protection
The process medium is a strong oxidizer and compatibility has not been verified
The joint lacks the stiffness to hold seating stress when hot

Process challenges

Elastomer degradation
Leaks from thermal cycling
Oxidation

Advantages

Thermal range above elastomers
Specialty gaskets and packings
Design by process condition

Limitations

Oxidation in air at very high temperature
Chemical compatibility of the medium
Does not replace mechanical joint design

[ Critical selection variables ]

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

Operating temperatureDecisive
Thermal and duty cyclingDecisive
Joint and housing designDecisive
Fluid or medium in contactRelevant
Differential pressureRelevant
Gasket seating stressRelevant
Bolt load and tightening sequenceRelevant

[ 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

Thermal expansion
Purity

[ Related ]

[ Frequently asked questions ]

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

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