Graphite gaskets are manufactured from expanded graphite, also known as flexible graphite. Produced by treating and heating natural graphite flakes before compressing them into sheets, this material provides a flexible, conformable seal without requiring a rubber binder. Its structure and sealing properties allow it to accommodate minor flange surface irregularities in steam, hot oil, gas and compatible chemical applications.
Available in unreinforced and metal-reinforced constructions, graphite gasket materials offer different handling strengths and load-bearing characteristics. Dobson Gaskets manufactures standard and bespoke profiles, helping customers select the grade, reinforcement and thickness to suit the joint’s temperature, pressure, media and available bolt load.
Unreinforced expanded graphite provides a highly conformable sealing material for compatible applications. Selection depends on the required purity, gasket dimensions, flange arrangement and operating conditions..
Metal-reinforced graphite combines a conformable sealing layer with additional strength and stability. Reinforcement options support handling and joint performance, with selection based on the application.
A tanged metal insert mechanically anchors the graphite layers, improving handling strength and resistance to blowout. Suitable grades are used in demanding steam and process sealing applications.
Graphite laminated with a metal foil insert provides improved handling and load-bearing properties. The foil material and graphite grade must be compatible with the operating conditions.
Graphite gasket performance depends on the complete joint, including flange condition, gasket thickness, reinforcement and the compressive stress applied during assembly. Chemical compatibility alone does not establish suitability.
| Materials | Temperature Range | Max Pressure |
|---|---|---|
| Pure Graphite | min 200 max 500 °C | 100 bar |
| Reinforced Graphite | min 200 max 500 °C | 150 bar |
| Tanged Graphite | min 200 max 500 °C | 200 bar |
| Foil Graphite | min 200 max 450 °C | 200 bar |
Expanded graphite compresses to accommodate minor flange surface irregularities. The joint must develop sufficient gasket stress to establish and retain a seal without exceeding the material’s allowable loading.
Use the thinnest gasket that accommodates the flange condition and joint design. Increasing thickness can affect the required sealing load and resistance to internal pressure; it should not be used as a substitute for correcting damaged or distorted flanges.
Tanged inserts, metal foils and wire mesh alter the gasket’s mechanical properties and handling characteristics. Reinforcement should be selected alongside the graphite grade, rather than treated as a guarantee of a higher temperature or pressure rating. Where specified, an inner metal eyelet protects the exposed graphite edge. Its compatibility with the process medium must also be checked.
Graphite resists many process media, but strong oxidising chemicals require particular attention. At elevated temperatures, oxygen exposure can cause graphite oxidation, including at the gasket’s outer edge. Selection must therefore consider the process medium, external atmosphere, continuous operating temperature and thermal cycling, not simply a headline maximum temperature.
Graphite gaskets are used in industrial joints where elevated temperatures, steam or compatible process chemicals make material selection particularly important. Typical duties include pipe flanges, valve connections, pump joints and heat exchanger connections.
Reinforced graphite grades can support demanding service conditions, but suitability depends on the joint’s available loading, temperature–pressure combination and exposure to oxidising media.
Steam boilers and associated pipework
Oil refinery equipment
Petrochemical process plant
Paper mill process systems
Heat exchangers
Industrial pumps, valves and flanged connections
Our highly experienced technicians can advise you on the best sheet materials and manufacturing processes for a wide range of gasket applications.
We supply a vast range of gasket materials, available to buy directly or order from us. For more information visit the Gasket Sheet Materials page