Extreme-high temperature gaskets play a crucial role in ensuring the integrity and efficiency of various systems under extreme conditions, where performance in very high temperatures is vital. Typically, an extreme-high temperature gasket would be required to operate at temperatures beyond 800°C. The performance of an extreme-high temperature gasket is heavily influenced by its material composition - the correct selection of materials is vital to withstand the extreme temperatures, pressures and chemicals they can be exposed to.

The need for high-temperature gaskets arose during the Industrial Revolution when significant gains were made in production processes, leading to greater performance demands on machine components. Before this time, the most common gasket material used was Oakum, a seal made from old rope that is not too dissimilar to gland packing. Oakum was made from old rope that had become slack and outlived its usefulness. The rope was untwisted and pulled apart before being tarred and caulked. It was mainly used within the edges of steam pistons, held in place by weights. Leather was another common material, mainly for water pumps, but often tore when exposed to steam.

Illustration of prisoners untwisting old rope to make oakum (left). Rope in various stages of being picked for oakum (right).

With technology advancing to a point where much higher steam temperatures and pressures were required, new sealing technology was needed too. One early method of sealing two nesting steam pipes was to pack iron filings and sulphur powder into the gap and apply water, which created a solid iron sulphate seal.

Other materials followed, including rubber and asbestos. With its ability to withstand steam, chemicals, water, and high pressure, asbestos sheet material, developed originally by Richard Klinger, was considered the ideal solution. Then in 1923, Whitby Chandler Ltd became the first UK manufacturer of gaskets, developing cutting machines for mass-producing new and replacement gaskets from asbestos sheets. This led to asbestos sheet material becoming the material of choice for most gasket manufacturers during the majority of the 20th century.

By the 1980s, however, the use of asbestos began to decrease as the detrimental effects asbestos had on health began to be fully understood. Certain versions were banned in the UK during the mid-1980s, with a full ban in 1999. By that point, however, most gasket manufacturers had turned to alternative materials as a replacement for their high-temperature gaskets such as graphite, Mica, ceramic fibre and metallic alloys.

Selection Criteria for High-Temperature Gaskets

When choosing extreme-high temperature gasket materials, several critical factors must be taken into consideration, to ensure optimal performance and longevity:

• Thermal Expansion

Different materials expand and contract at different rates. A mismatch between gasket material and flange material can lead to leakage or mechanical failure. Selecting a gasket with a compatible coefficient of thermal expansion is crucial.

• Pressure and Stress Distribution

High-pressure environments require gaskets that can maintain a reliable seal under fluctuating loads. The gasket design must ensure even stress distribution across the sealing surface to prevent blowouts or deformation.

• Chemical Compatibility

The gasket material must resist chemical degradation from the process media. For instance, graphite gaskets are suitable for acidic environments, whereas PTFE is ideal for highly corrosive substances.

Manufacturing Micatherm Gaskets with a CnC Press at Dobson Gaskets

Extreme high-temperature gaskets are typical in various industries, including industrial power plants and chemical processing facilities. Choosing the right gasket material involves numerous factors like material type, design, application, and regulatory compliance. 

Crucially, quality should always be your top priority. A low-quality gasket could cost you much more in maintenance, replacements, and potential safety risks. Our technicians offer a broad range of options, exceptional quality, and expertise to help you choose the perfect gasket for your needs.