The Basics of Silicone Gaskets: Properties and Performance

• Properties of Silicone Gaskets
• Performance Characteristics
• Adaptable Solutions
• Applications of Silicone Gaskets
• How Do Silicone Gaskets Compare to Other Materials?
• In Conclusion

Properties of Silicone Gaskets

Silicone gaskets play an important role in many industries. This is mainly due to the unique properties of this material. Let’s review them.

Temperature Resistance

Silicone gaskets offer exceptional temperature resistance, withstanding temperatures from -50°C to +250°C (-58°F to +482°F). Some specialized grades endure even higher temperatures. This delivers long-term durability, flexibility, and effective sealing in extreme heat or cold for demanding environments like automotive, aerospace, and industrial applications.

Flexibility and Compression Set

Silicone gaskets are appreciated for their flexibility and low compression set, delivering effectiveness in sealing.

• Silicone gaskets remain flexible from -50°C to +250°C (-58°F to +482°F). This delivers conformance to irregular surfaces and effectively seals joints. High elasticity ensures a reliable seal.
• They also exhibit low compression-set, retaining their shape and sealing properties after prolonged compression. This ensures that they maintain long-term seal efficacy, reducing the risk of leakage and the need for frequent replacements.

Chemical Resistance

Silicone gaskets offer high chemical resilience, making them suitable for demanding environments. They exhibit excellent resistance to:

• Oils and fuels, resisting degradation from contact with hydrocarbons, crucial in automotive and industrial applications.
• Acids and bases, maintaining integrity when exposed to dilute solutions (i.e. relatively mild pH variations), suitable for use in chemical processing and laboratory settings.
• Solvent resistance is common in silicones, including alcohols and ketones, ensuring they do not degrade or lose their sealing properties in such environments.

Electrical Insulation

Silicone gaskets offer excellent electrical insulation properties, making them suitable for various electrical applications, including wire insulation, connectors, and electronic encapsulation. Key features include:

• Silicone’s high dielectric strength prevents electrical current from passing through, protecting sensitive electronic components from interference and ensuring reliable operation.
• The insulation behavior also helps prevent electrical shorts and signal degradation in electronics, telecommunications, and other industries requiring electrical isolation.

Note that specially formulated conductive silicones are available for applications requiring EMI/RFI shielding, which exhibit very different electrical properties compared to standard insulating silicone gaskets.

Performance Characteristics

Durability and Longevity

Silicones are exploited in seals/gaskets for their durability and longevity, significantly reducing the need for replacements and minimizing downtime. Their resilience stems from:

• Maintained flexibility and sealing capabilities across a broad temperature range, which ensures that they perform reliably in extreme heat and cold, preventing failures by either slow or rapid thermal decomposition.
• High chemical resistance prevents most degradation from oils, fuels, solvents, alkalis and acids, extending lifespan in harsh and aggressive chemical environments.
• Compression set resistance ensures low permanent distortion, resulting in maintained seal pressure and effectiveness even after prolonged service. This reduces the incidence of leaks in long term use and reduces the need for maintenance/replacement.
• UV, radiation and ozone resistance is intrinsic to silicone, preventing deterioration from exposure to sunlight, ionizing radiation and environmental pollutants.

This unique group of properties delivers long-term performance in silicone gaskets, reducing maintenance costs and the potential for leakage events and operational interruptions.

Environmental Resistance

Silicone sealing gaskets excel in environmental resistance, making them ideal for outdoor or exposed conditions:

• Silicone gaskets are highly resistant to UV radiation. They do not degrade or become brittle when exposed to sunlight, delivering long-term durability in outdoor applications such as sealing electronic enclosures in telecommunications equipment.
• Silicones maintain structural integrity and flexibility when exposed to ozone, which typically drives degradation in many other gasket-appropriate polymers. This resistance is crucial for applications in environments with risk of high ozone levels, such as many industrial/chemical applications.
• The specific resiliences of silicones make them highly durable against weather conditions, and they resist moisture absorption, which prevents swelling and loss of sealing effectiveness.

The unquestionable toughness of silicones ensures that these gaskets perform reliably over time, even in harsh or fluctuating weather conditions.

Adaptable Solutions

Silicone gaskets offer essentially unlimited customization options to meet specific application requirements without suffering the extreme tooling costs of many other polymers that rule them out of lower-volume applications:

• Silicone gaskets can be molded into virtually any shape or size, including very complex geometries. Custom tooling allows for precise cuts and profiles, accommodating diverse sealing needs from simple O-rings to intricate flange gaskets.
• Silicone gaskets can be manufactured in hardness levels ranging from 30 to 90 Shore A and at higher levels in some cases. Softer gaskets provide excellent compression and conformability for tight seals, while harder gaskets offer greater resistance to wear and deformation.
• Custom colors and transparency options are available, aiding in visual identification or conforming to branding or visual minimization benefits.
• Silicone gaskets can be enhanced with reinforcements (e.g., fabrics or metal mesh) for added strength or additives to improve specific properties, such as fire resistance or chemical resistance.

This allows silicones to be precisely tailored to meet the unique demands of most applications, delivering great performance and durability.

Applications of Silicone Gaskets

Silicone gaskets are effective and widely used across most industries due to their exceptional properties.

• Space and Aerospace: Silicone gaskets are crucial in space and aerospace industries, where they endure extreme temperatures and harsh conditions. For instance, silicone gaskets are used in spacecraft and satellites to maintain vacuum-tight seals and protect against extreme temperature gradients, ensuring the reliability and safety of critical components. Silicones do not outgas and are essentially unaffected by orbital conditions.
• Vehicles – Air, Land, and Sea: In the transportation sector, silicone sealing gaskets provide essential vibration isolation and chemical resistance. In automotive engines, seals withstand engine vibrations, resist heat and automotive fluids, and sustain long-term reliability. Thanks to their ability to withstand exposure to water, salt, UV light, and temperature fluctuations, silicone gaskets are perfect for applications like off-road vehicles, boats, and ships.
• Oil and Gas Exploration/Production/Refining: Silicone gaskets are employed in the oil and gas industry due to their resistance to chemical exposure and high temperatures. They are used in seals for pipelines and equipment to prevent leaks and ensure safe operation in environments where exposure to chemically aggressive and extreme conditions is common.

How Do Silicone Gaskets Compare to Other Materials?

Silicone gaskets outperform almost all other materials in extreme temperature ranges (-50°C to +250°C) and offer superior chemical, UV, and ozone resistance that beats most alternatives.

Unlike neoprene, EPDM, and PTFE, silicone remains long-term flexible and durable under harsh conditions, making it ideal for demanding applications. It excels where high temperatures, chemical exposure, and weather resistance are critical, such as in aerospace, automotive, and industrial environments.

However, while offering excellent flexibility and resistance to high temperatures, silicone gaskets have some limitations. In terms of mechanical strength, they generally fall short compared to other materials like EPDM or nitrile rubber (Buna-N). Additionally, silicone tends to be more expensive than other gasket materials, which opens the door to more affordable alternatives that may be better suited for environments where extreme temperatures or chemical exposure are not primary concerns.

Comparison with Other Gasket Materials:

EPDM (Ethylene Propylene Diene Monomer): EPDM gaskets are known for their superior resistance to weathering and ozone, making them excellent for outdoor applications. However, their narrower temperature range compared to silicone limits their use in high-temperature environments.

Nitrile Rubber (Buna-N): Nitrile gaskets excel in applications involving oils and fuels, such as automotive and industrial settings. They offer better mechanical strength and resistance to petroleum-based fluids, but their temperature range is more limited than silicone.

Neoprene: Neoprene gaskets provide good resistance to oils, chemicals, and weathering at a more affordable price. However, they lack the high-temperature flexibility of silicone and are not suitable for extreme-temperature applications.

PTFE (Teflon): PTFE gaskets are highly resistant to a broad range of chemicals and can withstand extremely high temperatures. However, they lack the flexibility and elasticity of silicone, making them less effective in applications requiring tight conformance to irregular surfaces.

In Conclusion

My clients often ask me for the ideal gasket solution, and much of the time the answer lies in silicone rubber.

Silicone gaskets offer broad spectrum and hard to replicate benefits, including exceptional temperature resistance, superior chemical, UV, and ozone resistance, and long-term durability. Their flexibility and low compression set ensure reliable performance under extreme conditions, making them ideal for aerospace, automotive, and industrial applications.

Choosing the right gasket material is crucial for meeting industry-specific needs, as it impacts sealing efficacy, longevity, and overall performance. Selecting silicone for demanding environments ensures optimal operation, reduces maintenance, and enhances reliability, ultimately supporting safety and efficiency in various high-stakes applications.

Contact The ID Group today for expert advice and customized silicone gasket solutions tailored to meet the exact demands of your application. Our team of experts is ready to help you find the perfect gasket material to optimize your product’s performance. In addition to silicone gaskets, we offer other types of gaskets, including foam gaskets and metalized fabric gaskets and conductive shielding gaskets for EMI RFI shielding.