The Pressure Test: AFLAS® Under Extremes

Summary

• AFLAS® o-rings offer exceptional resistance to heat, steam, and aggressive chemicals, making them ideal for long-term performance in extreme sealing environments.
• Designed for durability, AFLAS® maintains sealing integrity under thermal cycling, chemical exposure, and extended service intervals, reducing downtime and improving reliability.
• Global O-Ring and Seal supports informed selection with expert guidance, compatibility tools, and a self-service online store for confident AFLAS® sourcing and application support.

Why AFLAS®? Built for the Extremes

In high-performance sealing environments, material selection is critical to withstand environmental stressors. System exposure to high heat, aggressive chemicals, and steam requires a material that can endure these conditions without degrading, swelling, or hardening over time. 

AFLAS® offers a level of durability that general-purpose elastomers can’t match. Classified as a fluoroelastomer, AFLAS® is a copolymer of tetrafluoroethylene and propylene (TFE/P). Its fluorine content of approximately 54% contributes to its exceptional resistance to oxidation, thermal breakdown, and chemical attack. The strength of the carbon-fluorine bond and the copolymer’s structural stability make AFLAS® especially effective in environments with polar solvents, strong bases, and saturated steam. AFLAS® generally performs between standard FKM compounds and FFKMs, offering robust resistance without the high cost. 

Thriving in High Temperatures

Extreme heat is one of the most common causes of seal failure. In systems that operate continuously at elevated temperatures, many elastomers begin to harden, lose elasticity, or develop surface cracking from prolonged exposure to thermal stress. AFLAS® stands apart by offering long-term resilience in high-heat environments. With a recommended static temperature range of 14°F (-10°C) to 428°F (220°C), AFLAS® retains its physical properties in conditions that push other compounds beyond their limitations, making it a reliable choice for thermal applications with limited downtime.

AFLAS® also performs exceptionally well under thermal cycling conditions with repeated heating and cooling. These cycles introduce mechanical stress as materials expand and contract, often leading to embrittlement, surface cracking, or loss of sealing force in less robust compounds. AFLAS® resists these effects with its flexible, dimensionally stable molecular structure, making it especially valuable in heat exchanges, sterilization units, or thermal reactors.

Chemical Resistance: AFLAS® vs. the Toughest Fluids

Seals used in chemically aggressive environments must withstand fluid exposure without breaking down. AFLAS® maintains its integrity when exposed to harsh substances such as amines, strong bases, acids, and polar solvents. It also performs well in systems containing steam and hydrogen sulfide (H₂S), where chemical and thermal stresses are present. Additionally, AFLAS® is compatible with phosphate ester-based hydraulic fluids, which are known for their aggressive chemistry and incompatibility with many sealing materials.

While AFLAS® offers broad chemical resistance, it does have limitations. It is unsuitable for use with ketones, aromatic fuels, or chlorinated hydrocarbons, as these substances can lead to swelling, softening, or degradation over time. To ensure long-term performance, careful material selection based on the complete chemical profile of the system is essential.

Steam, Hot Water, and Thermal Shock

Steam and hot water systems are uniquely challenging for sealing materials, especially when combining high temperatures with chemically treated fluids. Prolonged exposure to saturated steam, pressurized water, and system additives can cause elastomers to soften, crack, or degrade. However, AFLAS® delivers reliable sealing in these demanding conditions.

AFLAS® offers excellent resistance to steam and hot aqueous environments, including systems that utilize anti-corrosive or oxidative additives. It is well suited for processes such as sterilization, washdown cycles, and high-temperature coolant systems, where fluid chemistry is as demanding as the temperature itself.

AFLAS®’s proven performance in SIP (Steam-in-Place) and CIP (Clean-in-Place) systems defines its value in dynamic environments. These applications involve repeated cycles of steam flushing, chemical cleaning, and pressurization. AFLAS® has shown strong reliability in applications involving rapid temperature changes and fluctuating loads and provides a dependable sealing solution in hot water and steam systems that operate under constant stress by resisting softening, chemical attacks, and steam-related degradation.

Performance Under Stress: Compression Set and Elastic Recovery

Long-term sealing performance depends on how well a material maintains its shape and sealing force over time, particularly in high-temperature, chemically aggressive environments. A key indicator of this is compression set, or the tendency of an elastomer to retain permanent deformation after being compressed.

AFLAS® performs exceptionally well in static sealing applications by maintaining reliable sealing capability during prolonged exposure to heat and corrosive fluids. This characteristic makes it a strong choice for systems that demand chemical resistance and temperature stability over extended service intervals.

In dynamic applications, AFLAS® offers an advantage through its elastic recovery and rebound properties, allowing it to sustain sealing performance under intermittent motion or vibration.

By balancing chemical durability with a functional level of elasticity, AFLAS® gives engineers a versatile option for both static and moderate dynamic sealing demands, especially in harsh operating conditions.

Durability That Outlasts the Demands

Long-term durability is essential in sealing environments with high temperatures, aggressive chemicals, and continuous exposure. AFLAS® resists the compound effects of these stressors and maintains performance where many materials begin to fail.

AFLAS®’s resistance to oxidative aging, thermal hardening, and chemical swelling allows it to maintain sealing properties over time. This property makes AFLAS® an ideal candidate for applications with extended service intervals or limited access for maintenance. AFLAS® performs without breaking down, shrinking, or losing flexibility when exposed to fluctuating temperatures, chemically reactive fluids, or system additives.

This durability translates into particular advantages across a wide range of applications. AFLAS® seals are less likely to require early replacement due to material degradation, which reduces unscheduled downtime, extends maintenance cycles, and supports long-term system reliability in severe service environments.

Where AFLAS® Excels: Real-World Application Conditions

AFLAS® delivers reliable performance in environments that challenge most sealing materials. Its unique combination of heat, steam, and chemical resistance makes it ideal for systems where multiple stressors occur simultaneously. These conditions often include:

• Sustained high temperatures combined with aggressive chemical exposure
• Steam and hot water cycling, especially in systems with oxidative or anti-corrosive additives
• Long-duration service intervals, where seal replacement is infrequent or difficult

In these scenarios, AFLAS® provides a strong balance between durability, compatibility, and cost, filling a performance gap between standard FKM compounds and premium FFKMs.

Property	AFLAS®	FKM (Viton®)	FFKM (Kalrez®)
Max. Temperature	428°F~482°F	400°F~482°F	428°F~620°F
Steam Resistance	Excellent	Poor	Excellent
Base Resistance	Excellent	Moderate	Excellent
Cost	$$	$$	$$$$
Best Use Case	Steam/Chemical Mixes	Oils/Fuels	Full-Spectrum Chemical Exposure

FKM may not provide adequate steam or base resistance for many sealing applications, while FFKM is often cost-prohibitive. AFLAS® offers a cost-effective solution that bridges this gap by delivering excellent resistance to steam, amines, and harsh fluids at a significantly lower price than perfluoroelastomers. When sealing systems are exposed to thermal and chemical extremes, AFLAS® provides proven solutions without overengineering the application or overextending the budget.

Ask the Experts: Choosing AFLAS® with Confidence

There is rarely a one-size-fits-all solution for sealing in extreme conditions. AFLAS® is a high-performance material, but getting the most out of it means matching the right compound to specific application conditions such as temperature, chemical exposure, system design, and service life expectations.

At Global O-Ring and Seal, our team is here to help you make the right choice. We know the materials, the trade-offs, and the questions to ask. We’re ready to work with you to find the best fit for your application. We also offer self-service resources to make your selection process easier, such as our interactive chemical compatibility tool, material data sheets, and a fully stocked online store. These tools empower your research and purchasing experience and give you confidence at every step. Whether starting a new project or trying to solve a recurring issue, we’ll guide you through the options and help you confidently move forward.