Chemical Damage in O-Rings: Causes, Symptoms, and Prevention
Updated: Oct 27, 2025
Introduction
Chemical exposure is one of the most common and destructive causes of O-ring failure. In industries ranging from chemical processing and oil refining to pharmaceutical production and semiconductor fabrication, O-rings must survive contact with highly aggressive fluids and gases. When elastomer materials encounter incompatible chemicals, their structure can rapidly deteriorate, leading to swelling, softening, cracking, and complete seal failure.
Chemical damage often occurs silently. An O-ring may appear intact at installation, only to degrade within days or weeks as chemical reactions progress beneath the surface. The result is loss of compression, leakage, and costly downtime. Understanding how and why this happens allows engineers to make better material choices, extend seal life, and maintain safe, efficient systems. If you have questions, feel free to reach out to the Canyon Components Engineering Team.
What is Chemical Damage?
Chemical damage occurs when an elastomer reacts chemically with substances in its environment. These reactions may involve oxidation, hydrolysis, depolymerization, or plasticizer extraction. The outcome depends on the chemistry of both the seal material and the fluid it contacts.
For instance, hydrocarbon-based oils attack elastomers such as EPDM, while solvents like acetone or ethanol degrade materials such as nitrile. The reaction may cause swelling, softening, or embrittlement, all of which compromise the O-ring’s ability to maintain a seal.
In essence, chemical damage is not just surface corrosion; it is a molecular breakdown that changes the physical properties of the elastomer itself. Once this process begins, the degradation is irreversible. If you have questions, feel free to reach out to the Canyon Components Engineering Team.
Common Causes of Chemical Damage
1. Incompatible Chemical Environments
Each elastomer has specific chemical compatibilities. When an O-ring is exposed to substances outside its resistance range, the polymer structure begins to fail.
- Example: EPDM performs well in hot water and steam, but degrades rapidly in petroleum-based oils or fuels.
- Example: NBR (Nitrile) handles oils effectively but softens and swells in strong oxidizers, ketones, or brake fluids.
Selecting a material with proven resistance to the specific chemicals present in the system is the most direct method of prevention.
2. High Concentrations of Aggressive Chemicals
Strong acids, alkalis, and solvents can directly attack certain polymers, breaking their molecular bonds. Concentrated sulfuric acid, for instance, oxidizes natural rubber almost immediately. Similarly, strong amines and caustic solutions can destroy fluorocarbon chains that would otherwise resist milder acids.
3. Elevated Temperature Reactions
Heat accelerates most chemical reactions. Even a compatible material may fail prematurely when exposed to high temperatures combined with aggressive fluids.
- In oil refining and amine gas treatment, exposure above 400 °F can cause conventional FKMs to soften and blister.
- Aflas® or perfluoroelastomers such as Canrez® FFKM are often required to withstand these conditions.
4. Absorption and Swelling
Some chemicals penetrate elastomers, causing the material to absorb fluid and expand. This changes the O-ring’s dimensions and elasticity, reducing sealing contact. Over time, the absorbed chemical can leach out additives, further weakening the material. If you have questions, feel free to reach out to the Canyon Components Engineering Team.
5. Environmental Exposure
External chemical factors like ozone, UV radiation, and atmospheric oxygen contribute to degradation, especially in outdoor installations. Ozone cracks in NBR or natural rubber are common examples. Fluorocarbon and EPDM materials offer better weathering resistance.
Signs of Chemical Damage
1. Swelling or Expansion
Excessive volume increase is one of the earliest indicators. The O-ring may grow too large to fit properly in its groove or feel soft and tacky to the touch. If you have questions, feel free to reach out to the Canyon Components Engineering Team.
2. Cracking and Brittleness
When chemical attack removes plasticizers or breaks down polymer chains, the material becomes hard and brittle. Cracks may appear on the sealing surface or around the circumference.
3. Surface Erosion or Pitting
Aggressive chemicals can erode the surface layer of the O-ring, leaving a rough, pitted texture that disrupts sealing contact and accelerates wear.
4. Discoloration
Chemical reactions often change the O-ring’s color. Darkening, fading, or whitening can indicate oxidative or chemical degradation even before mechanical failure occurs.
5. Loss of Elasticity
An O-ring that no longer rebounds when compressed has suffered structural loss. Permanent deformation and compression set typically accompany chemical attack.
How Chemical Reactions Affect Elastomers
When chemicals attack elastomer materials, the reactions can include:
- Swelling through solvation: Small molecules penetrate and expand the polymer matrix. If you have questions, feel free to reach out to the Canyon Components Engineering Team.
- Chain scission: Strong acids or oxidizers break molecular chains, reducing strength.
- Crosslink disruption: Some chemicals interfere with sulfur or peroxide crosslinks, causing softening or melting.
- Dehydrofluorination: In FKMs, high-temperature amine or base exposure removes fluorine atoms, leading to hardening and cracks.
- Hydrolysis: In polyurethane or polyester-based elastomers, water or alcohol breaks ester linkages, causing rapid deterioration.
Understanding which reaction dominates helps predict which elastomer will last in a given chemical environment.
Prevention Strategies
1. Select Compatible Materials
The most effective defense against chemical damage is using a material designed for the environment. Canyon Components offers a full range of chemical-resistant elastomers and PTFE-based sealing materials, allowing engineers to match performance precisely to the application.
2. Consult Compatibility Charts
Chemical compatibility data from trusted sources such as tests using ASTM D471 and compatibility guides provide proven resistance ratings for hundreds of chemicals. Engineers should verify each elastomer’s performance against the actual media and concentration expected in service. If you have questions, feel free to reach out to the Canyon Components Engineering Team.
3. Avoid Excessive Heat
Where possible, lower the system temperature to slow reaction rates. A material rated for 300 °F service may degrade rapidly at 350 °F when exposed to acids or solvents. Selecting a higher temperature compound, such as Aflas® AF70BK00 (rated 14 to 455 °F) or Canrez FFKM CP75BK01 (rated to 608 °F), ensures long-term stability.
4. Use Protective Coatings
Surface treatments such as Parylene, surface fluorination, or plasma nano-coatings form chemical barriers that reduce direct attack. These coatings also lower friction, reducing wear in dynamic seals.
5. Regular Inspection
Periodic visual inspection of seals is essential. Look for swelling, cracks, or discoloration. Early detection allows replacement before full system leakage occurs.
6. Segregate Chemical Exposure Zones
When possible, use compatible secondary seals or gaskets to isolate the primary O-ring from incompatible media. For example, FFKM O-rings with PTFE backup rings can protect other elastomers from concentrated acids or solvents. If you have questions, feel free to reach out to the Canyon Components Engineering Team.
Recommended Materials for Chemical Resistance
FFKM (Perfluoroelastomer)
Perfluoroelastomers, including Canrez®, Kalrez®, and Chemraz®, offer the highest known chemical resistance of any elastomer family. Their fully fluorinated backbone resists nearly all solvents, acids, and bases at temperatures exceeding 600 °F. If you have questions, feel free to reach out to the Canyon Components Engineering Team.
Applications include:
- Semiconductor and plasma etch systems
- Chemical reactors
- Aerospace and vacuum environments
- Aggressive acid or solvent pumps
Canrez® CP75BK01 and CP90BK01 maintain tensile integrity across a wide temperature range while resisting strong oxidizers.
FKM (Fluorocarbon, Viton®)
FKM elastomers combine high-temperature capability with broad chemical resistance, especially against hydrocarbons, fuels, and oils. Standard grades operate between –15 °F and 437 °F, while low-temperature and AED-rated versions such as Canyons VT75BK30 (GLT) or Parker V1163-75 (GFLT) extend usability in extreme environments. If you have questions, feel free to reach out to the Canyon Components Engineering Team.
Typical applications:
EPDM (Ethylene Propylene Diene Monomer)
EPDM’s saturated backbone provides excellent resistance to water, steam, glycol-based fluids, and many alkalis. It performs poorly in petroleum-based oils but excels where steam or oxygen exposure is dominant. If you have questions, feel free to reach out to the Canyon Components Engineering Team.
Common uses include:
- Water treatment systems
- Steam sterilization and autoclaves
- Pharmaceutical production
- Outdoor seals exposed to ozone or sunlight
Compound like Canyons EP70BK03 and EP70BK60, or like Parkers EJ583-70 and E1583-70 are NSF 61 approved, demonstrating EPDM’s versatility.
PTFE (Polytetrafluoroethylene)
Though not an elastomer, PTFE is often used for spring-energized seals or encapsulated O-rings when absolute chemical resistance is required. PTFE resists virtually all industrial chemicals and maintains properties at temperatures over 500 °F. Its low friction and non-stick surface are beneficial in dynamic sealing against aggressive media. If you have questions, feel free to reach out to the Canyon Components Engineering Team.
Aflas® (TFE/P)
Aflas® bridges the gap between FKM and FFKM. Withstanding temperatures up to 455 °F, it resists steam, amines, and sour gases that quickly destroy other fluorocarbons. If you have questions, feel free to reach out to the Canyon Components Engineering Team.
Applications:
- Chemical process equipment exposed to caustics or amines
- Oil and gas sour service
- Power generation (steam valves and turbine seals)
See Canyon AF90BK00 and AF70BK00. Typical Parker formulations include VP103-90 and V1006-75.
Fluorosilicone (FVMQ)
Fluorosilicone combines silicone’s flexibility with enhanced fuel and chemical resistance. It remains flexible at low temperatures (–103 °F) while resisting fuels and solvents that would damage standard silicone.
Applications:
- Aerospace fuel handling systems
- Electronics exposed to solvents or lubricants
- Outdoor sealing requiring UV stability
Selecting the Right Material
When choosing an O-ring or gasket for chemical service, consider the following:
- Chemical composition of media – acids, bases, oxidizers, solvents, hydrocarbons, or amines.
- Concentration and temperature – higher concentrations and temperatures increase reaction rates.
- Pressure and mechanical stress – dynamic motion or extrusion can accelerate chemical ingress.
- Desired service life – higher resistance materials justify their cost by reducing downtime.
- Regulatory requirements – FDA, USP Class VI, or NORSOK M-710 compliance may narrow options.
Canyon Components can assist with precise material matching through chemical compatibility charts and laboratory testing. If you have questions, feel free to reach out to the Canyon Components Engineering Team.
Case Study 1: Chemical Reactor Gaskets
A customer in the chemical processing industry reported premature gasket swelling in a caustic wash system. The original EPDM gaskets expanded by 20% after 48 hours at 230 °F, causing leaks. Canyon Components recommended Aflas® , which offered resistance to both steam and caustic solution. The new seals extended service life by a factor of four and reduced unplanned shutdowns.
Case Study 2: Semiconductor Solvent Handling
A semiconductor manufacturer using photoresist solvents experienced cracking in FKM O-rings after several weeks of exposure. Switching to Canrez® FFKM eliminated swelling and discoloration, maintaining seal integrity through extended solvent cycles at elevated temperatures.
Case Study 3: Oil Refinery Amine System
An oil refinery using conventional FKM seals in an amine regenerator experienced seal hardening and cracking after 300 hours of service. Replacing these with anti-explosive decompression Aflas® AF90BK01 provided long-term resistance to both steam and amine vapor, doubling the maintenance interval.
Maintenance and Inspection Recommendations
- Visual Checks: Look for swelling, discoloration, or surface cracking during maintenance.
- Dimensional Measurement: Monitor cross-section diameter changes; even small variations indicate chemical absorption.
- Document Environmental Changes: If process fluids, concentrations, or cleaning agents change, review seal compatibility before restarting.
- Replace Proactively: Seals in critical systems should be replaced on schedule, not just after failure. If you have questions, feel free to reach out to the Canyon Components Engineering Team.
Conclusion
Chemical damage remains one of the leading causes of O-ring and gasket failure. It is often invisible until performance loss becomes catastrophic. However, by understanding how different elastomers interact with specific chemicals and conditions, engineers can prevent degradation before it begins.
For environments involving aggressive acids, solvents, amines, or steam, Canyon Components offers materials engineered to endure:
- Canrez® FFKM for universal chemical resistance
- Aflas® for hot amine and caustic service
- FKM for fuels and hydrocarbons
- EPDM for water and steam
- PTFE for the harshest chemical exposure
By pairing the right material with the right environment, and implementing proactive inspection and maintenance, chemical damage can be effectively eliminated, ensuring long-term sealing reliability in even the most demanding applications. If you have questions, feel free to reach out to the Canyon Components Engineering Team.
