Elastomers in Chemical Processing

Introduction to Elastomers in Chemical Processing

The chemical processing industry encompasses a vast range of manufacturing operations, from petrochemical refining and pharmaceutical synthesis to specialty chemical production and water treatment. In every chemical process, elastomer seals serve as critical barriers between aggressive chemicals and the external environment, protecting both plant personnel and equipment integrity. The consequences of seal failure in chemical processing can range from expensive product contamination and equipment damage to catastrophic safety incidents involving toxic or flammable chemical releases.

Selecting the right elastomer material for chemical processing applications requires a thorough understanding of the chemical environment, including the specific chemicals present, their concentrations, operating temperatures, pressures, and exposure durations. No single elastomer material can resist all chemicals, making informed material selection one of the most important engineering decisions in chemical plant design and maintenance.

Elastomer Material Options for Chemical Resistance

FKM (Fluoroelastomers)

FKM fluoroelastomers offer broad chemical resistance that makes them suitable for a wide range of chemical processing applications. Their fluorinated polymer structure provides excellent resistance to hydrocarbons, chlorinated solvents, acids, and many other aggressive chemicals. Different FKM types offer varying levels of chemical resistance:

• Type A (dipolymer, 66% fluorine): Good general chemical resistance, most common grade
• Type B (terpolymer, 68% fluorine): Improved chemical resistance, better for aromatic solvents
• Type F (terpolymer with TFE, 70% fluorine): Enhanced resistance to acids and oxidizing chemicals
• Specialty grades: Base-resistant FKM (GFLT), peroxide-cured FKM for improved chemical resistance
• Temperature range: -20 degrees Celsius to 200 degrees Celsius continuous

FFKM (Perfluoroelastomers)

When standard FKM reaches its chemical resistance limits, FFKM perfluoroelastomers provide near-universal chemical compatibility. FFKM combines the chemical resistance approaching that of PTFE with the elasticity of a rubber seal. In chemical processing, FFKM is specified for applications involving:

• Strong oxidizing acids (fuming nitric acid, oleum, chromic acid)
• Aggressive organic solvents (ketones, esters, ethers, amines)
• High-temperature chemical exposure (up to 325 degrees Celsius for some grades)
• Applications where seal failure would result in significant safety or environmental consequences
• Mixed chemical environments where no other single elastomer material is compatible

PTFE and PTFE-Encapsulated Seals

PTFE (polytetrafluoroethylene) offers the broadest chemical resistance of any sealing material but lacks the elasticity of true elastomers. PTFE-encapsulated O-rings and gaskets combine a PTFE outer shell with an elastomer core (typically FKM or silicone), providing universal chemical resistance with the resilience needed for reliable sealing. These hybrid seals are ideal for applications involving:

• Unknown or variable chemical compositions
• Chemicals that attack all elastomer materials
• Multi-product processing equipment requiring one seal material for all products
• High-purity applications where extractables from elastomers are a concern

Chemical Resistance Testing and Selection

Proper elastomer material selection for chemical processing requires systematic evaluation of the chemical environment. Volume swell testing per ASTM D471 provides quantitative data on elastomer-chemical compatibility by measuring changes in weight, volume, and hardness after controlled chemical exposure. Industry guidelines suggest that volume swell below 10% indicates good compatibility, 10-25% may be acceptable for static applications, and above 25% is generally unsuitable.

Chemical compatibility charts provide useful initial guidance but should be used with caution. Real-world conditions often involve chemical mixtures, elevated temperatures, and cyclic exposure that can produce different results than single-chemical immersion tests. When in doubt, field testing or consultation with elastomer material suppliers is recommended to validate material selection for critical applications.

Application-Specific Considerations

Reactor Vessel Sealing

Chemical reactors operate under combinations of pressure, temperature, and chemical exposure that create the most demanding sealing environments. Reactor head gaskets, agitator shaft seals, sampling port seals, and instrument connections all require materials selected for the specific reaction conditions. Batch processing adds complexity, as seals may be exposed to different chemicals during charging, reaction, and product discharge phases.

Piping and Valve Systems

Chemical piping systems use elastomer gaskets at flanged connections, O-rings in valve stems and seats, and diaphragms in control valves. The chemical resistance of these seals must match the process fluid, while the physical properties must accommodate the pressure, temperature, and mechanical conditions of the piping system. Valve packing materials must resist both the process chemical and any frictional wear from valve operation.

Pump Sealing

Chemical process pumps rely on mechanical seals with elastomer secondary sealing elements, or fully elastomeric diaphragms in positive displacement pumps. The elastomer components must resist the pumped chemical while withstanding the dynamic conditions of pump operation including pressure pulsation, vibration, and heat generation from fluid friction.

Safety and Compliance

Chemical processing facilities must comply with regulations including OSHA process safety management (PSM), EPA risk management planning (RMP), and ATEX directives for equipment in potentially explosive atmospheres. Elastomer seal selection contributes to process safety by ensuring containment of hazardous chemicals and preventing fugitive emissions. Proper documentation of material selection decisions, compatibility testing, and seal replacement schedules supports regulatory compliance and process safety management programs.

Tereefek Solutions: Chemical Processing Elastomer Expertise

Tereefek Solutions supplies elastomer sealing products for the full spectrum of chemical processing applications. Our product range includes FKM, FFKM, PTFE-encapsulated, and specialty elastomer seals in standard and custom sizes. Our technical team provides chemical compatibility guidance based on extensive material knowledge and can recommend the most cost-effective sealing solution for your specific chemical environment. From routine maintenance seals to engineered solutions for the most aggressive chemical processes, Tereefek Solutions is your trusted partner for chemical processing elastomer needs. Contact us today for material selection assistance and product availability.