O-Rings for Chemical Processing
Chemical-resistant sealing for pumps, valves, reactors and pipework handling aggressive acids, solvents and oxidising chemicals.
Overview
Chemical processing plants handle media that destroy standard elastomers — concentrated acids, chlorinated solvents, oxidising agents and aggressive organic chemicals. Seal failure in a chemical plant means not only process downtime but potential safety incidents, environmental release and regulatory consequences.
Material selection for chemical service requires verification against the specific chemical, concentration and temperature combination. A material that resists dilute sulfuric acid may fail in concentrated acid. Compatibility data must be verified against actual operating conditions, not generic material ratings.
Recommended Materials
FKM
Most chemical service: acids (excluding concentrated nitric/sulfuric), petroleum-based chemicals, solvents, aromatic compounds, H2S service
Temp: -20°C to +200°C
Note: First choice for most chemical environments
PTFE
Universal chemical resistance where elastomeric properties are not required: static seals, face seals, flange gaskets in aggressive chemical service
Temp: -200°C to +260°C
Note: Resists virtually all chemicals. Limited to static applications.
FFKM
Ketones, concentrated oxidising acids, amines, temperatures above 200°C — applications where FKM fails
Temp: -15°C to +325°C
Note: Premium material for extreme chemical environments
EPDM
Dilute acids, alkalis, steam, water — NOT for organic solvents or petroleum chemicals
Temp: -50°C to +150°C
Note: Good for aqueous chemical service
Typical Applications
- Reactor vessel seals
- Pump seals
- Agitator seals
- Heat exchanger seals
- Valve stem seals
- Flange gaskets
- Sampling port seals
- Pressure vessel seals
Relevant Standards
Frequently Asked Questions - Chemical Processing
What O-ring resists hydrofluoric acid (HF)?
FKM has good resistance to hydrofluoric acid in most concentrations. PTFE is an alternative for static applications requiring maximum resistance. FFKM is specified for high-concentration HF at elevated temperatures. NBR and EPDM are not suitable for HF service.
Which O-ring material for chlorinated solvent service?
FKM resists most chlorinated solvents including trichloroethylene, methylene chloride and perchloroethylene. NBR is attacked by chlorinated solvents. PTFE also provides excellent resistance and is used for static seals in chlorinated solvent service.
Can any O-ring resist concentrated sulfuric acid?
PTFE provides the best resistance to concentrated (fuming) sulfuric acid. FKM resists moderate concentrations but degrades in concentrated/fuming grades. FFKM resists a wider range. Verify your specific concentration and temperature against compatibility data.
What about ATEX requirements in chemical plants?
ATEX directives apply to equipment in explosive atmospheres — they govern equipment classification, not O-ring materials directly. O-ring material selection in ATEX zones should focus on preventing static charge accumulation (avoid highly insulating materials in certain applications) and ensuring compatibility with the explosive atmosphere media.