Seal Materials Guide – NBR / HNBR / FKM / AFLAS® / FFKM
Seal Materials Guide
Elastomer selection reference for industrial, oilfield, chemical, food, pharmaceutical, and hydraulic applications — UNIVERGO.
The correct elastomer determines whether a seal lasts years or fails within hours. Temperature, media chemistry, pressure, and regulatory requirements all drive material selection. This guide covers the five primary elastomer families used across UNIVERGO's product range — with compatibility data for the broadest possible range of industries and operating environments.
⚠ Field Identification — Color Code at UNIVERGO
At UNIVERGO, FKM and FFKM seals are supplied in brown. NBR and HNBR are black. AFLAS® is typically white/grey. Color-coding allows field crews, maintenance teams, and installers to instantly verify the correct material is in place — preventing grade mix-ups in multi-elastomer installations across any industry.
NBR — Nitrile Butadiene Rubber
General-purpose | Most widely used industrial elastomer
| Temperature Range | −40°C to +100°C continuous. Rapid degradation above 100°C as oxygen and fluids attack reactive double bonds in the polymer chain. |
| Compatible Media | Petroleum oils, hydraulic fluids (mineral-based), water, water-based muds, aliphatic hydrocarbons, diesel, fuels, compressed air, natural gas. |
| Limitations | Poor resistance to ozone, UV, ketones, esters, chlorinated hydrocarbons, aromatic solvents, strong acids/bases, amines, and steam above 120°C. |
| Industry Applications |
Oil & Gas: Surface wellhead seals, valve packing, WBM tool seals. Hydraulics & Pneumatics: Cylinders, pumps, hoses, O-rings in mineral oil hydraulic systems. Automotive: Fuel system seals, transmission gaskets, brake components. Industrial: General machine seals, compressor gaskets, pneumatic fittings. Marine: Deck equipment seals, bilge pump seals in fuel/oil environments. |
| Color at UNIVERGO | Black |
HNBR — Hydrogenated Nitrile Butadiene Rubber
High-performance upgrade | Abrasion & thermal resistance
| Temperature Range | −40°C to +150°C–160°C continuous. Hydrogenation eliminates the reactive double bonds of NBR, providing significantly improved thermal and oxidative stability. |
| Compatible Media | Petroleum and synthetic oils, oil-based muds, diesel, mineral oils, aliphatic and aromatic hydrocarbons (better than NBR), H₂S-containing sour gas, refrigerants (HFCs), and ozone. |
| Limitations | Not recommended for aggressive amines, polar solvents, ketones, or highly concentrated strong acids. Moderate steam resistance only. |
| Industry Applications |
Oil & Gas / Downhole: Packer elements, bridge plug seals, completion tool O-rings in OBM and abrasive drilling fluids; sour gas environments. Automotive: Belt systems, timing belt tensioners, power steering, supercharger seals. Refrigeration & HVAC: Seals compatible with modern HFC refrigerants. Mining: Slurry pump seals and abrasion-exposed components in harsh mining fluids. Industrial Machinery: High-cycle hydraulic seals where elevated temperature and wear resistance are required. |
| Color at UNIVERGO | Black |
FKM — Fluoroelastomer (Viton®)
🟫 BROWN at UNIVERGOHigh-temperature | Broad chemical resistance | HPHT & process industry
| Temperature Range | −20°C to +200°C continuous (short spikes to +230°C). Outstanding thermal stability across a broad range of aggressive environments. |
| Compatible Media | Hydrocarbons, mineral and synthetic oils, aromatic solvents, chlorinated solvents, fuels, H₂S, CO₂, aliphatic and aromatic hydrocarbons, many acids (non-oxidizing), and ozone. |
| Critical Limitation | ❌ Amines & high pH: Standard FKM reacts chemically with amine-based corrosion inhibitors, MEA, DEA, and high-alkalinity fluids — causing cross-linking, embrittlement, and seal failure. Do not use in amine-treated systems without confirming amine-resistant FKM grade. |
| Industry Applications |
Oil & Gas / Downhole: HPHT well seals, valve seats, BOP seals, wellhead O-rings in hydrocarbon-rich environments (no amines). Chemical Processing: Pump seals, valve packing, flange gaskets for aromatic solvents, fuels, and non-oxidizing acids. Automotive: Fuel injector O-rings, turbocharger seals, exhaust manifold gaskets, fuel hose inner liners. Aerospace: Aircraft fuel system seals, hydraulic seals for synthetic aircraft fluids. Semiconductor & Electronics: Process chamber seals exposed to aggressive solvents and process gases. Industrial Furnaces: High-temperature oven door seals and rotary kiln seals. |
| Color at UNIVERGO | Brown — instantly distinguishes fluoroelastomer-class seals from black NBR/HNBR in the field. |
AFLAS® — TFE/P Fluoroelastomer (FEPM)
Amine-resistant | Steam & caustic environments | Chemical processing
| Temperature Range | −5°C to +200°C+. Handles thermal spikes better than standard FKM in high-pressure steam. Excellent electrical insulation properties retained at elevated temperatures. |
| Compatible Media | Steam, hot water, amines (MEA, DEA, MDEA), strong alkalis (NaOH, KOH), oxidizing acids, engine oils, lubricants, ozone, electrical insulating fluids. Structurally immune to amine attack — TFE/propylene copolymer backbone provides this unique resistance. |
| Limitations | Lower resistance to aromatic hydrocarbons and chlorinated solvents compared to FKM. Higher cost than standard FKM; lower compression set resistance in some grades. |
| Industry Applications |
Oil & Gas — Amine Treating: Gas sweetening unit seals (MEA/DEA/MDEA absorbers, regenerators, heat exchangers) where FKM fails. Steam & Geothermal: Steam injection well packers, geothermal wellhead seals, steam turbine gaskets. Chemical Processing: Pump and valve seals in caustic soda, sodium hypochlorite, oxidizing acid environments. Power Generation: Seals in steam circuits, boiler feed systems, and turbine lube oil systems. EOR (Enhanced Oil Recovery): Alkaline, surfactant, and polymer flooding — caustic injection seals. Electrical: Cable insulation jackets and connector seals in high-temperature electrical environments. |
| Color at UNIVERGO | White / Grey (standard AFLAS® natural color) |
FFKM — Perfluoroelastomer
🟫 BROWN at UNIVERGOUltimate performance | Near-universal chemical resistance | Extreme HPHT
| Temperature Range | −20°C to +325°C continuous — the highest thermal rating of any elastomer class. Maintains full sealing integrity under extreme HPHT downhole and process conditions. |
| Compatible Media | Near-universal: hydrocarbons, strong acids (HF, H₂SO₄, HNO₃), strong alkalis, amines, steam, solvents, ketones, esters, aldehydes, H₂S, CO₂, halogens, aggressive process gases, ozone, and virtually all oilfield and industrial chemicals. The benchmark for chemical inertness among elastomers. |
| Amine Resistance | ✅ Fully resistant. No known amine or caustic failure mode. |
| Industry Applications |
Oil & Gas — Ultra-deep HPHT: Critical downhole seals, BOP rams, wellhead connectors in ultra-deep or extreme H₂S/CO₂ environments. Pharmaceutical & Biotech: CIP/SIP (clean-in-place/steam-in-place) seals, sterile process seals meeting USP Class VI and FDA compliance requirements. Semiconductor Fabrication: Plasma chamber O-rings, process gas seals exposed to aggressive etchants (HF, Cl₂, F₂) — FFKM is the industry standard. Chemical Processing: Seals in reactors handling the most aggressive acids, oxidizers, and solvent combinations where no other elastomer survives. Aerospace & Defense: Propellant-compatible seals, oxidizer-resistant O-rings, cryogenic fluid handling (some grades). Nuclear: Radiation-resistant seals in nuclear power plant environments. Food & Beverage (select grades): High-temperature steam cleaning processes where FDA-compliant FFKM grades can be specified. |
| Color at UNIVERGO | Brown — consistent with FKM color coding at UNIVERGO, clearly distinguishing perfluoroelastomer seals from all other grades at a glance. |
Quick Selection Reference
| Material | Max °C | Oils / OBM | Amines / High pH | Steam | Solvents | H₂S / Sour Gas | Color (UNIVERGO) |
|---|---|---|---|---|---|---|---|
| NBR | 100 | ✅ | ❌ | ❌ | ❌ | ⚠ | Black |
| HNBR | 160 | ✅ | ⚠ | ⚠ | ⚠ | ✅ | Black |
| FKM (Viton®) | 200+ | ✅ | ❌ | ⚠ | ✅ | ✅ | Brown |
| AFLAS® | 200+ | ✅ | ✅ | ✅ | ⚠ | ✅ | White / Grey |
| FFKM | 325 | ✅ | ✅ | ✅ | ✅ | ✅ | Brown |
Industry Application Matrix
| Industry | NBR | HNBR | FKM | AFLAS® | FFKM |
|---|---|---|---|---|---|
| Oil & Gas — Surface / Wellhead | ✅ | ✅ | ✅ | ⚠ | ✅ |
| Oil & Gas — Downhole / Completion | ❌ | ✅ | ✅ | ✅ | ✅ |
| Gas Sweetening / Amine Units | ❌ | ❌ | ❌ | ✅ | ✅ |
| Hydraulics & Pneumatics | ✅ | ✅ | ✅ | ⚠ | ✅ |
| Automotive | ✅ | ✅ | ✅ | ⚠ | ⚠ |
| Chemical Processing | ⚠ | ⚠ | ✅ | ✅ | ✅ |
| Steam / Power Generation | ❌ | ⚠ | ⚠ | ✅ | ✅ |
| Pharmaceutical / Biotech | ❌ | ❌ | ⚠ | ⚠ | ✅ |
| Semiconductor Fabrication | ❌ | ❌ | ⚠ | ❌ | ✅ |
| Aerospace & Defense | ❌ | ⚠ | ✅ | ⚠ | ✅ |
| Mining & Heavy Industry | ⚠ | ✅ | ✅ | ⚠ | ✅ |
| Marine | ✅ | ✅ | ✅ | ⚠ | ✅ |
✅ Recommended | ⚠ Conditional / grade-dependent | ❌ Not recommended
Need help selecting the right elastomer for your application?
Contact our technical team at sales@univergo.ro — we'll match the correct material to your temperature, media chemistry, pressure, and regulatory requirements.