Material

HNBR (Hydrogenated Nitrile)

HNBR (Hydrogenated Nitrile Butadiene Rubber) is produced by selectively hydrogenating the polybutadiene segment of the NBR backbone, replacing most of the carbon–carbon double bonds with saturated single bonds. This dramatically improves heat resistance, ozone resistance and mechanical durability while preserving NBR's proven oil and fuel compatibility. With a degree of hydrogenation typically above 90 %, HNBR delivers service temperatures 30–50 °C higher than standard nitrile, outstanding abrasion resistance for dynamic seals, and strong resistance to sour gas (H₂S) — making it the standard upgrade when NBR reaches its thermal, ozone or wear limit in automotive, oil-field and industrial compressor applications.

HNBR O-rings — heat and ozone resistant upgrade from NBR.

Material Data Sheet

Temperature range

-25 °C to +150 °C (+165 °C short-term; low-temp grades to -40 °C)

Hardness range

55–90 Shore A

Tensile strength

20–30 MPa (significantly higher than NBR)

Elongation at break

200–450 %

Compression set

15–30 % (at 150 °C × 70 h)

Resists

Petroleum oils & fuels, ozone, UV, sour gas (H₂S), refrigerants (R-134a), amine-based inhibitors, high abrasion

Avoid with

Aromatic solvents (toluene, xylene), polar solvents (ketones, esters), glycol-based brake fluids, strong oxidising acids

Standards

ASTM D2000 (DH class), ASTM D1418 (HNBR designation), ISO 1629, NORSOK M-710

Advantages

Why specify HNBR

Heat Resistance

Continuous service to +150 °C — 30–50 °C above standard NBR — with excellent retention of mechanical properties after prolonged heat ageing, extending seal replacement intervals.

Ozone & UV Resistance

The saturated backbone eliminates the ozone-cracking weakness of NBR. HNBR seals survive years of outdoor or engine-bay exposure without surface checking or embrittlement.

Abrasion & Tear Resistance

Among the toughest elastomers for dynamic sealing — tensile strength of 20–30 MPa and outstanding abrasion resistance make HNBR ideal for reciprocating rod seals, pistons and rotary shafts.

Oil & Fuel Compatibility

Retains NBR's proven resistance to petroleum oils, fuels, hydraulic fluids and greases at significantly higher temperatures — the go-to material for hot-oil and engine-compartment seals.

Sour-Gas (H₂S) Service

HNBR is approved under NORSOK M-710 and widely used for oil-field downhole seals, BOP components and wellhead packings in sour-gas environments where NBR or FKM may fail.

Refrigerant Compatibility

Excellent resistance to modern refrigerants (R-134a, R-1234yf) and associated PAG/POE lubricants, making HNBR the standard for automotive AC compressor shaft seals and plate gaskets.

Limitations

Where HNBR is not the best choice

Aromatic & Polar Solvents

HNBR swells in aromatic hydrocarbons (toluene, xylene) and polar solvents (ketones, esters, chlorinated solvents). FKM or FFKM should be specified for aggressive solvent service.

Brake Fluids (Glycol-Based)

Glycol-based DOT brake fluids attack HNBR. EPDM is the standard brake-system elastomer for DOT 3/4/5.1 fluid contact.

Higher Cost Than NBR

HNBR costs 3–5× more than standard nitrile. It is justified when the application demands higher heat, ozone or abrasion performance — not as a blanket NBR replacement.

Limited Low-Temperature Flexibility

Standard HNBR stiffens below -25 °C. Specialty low-ACN grades extend flexibility to -40 °C but sacrifice some oil resistance. For extreme cold, silicone or FFKM may be preferred.

Applications

Where HNBR seals are used

Automotive & Off-Highway

Timing-belt tensioner seals, crankshaft and camshaft seals, AC compressor shaft seals, fuel-injection O-rings, turbocharger oil-return seals, power-steering pump seals — anywhere engine-bay heat exceeds NBR's limit.

Oil & Gas

Downhole packer elements, BOP rams, wellhead bonnets, ESP (Electrical Submersible Pump) motor seals, completion-tool seals in sour-gas (H₂S) and high-temperature wells per NORSOK M-710.

Industrial Compressors

Reciprocating and rotary compressor rod-packing rings, piston seals and valve plates — HNBR's abrasion resistance and hot-oil compatibility outperform NBR in continuous-duty gas compression.

Refrigeration & HVAC

Compressor shaft seals, service-valve O-rings, plate heat-exchanger gaskets — compatible with R-134a, R-1234yf, R-410A and associated PAG/POE lubricants across the operating-temperature envelope.

Available as