Cork Nitrile Gaskets
Cork nitrile is a composite gasket material made by bonding natural cork granules with a nitrile rubber (NBR) binder. The result is a material that combines the high compressibility and conformability of cork with the oil, fuel, and solvent resistance of nitrile rubber. Cork nitrile gaskets seal effectively at low bolt loads and flange pressures, making them an ideal choice for applications where clamping force is limited, flange surfaces are uneven, or both. The material is rated for service temperatures from –4°F to +250°F (–20°C to +120°C).
Gasket and Seal Fabricators is a trusted cork nitrile gasket supplier and custom fabricator. We commonly stock nitrile bonded cork sheet in standard thicknesses from 1/32″ to 1/4″ and fabricate precision-cut gaskets to your exact specifications using die cutting and flash cutting. Cork nitrile gasket material is cost-effective, easy to fabricate, and available with or without pressure-sensitive adhesive (PSA) backing.
Common Applications for Nitrile Bonded Cork Gaskets
Cork nitrile’s combination of compressibility, oil resistance, and low closure force sealing makes it one of the most versatile and cost-effective gasket materials for light- to medium-duty industrial and automotive applications. Below is a closer look at where nitrile bonded cork gaskets perform best.
Oil, Fuel & Fluid Sealing
Cork nitrile gaskets provide reliable sealing against oils, fuels, and hydrocarbon-based fluids in low-pressure flange joints. The nitrile binder gives the material significantly better chemical resistance than plain cork or SBR-bonded cork, while the cork component conforms to surface irregularities without excessive lateral flow. Common applications include valve covers, oil pans, sump gaskets, crank case covers, gear box seals, and general cover and lid gaskets on engines, compressors, and industrial equipment.
Electrical Transformers & Switchgear
Nitrile bonded cork is one of the most widely specified gasket materials in the electrical power industry. Cork nitrile gaskets seal transformer lids, bushing flanges, inspection covers, and switchgear enclosures against transformer oil and environmental moisture. The material’s electrical insulation properties, oil compatibility, and ability to seal under low and uneven bolt loading make it a natural fit for this application. Cork nitrile gasket sheet for transformer use is typically supplied in 1/16″ to 1/4″ thicknesses
Vibration Damping & Noise Reduction
Beyond sealing, cork nitrile serves as an effective vibration-attenuating and sound-absorbing material. The combination of cork’s natural resilience and nitrile rubber’s elasticity absorbs and dampens transmitted vibrations across mechanical joints, equipment mounts, and enclosure panels. HVAC systems, industrial machinery, pumps, and compressors all benefit from the noise and vibration reduction that a cork nitrile gasket or pad can provide.
General-Purpose Industrial Sealing
Cork nitrile is frequently used as a general-purpose gasket material wherever a compressible, oil-resistant seal is needed at moderate temperatures and pressures. Its low cost and wide availability make it a practical choice for maintenance and replacement gaskets across a range of equipment. Typical general-purpose applications include inspection door gaskets, pipe flange gaskets, pump covers, marine engine seals, and aftermarket automotive gaskets.
Why Choose Cork Nitrile Over Other Gasket Materials?
Cork nitrile occupies a practical middle ground between lower-cost cellulose and felt gaskets and higher-performance engineered composites. Compared to plain composition cork, the nitrile binder adds meaningfully better resistance to oils, fuels, and solvents.
Compared to solid nitrile rubber sheet, cork nitrile offers far greater compressibility and conformability at low bolt loads, which makes it the better choice for flanges with surface imperfections, uneven loading, or limited clamping force.
The material is also significantly less expensive than engineered nonasbestos composites and specialty foams, making it a cost-effective solution for applications that don’t require extreme temperature or pressure performance. Cork is a renewable, naturally sourced material, and cork nitrile sheet contains no asbestos.
From a fabrication standpoint, cork nitrile cuts cleanly in standard thicknesses and accepts pressure-sensitive adhesive without surface preparation, keeping part costs and lead times low.
Cork Nitrile Material Properties
Cork nitrile gasket material provides a well-balanced combination of mechanical and chemical properties for light- to medium-duty sealing. The material conforms to ASTM D 194 and is classified under ASTM F 104. It exhibits minimal lateral flow under compression compared to solid rubber, which helps maintain gasket integrity in flanged joints. It retains flexibility down to –4°F (–20°C) and resists degradation from ozone, mild acids, and weathering. The material does not perform well with aromatic solvents, strong acids, or steam, and should not be used in applications that exceed its rated temperature or pressure limits.
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- Temperature Range: –4°F to +250°F (–20°C to +120°C)
- Hardness (Durometer): 50–70
- Shore A Density: ~40 lb/ft³ (640 kg/m³ min.)
- Tensile Strength: ~200 psi (1.38 MPa min.)
- Compressibility (@ 400 psi): 30–50%
- Recovery: 75–80% Cork
- Granule Size: 1–2 mm (standard)
- Oil Resistance: Good to excellent (ASTM No. 1 Oil, fuels, hydrocarbon solvents)
- Standard Thicknesses: 1/32″, 1/16″, 3/32″, 1/8″, 3/16″, 1/4″
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