CNAF Gaskets/NAF (Non-Asbestos Fibre Gaskets)
NAF or CNAF Gaskets (Compressed Non-Asbestos Fibre) are used widely throughout a range of industries to seal flanges and joints.
Asbestos used to be the material of choice for gaskets used in many industries including ships, boilers, refineries and engines. However, following health concerns, asbestos was finally banned in the UK in 1999, although many companies had been developing alternative materials since the 1980’s.
Richard Klinger, an Austrian engineer developed compressed asbestos material for gaskets in 1899 and the Flexitallic Gasket Company started selling the first asbestos filled Spiral Wound Gaskets in 1912.
You can read more here.
The Solution
Since the ban on asbestos, companies have had to develop a range of different fillers to cope with the demands of high temperature and high pressure service used in the transportation of hot gases, steam, acids and other chemicals.
These include aramid and inorganic fibres, graphite and vermiculite.
CNAF gaskets are made from sheet material where the fibres are combined with a rubber binder which is normally Nitrile, EPDM, Neoprene or SBR.
It is important to select the right grade, as unlike asbestos, CNAF materials have different chemical resistance and temperature ratings dependent on the grade.
Thankfully, as one of the largest gasket producers in the UK, we carry an immense range of materials which ensures that we can supply you with the correct product.
Details and specification sheets on our full range of CNAF gasket materials can be found here.
General Grades
General grades of Non Asbestos Fibre are suitable for use with oils,
solvents, gases, hot and cold water, low pressure steam and many dilute acids and alkalis.
Pressure and temperature ranges vary, typically up to 60 BAR and 300° C.
Examples of general purpose grades include Greeneseal© and Novus 45.
Some of these grades carry WRAS approval so they are suitable for making CNAF gaskets to be used use with potable (drinking) water.
Grade Y materials are suitable for use up to 80 BAR and 400° C depending on the grade selected. N.B. Both extremes may not be compatible together.
BS7531 Grade X materials include Novus 10, 34, and 49, Flexitallic SF3300, 3500 & 5000, Klinger C4430 and Reinz AFM-34.
Grade X CNAF gaskets are suitable for operation up to 100 BAR and 425° C depending on the grade selected. N.B. Both extremes may not be compatible together.
There are a wide range of approvals carried by these styles, including TA
-LUFT, WRAS, API 607 Fire Safe, BAM (Oxygen service), and KTW (German drinking water approval. Exact details can be found on each grade’s data sheets.
As an authorised distributor of Garlock materials, we are able to offer CNAF gaskets in their range of materials. See below for the styles we can supply where the fibres are bound with alternative polymers to the standard Nitrile grades.
MULTI-SWELL™ 3760 is possibly the ultimate material for those lightweight flanges where annoying oil or water leaks plague industrial facilities. Unlike traditional vegetable fibre and cork gaskets that allow water and oil to “wick” through the body of the gasket, MULTI-SWELL absorbs the media at the inside edge, swells, and creates a tighter, long term seal.
- Creates compressive load in lightweight flanges in oil and water service
- More universal than gaskets that swell in oil only — which reduces inventory
- Performs well in flanges that might crush an elastomer gasket, meaning it can be used in a wide array of applications
- More compressible than standard fibre gaskets and seals with low load
- Easy to cut and handle — extremely flexible, minimises waste
- Replaces vegetable fibre gaskets in many applications — won’t weep, improving plant safety
- Seals flanges in “less than perfect” conditions minimising maintenance
- Construction: Synthetic fibre sheet with a proprietary rubber binder
- Min. Temperature: -100°F -73°C
- Continuous Operation Max.: 400°F 205°C
- Max. Pressure: 500 PSI 34.5 bar
BLUE-GARD® Style 3200 CNAF gaskets are a blend of aramid fibres with a SBR binder, and provide excellent sealability and improved torque retention. 3200 is available in a variety of specifications, they meet MIL-DTL-24696C Type 2 specifications and can be used in water, saturated steam, and inert gas applications.
- Excellent sealability
- Improved torque retention
- Drastically lowered emissions levels
- Cuts operational costs through reduced waste, maintenance, stocked inventory, fluid loss, and energy consumption
- Unique blend of aramid fibres, fillers and a SBR rubber binder
- Off-white colour
- Full face or ring
- Meets ABS (American Bureau of Shipping) and MIL-DTL-24696C6 Specifications
- Min. Temperature: -100°F -73°C
- Max. Temperature: 700°F 371°C
- Continuous Max: 400°F 205°C
- Max Pressure: 1200 PSI 83 bar
- Maximum PxT 1/16: 350,000 (°F x PSIG) 12,000 bar x °C
- Maximum PxT 1/8: 250,000 (°F x PSIG) 8,600 bar x °C
BLUE-GARD® Style 3300 is a blend of aramid fibres with a Neoprene binder providing excellent sealability, which drastically lowers emissions levels and provides cost savings. This style can be used in many applications, including refrigerants, oils, and fuels.
- Excellent sealability
- Improved torque retention
- Drastically lowered emissions levels
- Cost savings through reduced waste, maintenance, stocked inventory, fluid loss, and energy consumption
- Aramid fibres with a neoprene binder
- Black colour
- Min. Temperature: -100°F -73°C
- Max. Temperature: 700°F 371°C
- Continuous Max: 400°F 205°C
- Max Pressure: 1200 PSI 83 bar
- Maximum PxT 1/16: 350,000 (°F x PSIG) 12,000 bar x °C
- Maximum PxT 1/8: 250,000 (°F x PSIG) 8,600 bar x °C
BLUE-GARD® Style 3700 is a compressed, non-asbestos gasket made from aramid fibres with an EPDM binder. This style drastically lowers emissions levels, fluid loss, and energy consumption.
- Excellent sealability
- Improved torque retention
- Drastically lowered emissions levels
- Cuts operational costs through reduced waste, maintenance, stocked inventory, fluid loss, and energy consumption
- Available in sheet or cut gasket form
- Aramid fibres, fillers and an EPDM rubber binder
- Light grey colour
- Min. Temperature: -100°F -73°C
- Max. Temperature: 700°F 371°C
- Continuous Max: 400°F 205°C
- Max Pressure: 1200 PSI 83 bar
- Maximum PxT 1/16: 350,000 (°F x PSIG) 12,000 bar x °C
- Maximum PxT 1/8: 250,000 (°F x PSIG) 8,600 bar x °C
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