Non-Asbestos Gasket Sheets — Safe, High-performance Sealing
What / Why — Modern non-asbestos gasket sheets (CNAS) combine aramid, mineral and elastomer binders to deliver reliable sealing without asbestos. They balance chemical resistance, compressibility and blowout safety for industrial flanges and equipment.
Executive Summary
Non-asbestos gasket sheets are engineered, asbestos-free materials used to produce flange gaskets and custom seals for industrial piping and equipment. They offer an optimized combination of chemical resistance, compressibility, mechanical strength and safety (no asbestos). This page helps procurement, design engineers and maintenance teams evaluate options, choose materials and access datasheets and installation guidance.What is a Non-Asbestos Gasket Sheet?
Non-asbestos gasket sheets (commonly abbreviated CNAS) are composite sheets typically manufactured from a blend of aramid/other reinforcing fibers, mineral fillers and elastomeric binders (NBR, EPDM, etc.). They are available in faced and unfaced variants and produced to industry standards such as ASTM F104 or industry OEM specifications. CNAS is widely used as a cost-effective replacement for legacy asbestos sheets across many services.-
Non-Asbestos Gasket SheetCompressed Non-Asbestos Gasket Sheet
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Non-Asbestos Gasket Sheet
Non-Asbestos Composite Sheet
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Non-Asbestos Gasket Sheet
Non-Asbestos Jointing Gasket Sheets
Classification — By Material, Specification & Application
By Material / Construction
- Aramid-fiber reinforced CNAS (high strength, abrasion resistant)
- Mineral-filled CNAS (good chemical resistance / cost effective)
- PTFE-filled or PTFE-coated CNAS (improved chemical compatibility)
- Elastomer-bonded CNAS (NBR/EPDM binder for improved resilience)
- Graphite-faced CNAS (for higher temperature resistance)
By Specification & Format
- Standard sheets (1000×1000, 1500×1500, 2000×1000 mm)
- Faced (metal/foil) sheets for coarse flange surfaces
- Pre-cut gaskets & kits (ANSI, DIN, JIS bolt patterns)
- Custom thickness & cut-to-size service
By Typical Applications
- Oil & gas process lines (hydrocarbons, fuels)
- Water & wastewater (potable or non-potable)
- Power plant auxiliaries (low-mid steam service)
- Petrochemical & refining (non-oxidizing chemicals)
- HVAC, compressors, general industrial
Selection Guide — How to Choose the Right Non-Asbestos Sheet
- Service media compatibility: consult chemical resistance charts — CNAS has varied performance vs aggressive oxidizers and strong acids.
- Temperature & pressure: confirm continuous and transient maxima. Standard CNAS typically suits up to ~230 °C; confirm by grade.
- Flange finish & bolt load: coarse finishes prefer faced sheets or metal-faced CNAS for blowout resistance.
- Thickness & seating stress: choose thickness to achieve recommended gasket stress at applied bolt load.
- Regulatory needs: check for food-grade / drinking water approvals where required.
- Abrasion / particle load: for slurry or particle-laden fluids prefer aramid-reinforced variants.
Design tip: when uncertain, request a small sample and lab compatibility test (soak / tensile / aging) under your exact service conditions.
Technical Parameters & Common Specifications
Reference typical ranges.| Grade / Type | Temp Range (°C) | Max Pressure (bar) | Typical Thickness (mm) | Key Characteristics |
|---|---|---|---|---|
| Aramid-reinforced CNAS | -50 to 230 | ≤ 100 | 0.5 / 1.0 / 1.5 / 2.0 | High tensile strength, abrasion resistance |
| Mineral-filled CNAS | -40 to 200 | ≤ 80 | 0.5 / 1.0 / 2.0 | Good general chemical resistance, economical |
| PTFE-filled / PTFE coated CNAS | -200 to 200 | ≤ 100 | 0.5 / 1.0 / 1.5 | Improved chemical resistance, low friction |
| Graphite-faced CNAS | -200 to 350 | ≤ 150 | 0.5 / 1.0 | Higher temperature capability, better seal on rough flanges |
Common Sheet Sizes & Packaging
| Sheet Size (mm) | Common Thicknesses (mm) | Typical Pack |
|---|---|---|
| 1000 × 1000 | 0.5, 1.0, 1.5 | Carton / pallet |
| 1500 × 1500 | 1.0, 2.0, 3.0 | Wood pallet |
| 2000 × 1000 | 1.5, 3.0 | Bulk / custom crates |
Product Data & Technical Documents
Download datasheets, chemical resistance charts, test reports and cutting templates.Installation, Bolt Tightening & Maintenance Guidelines
- Surface prep: clean flange faces — remove old gasket material, rust and debris.
- Flange check: inspect for flatness, parallelism and surface finish — repair if outside tolerance.
- Cutting: use waterjet/CNC or die-cut for precision; PTFE-coated edges may require sealing.
- Fit and centring: ensure gasket centered and not overcompressed at bolt holes.
- Tightening: follow incremental cross-pattern torque sequence; tighten to recommended torque based on gasket seating stress charts (consult datasheet).
- Initial run & re-torque: after first heat/cool cycle recheck flange torque if required.
- Inspection: schedule periodic inspection in critical services — look for extrusions, blowout signs or chemical attack.
Application Industries & Case Studies
- Chemical processing (non-oxidizing chemicals)
- Oil & Gas midstream and downstream
- Power station auxiliaries (cooling, fuel lines)
- Water treatment and desalination
- General manufacturing & HVAC
Performance Comparison & Material Selection Matrix
| Property | Aramid CNAS | Mineral CNAS | PTFE-filled CNAS | Graphite-faced CNAS |
|---|---|---|---|---|
| Chemical resistance | Good | Moderate | Excellent | Good |
| Temp range | Up to ~230°C | Up to ~200°C | Wide (PTFE limits) | Up to ~350°C |
| Compressibility / recovery | Good | High | Moderate | Low-Moderate |
| Abrasion resistance | High | Medium | Low | Medium |
| Suitable for coarse flange | Yes | Yes | Better with facing | Yes |
Common Failures & Troubleshooting
- Leak immediately after installation
- Cause: Insufficient bolt load, misaligned gasket, wrong thickness. Action: Recheck torque pattern, confirm gasket seating stress and re-install if necessary.
- Gasket blowout / extrusion
- Cause: Overpressure or coarse flange finish without facing. Action: Use metal/foil faced CNAS, increase stiffness or choose graphite-faced/laminate solution.
- Chemical degradation
- Cause: Incompatible material (oxidizers, strong acids). Action: Refer to chemical compatibility chart and switch to PTFE or proper specialty grade.
- Premature embrittlement or aging
- Cause: Elevated temperature or oxidative environment beyond material limits. Action: Use higher temperature grade (graphite-faced) or re-evaluate service conditions.