Executive Summary

Non-asbestos gaskets include composite, PTFE, graphite-faced and aramid-reinforced constructions. They meet modern safety and environmental standards while delivering tailored performance across temperature, pressure and chemical exposure profiles. This page is a one-stop reference for procurement, engineering and maintenance teams: selection rules, specs, installation guidance, failure modes and downloadable material data.

What is a Non-Asbestos Gasket?

A non-asbestos gasket is any sealing element engineered without asbestos fibers. Typical materials include compressed non-asbestos sheets (CNAS), PTFE (virgin and filled), flexible graphite (faced or unfaced), aramid/aramid-hybrid packings, and metal-faced laminates. Each construction targets a set of service demands: chemical compatibility, temperature tolerance, compressibility and blowout safety.

Classification — By Material, Construction & Application

By Material

  • Compressed Non-Asbestos (CNAS) — aramid/mineral blends
  • PTFE — virgin, filled, conductive
  • Flexible Graphite — plain or metal-faced
  • Metallic / Semi-metallic — MLS, corrugated
  • Rubber & Elastomeric — NBR, EPDM, FKM for low-pressure seals

By Construction

  • Full-face cut gaskets
  • Ring gaskets (cut, formed or segmented)
  • Spiral-wound & RTJ (ring joint) gaskets
  • Metal-faced laminate & PTFE-faced gaskets

By Application

  • Chemical processing & solvents
  • Steam & power generation
  • Oil & gas high-pressure lines
  • Water, HVAC & general utilities
  • Food, pharma & clean services (certified PTFE or silicone)

Selection Guide — How to Choose the Right Non-Asbestos Gasket

  1. Service media: identify chemical class, concentration, abrasive solids and any contamination risks.
  2. Temperature & pressure: list continuous and transient maxima — choose graphite/PTFE/metallic accordingly.
  3. Flange details: face type (FF, RF, RTJ), finish, flatness and bolt load determine suitable gasket family.
  4. Seating stress & thickness: select gasket thickness to achieve seating stress without overcompressing or extruding.
  5. Special requirements: food-grade approvals, low extractables, electrical conductivity, fire safety.
  6. Economics & maintenance: consider replacement interval, downtime cost, and ease of installation (segmented rings vs full face).

Quick rule: use PTFE for aggressive chemicals, graphite for high temperature steam, and CNAS or rubber for general oil/water services — validate by flange and pressure class.

Technical Parameters & Common Sizes

Sample reference values
Material / Type Temp Range (°C) Max Pressure (bar) Common Thickness Typical Use
CNAS (aramid/mineral) -40 to 230 ≤ 100 0.5 / 1.0 / 1.5 / 2.0 mm Oil & water, general purpose
PTFE (virgin / filled) -200 to 260 ≤ 160 0.25 / 0.5 / 1.0 / 2.0 mm Corrosive chemicals, pharma
Flexible Graphite (faced / unfaced) -200 to 450 ≤ 250 0.5 / 1.0 / 2.0 mm Steam, high temp services
MLS / Metal -200 to 700 (material dep.) ≤ 400 0.5 — 2.0 mm High pressure, critical flanges

Common Gasket Forms

Form Typical Dimensions Notes
Full-face Custom to flange OD, bolt circle Easy to cut, covers entire flange
Ring / RTJ ID × thickness RTJ for high pressure, ring gaskets for ease of replacement
Spiral-wound Standard ring sizes (ASME) Good for alternating T/P and tightness

Product Data & Technical Documents

Download datasheets, chemical resistance charts, gasket selection & torque guides.

Installation, Bolt Tightening & Maintenance

  1. Face preparation: clean flange faces thoroughly; remove residual gasket, corrosion and deposits.
  2. Inspect flange: check flatness, parallelism and surface finish; machine or shim if out of tolerance.
  3. Fit and centering: ensure correct gasket orientation; for faced sheets face the facing toward coarse finish when recommended.
  4. Tightening sequence: tighten bolts in a star/cross pattern in multiple increments to specified torque; follow seating stress recommendations.
  5. Initial run & re-torque: after first thermal cycle inspect and re-torque if specified by manufacturer.
  6. Maintenance inspection: schedule checks for leakage, extrusion, creep or chemical attack in critical services.
non-asbestos gasket
Typical installation workflow — use supplier torque table for final values.

Application Industries & Case Studies

  • Chemical & Petrochemical processing
  • Power generation & boilers
  • Oil & gas pipelines and refineries
  • Water & wastewater
  • Food, beverage & pharmaceutical plants

Case Study — Chemical Reactor Flange Retrofit

Problem: Repeated gasket failures in a corrosive solvent feed line. Solution: Replaced compressed fiber gaskets with PTFE-filled ring gaskets and upgraded flange bolts to higher grade; introduced routine inspection schedule. Result: Leak incidents reduced to zero in 18 months and maintenance downtime decreased by 60%.

Performance Comparison & Material Selection Matrix

Property CNAS PTFE Flexible Graphite MLS / Metal
Chemical resistance Good Excellent Good Depends on metal
Temperature tolerance Moderate Wide Very wide Very wide
Compressibility High Moderate High Low
Blowout resistance Moderate Low-Moderate Moderate High
Suitable for sanitary / food Limited Yes No No

Common Failures & Troubleshooting

Immediate leak after installation
Causes: Improper torque, damaged gasket, or flange face contamination. Action: Shutdown if required, re-torque in sequence, inspect gasket and flange faces; replace gasket if deformed.
Gradual leak developing over months
Causes: Creep (PTFE), chemical attack, or bolt relaxation. Action: review material suitability, consider filled grades or metal-faced options, implement retorque schedule.
Gasket blowout or extrusion
Causes: Incorrect gasket type for pressure/temperature or insufficient confinement. Action: select higher strength or metal-faced gasket and ensure correct bolt preload.

FAQ — For Purchasing, Engineering & Maintenance

Q: Can I replace an asbestos gasket with a single non-asbestos material?A: Not always. Replacement depends on service conditions. For high temp steam consider graphite-faced laminates; for corrosive chemicals choose PTFE variants. Conduct compatibility and mechanical checks before replacement.
Q: How do I choose thickness for a flange?A: Thickness depends on flange finish, seat load and pressure. Use seating stress tables or consult supplier for recommended thickness given bolt torque and flange class.
Q: What info speeds up a quote?A: Provide flange drawing (OD/ID/bolt circle), gasket form (full face/ring), operating T & P, media, required certifications (e.g., FDA), quantity and lead time.
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Need help specifying non-asbestos gaskets?

Contact our technical team for sample kits, compatibility testing and cut-to-size gasket services.
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