Last updated: April 2026
Gasket sheet is the raw material from which cut flange gaskets are produced — supplied in 1.5 m × 1.5 m sheets or continuous rolls, in rubber, compressed non-asbestos fibre (CNAF), PTFE, graphite, or cork-rubber. Industrial users either keep sheet on hand to cut their own gaskets, or specify sheet grades for their contract cutting supplier.
GritGasket stocks the main gasket sheet families in standard thicknesses (0.8, 1.5, 3.0, 5.0 mm), and can plot-cut any flange pattern from the same stock — AS 2129, ASME B16.21, BS 10, or bespoke. Supplied across Australia and New Zealand.
What Is Gasket Sheet?
Gasket sheet is a generic term for flat sealing stock supplied in large-format rolls or sheets and cut to pattern by the user or their supplier. It differs from a finished gasket in that the sheet has no specific flange dimension — it is inventory, ready for plot-cutting, die-cutting, or hand-cutting against a flange template.
Every gasket sheet grade is a composite of a reinforcing matrix and a binder, selected for temperature, pressure, and chemical compatibility. The six common families:
- Compressed non-asbestos fibre (CNAF) — aramid + mineral fibre in NBR binder. General-purpose workhorse.
- Rubber sheet — EPDM, NBR, neoprene, Viton, silicone. Low-pressure, elastomer-specific service.
- PTFE sheet — virgin, expanded, or filled. Chemical service.
- Flexible graphite sheet — reinforced or plain. HP steam, refinery service.
- Cork-rubber — cork particles in NBR binder. Low-pressure oil seals, transformer lids.
- Insulation board — ceramic fibre, silicate, or Millboard™. High-temperature static seals (furnace doors, flue flanges).
Gasket Sheet Selection Chart
| Sheet grade | Max temp | Max pressure | Best for |
|---|---|---|---|
| CNAF (general) | 200 °C | 80 bar | Steam, oil, water, hydrocarbons — default industrial sheet |
| High-performance CNAF | 260 °C | 100 bar | Refinery, petrochemical, hot oil |
| EPDM rubber | 120 °C | Class 150 | Potable water, HVAC, LP steam |
| Nitrile (NBR) rubber | 110 °C | Class 150 | Oil, fuel, hydraulic |
| Viton (FKM) rubber | 200 °C | Class 150 | Aggressive chemicals, hot oil |
| Virgin PTFE sheet | 260 °C | Class 150 (flat face) | Acids, alkalis, FDA food-contact |
| Filled PTFE sheet (glass/graphite) | 260 °C | Class 300 | Chemical service, lower creep than virgin |
| Graphite with tanged SS | 450 °C (air) | Class 600 | HP steam, refinery |
| Cork-rubber | 80 °C | 5 bar | Oil pans, transformer lids, LP gaskets |
| Ceramic fibre board | 1000 °C+ | Static seals | Furnace doors, boiler access flanges |
Thickness — How Thick Should Gasket Sheet Be?
For flange gasket work, thicker is not better. Thin gaskets give tighter joints (less creep, lower bolt relaxation) but require better flange face condition. A rough rule:
- 0.8–1.0 mm — new, flat, machined flanges. Heat exchangers. Best sealability.
- 1.5 mm — general Class 150 raised-face service. The most-sold thickness.
- 3.0 mm — worn or slightly uneven flanges. Large low-pressure flanges (water, HVAC).
- 5.0–6.0 mm — corroded or patched flanges. Anti-vibration duties.
- 10 mm+ — mining duct flanges, wooden-tank lids, bespoke static seals.
Standard Sheet Sizes
Most sheet grades ship in one of two standard formats:
- 1500 × 1500 mm sheet — CNAF, graphite, PTFE, most rubber grades.
- Continuous roll — EPDM, NBR, neoprene (commercial rubber grades) in 1.2–1.4 m widths, 10 m rolls.
Off-cuts are reusable — we maintain a small offcut stock for one-off cutting jobs.
Sheet vs Ready-Cut Gasket — What's Cheaper?
If you fit more than ~20 gaskets per month, or your flanges are non-standard, buying sheet and cutting in-house usually comes out cheaper — especially on large-diameter flanges where freight on a pre-cut gasket dominates the cost. For maintenance stock where each part is used once and variety is high, pre-cut gaskets from our cutting service save labour.
Stocked Gasket Sheet
SHEET-CNAF-1.5
SHEET-EPDM-3
Frequently Asked Questions
Gasket sheet is flat sealing material supplied in large-format sheets (typically 1.5 × 1.5 m) or continuous rolls, ready to be cut into flange gaskets. Common grades are compressed non-asbestos fibre (CNAF), rubber (EPDM, NBR, neoprene, Viton), PTFE, flexible graphite, and cork-rubber. Industrial users either cut their own gaskets from sheet or specify sheet grades for their contract cutting supplier.
For most Class 150 raised-face pipe flanges, 1.5 mm is the standard thickness. Thinner (0.8–1.0 mm) gives tighter joints on new, machined flanges. Thicker sheet (3–6 mm) is used for worn, uneven, or corroded flanges, and for low-pressure large-diameter flanges. Thinner gaskets generally give better sealability because they creep and relax less.
CNAF (compressed non-asbestos fibre) is the generic product family — Klingerit, Garlock, and Temac are the best-known brand names. They differ in binder chemistry, fibre blend, and temperature/pressure rating, but all are the modern non-asbestos replacement for the old "Klingerit 1000" asbestos jointing. Any reputable gasket supplier stocks equivalent-grade CNAF sheet.
Yes — our custom gasket cutting service plot-cuts any flange pattern from the same sheet stock. Send a drawing, sample, or just the flange standard and size (e.g. "AS 2129 Table E DN100"), and we cut the gasket and dispatch. Large batches go on our CNC knife table; one-offs can be hand-cut the same day.
Rubber sheets (EPDM, NBR, neoprene) have a shelf life of 5–10 years when stored cool, dark, and flat — longer for EPDM and Viton, shorter for NBR. CNAF, PTFE, and graphite sheets are effectively indefinite under normal storage. Discard any sheet that has hardened, cracked, or shows obvious age degradation — do not cut old stock for critical service.
Related Products
- Rubber gaskets — cut-to-pattern EPDM, NBR, Viton
- PTFE gaskets — virgin and expanded PTFE cut gaskets
- Graphite gaskets — flexible graphite cut gaskets
- Custom gasket cutting — we cut the sheet for you
Learn More
Sources
- ASME B16.21 — Nonmetallic Flat Gaskets for Pipe Flanges
- ASTM F104 — Standard Classification System for Nonmetallic Gasket Materials
- AS/NZS 4020 — Testing of products for use in contact with drinking water
- BS 7531 — Rubber bonded fibre jointings for gas installations