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Read moreGasket Chemical Compatibility Chart: Rubber, PTFE, Graphite and CNAF
09 October, 2026 | Admin
Short answer: this gasket chemical compatibility chart gives a first-pass guide to which gasket materials suit common media. PTFE is the broadest; graphite suits steam and hydrocarbons but not strong oxidisers; each rubber has its own strengths. The ratings are general, drawn from widely published elastomer and sealing references. Always verify compatibility for your exact chemical, concentration, temperature and pressure with the manufacturer’s data for the grade you buy.
How to Read the Chart
- A = generally suitable
- B = suitable with limits (temperature, concentration or grade)
- C = generally not recommended
Chemical Compatibility Chart
| Medium | NBR | EPDM | Neoprene | Silicone | Viton (FKM) | PTFE | Graphite | CNAF |
|---|---|---|---|---|---|---|---|---|
| Water (ambient) | A | A | A | A | A | A | A | A |
| Hot water / steam | C | A | C | B | B | A | A | B |
| Mineral oils and lubricants | A | C | B | B | A | A | A | A |
| Diesel and petrol | A | C | B | C | A | A | A | B |
| Dilute acids | B | A | B | B | A | A | A | B |
| Concentrated / oxidising acids | C | C | C | C | B | A | C | C |
| Dilute alkalis | B | A | A | B | B | A | A | B |
| Strong alkalis (hot) | C | B | B | C | C | A | B | C |
| Aromatic solvents | C | C | C | C | A | A | A | C |
| Ketones (e.g. acetone) | C | A | C | C | C | A | A | C |
| Ozone / weathering | C | A | A | A | A | A | A | B |
| Seawater / brine | A | A | A | A | A | A | A | A |
CNAF ratings vary widely with the fibre and binder; the table assumes a general-purpose aramid/NBR grade. Graphite is attacked by strong oxidising agents. PTFE is attacked only by a few substances such as molten alkali metals and elemental fluorine. Filled PTFE takes on the limits of its filler (for example, glass is attacked by hydrofluoric acid and strong alkalis).
Beyond Chemistry: Temperature and Pressure
A material that resists a chemical at room temperature may fail at higher temperature or pressure. Always check the gasket material’s temperature limit and P×T (pressure × temperature) chart, and the flange class. See flange gasket types.
Sources and Further Reading
- Elastomer compatibility ratings are broadly consistent with published sealing references such as the Parker O-Ring Handbook (ORD 5700) chemical compatibility tables.
- Gasket sheet manufacturers publish chemical resistance guides for their CNAF, PTFE and graphite grades; use the guide for the exact grade supplied.
- Our PTFE and filled PTFE technical data sheet lists typical PTFE properties.
How to Use This Chart
- Find your medium and shortlist materials rated A.
- Check temperature and pressure limits for those materials.
- Check the flange type and bolt load; see gasket selection.
- Confirm with the manufacturer’s data for the exact grade.
Related: PTFE gasket types, NBR vs EPDM vs neoprene rubber sheet and rubber gaskets for piping. For the full selection process, see our guide on how to choose engineering plastic. Products: Gaskets & Seal Materials and PTFE (Teflon) products. Every order from Diode Trading EST is supplied with a Material Test Certificate.
When to Ask for a Second Opinion
Treat this chart as a first filter. Ask for a material review before ordering in these cases:
- The medium is a mixture or contains solvents, oxidisers or traces of other chemicals.
- The temperature is close to the upper limit of the material.
- The service cycles between hot and cold, or between wet and dry.
- The line carries steam, hydrocarbons at pressure or toxic media.
In these cases, a sample test or the manufacturer data sheet is the safest basis for selection.
Frequently Asked Questions
Which gasket material has the best chemical resistance?
PTFE resists almost all industrial chemicals, apart from a few such as molten alkali metals and fluorine.
Can EPDM gaskets be used with oil?
Generally not. EPDM swells in mineral oils and fuels; NBR or Viton are usual choices for oil.
Is graphite suitable for acids?
Graphite resists many acids but is attacked by strong oxidising acids and oxidising agents.
Is this chart enough to specify a gasket?
No. Use it as a first pass, then verify with the manufacturer’s data for your exact grade, chemical, concentration, temperature and pressure.
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