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Read morePTFE Chemical Compatibility & Temperature Guide: Grade Selection
01 October, 2026 | Admin
PTFE chemical compatibility is the first check when selecting a grade for a chemical process application. The choice comes down to two questions in sequence: is PTFE chemically compatible with this fluid at this temperature, and does the mechanical duty (static seal or dynamic wear) call for virgin or a filled grade? This guide walks through both.
Chemical compatibility figures are general industry reference points. Always confirm against your specific process fluid, concentration and temperature with the material manufacturer before final specification.
Step 1: Confirm Chemical Compatibility
PTFE resists the overwhelming majority of industrial chemicals, which is why it is the default choice when compatibility is uncertain. The table gives a general reference for common categories. Confirm your exact chemical, concentration and temperature against a manufacturer compatibility chart before finalising a specification for a critical application.
| Chemical Category | PTFE Compatibility | Notes |
|---|---|---|
| Strong acids (sulphuric, hydrochloric, nitric) | Excellent | A standard choice for strong acid service |
| Strong alkalis / caustics | Excellent | Resistant across typical concentrations and temperatures |
| Organic solvents (most) | Excellent | One of PTFE’s strongest use cases |
| Hydrocarbons / fuels | Excellent | Common in oil and gas gasket and seal applications |
| Molten alkali metals | Poor | One of the few genuine PTFE incompatibilities; rare in general industry |
| Elemental fluorine gas at high temperature | Poor | Specialised and rare exposure case |
Step 2: Check the Operating Temperature
PTFE’s standard service range runs roughly -200°C to +260°C. The practical ceiling for a specific application depends on the combination of temperature and pressure, and on whether exposure is continuous or intermittent. As temperature approaches the upper end of the range, mechanical properties such as compressive strength decline even though chemical resistance remains strong. This is where grade selection in Step 3 matters more.
Step 3: Match the Mechanical Application to a Grade
Once chemical and temperature compatibility are confirmed, the remaining decision is mechanical. Static seals under purity-sensitive conditions favour virgin PTFE; components under continuous mechanical wear or compression favour a filled grade.
| Duty | Typical Choice | Product |
|---|---|---|
| Static seal, purity-sensitive | Virgin PTFE | Virgin PTFE sheets and rods |
| Wear and compression, general | Glass-filled PTFE | 15% glass-filled PTFE |
| Wear with improved compressive performance | Carbon-filled PTFE | 25% carbon-filled PTFE |
| Dynamic wear and heat conduction | Bronze-filled PTFE | 40% bronze-filled PTFE |
The PTFE grades guide gives the full breakdown by filler type, and our PTFE product range lists the forms available. For sealing applications see PTFE gland packing, tapes and seals and ready-cut gaskets.
Common Selection Mistakes
- Assuming ‘PTFE resists everything’ without checking the small number of genuine exceptions relevant to specialised processes
- Specifying virgin PTFE for a continuous dynamic wear application where a filled grade would last significantly longer
- Not accounting for combined temperature and pressure: a chemical and temperature combination that is fine at atmospheric pressure may behave differently under process pressure
- Reusing a PTFE gasket after removal: most PTFE gaskets take a compression set and should be replaced, not reinstalled
When to Get Engineering Sign-Off
For critical process applications, such as high-pressure systems, hazardous chemical service, or anywhere a seal failure has serious safety or environmental consequences, treat this guide as a starting reference and not a final specification. Confirm compatibility with the material manufacturer’s detailed chemical resistance chart for your exact fluid, concentration and temperature, and obtain engineering sign-off before finalising critical specifications.
Frequently Asked Questions
Is PTFE compatible with all acids?
PTFE resists the vast majority of acids, including strong acids such as sulphuric and hydrochloric, across typical industrial concentrations and temperatures. It is not universally compatible with every chemical, so always confirm your exact fluid against a detailed compatibility chart for critical applications.
What happens to PTFE at temperatures above its rated range?
Above its rated continuous service temperature, PTFE can begin to degrade and, at very high temperatures, release fumes that are hazardous to inhale. Operate within the rated range with an appropriate safety margin, particularly in enclosed or poorly ventilated spaces.
Which PTFE grade should I use for a chemical process?
Start with chemical and temperature compatibility, then choose virgin PTFE for static, purity-sensitive seals or a filled grade for continuous wear or compression.
Request a Quotation
Send your process fluid, concentration, temperature, drawings and quantities to the Al Khobar team and we will help you select and quote the right PTFE grade.
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