Engineering plastics
PEEK
Polyether ether ketone
A high-performance thermoplastic. Strength approaching metal, continuous service around 250 °C and steam resistance; replaces PTFE in high-temperature, high-pressure ball valve seats.
- HARDNESS
- Rockwell R126
- Rm · MPa (typical)
- 97–120
- TEMPERATURE
- −60 … +250 °C
- COST
Design
Polymer; defined by its structure and filler type rather than chemical composition.
Mechanical properties
| TYPE · CONDITION | Rm MPa | Elongation at break % | Hardness | Coefficient of friction | Water absorption % |
|---|---|---|---|---|---|
| Unfilled, typical | 97–120 | 20–50 | Rockwell R126 | 0.18–0.40 | 0.1–0.5 |
Typical values (the standard gives no minimum values); they vary with grade and filler. Converted from US units.
Service temperature
−60 °C+250 °C−200−1000100200300400500600700800
Continuous service −60 … 250 °C (supplier guide 260 °C).
Physical properties and heat treatment
- DENSITY
- ≈ 1.30 g/cm³
Media suitability GENERAL TREND
Water
Steam
Mineral oil
Fuel, aliphatic HC
Ozone, outdoor
Dilute acid
Caustic
Ketones, esters
Emsal assessment. The final choice is made from corrosion tables, taking concentration, temperature, chloride content and flow velocity into account.
Strengths and weaknesses
Strengths
- High strength and creep resistance at high temperature
- Resistant to hot water and steam
- High wear resistance
Weaknesses
- Very expensive
- Weak in concentrated sulphuric and nitric acid
- Higher friction than PTFE
Manufacturing and use
- ECONOMY
- Very high.
- MANUFACTURING METHODS
- Injection moulding · Turning from bar
- TYPICAL VALVE PARTS
- Ball seat (high temperature) · Packing ring · Bushing
Source: ASTM D6262. Values compiled and verified by Emsal Vana; for binding values, refer to the current edition of the standard and the material certificate.