Overview

PEEK (PolyEtherEtherKetone) is a high‑performance polymer used extensively in chromatography systems because of its chemical resistance and dimensional stability.

However, its mechanical and pressure‑handling characteristics change significantly with temperature. MICROSOLV provides specific guidance on how PEEK tubing, fittings, and related components perform under heat.

Recommended Temperature Limits

PEEK Tubing

• Safe useful temperature rating: up to 100 °C
• At temperatures above this level, tubing strength decreases and burst pressure can drop significantly.

PEEK Fittings

• Useful up to 125 °C for most PEEK fittings.
• Beyond this temperature, mechanical stability declines, and sealing reliability can be affected.

General Note on Higher Temperature Ratings

• While PEEK is sometimes cited as stable up to 250 °C, this does not apply to chromatography use because:

  • Tubing burst pressure decreases at elevated temperatures
  • Solvent interactions may become more aggressive
  • Dimensional stability is reduced compared to room‑temperature conditions

Overall Recommendation

• PEEK should be used with caution at any elevated temperature.
   

Why Temperature Matters for PEEK Components

Mechanical Considerations

• Higher temperatures soften PEEK, reducing tensile strength and compressive stability.
• Fittings may deform under mechanical load, leading to leaks.

Pressure Concerns

• Tubing burst strength declines as temperature rises, even with non‑aggressive solvents.
• Systems operating near their pressure limits should stay well below maximum temperature recommendations.

Solvent Compatibility Effects

• Certain solvents interact more strongly with PEEK at higher temperatures, potentially leading to:

  • Swelling
  • Stress cracking
  • Chemical weakening

Practical Usage Guidance

When Operating Near Temperature Limits

• Reduce system pressure to prevent tubing failure.
• Avoid aggressive or swelling solvents at high temperatures.
• Inspect tubing and fittings regularly for softening or distortion.

Best Practice

• Prefer temperatures ≤ 100 °C for PEEK tubing and ≤ 125 °C for fittings unless absolutely necessary.
• For higher‑temperature applications, consider alternative materials such as stainless steel or titanium hardware.