Polyether ether ketone (PEEK) has become a widely used material in HPLC column hardware because of its excellent chemical resistance and metal-free flow path. PEEK hardware is particularly valuable for applications involving:

• Metal-sensitive analytes
• Biomolecules
• Proteins and peptides
• Ion-exchange chromatography
• Bioanalytical methods
• Trace metal analysis

Although PEEK offers many advantages, its mechanical properties differ significantly from stainless steel. Understanding the pressure limitations of PEEK hardware is essential for maintaining column integrity, reproducibility, and long-term reliability.

Why Pressure Limits Matter

Unlike stainless steel, PEEK is a high-performance engineering polymer.

While it provides excellent chemical compatibility, it has lower mechanical strength than metal hardware and is more sensitive to:

• Pressure
• Temperature
• Solvent exposure
• Long-term mechanical stress

Operating within recommended limits helps prevent:

• Hardware deformation
• Thread damage
• Frit-seat distortion
• Leakage
• Reduced column lifetime

Short-Term Pressure Limits During Column Packing

ARE-Applied Research Brand™ PEEK column hardware is designed to withstand elevated pressures during column packing procedures.

Maximum Recommended Packing Pressure:  500 Bar (7,250 psi)

This limit applies only during short-term packing operations performed using recommended packing procedures.

Important Note:  The packing pressure specification is not intended for routine analytical operation.  Prolonged exposure to packing-level pressures may permanently damage the hardware.

Long-Term Operating Pressure Limits

For routine chromatographic use, lower pressure limits should be observed.

• 2.1 mm ID PEEK Columns:  Maximum Recommended Continuous Pressure: 250 Bar
• 7.5 mm ID PEEK Columns:  Maximum Recommended Continuous Pressure: 250 Bar
• 4.6 mm ID PEEK Columns:  Maximum Recommended Continuous Pressure: 350 Bar

These values represent recommended long-term operating conditions for maximum reliability and performance.

Effect of Temperature on Pressure Capability

Temperature has a significant influence on the mechanical properties of PEEK.

As temperature increases:

• Material rigidity decreases
• Mechanical strength decreases
• Pressure tolerance decreases

Elevated-Temperature Operation

When operating at approximately:  150°C to 200°C   recommended system pressures should generally be reduced to:  50 to 75 Bar  to maintain safe operation.

High-Temperature Precautions

Extended exposure to elevated temperatures may permanently affect the physical properties of PEEK.

Potential consequences include:

• Reduced mechanical strength
• Decreased pressure tolerance
• Permanent dimensional changes
• Reduced long-term durability

For this reason, conservative operating pressures should always be used during high-temperature applications.

Solvent Compatibility Considerations

Pressure capability is directly influenced by solvent compatibility.

Certain solvents may:

• Swell PEEK
• Soften PEEK
• Extract components from the polymer
• Reduce thread strength
• Alter sealing performance

The use of incompatible solvents may lower the effective pressure rating of the hardware regardless of the original operating specification.

Before using unfamiliar solvents, always verify:

• PEEK compatibility
• Temperature compatibility
• Pressure compatibility

for the intended application.

Selecting PEEK Versus Stainless Steel Hardware

PEEK hardware is often preferred when:

• Metal interactions must be minimized.
• Biomolecule recovery is critical.
• Corrosive mobile phases are being used.
• Metal-sensitive compounds are analyzed.

Stainless steel hardware may be preferred when:

• Extremely high pressures are required.
• UHPLC pressures are routinely encountered.
• Maximum mechanical strength is needed.

The choice should be based on both chromatographic requirements and operating conditions.

Best Practices for Maximizing Hardware Life

To extend the service life of PEEK column hardware:

• Operate within recommended pressure limits.
• Minimize exposure to incompatible solvents.
• Reduce pressure at elevated temperatures.
• Avoid unnecessary pressure cycling.
• Inspect fittings and threads regularly.
• Replace worn components before leakage occurs.

Following these practices helps maintain reproducible performance and protects packed column beds.

Ordering Information

For column hardware, frits, sealing rings, tubing components, and accessories, see:  PEEK Column Hardware Products, Accessories, and Ordering Information

Key Takeaways

• ARE-Applied Research Brand™ PEEK column hardware supports short-term packing pressures up to 500 Bar.
• Continuous operating pressures should remain at 250-350 Bar depending on column dimensions.
• Elevated temperatures significantly reduce allowable operating pressure.
• Solvent compatibility can affect hardware strength and pressure tolerance.
• PEEK provides a valuable metal-free alternative for sensitive chromatographic applications.
• Operating within recommended specifications maximizes column hardware longevity and