Complete Guide to PEEK Tubing Sizes: Compatibility with Polyimide for Advanced Applications

PEEK Tubing Sizes come in standard ranges. Inner diameter, outer diameter, and wall thickness set each size. The size you pick controls flow rate, pressure rating, and connector fit. PEEK and polyimide tubing work well together in advanced uses. Both materials have strong chemical and thermal resistance. But they are different in flexibility and thermal expansion. These differences require careful sizing and installation. You must match dimensions and think about temperature changes. A small mismatch can cause leaks or connection failures. Good planning stops these problems. Always check manufacturer data before you finalize your assembly. This step protects your system from costly downtime.

Key Takeaways

• PEEK tubing comes in standard sizes from 1/32" to 1/4" outer diameter. The 1/16" size is used most often for HPLC.

• Match the inner diameter, outer diameter, and wall thickness to control flow rate and pressure. Thicker walls can handle more pressure.

• PEEK and polyimide stand up to many chemicals, but keep them away from strong sulfuric acid, nitric acid, and swelling solvents like DMSO.

• PEEK gets soft above 143°C, but polyimide works up to 400°C. Design connections so they allow for different expansion rates.

• Always check the manufacturer's tolerances and use the right fittings to stop leaks. Color coding helps you find inner diameters fast.

Standard PEEK Tubing Sizes

Inner Diameter, Outer Diameter, and Wall Thickness

PEEK tubing is made in many standard outer diameters. Sizes go from 1/32" up to 1/4" for work with high-pressure fluids. The most common size for HPLC is 1/16" outer diameter. Each outer diameter works with many inner diameters. This pairing lets you control flow rate and pressure rating exactly.

Wall thickness is easy to find: wall thickness = (outer diameter - inner diameter) / 2. A thicker wall handles more pressure. A thinner wall gives a larger inner diameter and higher flow. You must choose between these two needs for your work.

The table below shows how inner diameter changes pressure capacity for 1/16" outer diameter tubing.

For smaller outer diameters, pressure ratings can go higher. A 360 µm outer diameter tube with a 150 µm inner diameter has a wall thickness of 0.00413 inches. This tube can handle 10,000 psi. This example shows the smallest wall thickness among all tubing that holds at least 5,000 psi.

PEEK tubing meets USP Class VI and ISO 10993 standards for safety with living tissue. These standards matter for medical and drug work. They make sure the material will not harm patients or dirty fluids.

Tolerances and Measurement Units

Tolerance control is very important for PEEK Tubing Sizes. A loose tolerance causes connection failures and leaks. A tight tolerance makes sure your tubing fits well with fittings and connectors.

For 1/16" outer diameter tubing, the outer diameter tolerance is ±0.0012" (30 μm). Inner diameter tolerances are often ±0.001" for common sizes. You will see both inch and metric units in manufacturer data. Always check which unit the supplier uses before you order.

Color coding helps you see inner diameters at a quick look. For example, a 1/16" tube with 0.010" inner diameter is blue. A 0.020" inner diameter is orange. A 0.030" inner diameter is green. This system cuts down on mistakes during assembly.

The table below lists common 1/16" outer diameter PEEK Tubing Sizes and their color codes.

You must check tolerance overlap between your tubing and your fittings. A small difference in outer diameter can cause leaks under high pressure. Always look at the manufacturer datasheet for exact tolerance values. This step protects your system from breakdown.

Common PEEK Tubing Sizes by Application

Narrow-Bore Sizes for Analytical Instrumentation

You encounter narrow-bore PEEK tubing in HPLC and LC-MS systems. These instruments need precise flow control and chemical resistance. PEEK delivers both qualities at a lower cost than stainless steel. The 1/16" outer diameter size is the standard choice. You select an inner diameter from 0.005" to 0.030" based on your flow requirements. The table of color-coded tubing in the previous section helps you identify the correct size quickly. Color coding lets you verify the inner diameter at a glance. This system reduces assembly errors.

Micro tubing and capillary tubing represent specialized size categories for precision work. A 360 µm outer diameter capillary with a 150 µm inner diameter handles up to 10,000 psi. This small cross-section reduces dead volume in your fluid path. It also minimizes sample dispersion and solvent consumption. You need tight tolerance control for these miniature sizes. A deviation of only a few microns can cause leaks under high pressure. These PEEK Tubing Sizes meet the demands of high-purity analytical chemistry.

Wide-Bore Sizes for Fluid Transfer and Medical Devices

Wide-bore PEEK tubing supports higher flow rates for fluid transfer and medical devices. The 1/8" outer diameter size is common for these tasks. You can choose from several inner diameters to match your flow requirements. The larger bore lowers flow resistance along the tube. But it also reduces the maximum operating pressure. You must balance flow capacity against pressure rating for your specific application.

Medical catheters and interventional devices use wide-bore PEEK tubing. The material meets USP Class VI and ISO 10993 biocompatibility standards. You get dimensional stability and chemical resistance in one tube. Polyimide tubing often works alongside PEEK in these assemblies. You must match diameters carefully and account for differences in flexibility during installation. This compatibility extends the design options for complex medical devices.

Diagnostic systems use wide-bore PEEK for reagent and waste fluid transfer. The smooth inner bore resists particle buildup and biofilm formation. It also withstands attack from aggressive solvents and strong acids. You can sterilize the tubing using autoclave or ethylene oxide while the material retains its mechanical properties.

Chemical Compatibility of PEEK and Polyimide

Solvent and Acid Resistance

You pick both PEEK and polyimide because they resist many chemicals. Each material holds up against a wide range of harsh chemicals. But neither material can survive everything. You must know what each polymer can and cannot handle before you design your system.

PEEK tubing works very well with common HPLC solvents. The table below shows the chemical resistance rating at 20°C.

The rating scale uses A for suitable, B for marginal, and C for not recommended. Both acetonitrile and methanol get the highest rating. You can use PEEK tubing with these solvents without any worry. This compatibility covers everyday analytical work.

PEEK tubing stands up well against many acids and organic solvents. But you must watch out for certain harsh chemicals. Concentrated sulfuric acid harms PEEK when the concentration goes above 10%. This acid weakens the structure of the tubing. Concentrated nitric acid also attacks PEEK directly. Halogenated acids like hydrofluoric acid, hydrobromic acid, and hydroiodic acid bring extra risks. Pure halogenated gases also harm the material. You need to check manufacturer data before you use these chemicals with PEEK.

Some chemicals make PEEK tubing swell up. These chemicals include methylene chloride, dimethyl sulfoxide (DMSO), and tetrahydrofuran (THF). The swelling changes the inner diameter and outer diameter of your tubing. You may find that connectors no longer fit well. The chemical does not always harm PEEK fittings the same way. Fittings often resist swelling better than tubing does. But a swollen tube can still leak at connection points. You should test your own assembly with the planned solvent mixture before you start full production.

Polyimide tubing shares many of these same chemical resistance traits. It stands up to most organic solvents and dilute acids. Its limits often match those of PEEK. You should always check how both materials react to your specific chemicals. A manufacturer data sheet gives you trustworthy information. Test coupons from your supplier also help you confirm performance before installation.

Leaching and Contamination Risks

Purity matters in analytical and medical applications. You cannot let contaminants get into your fluid stream. Leaching happens when molecules from the tubing material move into the fluid flowing through it. PEEK tubing has low leaching properties compared to many other polymers. This low extractables profile makes it good for HPLC and LC-MS work. You get clean baselines and accurate results.

You should still check leaching risk under your own conditions. High temperatures speed up the rate of molecular movement. Harsh solvents near the material's compatibility limits can also raise extractables. You want to test your system at its highest operating temperature. Use the worst-case solvent combination. This test gives you confidence that your tubing will not contaminate your samples. Write down the test results for your quality records.

Polyimide tubing also offers low leaching in most applications. Its high temperature rating gives it an edge in thermal cycling. But you should still check extractable levels for your own use case. Each material has its own additive package and manufacturing process. These factors affect the final purity profile. Ask your supplier for extractables data before you finalize your design.

You can lower contamination risks through proper preparation. Flush your tubing with your working solvent before you connect it to the system. This step removes any surface residues from the manufacturing process. Use dedicated tubing for each chemical line. Avoid cross-contamination between different solvents or samples. Replace tubing on a regular schedule based on your maintenance plan. A simple log helps you track replacement dates.

For medical devices, you must meet USP Class VI and ISO 10993 standards. These standards require specific biocompatibility testing. The test results give you extractables data for the material. Always ask your tubing supplier for this data. Use it to guide your material selection. This step protects your patients and your device performance.

Thermal and Mechanical Compatibility

Temperature Ranges and Thermal Expansion

Polyimide tubing can work at up to 400°C. This makes it good for high-temperature uses. PEEK gets soft when it reaches its glass transition temperature, which is about 143°C. At that point, the loose parts inside the semi-crystalline polymer start moving. You will see the material become less stiff and lose some strength. But PEEK is semi-crystalline with 35-45% crystallinity. The crystal parts stay stable until its melting point, around 343°C. These parts act like a strong frame that stops the tube from collapsing. You can still put weight on it at higher temperatures. But too much stress above the glass transition temperature can cause it to change shape or creep. You must think about this when you use PEEK with polyimide in systems that go through heating and cooling cycles. The two materials expand at different rates. This difference creates stress at the points where they connect. You should design your assembly so that there is room for movement.

Flexibility, Stiffness, and Connection Methods

PEEK is chosen for high strength, heat resistance, purity, and lubricity in advanced uses. These qualities make it a top pick for demanding fluid handling systems. Polyimide is more flexible than PEEK. This difference affects how you route and connect your tubing. You must respect the minimum bend radius to avoid kinking during installation. The table below shows acceptable bend radius limits for common PEEK tubing sizes.

You should use proper connectors when you join PEEK and polyimide tubing. Compression fittings work well for PEEK. Polyimide may need a different ferrule type because it is more flexible. You must match the outer diameter of both tubes to your fitting specifications. A mismatch causes leaks under pressure. Always check the manufacturer datasheet for the correct connector pair. This step protects your system from failure.

Medical Applications of PEEK and Polyimide

Medical Catheters and Interventional Devices

You will see PEEK and polyimide used together in catheters and interventional devices. Each material adds its own strengths to the assembly. PEEK gives high strength, heat resistance, purity, and lubricity. Polyimide adds flexibility and can handle temperatures up to 400°C. You pick these materials together based on five key factors. These are biocompatibility, chemical resistance, temperature performance, dimensional stability, and flexibility. Both materials meet USP Class VI and ISO 10993 standards for patient safety.

A medical PEEK retraction inner tube used in neurovascular systems shows common dimensions. This tube has an outer diameter of 1.8 mm. It has an inner diameter of 1.168 mm and a wall thickness of 0.316 mm. Manufacturers make it through precision extrusion. You use this kind of tubing for interventional catheter inner tubing and neurovascular systems.

The table below lists PEEK tubing dimensions for neurovascular applications.

You must check material compatibility for your specific device design. The sterilization method matters. Ethylene oxide and autoclave sterilization affect each polymer in different ways. The planned length of patient contact also changes your material choice. Short-term devices have different needs than long-term implants.

Medical Diagnostic and Fluid-Handling Systems

Diagnostic systems depend on PEEK and polyimide for precise fluid handling. You need tubing that stands up to aggressive solvents and strong acids. Both materials give you this resistance. PEEK has a smooth inner bore that resists particle buildup and biofilm formation. Polyimide adds thermal stability in systems that go through temperature changes.

You can sterilize PEEK tubing using autoclave or ethylene oxide. The material keeps its mechanical properties after sterilization. This durability protects your diagnostic results across many test cycles. Polyimide tubing helps these systems with its high temperature rating. You pair the two materials to balance flexibility and stiffness along your fluid path.

Compatibility verification is still essential for every diagnostic application. You must test your assembly with the actual solvents and temperatures your system will meet. A manufacturer datasheet gives you baseline data. Your own testing confirms performance under real conditions. This step protects your equipment and your test results.

Selecting and Installing Compatible Tubing

Matching Diameters and Fittings

You must match the outer diameter of your PEEK and polyimide tubing to the same fitting specification. A 1/16" outer diameter tube works with a 1/16" compression fitting. The outer diameter tolerance for this size is ±0.0012" (30 μm). A polyimide tube with a different tolerance may not seal right in the same fitting. Always compare the tolerance ranges from both makers before you put the connection together.

Check the inner diameter match when you join two tube sections. A sudden change in inner diameter causes turbulence and dead volume. This change hurts how well your analytical system works. Pick PEEK Tubing Sizes that keep the inner diameter the same across the connection point. Color coding helps you check the inner diameter at a glance. A blue tube has a 0.010" inner diameter. An orange tube has a 0.020" inner diameter. You can confirm the match without measuring.

Cutting, Bending, and Sealing Best Practices

You need a clean, square cut for a connection that will not leak. Use a tubing cutter made for polymer tubing. A razor blade can work for small sizes. But a dull blade makes cracks and rough edges. Those flaws cause leaks under pressure. Push the tube firmly into the fitting after you cut it. The tube must reach the bottom inside the connector.

Respect the minimum bend radius to stop kinking. The table below shows acceptable limits for common PEEK tubing sizes.

Polyimide is more flexible than PEEK. You can bend it tighter without damage. But you must still avoid sharp angles at the connection point. A gentle curve lowers stress on the fitting. For sealing, compression fittings work well for PEEK. Polyimide may need a different ferrule type. Always follow the maker's datasheet for your specific connector pair.

You now know the main PEEK Tubing Sizes, from 1/32" up to 1/4" outer diameter. Three compatibility dimensions decide if PEEK and polyimide work well together. Chemical resistance covers solvents and acids. Thermal performance spans PEEK's glass transition near 143°C and polyimide's rating up to 400°C. Mechanical fit depends on flexibility, stiffness, and bend radius. Always check tolerance overlap before you put your system together. The right connectors stop leaks and failures under pressure. Check manufacturer datasheets for exact size and compatibility data. This last step saves your advanced application from costly downtime.

FAQ

What outer diameter does standard HPLC PEEK tubing use?

Standard HPLC PEEK tubing uses a 1/16 inch outer diameter. You pair it with inner diameters from 0.005 to 0.030 inches. This size fits common compression fittings and handles pressures up to 5,000 psi.

Can you use the same fitting for PEEK and polyimide tubing?

You can if both tubes share the same outer diameter. Check the tolerance ranges first. A ±0.0012 inch difference in outer diameter can cause a leak. Polyimide may need a different ferrule type for a proper seal.

What temperature limits PEEK tubing before it softens?

PEEK softens above 143°C, its glass transition temperature. Crystal structures keep it stable until 343°C. Too much stress above 143°C deforms the tube over time. Polyimide tubing handles up to 400°C.

Which chemicals damage PEEK tubing?

Avoid concentrated sulfuric acid above 10% and concentrated nitric acid. Methylene chloride, DMSO, and THF cause PEEK to swell. Always check the manufacturer datasheet before using these chemicals with your tubing.

How do you select the right PEEK tubing inner diameter?

Pick your inner diameter based on flow rate and pressure needs. A larger inner diameter gives higher flow but a lower pressure rating. Color coding helps you identify inner diameters quickly without measuring.

See Also

How To Select Optimal Biocompatible FEP Heat Shrink Tubing For Applications

A Comprehensive Guide To Medical Grade FEP Tubing Essentials

What You Need To Know About FEP Tubing 1.3:1 Shrink Ratio

Key Factors To Evaluate When Selecting FEP Heat Shrink Tubing

Important Tips For Effective Use Of FEP Heat Shrink Tubing