Can You Use Compression Fittings on Stainless Steel Tubing? 

Compression fittings are widely used in plumbing, hydraulic, chemical, and industrial piping systems. They allow secure, leak-resistant connections without welding or soldering, making installation quick and reliable. But when it comes to stainless steel tubing, questions often arise: Can compression fittings be used safely? Are there limitations? What best practices ensure long-term reliability?

This guide answers these questions while exploring the nuances of stainless steel tubing, the proper use of compression fittings, alternatives like stainless steel and carbon steel bulkhead fittings, and considerations for industrial and global applications.

What Are Compression Fittings?

Compression fittings are mechanical connectors that join a pipe to another pipe or a pipe to a fixture. Unlike welded or soldered connections, they rely on a ferrule or sleeve that compresses onto the tubing when the nut is tightened, forming a tight seal.

Main Components

• Body: Connects to the tubing and accommodates the ferrule.

• Ferrule (Sleeve): Compresses onto the tube to prevent leaks.

• Nut: Tightens the ferrule and maintains the seal.

• Threaded Ends: Connect to pipes, hoses, valves, or other fittings.

Compression fittings are favored in applications that require:

• Quick installation without heat or welding

• Minimal maintenance

• Compatibility with high-pressure systems

Can You Use Compression Fittings on Stainless Steel Tubing?

Yes, compression fittings can be used on stainless steel tubing, but certain factors must be considered to ensure safety, performance, and longevity.

How Compression Fittings Work on Stainless Steel

• Stainless steel tubing is harder and more rigid than copper or plastic, which provides excellent support for the ferrule.

• When the nut is tightened, the ferrule deforms slightly and grips the tubing, creating a high-pressure seal.

• Proper axial alignment is essential to avoid leaks or stress fractures.

Titan Fittings and other industrial sources report that stainless steel compression fittings can handle pressures exceeding 10,000 psi, making them suitable for hydraulic, oil, and gas applications.

Material Compatibility

• Stainless Steel Grades: 304 and 316 are preferred for high corrosion resistance.

• Tubing Wall Thickness: Standard tubing provides enough support for the ferrule without deformation.

• Temperature and Pressure: Stainless steel tubing with compression fittings can operate safely in high-temperature and high-pressure environments.

Key Consideration: While compression fittings are effective, for applications involving tank penetration, extreme pressures, or vibration, stainless steel or carbon steel bulkhead fittings offer superior reliability and long-term sealing.

Where Compression Fittings Should Not Be Used

Despite their versatility, compression fittings have limitations. Avoid using them in:

1. High Vibration or Shock Environments

• Vibration can loosen the nut, deform the ferrule, or cause leaks.

• Use threaded or welded fittings, or bulkhead fittings for secure wall-penetrating connections.

2. Thin-Walled or Soft Tubing

• Plastic or thin-wall stainless tubing may crush under compression.

• Alternative fittings or reinforced tubing should be used in such cases.

3. Corrosive or Aggressive Fluids

• Some chemicals may attack the ferrule or nut material, even if the tubing is stainless steel.

• Always verify material compatibility with the fluid.

4. Frequently Disassembled Systems

• Repeated tightening and loosening can degrade the ferrule and compromise the seal.

• Quick-connect or modular fittings may be more suitable for systems requiring frequent maintenance.

Which Classes of Tubing Are Not Suitable for Compression Fittings?

Tubing classification is essential when using compression fittings. Not all tubing types are compatible:

Unsuitable Tubing

• Thin-Walled Stainless Steel Tubes: May deform or leak.

• Soft Copper Tubing: Susceptible to crushing under ferrule pressure.

• Non-Standard or Low-Grade Tubing: Dimensions or tolerances may be inconsistent, reducing seal reliability.

Recommended Tubing

• ASTM A269 Type 304 or 316 Stainless Steel

• Carbon Steel Tubing (for high-pressure industrial applications)

Tip: Always select tubing according to standard dimensions and tolerances to ensure proper compression fitting performance.

Can You Use Stainless Steel and Copper Fittings Together?

Mixing stainless steel tubing with copper fittings is common in low-pressure or domestic systems but has caveats:

Galvanic Corrosion

• When two dissimilar metals contact an electrolyte, galvanic corrosion may occur.

• Stainless steel is more noble than copper, which may accelerate copper corrosion.

Practical Application

• Safe in low-pressure or non-corrosive systems.

• For high-pressure hydraulic or chemical systems, use same-material fittings (stainless steel or carbon steel) to prevent corrosion and ensure long-term reliability.

Recommendation: Use insulating washers or coatings if dissimilar metals must be connected. For high-stakes industrial setups, bulkhead fittings are preferred.

Installation Best Practices for Compression Fittings

Proper installation ensures maximum sealing efficiency and reliability:

1. Align the Tubing

• Misalignment can stress the ferrule and compromise the seal.

• Ensure tubing is cut cleanly and squarely.

2. Tighten Correctly

• Hand-tighten first, then apply recommended torque.

• Avoid over-tightening to prevent deformation.

3. Inspect Seals

• Check for leaks after installation.

• Replace worn ferrules or gaskets.

4. Use Compatible Materials

• Stainless steel ferrules for corrosive or high-pressure applications.

• Ensure the nut and body material match the tubing and fluid environment.

When to Use Bulkhead Fittings Instead

For tank penetration, vibration-heavy systems, or high-pressure scenarios, bulkhead fittings offer superior performance:

• Stainless Steel Bulkhead Fittings

  • Corrosion-resistant

  • Ideal for chemical, marine, and industrial applications

• Carbon Steel Bulkhead Fittings

  • High mechanical strength

  • Suitable for hydraulic systems and heavy-duty tanks

• Advantages Over Compression Fittings

  • Leak-proof seal for tank walls

  • Can withstand vibration and thermal expansion

  • Customizable for wall thickness and pipe diameter

OEMs and industrial buyers often prefer bulkhead fittings for stainless steel or carbon steel tank penetration, ensuring safety and durability.

Applications of Compression and Bulkhead Fittings

1. Hydraulic Systems

• Compression fittings connect tubing in hydraulic circuits.

• Bulkhead fittings allow hydraulic fluid to pass safely through tank walls.

2. Water Treatment and Plumbing

• Compression fittings are ideal for connecting water filtration and distribution tubing.

• Bulkhead fittings secure reservoirs and storage tanks.

3. Chemical and Industrial Processes

• Stainless steel compression fittings resist corrosion from aggressive fluids.

• Bulkhead fittings provide safe tank penetration for chemical storage or processing systems.

4. Marine and Fuel Systems

• Stainless steel components resist saltwater corrosion.

• Carbon steel bulkhead fittings handle fuel and oil under high pressure.

Common Mistakes to Avoid

• Over-tightening fittings, leading to ferrule or tubing damage

• Using thin-walled or soft tubing incompatible with compression fittings

• Mixing stainless steel and copper in high-pressure or corrosive applications

• Ignoring torque specifications and axial alignment

Following correct installation procedures and selecting compatible materials are critical to ensuring reliability.

Conclusion

Compression fittings can safely be used on stainless steel tubing if proper materials, installation, and system conditions are considered. However, for high-pressure, tank penetration, or industrial-grade applications, stainless steel and carbon steel bulkhead fittings provide superior reliability and leak-proof performance.

Key takeaways:

• Use compression fittings only with appropriate tubing classes and wall thicknesses.

• Avoid mixing dissimilar metals in high-pressure or corrosive environments.

• Consider bulkhead fittings for industrial, hydraulic, or high-vibration applications.

• Follow installation best practices, including proper alignment, torque, and inspection.

For industrial buyers and OEMs, our factory produces high-quality stainless steel and carbon steel bulkhead fittings, customizable to specifications, with global shipping and technical support.