Swagelok Tube Fittings vs. Flare Fittings

A customer recently reached out to us via our website with an interesting inquiry. They explained that they currently have a hydraulic system with both flared fittings and Swagelok tube fittings. However, they have been facing pressure to replace the Swagelok fittings with flared fittings due to concerns about reliability. They requested any literature we could provide regarding the effectiveness of Swagelok fittings and any practical limitations they may have.

More Details

We immediately reached out to the customer to delve deeper into their concerns. This particular customer, who operates in the defense industry, has been using Swagelok tube fittings for over a decade without encountering any issues. However, their stringent quality process prompted them to conduct a thorough evaluation of the potential failure risks in their application. In fact, the engineering management even encouraged our contact, an operations engineer, to scrutinize the reliability of our tube fittings in their high-pressure 3000 psig hydraulic system rotary application, ensuring that the Swagelok tube fitting could truly meet their requirements without the nut ever loosening.

Our Response   

Our account manager promptly provided the customer with 3 product test reports (PTRs) and a detailed copy of Swagelok's limited lifetime warranty. Among these reports, PTR-3222 proved to be exactly what they needed. In this particular report, Swagelok conducted rigorous testing on their tube fitting assemblies, specifically focusing on the fatigue endurance of 316 stainless steel Swagelok tube fittings with advanced geometry back ferrules. The tests were conducted under controlled laboratory conditions, subjecting the fittings to various levels of applied alternating bending stress. Throughout the entire duration of the test, there was absolutely no leakage detected from the fittings. The test only concluded when the tube fractured or when the test sample surpassed an impressive 10 million cycles. For a more in-depth look at the findings, you can refer to the comprehensive product test report PTR-3222.

A Quick Defense

As a result of this interaction, we decided to write up a quick defense of Swagelok tube fittings in relation to flare fittings. 

Swagelok tube fittings are commonly preferred over flare fittings for various reasons:

1. Leak-free performance: Swagelok tube fittings are designed to provide a leak-free connection, ensuring the integrity of the system. The two ferrules in Swagelok fittings create a strong and reliable seal, minimizing the risk of leakage.
2. Reusability: Swagelok fittings can be disassembled and reassembled multiple times without compromising their sealing performance. This reusability feature is beneficial during system maintenance or modifications.
3. Vibration resistance: Swagelok fittings are more resistant to vibration and mechanical stresses compared to flare fittings. This makes them suitable for high-vibration environments, preventing accidental loosening or leakage.
4. Easy installation: Swagelok fittings require fewer steps and tools for installation compared to flare fittings, which involve flaring the end of the tubing and using a flare nut to create the connection.
5. Space efficiency: Swagelok tube fittings have a compact design, making them ideal for applications with limited space or tight installations.
6. Wide range of materials: Swagelok fittings are available in various materials, including stainless steel, brass, and other alloys, making them compatible with different fluids and environments.
7. Higher pressure and temperature ratings: Swagelok fittings typically have higher pressure and temperature ratings than flare fittings, making them suitable for more demanding applications.

While flare fittings have their specific use cases, Swagelok tube fittings are generally preferred in industries where leak-free and reliable connections are critical, such as oil and gas, chemical processing, aerospace, and semiconductor manufacturing, among others.

To find out more about how Swagelok Northern California can help you make a selection between single ferrule vs. double ferrule tube fittings for your fluid system installation, contact our team today by calling 510-933-6200.

About Morgan Zealear | Product Engineer, Assembly Services

Morgan holds a Bachelor of Science in Mechanical Engineering from University of California at Santa Barbara. He is certified in Section IX, Grab Sample Panel Configuration and Mechanical Efficiency Program Specification (API 682), and he is well versed in B31.3 Process Piping Code. Before joining Swagelok Northern, he was a manufacturing engineer at Sierra Instruments, primarily focused on capillary thermal meters for the semiconductor industry (ASML).