How to Properly Swage HPLC Fittings

To properly swage an HPLC fitting, slide the nut and ferrule onto the tubing, insert the tubing fully into the port, then tighten the nut finger-tight followed by additional wrench tightening to permanently compress the ferrule onto the tubing. This creates a durable, high-pressure seal commonly used with stainless steel HPLC tubing.

A correctly swaged ferrule stays fixed on the tubing when the fitting is removed from the port. If the ferrule still slides, additional tightening is needed. Swaged fittings are reliable for high-pressure HPLC and UHPLC applications, but they should generally only be reused in the same port where they were originally swaged.

Swaging HPLC Fittings for Reliable High-Pressure Connections

Learn how to seat the tubing correctly, secure the ferrule, and avoid leaks or dead volume in stainless steel connections

HPLC Accessories

Learning how to correctly install and tighten HPLC fittings is an important skill for any chromatographer. Whether setting up a new instrument or performing routine maintenance, fitting connections eventually need to be adjusted, replaced, or tightened. Most HPLC fitting assemblies consist of two main parts: a nut and a ferrule.

In lower-pressure systems, the ferrule may attach to the tubing by simple friction. In higher-pressure systems, especially with stainless steel tubing, the ferrule is usually attached through a permanent compression process called swaging.

How to Swage a Fitting onto a Piece of Tubing

Swaging creates a strong, leak-free connection by permanently compressing the ferrule onto the tubing. This process is commonly used with stainless steel tubing and fittings in HPLC and UHPLC systems. A general swaging procedure is as follows:

  1. Slide the nut over the tubing that will be connected.
  2. Position the ferrule under the nut, with the tapered end facing away from the nut and toward the receiving port.
  3. Insert the tubing assembly into the port until the tubing bottoms out against the internal stop in the port, if one is present.
  4. Tighten the nut finger-tight, then use a wrench to turn it an additional 3/4 turn to complete the swage.

Note: Some ports do not contain a firm internal stop. In these cases, the tubing should extend slightly past the ferrule nose, but not excessively, to avoid improper seating, leaks, or added dead volume.

After tightening, loosen the nut and inspect the connection. A properly swaged ferrule should remain fixed on the tubing. If it still slides freely, reinsert the tubing and tighten the nut in 1/4-turn increments until the ferrule is securely attached. For UHPLC systems operating at higher pressures, additional tightening may be required to achieve a proper seal.

Why Permanently Swage a Fitting to Tubing?

Permanently swaging a ferrule provides a robust, high-pressure connection suited to demanding chromatography systems. As instrument pressures rise, swaged fittings help ensure the connection remains stable and leak-free.

Advantages of swaged fittings include:

  • Increased reliability: Once swaged, the nut and ferrule assembly remains fixed on the tubing
  • Higher pressure tolerance: Important for UHPLC and high-pressure solvent delivery systems
  • Reduced risk of losing small parts: The ferrule stays attached to the tubing after disconnection

There are also practical limitations. A swaged fitting should generally only be reused in the original port where it was formed. Slight differences in port dimensions can lead to leaks, dead volume, or alignment problems if the same swaged connection is used elsewhere.

When Fingertight Fittings May Be Better

For users who need easier fitting changes or more flexibility between ports, Fingertight Fittings can be a practical alternative. These fittings are reusable and do not require permanent swaging, which makes them useful when connections need to be changed more frequently.

Choosing between swaged and fingertight fittings depends on the tubing material, the operating pressure, and how often the connection needs to be moved or replaced. For high-pressure stainless steel connections, swaging remains a standard and reliable approach.

For help selecting the best fitting style for a specific chromatography system, contact Chrom Tech for application guidance and fitting recommendations.

Shop HPLC Accessories Visit Chromatography Knowledge Center
Key Definitions ▶
Swaging
The process of permanently compressing a ferrule onto tubing so it forms a durable, high-pressure connection.
Ferrule
A small conical component used with a nut to grip tubing and create a seal inside an HPLC fitting connection.
Nut
The threaded part of an HPLC fitting that tightens the ferrule and tubing assembly into the receiving port.
Receiving Port
The fitting port on an HPLC component where the tubing assembly is inserted and sealed.
Dead Volume
Extra internal space in a connection that can lead to peak broadening, poorer efficiency, and less reproducible chromatography.
Frequently Asked Questions ▶
What is swaging in HPLC fittings?
Swaging is the process of permanently attaching a ferrule to tubing by tightening the fitting so the ferrule compresses and locks onto the tubing, creating a durable high-pressure seal.
How can I tell if my ferrule is properly swaged?
After tightening, remove the fitting and check whether the ferrule remains fixed on the tubing. If it slides, it is not fully swaged and should be tightened further in small increments.
Can a swaged fitting be reused in a different port?
Generally no. A swaged fitting should usually only be reused in the original port where it was formed, because small dimensional differences between ports can cause leaks or dead volume.