Ferrule Compression Fitting

Ferrule Compression Fitting

What is a ferrule compression fitting?

A ferrule compression fitting is used to connect the metal or hard plastic tubing, which is suitable for extreme temperatures and high pressure. Ferrule compression fittings are corrosion-resistant. A ferrule compression fitting is made up of three parts: nuts, ferrules(single ferrule or double ferrules), and body. A ferrule compression fitting has United National Extra Fine threads. A ferrule compression fitting size is determined by the tubing outside diameter. Ferrule compression fittings are used in aerospace, defense, chemical process plants, and oil & gas industries. Ferrule compression fittings are easy to assemble and have no leaks. Ferrule compression fittings sizes are from 1/16”-2” (fractional sizes), or 2mm to 50mm(metric sizes).

Ferrule compression fittings types

There are many varieties of ferrule compression types:

Male connector, female connector, bulkhead male connector, bulkhead female connector

Male elbow, female elbows

Tees ( male branch tee, female run tee)

Unions (union tube fittings, reducing union, union elbow, union tee)

Ferrule compression fittings assemble

It is better to understand how to assemble ferrule compression fittings by video.

How to select tubing to connect ferrule compression fittings?

It is important to select the right tubing to connect ferrule compression fittings. If the tubing is wrong, it will result in a leaking connection.

It is different to select tubing for single-ferrule compression fitting and double-ferrule compression fitting.

For the double ferrule compression fittings, the tubing should be polished and seamlessly smooth, there is no leakage for the double ferrule to connect polished tubing.

For the single ferrule compression fittings, the tubing should be blank tubing (acid white tube, not polished). The single ferrule is connected with blank tubing without leakage.

So, the double ferrule can not be connected with the blank tubing, and the single ferrule can not be connected with the polished tubing. Or there will be leakage of connections. These mistakes have happened to our customers in the past.

Ferrule compression fitting materials

There are several materials for you to choose from. Normally, stainless steel ferrule compression fitting, brass ferrule compression fitting, carbon steel ferrule compression fitting, and special materials like Monel, Super duplex steel, Inconel alloy, and so on.

Ferrule compression fittings application

ferrule compression fittings are usually used in multiple industries: pulp & paper, downstream petrochemicals, shipping buildings, defense, power generation, semiconductors manufacturing, laboratories, and other heavy industries.

Single-ferrule compression fittings and double-ferrule compression fittings

Single ferrule compression fittings are made up of nuts, body, and front ferrule, which design minimizes the total number of parts. Single ferrule compression fittings tend to work best from softer materials, for example, plastic and brass.

Double ferrule compression fittings are made up of nuts, body, front ferrule, and rear ferrule. Double ferrule compression fittings are suitable for high-pressure materials, for example, stainless steel, and special materials like Monel, Super duplex steel, and so on.

Whether single-ferrule compression fittings or double-ferrule compression fittings, the ferrule is the most important sealing component of a compression fitting. Ferrules are made of metal with a higher material grade, which can withstand high pressure and high temperature.

Don’t mix and match components of ferrule compression fittings from different manufacturers

There are differences in key internal dimensions between different manufacturers, for example, ferrule length, thread size, and pitch. There will be unexpected results if you mix and match components from different manufacturers. Below are quotes from Swagelok’s claim about mixing and matching components from different manufacturers:

“Over the years, we’ve become aware of many manufacturers with products that claim to be interchangeable with the Swagelok Tube Fitting.

We do not believe that any manufacturer can reliably, repeatedly, and uniformly replicate the products of another manufacturer.  For this reason, we believe that interchanging and intermixing component parts made by different manufacturers can result in unpredictable performance and increased costs.  We believe also that this is an unsound practice and can be dangerous in critical applications.”

Ferrule compression fittings’ advantages

Ferrule compression fittings do not need to be welded. They are easy to assemble and disassemble without special tools. However, to ensure the leak-tight seal, ferrule compression fittings can only be disassembled and reassembled a few times.

Ferrule compression fittings can withstand higher pressure and extreme temperatures.


Ferrule compression fittings are used in a wide range of industries. Choose the right ferrule compression fittings for your project.

If you want to know more about ferrule compression fittings, contact us for more details.

Mobile / What’s app: 0086 13218868008

Email: yolanda2021@npt-lok.com

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