What is a Compression Tube Fitting and How Does it Work?

Rohan Vaghela
4 min readJan 4, 2023

Compression tube fittings are the old-school version of the quick-connect fitting. While these fittings may require more work upon installation, they still provide strong, tight, and reliable seals for any of your water treatment configurations. This blog offers a better understanding of how a compression fitting works and how to install it properly.

316L Compression Tube Fittings

What is a compression tube fitting?

A compression tube fitting compresses a component of the fitting into another component, usually some type of tubing, to create a watertight seal between two different lines. With the introduction of quick-connect style fittings to the water treatment industry, the compression fitting was used less frequently, but it’s still a great fitting that can handle high pressure and give you a reliable, tight seal. 316L Compression Tube Fittings are comprised of a sleeve, a nut, and the fitting body itself. The sleeve acts as the seal when the nut compresses it into the fitting body.

What are compression tube fittings made from?

Several materials are used to create 316L Compression Tube Fittings. Brass is the most typical material for compression fittings, however, you must make sure to choose lead-free brass fittings because using any fitting with lead content in the United States is prohibited. They are frequently made of stainless steel and plastic as well. The amount of pressure or temperature that the fitting can withstand varies depending on the material or your fitting.

How are compression tube fittings used?

Stainless steel 316l compression tube fittings are used in a variety of applications. Anywhere you’re connecting a waterline or air pneumatic lines you will see a compression fitting used. If you’re just hooking up drinking water systems, you’re probably going to use a quick-connect or a quick-disconnect type fitting.

The angle stop underneath your sink is an example of a compression thread. These types of flex lines often will use compression-type threads to hook up to a coffee brewer, for example. Some have a faucet connection on one side and then the angle-stop connection, which is your compression thread, on the other. You can use just a regular compression nut and sleeve to attach tubing to the top of an angle stop. These fittings all connect the same way.

What to do if your compression tube fitting is leaking?

If SS 316L Compression Tube Fittings are leaking, you should determine where the leak is coming from. Usually, if you have a sound connection, you’ve put the fitting together properly, and you’ve wrenched it down to where it’s good and tight, the fitting is not likely to leak. Unless a piece of tubing is moved and puts some strain or torque on the fitting itself, the seal should be tight and complete.

Plastic fittings might be more prone to start leaking once they’ve been installed, but again, usually that’s because something has happened externally to alter or stress the component. Areas of excess vibration may stress plastic components. If you’re using a fitting on an appliance or a piece of equipment with a pump or a motor that causes vibration, the nut might back off of the fitting body.

Turning off the water is the best approach to halt a leak with this type of fitting. Once you’ve checked it for any problems, you’ll need to disassemble the fitting and put it back together. Hopefully, your leak will stop after being reassembled. If not, you could need to swap out the fitting, or a portion of it, along with the tubing that was attached to it.

Guide to installing and removing a compression tube fitting

316L Compression tube fittings are simple to install but require a wrench in most cases. They consist of three components: the sleeve, nut, and fitting body. All components work together to create a watertight seal. To create this seal, you must:

  1. Slide the nut onto your tubing.
  2. Slide the sleeve up to the nut on its threaded side.
  3. Put the tubing into the connector on the fitting body, and pull the nut, and then the sleeve, down so that the threads on the nut meet the threads on the fitting body.
  4. At that point, you will screw the nut onto the fitting body.
  5. Use your wrench to tighten the connection.

Simply carry out the same procedure backward to remove the fitting. The sleeve will stick to the tubing when you pull it out of the fitting body. Reusing the sleeve is only necessary if you are simply inserting it back into the fitting body or if you are using it to connect the same tubing to a different angle-stop configuration. To remove the sleeve from your tubing, you will need to cut it off if you are not reconnecting the tubing to another type of compression fitting.

Reference Link: https://www.freshwatersystems.com/blogs/blog/what-is-a-compression-fitting-and-how-does-it-work

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Rohan Vaghela

Rohan here!! Metallurgical Eng. From Mumbai India. Here to share some studies and blogs related to my work.