What Are Compression Fittings?

Compression fittings are commonly used in plumbing and electrical conduit systems to join two tubes or thin-walled pipes together. They are especially useful for joining pipes or tubes with a small flow diameter as well as for those in low-pressure environments between -5 PSI and 125 PSI. Compression fittings can be categorized into two general types: Type A and Type B. Knowing the different designs, uses, and installation processes for these two types can be helpful for choosing the right option to fit any application.

What Are Type A Compression Fittings?

Type A compression fittings are also called non-manipulative or flareless fittings as they can be installed without needing to make modifications to the pipe or tubing that they are being applied to. In addition, a standard wrench is all that is needed to position this type of fitting, making them quick and easy to install. Type A compression fittings are also well designed for thin-walled pipes and are therefore used in many plumbing applications such as to connect hot or cold faucets in a shower.

How to Install and Remove Type A Fittings

Installation of Type A fittings vary by the material of the associated pipe or tubing. However, copper and plastic are the most common materials used. As such, the following steps are meant to be used for installing fittings on copper or plastic components:

For a copper pipe, a compression fitting must be installed along with a nut and a brass ring. First, a nut is slid onto the copper pipe, making sure that the threads face the compression fitting. Then, a brass ring is slid onto the copper pipe in between the nut and the fitting.

For plastic tubing, a compression fitting must be installed with a nut, plastic sleeve, and a brass tube. Like installation on a copper pipe, the first step is to slide the nut onto the plastic tubing. Then, the plastic sleeve is slid onto the tube with the fatter end facing the nut and the tapered end facing the fitting. After that, the brass fitting is inserted into the plastic tubing.

The final step of installation for either copper or plastic tubing is to insert the tube or pipe into the back of the compression fitting and tighten the nut. To do this, the nut should first be twisted by hand onto the tube or pipe until it cannot be moved any more and then fully tightened with a wrench. For copper pipes, the nut should be moved by a half a revolution with the wrench whereas for plastic tubing, the nut should be moved a full revolution. For easy removal, the nut can be loosened with a wrench so the parts can be disassembled.

What Are Type B Compression Fittings?

Also called manipulative fittings, in order to install this type of fitting, you will need to modify the tubing it is applied to. Most Type B compression fittings require that the tubing is flared on one end to insert the fitting. Though these compression fittings can be used for water pipes, they are mainly used in below-ground connections such as in gas lines.

How to Install and Remove Type B Fitting

The same steps are taken to install Type B fittings as for Type A fittings, except that the pipe must first be flared before the Type B fitting is installed. This step should be executed only after the nut and brass ring, or plastic sleeve and brass tube, are installed. Tubing should have a 45-degree flare whereas pipes should have a 37-degree flare. After flaring the tube or pipe, the compression fitting is inserted into the flared end. Then, the nut can be tightened in the same way as in the installation of Type A fittings. However, in contrast with Type A fittings, removal requires the use of a specialized pulling tool to help slide the nut and other pieces from the tube or pipe.

When and When Not to Use Compression Fittings

Type A and Type B compression fittings are both ideal for small diameter pipes and tubing within a low-pressure environment. They are designed to restrict pipe movement away from the fitting, so care should be taken to not overtighten them. In addition, neither fitting should be used with bent tubes or pipes.


Compression fittings are a useful type of fastener for connecting tubes and thin-walled pipes in plumbing, gas lines, and more. If you are in search of dependable fitting and/or other mechanical components for your next project, Fulfillment 3Sixty is here to assist you. With an inventory of over 2 billion new, used, obsolete, and hard-to-find NSN components, our customers are sure to find all the high-quality parts they require. In addition, our widespread supply chain of trusted manufacturers ensures that our items can be shipped with rapid lead times and offered at competitive prices. Get started today to see how Fulfillment 3Sixty could become your premier strategic sourcing partner. You may browse our catalog of available parts on our website and send us a completed Request for Quote (RFQ) form to get a competitive quote for your comparisons in just 15 minutes!


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