How to install brass compression fittings for plumbing

Updated February 21, 2017

Brass compression fittings form leak-free copper pipe connections without needing a blowtorch. Brass compression fittings have a ferrule -- also known as an "olive" -- and compression nut at every plumbing pipe connection. The compression nut squeezes the ferrule, a brass ring, against the plumbing pipe and the compression fitting's brass body. The pressure applied to the ferrule by the compression nut seals the connection. Unscrewing the compression nut will disconnect the compression fitting from the plumbing pipe; the ferrule and compression nut stay on the pipe.

Cut the end of the copper plumbing pipe with a copper tube cutter. Place the plumbing pipe between the tubing cutter's wheels and tighten the handle until the wheels grip the pipe. Rotate the tubing cutter one time around the pipe, then tighten the cutter's handle. Repeat this until the pipe snaps.

Clean the last 5 cm (2 inches) of the plumbing pipe with sandpaper. A compression fitting must connect to a clean and corrosion-free plumbing pipe.

Slip the compression fitting's compression nut over the clean end of the plumbing pipe. The nut's threads must face the end of the pipe the compression fitting mounts to.

Slide the brass ferrule or olive over the end of the pipe. Push the ferrule about 1.25 cm (1/4 inch) down the pipe.

Insert the clean end of the plumbing pipe into the compression fitting. Push the pipe into the fitting until the pipe's end hits the fitting's pipe stop. The pipe will stop sliding into the fitting once it hits the pipe stop.

Push the ferrule against the compression fitting's body.

Slide the compression nut to the compression fitting's threads. Spin the nut onto the fitting's threads. Finger tighten the nut.

Check the compression fitting's alignment. Insert all of the plumbing pipes into the compression fitting and finger tighten the nuts before continuing.

Place the correct sized open-ended wrench on the compression fitting's body. Hold the fitting still with the wrench.

Place the correct sized open-ended wrench on the compression nut. Tighten the nut with the wrench. Only turn the nut; the body must remain still. Repeat this for each compression nut.


If the compression fitting leaks water, then hold its body with one wrench and tighten the compression nut with another wrench. If the leak persists, then replace the ferrule.

Things You'll Need

  • Copper tube cutter
  • Sandpaper
  • Open-ended wrench set
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About the Author

Based out of Central Florida, Robert Sylvus has been writing how-to and outdoor sports articles for various online publications since 2008. Sylvus has been a home improvement contractor since 1992. He is a certified HVAC universal technician.