How to Replace Compression Fittings

Written by richard asmus
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Plumbers use compression fittings mostly to connect copper tubing to appliances or fixtures that will eventually be replaced, such as dishwashers, faucets, and refrigerators with icemakers. When you replace the appliance or fixture, you need to replace the compression fitting. You don’t need to replace the entire fitting, only the ferrule inside to make a new compressed seal. You could possibly reuse the old one, but this creates a risk of an improper seal and an eventual leak.

Skill level:

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Things you need

  • Wrench
  • Copper tubing cutter
  • Emery cloth
  • New ferrule
  • Pipe joint compound

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  1. 1

    Shut off the water supply to the appliance or fixture.

  2. 2

    Loosen the compression nut from the body of the compression fitting with a wrench.

  3. 3

    Pull the copper tubing out of the fitting. The ferrule will come out with the tubing as it should be stuck to it from the original installation that compressed it to the tubing.

  4. 4

    Cut the copper tubing as close to the ferrule as you can using the copper tubing cutter.

  5. 5

    Clean the copper tubing with emery cloth to remove any corrosion or dirt.

  6. 6

    Slide the new ferrule onto the copper tubing.

  7. 7

    Apply a light coat of pipe joint compound to the ferrule and the male threads.

  8. 8

    Replace the tubing into the fitting. Be careful not to let the ferrule slip off. Push the tubing all the way into the fitting until it seats.

  9. 9

    Tighten the nut with the wrench. Hold the tubing in place while you tighten it to keep it from slipping out.

  10. 10

    Turn on the water and check for a leak. If there is a leak, gently tighten the fitting until the leak stops.

Tips and warnings

  • You may need a second wrench to hold the body of the fitting while loosening or tightening the nut, depending on the layout of the fitting.
  • Do not over tighten the fitting. Once you start to feel a resistance in the tightening process, continue tightening only one half of a turn. An over tightened fitting can crack and leak. Make sure there are no bends or dents in the tubing where the ferrule will compress onto it. A bend or dent will cause an improper seal and a leak.

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