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How to Flare Copper Tubing

If you need to connect copper tubing to another tube, you'll have to flare the end of it so that it doesn't slide away from the connector. You can only flare flexible copper---the kind that can be bent to maneuver it around curves and corners. Flaring hard copper tubing will cause splits, thus making the tubing useless. When you need to flare copper tubing, you'll have to use a copper tubing flaring tool, which makes the procedure quick and painless.


  1. Determine the size of the copper tubing that you want to flare by measuring its diameter.
  2. Insert the copper tubing into the part of the copper tubing flaring tool that holds the copper in place so that some of the tubing sticks out of the holder. The more tubing you have sticking out, the bigger the flare. If you have too much sticking out, the tubing may split, so be careful.
  3. Adjust the copper tubing flaring tool so that the tubing fits tightly inside. You don't want the tubing to be loose because if it moves around inside the holder, flaring the copper will be more difficult than it should be.
  4. Once the copper tubing is secure in the holder, insert the conical part of the copper tubing flaring tool into the end of the tubing and attach the arms to the holder.
  5. With everything attached, twist the handle on the conical part of the tool clockwise to flare the copper tubing. When you're finished, the end of the tubing that you flared should look like the end of a trumpet.

Things You Will Need

  • Copper tubing flaring tool