How to Flare a Copper Pipe

web of copper piping
What You'll Need
Copper pipe
Flaring tool
Tube cutter
Compression fitting

When you’re using copper pipe for plumbing, you will need to use compression fittings. To use them correctly, you’ll need to flare the copper pipe so that the fittings will be tight. It’s a very common plumbing procedure, so if you’re going to be doing much plumbing work, you can expect to encounter if regularly. With the right equipment, it’s very easy to flare copper piping. The correct equipment is cheap and makes a very good DIY investment. You can buy flaring tools and copper pipe cutters at all hardware stores.

Step 1 - Cut the Pipe

cutting a long piece of copper

Before you flare the copper pipe, you need to cut it to the right length. For this, you need to use a proper cutting tool rather than a hacksaw. The hacksaw will cut the pipe but can leave the edges ragged which won’t be ideal for precision plumbing.

The cutting tool circles around the pipe, gradually cutting through the copper and leaves a clean edge, which is perfect for plumbing fixtures and fittings. It’s always best to cut the pipe a little longer than you need; this makes allowances for any problems you might encounter when flaring the tubing, as rectifications can be made.

Step 2 - Put in the Flare Form

The flaring tool consists of two elements made of a reamer, which does the actual flaring, and a flare form. The flare form holds the copper pipe firm so it can be flared evenly with minimal effort. Before starting to fit the pipe in the flare form, remember to slide the compression nut over the tubing, making sure it’s facing the right way.

The flare form will be in two halves and will have several different holes. Each of these can accommodate a different diameter of copper pipe. Select the right one for the pipe you’re working on and insert the tube, closing the flare form on it. The top of the pipe needs to be flush with the top of the flare form but not extending beyond it. The flare form will be beveled; this will allow for the flare on the pipe.

The flare form will have wing nuts at each end. Tighten these to hold the tubing firm. Tighten alternately to ensure the tubing is held evenly.

Step 3 - Flare the Pipe

heating a copper piping seam

To flare the pipe, place the reamer on top of the flare form with the reamer against the pipe. The arms of the reamer will tighten against the flare form as you tighten the reamer.

Slowly tighten the reamer as you push down on the pipe. As the pipe flares, tightening the reamer will become more difficult. Keep tightening until you can’t turn the reamer any more.

Loosen the reamer until you can remove it. The flaring should be even and smooth. Loosen the clamps on the flare form and remove the copper tubing. If the flaring isn’t even or smooth, this is due to the pipe slipping as you used the reamer. To correct this, you’ll need to cut the tubing below the flare and repeat the procedure.