With a wide variety of compression fittings and push-on pipe connectors readily available in the marketplace, flaring copper tubing has become all but obsolete. Relegated primarily for use with liquefied petroleum gas appliances, flare fittings used with flexible copper tubing require a properly shaped and sized flared tubing end to create a leak-proof seal.

Step 1: Use a tubing cutter to cut an appropriately sized section of type M or type L flexible copper tubing. Place the tubing between the cutter jaws and blade. Turn the tubing cutter’s knob to gently tighten the blade down onto the tubing.

Step 2: Swing the tubing cutter halfway around the tube in one direction and then back again around in the opposite direction. Turn the cutter knob to tighten the blade onto the tubing a little more and repeat the process, swinging the cutter back and forth and tightening the knob gently, until the blade cuts through the tubing.

Step 3: Ream the tubing end and remove any burrs to create a smooth and round opening before proceeding.

Step 4: With the wide end of the nut facing up, slip the flare nut onto the tubing.

Step 5: Secure the tubing into the flaring block so the cut end of the tube is flush with the top of the block.

Step 6: Position the reaming portion of the flaring tool over the tube opening and gently tighten the reamer down, forcing the cone-shaped end of the tool into the tubing opening. Allow the edges of the copper to splay open until the flared portion of the tubing appears to be the same size as the flaring block opening. If the tubing becomes misshaped or cracked, cut the end off and begin again.

Step 7: Place the rounded tip of the male flare fitting into the concave shape of the flared tube end to test the size and shape. The two pieces should fit together perfectly, creating a smooth metal-to-metal bond.

Step 8: Remove the tubing from the flare block and pull the flare nut up to the tubing end. The flared end should fit smoothly into the nut and the edges of the flare should not interfere with the threads of the nut.

Step 9: Hand tighten the flare nut onto the male flare fitting. Use an adjustable wrench to finish tightening it to assure a leak proof connection.