How to Anneal Copper Tubing

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Things You'll Need

  • Oxygen acetylene torch

  • Striker

  • Copper tubing

  • Water

Image Credit: Comstock/Comstock/Getty Images

Bending copper alters its internal structure, and the more the metal is worked the more brittle it becomes, until it reaches a breaking point and fractures. Working with copper tubing you'll find occasions that require tubing to be bent. To bend the tubing without creating a brittle metal, you must anneal the tubing. Annealing copper requires you to heat the copper so that it softens, as soft copper can be worked without becoming brittle.


Step 1

Completely shut off the valves on the oxygen and acetylene tanks. Connect the torch head to the oxygen and acetylene tanks using the torch hoses. Put on a pair of welding gloves and switch on the acetylene but turning the valve. Light the acetylene with a striker. A clear flow of the gas should produce an orange-red flame. Start the oxygen flow by turning the valve on slowly. Add the oxygen to the acetylene until the flame burns blue.

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Step 2

Aim the torch at the place on the tubing you want to bend. Run the flame over the copper, moving steadily over it, heating the copper until it glows a dull cherry red.

Step 3

Turn the torch off by closing the oxygen valve, followed by the acetylene valve.


Step 4

Set the copper tubing aside for it to cool by air, or quench the tubing in water. Cool the copper fast so that it becomes soft. Water cool the tubing for a more workable material.

Step 5

Work the cooled tubing, bending to shape as needed.


If the copper becomes rigid as it’s worked, anneal the tubing again to return its softness.


Always maintain a fire extinguisher nearby when welding. Do not continue heating the copper once it reaches the cherry red stage as you may burn the metal, turning it a yellow color and making it brittle.


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