How to Re-Round Copper Tubing

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Things You'll Need

  • Steel rod or mandrel

  • Vise

  • Hammer

  • Mallet

Repair rather than replace copper tubing.

Copper tubing has many residential and commercial applications including plumbing, heating, refrigeration and air conditioning. Copper tubing is easy to work with, long lasting and durable, making it a dependable choice. It is flexible, allowing installation without the need for cutting and attaching elbows, thus allowing for easier installation. It can incur damage and crush or kink. Straightening and re-rounding copper tubing to permit the maximum flow is important to the project you have in mind.


Step 1

Straighten the copper tubing as much as possible by hand. Roll it out flat rather than leaving it coiled.

Step 2

Place the copper tubing on a flat and level surface or on the ground.

Step 3

Place a steel rod that is slightly smaller in diameter than the diameter of the copper tubing into a vise with 1/2 inch standing above the top of the vise. Hit the top of the rod with a hammer to mushroom it. Creating a mushroom top prevents the steel rod from becoming stuck inside the copper tubing. Choose a steel rod length that equals at least half of the total length of the copper tubing.


Step 4

Insert the steel rod into an open end of the copper tubing. If the kink or crush is near the end of the copper tubing, you can also use a steel mandrel to open up the copper tubing.

Step 5

Tap the end of the steel rod or mandrel lightly with a mallet while holding the tube firmly against the work surface. Make sure the tubing is free of bends. If there are bends, you can drive the steel rod or mandrel through the wall of the copper tubing.

Step 6

Continue to hand-straighten and tap the steel rod or mandrel into the tubing, expanding the tubing and making it round again. Remove the steel rod from the end of the copper tubing and place it in the other end. Hand-straighten the copper tubing and tap the steel rod until it is round again.


Stop tapping the rod when you have almost reached the end of the tube to prevent widening the opening of the copper tubing with the mushroom head on the rod.


Sal Marco

Sal Marco began writing professionally in 2009. He has written many online home improvement articles based on his more than 20 years of experience in the home improvement and building industries. He has worked as both part of a team and as a site supervisor. Marco has a Bachelor of Science in management science from Kean University.