Things You'll Need
Dremel tool with wire brush attachment
Epoxy putty and hardener
Sealing pipe wrap
Cracks in copper water pipes can lead to property damage and increased water costs, and gas line cracks can be extremely dangerous. Depending on your skills and resources, you can repair cracked copper pipes through soldering, plugging with epoxy or wrapping with a commercial wrap seal kit. All three techniques make a watertight, permanent repair.
Turn off the water or gas supply and remove the damaged pipe, using a wrench.
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Sand the damaged area with a dremel tool and wire brush attachment to reveal shiny bare metal. If you want to apply epoxy putty or sealing wrap, wash the entire pipe with a commercial copper cleaner in addition to sanding.
Paint flux paste onto the cracked portion and solder it with a propane torch and lead-free solder. Alternately, mix epoxy putty and hardener according to package directions and press it around the pipe to cover the cracked portion completely. Only use an epoxy putty labeled for use with copper.
Cut a piece of sealing pipe wrap large enough to fit around the damaged section and press it in place over the dried epoxy or solder for added, optional protection. If your pipe's pressure is 15 psi or less, meaning you can stop the leak effectively with your thumb, you can use the wrap alone instead of soldering or applying epoxy. Only use the wrap on pipes with temperatures lower than 160 degrees Fahrenheit.