Copper Pipe and Cathodic Protection

I was recently contacted about what to do when cathodic protection is required on copper piping. Copper, being a more noble metal (around -0.20V-Cu/CuSO4 vs. around -0.60-Cu/CuSO4 for steel), tends to corrode at a much slower rate than steel. Because of this typically you don’t see cathodic placed on copper piping. However, this in not always the case. In soil that is more corrosive, you may need to add cathodic protection to your copper piping.

If you do need to put cathodic protection on your copper line, typical exothermic welding used to attached test leads and/or anodes to steel and ductile pipe does not work for copper. Exothermic welding gets too hot for copper piping. To attach these leads to copper pipes, you will need to use a silver solder, just like is used for household plumbing. It is also a good idea to wrap the copper pipe with a coating like wax tape.

One final note about copper pipe: if you ever need to connect copper to steel, they need to be electrically isolated from each other. Otherwise, your steel will act as an anode to protect your copper pipe and corrode at a faster rate.

If you have any questions, feel free to contact me.