How does „galvanic corrosion” occur in the case of a cast iron valve installed in copper pipework system?
The copper piping acts as a cathode and the valve body made of cast iron acts as the anode. If the total surface of the cathode is larger then the surface of the anode, then the anode will be sacrificed or consumed during this process. Avoid making (material) combinations where the area of the less noble anodic metal (cast iron) is relatively small compared with the area of the more noble cathodic metal (copper piping).