Copper-copper sulfate electrodes are used ________.

Copper-copper sulfate electrodes are primarily used to make potential measurements in corrosion control applications. These electrodes serve as reference points for assessing the corrosion potential of a metal structure in its surrounding environment, particularly in pipelines and other buried metallic structures.

When immersed in soil or water, the copper electrode and the saturated copper sulfate solution create a stable potential, allowing for accurate measurements of the electrochemical potential of the structure being tested. This information is crucial when evaluating the effectiveness of cathodic protection systems, as it helps identify whether a pipeline is adequately protected against corrosion.

While the other options may relate to various practices in corrosion control and monitoring, they do not specifically utilize copper-copper sulfate electrodes for their primary function. For example, monitoring foreign structures may involve different methods or sensors, and while galvanic protection is a way to mitigate corrosion, it relies on different materials and setups rather than solely on the use of copper-copper sulfate electrodes.