AMPP Cathodic Protection Technician (CP2) Practice Exam

In a cathodic protection system, the purpose is to reduce corrosion on pipeline surfaces by providing a more negative potential to the metal surface compared to its environment. When a reference electrode—typically a stable electrode such as a copper-copper sulfate electrode—is used to measure the potential of the buried pipeline, the areas that are experiencing corrosion (i.e., the anodes) will have a more negative potential relative to the reference electrode.

This is due to the electrochemical processes occurring at the corroding areas. These areas lose electrons (oxidation) and are therefore at a more negative electrochemical potential compared to areas that are protected or not experiencing corrosion. This negative shift indicates a higher likelihood of corrosion occurring at those sites.

Thus, when the potential is measured, corroding areas will show a potential value that is more negative than that of the reference electrode, which confirms that those areas are susceptible to corrosion. Understanding this relationship is crucial for assessing the effectiveness of cathodic protection systems and ensuring that pipelines remain well protected against corrosion.