What factor can significantly affect cathodic protection efficiency over time?

Changes in soil resistivity are a crucial factor that can significantly affect the efficiency of cathodic protection systems over time. Soil resistivity influences how well electrical currents can flow through the soil to reach the metallic structures that require protection. Variations in soil composition, moisture content, temperature, and the presence of contaminants can result in fluctuating resistivity values.

When resistivity increases, the effectiveness of the cathodic protection system may decrease because the current has a harder time reaching the structure, potentially leading to localized corrosion or insufficient protection. Conversely, if resistivity decreases, the current can travel more easily, which can enhance protection but may also lead to excessive current density that can cause other forms of damage, such as overstressing the coating.

Other factors like weather conditions, pipeline materials, and the location of the electrode do have some impact on the overall cathodic protection system but are not as directly influential on the fundamental electrical characteristics of the soil that governs current flow. Therefore, monitoring changes in soil resistivity is critical for maintaining effective cathodic protection over time.