What are the two primary types of cathodic protection?

The two primary types of cathodic protection are indeed impressed current and galvanic.

Impressed current cathodic protection (ICCP) involves using an external power source to provide a constant electric current to the metal structure, which helps to counteract the corrosion process. This method is particularly effective for large structures, such as pipelines and storage tanks, where it can provide a consistent and adjustable level of protection. The impressed current is delivered through anodes that are strategically placed near the structure, creating a controlled environment for protection.

Galvanic cathodic protection operates on the principle of using sacrificial anodes made from more reactive metals. These anodes corrode preferentially, providing electrons to the protected structure, thus reducing its corrosion potential. This method is simpler and does not require a power source, making it suitable for smaller structures like pipelines and vessels in environments where electrical power may not be easily accessible.

Understanding these two primary types allows for selecting the appropriate cathodic protection system based on the specific requirements of the structure being protected, including its size, environment, and the nature of potential corrosion risks.