What is the primary purpose of anodes in cathodic protection?

The primary purpose of anodes in cathodic protection is to discharge current and protect against corrosion. In a cathodic protection system, the anodes are deliberately corroded in order to prevent corrosion of the protected metal structure, which is referred to as the cathode.

When the anodes are connected into the circuit, they develop a potential that drives current towards the cathode, effectively making the cathode less susceptible to electrochemical reactions that can cause corrosion. This is known as "sacrificial cathodic protection" when the anodes are consumed (like zinc anodes used in marine applications) or "impressed current" when an external power source is utilized to maintain the protective current.

This approach is vital in preserving the integrity and longevity of metal structures such as pipelines, tanks, and other submerged or buried constructs that are at risk of corrosion due to environmental conditions. The ability of anodes to discharge current efficiently is what enables these protective measures to be successful in reducing the rate of corrosion at the cathode.