What is the minimum requirement for cathodic polarization in order to effectively control corrosion?

The minimum requirement for cathodic polarization to effectively control corrosion is 100mV. This threshold is based on industry standards that indicate a minimum potential shift must be achieved to adequately protect metal surfaces, particularly those exposed to corrosive environments.

When a cathodic protection system is applied, the goal is to shift the corrosion potential of the metal a sufficient distance into the cathodic area of the polarization curve. A 100mV shift is established as a benchmark because it generally indicates that the protection system is functioning well, providing a level of polarization that interferes with the electrochemical reactions causing corrosion. This ensures the metal structure remains passive and less prone to corrosion damage over time.

A shift of this magnitude allows for a robust protective effect in most scenarios, ensuring that varying conditions such as soil resistivity, current density, and the specific environment do not lead to corrosion activity. Hence, achieving at least 100mV is critical for confirming that cathodic protection is active and effective against corrosion.