Cathodic Protection Requirements

Cathodic protection principle focuses in connecting an external anode to a metallic structure to be protected and passing through a dc current in order that the surface of the metal structure becomes cathodic and will not corrode or rust. The most important features of the cathodic protection system applied to metals exposed to a conducting electrolyte are as follows:

Galvanic Systems

• Sacrificial anodes.

• A secure and low resistance connection between structure and conductor, and between anode and conductor.

• A conductor that connects the anode to the structure, or directly welded to the structure.

Impressed-current Systems

• Source of dc power.

• A volume of inactive anodes, connected together in a grounded or in a backfill.

• Well insulated, low resistance and secure conductors between anodes and dc power source.

• A secure and low resistance connection between structure and conductor and between structure and dc power source.

The effectiveness of cathodic protection systems is assessed by a successive structure of electrolyte dc measurements at regular gaps or referred to as the close interval surveys. Close interval survey does not refer to cell-to-cell survey techniques that are used to evaluate the current direction using RTU remote, or the coating’s effectiveness. Using terminal unit, close interval surveys could detect the presence of copper sulfate in the metal, which is an indication of corrosion.