Impressed current protection anodes are widely recognised as a superior alternative to sacrificial anode systems in solving corrosion problems. In this guide we explain what they are, how they work and the different types available.
What are impressed current cathodic protection anodes?
Impressed Current Protection Anodes, or Impressed Current Cathodic Protection (ICCP) systems, are a method of corrosion protection that uses a source of electricity to apply an electric current to the anodes that are then used to protect a steel structure, such as a pipeline or steel tower.
These systems are generally seen as beneficial for larger structures, or where sacrificial anodes cannot economically deliver sufficient current protection to provide the required cathodic protection output.
Impressed anodes are widely seen as a more sophisticated and long-term solution to a corrosion problem. The impressed current system enables the current or driving output to be accurately controlled or varied and it gives the corrosion engineer greater flexibility than a sacrificial anode system.
How do impressed current cathodic protection anodes work?
Impressed current anodes use and require a source of electricity to “power” the anodes and thus set up the same type of cell that is seen with sacrificial anodes where electrons flow from the anode, through the electrolyte (often the soil) and to the cathode (often the pipeline).
These anodes can be made of various materials, including cast iron, mixed metal oxide (MMO), or graphite. The anode itself can come in many shapes and sizes, such as rods, tubes, wires, plates or even in mesh form.
The anode is installed within the electrolyte around the structure to be protected and connected to the positive output, while the structure is connected to the negative terminal.
Types of impressed current protection anodes
Mixed Metal Oxide anodes (MMO), or dimensionally stable anodes, consist of a rare earth oxide coated onto a titanium substrate. They provide a highly effective corrosion prevention system for various applications and environments, including seawater, brackish water, fresh water, with or without carbon backfill, and also in concrete.
Due to the high stability and low consumption rate of the MMO coating, this type of anode has a much longer lifespan than alternative solutions and provides excellent chemical resistance, especially in acidic conditions.
Silicon Iron anodes, available in both tubular and stick varieties, are a proven cathodic protection solution commonly used in fresh water, seawater, and deep grounded applications.
They are a popular choice for cathodic protection systems due to their low specific resistance, suitability for a variety of applications, proven low consumption rate and dependability.