Understanding Corrosion in Water Pipelines: A Guide for Pipeline Designers


Protective Potential

Last updated: December 27, 2013

What Does Protective Potential Mean?

Protective potential is the threshold value of voltage for a given metal at which it remains passive in the specified environment.

Protective potential is used for:

  • Ascertaining the effectiveness of corrosion protection of critical pipelines and structures
  • Designing and choosing the components of cathodic and other protection systems
  • Calibrating systems and research work related to metal repassivation and problems of pitting

Corrosionpedia Explains Protective Potential

To ensure the effectiveness of a corrosion protection system, the potential of the metal must be maintained within a zone known as the protective potential range. Within this range, the potential remains protective and metal remains passive. The corrosion potential of the metal remains outside this range.

The methods used for preventing corrosion include anodic or cathodic protection as well as chemical inhibitors. These methods involve controlling the electrical charge on the surface of the metal. Monitoring can be done by measuring the voltage of the metal with reference to a standard reference electrode. The amount of protective voltage needed to be maintained on the metal surface to stop corrosion can be estimated from the phase diagram.

In the case of cathodic protection, the potential of the metal surface is forced into a negative region relative to the sacrificial anode, which is made of a reactive metal. This region represents the zone of protective potential.


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