Impressed Current

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Definition - What does Impressed Current mean?

Impressed current is a type of cathodic protection utilizing electrochemical means to obtain protection against corrosion. This reduces the dissolution of anodic structures by decreasing the difference between potential energy and the cathodic and anodic sites on the metal surface when put into a conductive electrolyte such as water, concrete or soil.

Theoretically, impressed current cathodic protection is obtained during the stage where open circuit potential of cathodic areas gets polarized into the same circuit potential of anodic sites. The key in impressed current protection is to turn the whole structure cathodic in nature, or make it a current receiver rather than a current provider.

Corrosionpedia explains Impressed Current

An impressed current protection system can offer protection to structures and metals like:

  • Fuel pipes
  • Steel
  • Water
  • Hulls
  • Tanks
  • Water heaters
  • Oil casings
  • It can also serve as a metal reinforcement in the case of concrete buildings, structures and bars. It can be applied in galvanized steel, where sacrificial zinc coatings protect steel parts from the harmful effects of rusting.

    Utilizing this type of protection offers the following practical benefits:

  • Reduction in infrastructure corrosion cost
  • Fewer incidences of infrastructure failure
  • Lower chances of product loss from corrosion
  • Lower downtime in terms of emergency repairs
  • Increased service life of infrastructures
  • Enhanced quality of infrastructure service
  • Increased security and health to underlying infrastructures
  • An impressed current system serves as an ideal protection system for bigger structures that are not capable of delivering ample current to offer protection. This system is mainly composed of anodes attached to a power source (DC), which can be a rectifier connected to power (AC). In the absence of an AC power supply, other power sources may be used like wind power, solar panels and gas power. The anodes in the impressed current protection system can be found in various sizes and shapes. The most common ones are tubes and solid rods, while there are also continuous ribbons made from various materials like:

  • Platinum
  • Graphite
  • Silicon
  • Cast iron
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