Types of Cathodic Protection

Cathodic protection is a method for corrosion control. It works by eliminating some of the elements of the corrosion cell.

Galvanic Anodes:

This involves the creation of a galvanic cell in which the metal to be protected acts as a cathode (positive pole of the battery) while the anodic metal is sacrificed, which means it gets dissolved in the medium. Due to its low price and high mechanical strength, steel is the metal most commonly used. Therefore, the metals that can be connected to it should have a more negative potential such as zinc (ZN), aluminum (Al) and magnesium (Mg).

ADVANTAGES

  • Easy installation
  • Low maintenance
  • Uniform current distribution
  • No need for external power source

LIMITATIONS

  • Low current supplied
  • Inefficient in environments of high resistivity

• Impressed current:

This involves connecting the metal to protect the negative pole of a DC power source and the positive pole to an auxiliary electrode (anode). This system is known as cathodic protection impressed current.

ADVANTAGES

  • Wide range of voltage and current output
  • Effective for bare or poorly coated structures
  • Effective in high resistivity environments

LIMITATIONS

  • Requires more maintenance
  • Cost for continuous power supply
  • It may cause interference by stray currents
  • Damage Protection in the lining
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