Corrosion Mechanisms

Corrosion is defined as the destruction of deterioration of a material because of reaction with its environment. There are three principle elements in this deterioration process.

  • Nature of material (composition and microstructure)
  • Environment interacting with the materials
  • Reactions (electrochemical reactions and phase transition reactions

The corrosion may be categorised by different norms. The most common types of corrosion in oil and gas industry are listed here:

  • CO2 corrosion
  • H2S corrosion
  • Microbiologically influenced corrosion (MIC)
  • Galvanic corrosion
  • Crevice
  • Oxygen corrosion
  • Welding corrosion
  • Pitting corrosion
  • Erosion and cavitation
  • Flow assisted corrosion (FAC)
  • Stress corrosion cracking (SCC)
  • Hydrogen induced cracking (HIC)
  • Liquid metal embrittlement
  • Atmospheric external corrosion
  • Corrosion under insulation (CUI)

It is obvious that some items are forms of corrosion rather than the corrosion mechanism itself. For example, CUI could be either oxygen corrosion or SCC depending on the type of materials under insulation.  However, the advantage is  that most of them can be easily identified and reported through visual inspection without special equipment.

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