API 571 Certification (Corrosion & Materials) Practice Test

Dissolved oxygen plays a significant role in metal corrosion, particularly in aqueous environments. When oxygen is present in water, it can participate in electrochemical reactions that accelerate the corrosion process of metals. In the presence of moisture, metals can undergo oxidation, where the metal loses electrons and forms metal ions. Dissolved oxygen acts as a cathodic reactant in these reactions, meaning it facilitates the reduction half-reaction that occurs at the cathode, which supports the overall corrosion process.

The presence of dissolved oxygen enables the formation of tiny corrosion cells on the metal surface. This can lead to localized corrosion phenomena such as pitting, where small and aggressive areas of corrosion cause significant damage to the structure over time. Therefore, the increased availability of dissolved oxygen generally corresponds with a higher corrosion rate in metals due to its role in enhancing the electrochemical reactions involved in corrosion.

Understanding the role of dissolved oxygen in corrosion is critical for preventing and mitigating corrosion in various environments, especially in systems that involve water, such as pipelines, storage tanks, and marine structures. Thus, stating that dissolved oxygen increases the corrosion rate accurately reflects its detrimental effect on the integrity of metals in corrosive environments.