API 571 Certification (Corrosion & Materials) Practice Test

Which material is less affected by aqueous organic corrosion?

1. Carbon steel

2. High-strength steel

3. Most corrosion-resistant alloys

4. Aluminum alloys

The correct answer is: Most corrosion-resistant alloys

The correct choice is that most corrosion-resistant alloys are less affected by aqueous organic corrosion due to their unique compositions and protective passive films that form on their surfaces. These materials, often containing elements like chromium or nickel, enhance their resistance to corrosion processes, including those caused by organic compounds in aqueous environments. Corrosion-resistant alloys are designed specifically to withstand harsh environments, including exposure to chloride ions and organic acids, which can lead to corrosion in less resistant materials like carbon steel or aluminum alloys. Their ability to maintain integrity and performance is crucial in applications where aqueous organic corrosion is a concern, making them suitable for a variety of chemical processing environments. In contrast, carbon steel and high-strength steels are generally more susceptible to corrosion when exposed to aqueous organic substances. They lack the same level of protection from passive films and thus can corrode more easily in these environments. Similarly, while aluminum alloys have good corrosion resistance due to their oxide layer, they can still be adversely affected by specific organic acids or aggressive environments, leading to localized corrosion.