API 571 Certification (Corrosion & Materials) Practice Test

Which type of corrosion affects all commonly used materials in the presence of ammonium chloride?

1. Localized corrosion

2. Crevice corrosion

3. General corrosion

4. All materials are susceptible

The correct answer is: All materials are susceptible

The correct response acknowledges the broad susceptibility of all commonly used materials to corrosion in the presence of ammonium chloride. Ammonium chloride, being a salt, can create a highly corrosive environment, particularly under certain conditions such as moisture or elevated temperatures. When ammonium chloride absorbs moisture from the air or is present in a humid environment, it can dissolve and form an acidic solution, leading to different types of corrosion mechanisms. These include localized and general corrosion, impacting metals and alloys alike. This susceptibility is not limited to certain alloys or materials; rather, it is a general characteristic of metals in aggressive environments, making it imperative for engineers and materials scientists to consider protective measures whenever ammonium chloride is a potential exposure risk. Hence, the idea that all materials are affected reflects the reality that there is no immunity in the case of ammonium chloride, further reinforcing the importance of implementing effective corrosion control strategies.