API 571 Certification (Corrosion & Materials) Practice Test

Which materials are preferred for use in oxygen-rich environments?

1. Copper Alloys

2. Polymeric Materials

3. Ni-Cr-Mo Alloys

4. Titanium Alloys

The correct answer is: Ni-Cr-Mo Alloys

Titanium alloys are preferred for use in oxygen-rich environments due to their specific properties that make them highly resistant to oxidation and corrosion. When titanium is exposed to oxygen, it forms a stable and adherent oxide layer on its surface that protects the underlying metal from further oxidation. This layer is a barrier that not only prevents oxygen from penetrating deeper but also provides a passive environment for the titanium itself. In addition, titanium alloys exhibit excellent mechanical properties, high strength-to-weight ratio, and good fatigue resistance, making them suitable for various structural applications in oxygen-rich conditions, such as in aerospace and marine environments. These alloys are also relatively lightweight compared to many other metals, which further enhances their suitability for diverse applications. While some of the other materials listed can have utility in specific conditions, they do not possess the same level of inherent resistance to oxidation as titanium alloys do in oxygen-rich environments, making titanium the material of choice in such applications.