What materials are often specified for fabricating tanks according to API 650?

• A. Titanium and aluminum alloys
• B. Carbon steel and certain low-alloy steels
• C. Fiberglass composites and polymers
• D. Concrete and reinforced plastics

Answer: (B)

The specification for materials used in fabricating tanks according to API 650 primarily includes carbon steel and certain low-alloy steels. These materials are favored due to their strength, weldability, cost-effectiveness, and suitability for various tank applications in oil storage.

Carbon steel provides a good balance of mechanical properties and is well-suited for the fabrication of large tanks that can withstand the stresses associated with oil storage. Low-alloy steels, which contain other elements in addition to carbon, offer improved mechanical properties such as better resistance to corrosion and higher strength compared to standard carbon steels, making them preferable for certain environments and applications.

In contrast, the other mentioned materials, while suitable for various applications, do not typically meet the requirements set forth in API 650 for the storage of oil in welded tanks. For instance, titanium and aluminum alloys are generally used in specialized applications where weight and resistance to corrosion are critical factors, but they are not the primary materials for large storage tanks. Fiberglass composites and polymers are more common in smaller storage systems and are not typically used in bulk oil storage due to their limitations in strength and longevity. Concrete and reinforced plastics are used in specific applications but do not align with the standards and practices outlined in API 650 for large welded