What is a common structural material specified in API 650 for tank fabrication?

• A. Copper alloy
• B. Reinforced concrete
• C. Carbon steel
• D. Plastic sheeting

Answer: (C)

The choice of carbon steel as a common structural material specified in API 650 for tank fabrication is due to its excellent strength-to-weight ratio, weldability, and resistance to environmental factors when properly coated. Carbon steel tanks provide the necessary durability and support to store various types of oil and other fluids safely and effectively. Additionally, carbon steel is widely available and cost-effective, making it the preferred choice for large storage tanks in the oil industry.

In the context of API 650, carbon steel is specified primarily because it meets the rigorous standards required for structural integrity and safety in large-scale storage applications. The material can also be treated with various coatings to enhance its corrosion resistance, further extending the lifespan of the tanks. Other materials, like copper alloys and plastic sheeting, do not have the strength and durability needed to support the structural demands of large welded tanks. Reinforced concrete, while strong and useful in certain applications, is not typically used for the type of tanks outlined in API 650. Thus, carbon steel stands out as the optimal choice in this context.