API 650 applies only to tanks whose bottom is uniformly supported and have a maximum design temperature not exceeding what?

• A. 150F
• B. 200F
• C. 250F
• D. 300F

Answer: (B)

API 650 specifically pertains to the design and construction of welded tanks for oil storage, with particular emphasis on the conditions under which these tanks are constructed and operated. The standard sets a limit on the maximum design temperature for storage tanks, which is crucial for ensuring structural integrity and preventing failure.

With a maximum design temperature not exceeding 200°F, API 650 is ensuring that the materials used in tank construction, typically carbon steel, maintain their required mechanical properties and do not undergo undesirable transformations that could lead to failure or leaks. At temperatures above this limit, the mechanical behavior of the materials can change, affecting their strength and ductility.

This is why the choice of 200°F is significant within the standard—it's a line drawn to ensure safe storage conditions for petroleum products. Tanks operating above this limit would need to adhere to different standards that consider the variations in behavior of materials at elevated temperatures.