What is the maximum allowable deviation for a concrete ring wall's level within any 30 ft of circumference according to API 650?

• A. 1/4"
• B. 1/8"
• C. 1/2"
• D. 3/8"

Answer: (B)

The maximum allowable deviation for a concrete ring wall's level within any 30 ft of circumference according to API 650 is established to ensure proper alignment and structural integrity of the tank being constructed. A deviation of 1/8" is specified because it allows for a high degree of precision, which is crucial in the context of storing liquids. This level of accuracy helps prevent issues such as uneven stresses on the tank shell, water pooling, and potential unforeseen structural failures.

When the concrete ring wall is leveled to such precise tolerances, it ensures that the tank's shell can be uniformly constructed and maintained. This adherence to stringent criteria reflects the importance of maintaining safety and operational standards in the design and installation of welded tanks for oil storage. The choice of 1/8" embodies the need for careful structural engineering and construction practices in the industry.

In contrast, other options suggest greater levels of deviation, which could lead to safety issues and operational inefficiencies. Adhering to the standard of 1/8" helps mitigate these risks effectively.