What aspect of the tank bottom's final layer is emphasized in API 650?

• A. It should be coarse and uneven
• B. It must be fine and uniform
• C. It must be thick and solid
• D. It should be filled with large rocks

Answer: (B)

The emphasis on the final layer of the tank bottom in API 650 being fine and uniform is critical for ensuring the overall integrity and stability of the tank. A fine and uniform final layer provides a stable supporting base for the tank structure, which is essential in preventing uneven settlement and potential structural failure. This uniformity helps to distribute the weight of the tank and the stored product evenly across the underlying soil, minimizing stresses that could lead to damage over time.

In the context of tank design and operation, a smooth, uniform surface also aids in proper sealing and minimizes the risk of leaks or corrosion that could result from uneven surfaces. The specifications outlined in API 650 ensure not only compliance with safety standards but also the longevity and reliability of the tank system. This careful attention to the quality of the final layer is an integral part of good engineering practice in tank design and installation.