What type of load combinations does API 650 consider in tank design?

• A. Only dead loads and live loads
• B. Seismic loads and thermal effects exclusively
• C. Dead loads, live loads, wind loads, seismic loads, and thermal effects
• D. Only wind loads and thermal effects

Answer: (C)

The correct response reflects a comprehensive approach to tank design as outlined in API 650, which emphasizes the importance of considering a variety of load combinations to ensure structural integrity and safety. In tank design, various loads can act on the structure, and API 650 specifically incorporates dead loads, live loads, wind loads, seismic loads, and thermal effects as critical factors to evaluate.

Dead loads refer to the weight of the tank and any permanent attachments, while live loads pertain to external influences that may change, such as occupancy or maintenance activities. Wind loads are significant, particularly for structures of considerable height, as they can introduce lateral forces. Seismic loads are also crucial, especially in regions that are prone to earthquakes, as they can result in substantial stresses on tanks. Additionally, thermal effects must be taken into account since changes in temperature can affect both the fluid inside the tank and the material properties of the tank itself.

By recognizing and analyzing all these potential loads, API 650 ensures that the design of welded tanks for oil storage is robust, safe, and compliant with industry standards, thereby enhancing operational reliability and minimizing risks associated with tank failure. This holistic view of load combinations is essential for engineers to create effective designs that can withstand a variety of conditions during the