Which term refers to the condition where bottom plates are designed under certain material stresses?

• A. Minimum thickness
• B. Butt-welded plates
• C. Allowable stresses
• D. Annular bottom plates

Answer: (C)

The correct choice is based on the concept of allowable stresses, which are the maximum levels of stress that materials can withstand without failure. In the context of bottom plates in welded tanks, the design must consider various stress factors, including tensile, compressive, and shear stresses due to the weight of the liquid stored and external loads.

Allowable stresses provide guidelines to ensure safety and structural integrity. They account for factors such as material properties, temperature variations, and load conditions to prevent failure of the tank structure. By adhering to allowable stresses, engineers can determine the minimum thickness of plates needed and ensure that designs are robust under expected service conditions. This is critical in maintaining the safety standards outlined in API 650.

In contrast, minimum thickness relates specifically to how thin the plate can be without compromising structural integrity, butt-welded plates describe a method of joining plates together, and annular bottom plates refer to a specific configuration of the plates in relation to tank design rather than the stress conditions.