What is the minimum radius required for the rounded corners of insert plates?

• A. 5" or 5t where t is the thickness of the shell
• B. 4" or 4t where t is the thickness of the shell
• C. 6" or 6t where t is the thickness of the shell
• D. 8" or 8t where t is the thickness of the shell

Answer: (C)

The minimum radius required for the rounded corners of insert plates is critical for ensuring both the structural integrity of the tank and the optimal performance of the welded seams. A radius of 6 inches or 6 times the thickness of the shell, represented as 6t, effectively provides the necessary support and reduces stress concentration in these areas. This helps to avoid potential points of failure during service, especially when the tank undergoes thermal expansion, pressure variations, and other operational stresses. The 6-inch radius is stipulated in standards to cultivate a balance between manufacturability and mechanical performance, making it a widely accepted practice in the design and construction of welded tanks for oil storage. This standard ensures that the transition from flat surfaces to the rounded corners does not compromise the overall integrity and safety of the storage tank.