When using the 1 ft method, what does 'G' represent?

• A. Design liquid level in feet
• B. Corrosion allowance in inches
• C. Specific gravity of the liquid
• D. Allowable stress for design condition

Answer: (C)

In the context of the 1 ft method used in API 650 for determining the thickness of tanks, 'G' signifies the specific gravity of the liquid being stored. This is essential because specific gravity, which is the ratio of the density of the liquid to the density of water, directly affects the hydrostatic pressure exerted on the tank walls. Understanding the specific gravity allows engineers to calculate the corresponding pressure and, thus, determine the appropriate thickness of the tank material needed to safely accommodate the weight of the liquid. This metric plays a crucial role in ensuring that the storage tank is designed to withstand the stresses and pressures generated by the stored contents, enhancing both safety and structural integrity.