A cylindrical oil-storage tank, whose diameter is 120 ft, is 60 ft deep when it is fully filled with an oil of density 55lbm/ft³. Its top is open to the atmosphere.
a. What is the gauge pressure (psig) at the bottom of this tank?
b. If the design tensile stress (about 1/4 of the stress at rupture) of a cylindrical storage tank wall is 20,000 psi, how thick must the shell of the tank be at the bottom of it?
(Hint: Write a force balance between the tensile stress (or hoop stress) and the pressure for a thin slice (i.e., height, ?z and thickness, t? of the tank.)
c. What if the diameter of the tank is 60 ft? (The liquid height is still 60 ft when it is full.)