A crude oil storage tank has an internal radius r of 80 feet

A crude oil storage tank has an internal radius \"r\" of 80 feet is filled with crude oil weighing 53 lbs/ft^3 to a depth \"H\" of 50 feet. If the tank is made of steel having a specific weight of 490 lbs/ft^3 and a thickness Y of 1.0 inches, find the circumferential stress and the longitudinal stress at the base of the tank.

Solution

Pressure acting at the bottom due to oil:

p = 53*50 = 2650 lbf/ft² = 18.4 psi

Circumferential stress = (pr/t) = (18.4*80*12)/(1) = 17666 psi = 17.666 ksi

Longitudinal stress = Tensile stress due to oil pressure - compressive stress due to slef weight

= (pr/2t) - (mg)/A = (pr/2t) - (density*A*H*g)/A

= (18.4*80*12)/(2*1) - 490*50/(144) psi = (8832-170) psi = 8662 psi = 8.66 ksi