It is desired to purchase a steel tank to store 20,000 US gallons of liquid propane; design pressure is 250 psig, and design stress is 20,000 psi. For steel, SG = 7.9. What will be the weight of metal in the shell (excluding foundation, valves, manholes, etc.) if the tank is a) Cylindrical with hemispherical end. The cylindrical section will have length = 6 times diameter. b) Spherical.