A cylindrical storage tank is to have an inner diameter of 12 ft. and a length of 36 ft. The seams will be welded and the material of construction will be plain carbon steel (0.15% C). The maximum working pressure in the tank will be 100 psig and the maximum temperature will be 25 C. No corrosion problems are anticipated. On the basis of the ASME equations, estimate the necessary wall thickness.
For the design of internal-pressure cylindrical vessels, the API-ASME Code for Unified Pressure Vessels recommends the following equations for determining the minimum wall thickness when extreme operating pressures are not involved:
Note: Equations in the two editions differ as they refer to two different versions of the ASME Boiler and Pressure Vessel Code and use either English or meteric units for the specifications. For purposes of this problem, state the Peters edition that you are using and use the equations and units given in that edition.
Continuing, for example,…
where
t = wall thickness, in.
P = internal pressure, psig (this assumes atmospheric pressure surrounding the vessel)
Dm = mean diameter, in.
D, = ID, in. Do = OD, in.
E = fractional efficiency of welded or other joints
C = allowances, for corrosion, threading, and machining, in.
S = design stress, lb/in2 (for the purpose of this problem, S may be taken as one-fourth of the ultimate tensile strength)
