S = Mc / I Wherever: S = Tensile tension in psi; M = Bending moment in inch-pounds (wl2/eight); I = Instant of inertia—0.04909 (D4?d4) in inches fourth; c = Radius (D/two) of cylinder in inches; w = Weight for each inch of cylinder full of h2o; l = Length of cylinder in inches; D = Outdoors diameter in inches; d = Inside of diameter in inches.S =