Question
Pressure
A closed-end cylindrical pressure vessel constructed of carbon steel has a wall thickness of 2 mm, a diameter of 150 mm, and a length of 760 mm. What are the hoop and axial stresses sigmatheta, sigmaz when the cylinder carries an internal pressure of 10 MPa? How much does the radius of the cylinder expand due to the internal pressure?
Explanation / Answer
t = 2 mm D = 150 mm t/d = 1/75 since (t/d) < (1/10 to 1/15) => thin cylindrical vessel hoop stress = p*D/(2*t) = (10*10^6 Pa)*(0.15 m)/(2*0.002 m) = 3.75* 10^8 Pa axial stress = p*D/(4*t) = hoop stress/2 = 1.875 *10^8 Pa for carbon steel, poisson's ratio (u) = 0.286 and modulus of elasticity for carbon steel = 2.1*10^5 N/mm^2 = 2.1*10^11 N/m^2 hoop strain /circumferential strain = [p*D/(4*t*E)] *(2-u) = [10*10^6*0.15/(4*0.002*2.1*10^11)] *(2-0.286) = 1.53 *10^-3 circumferential strain = change in radius/original radius => 1.53 *10^-3 = change in radius/(150/2) => change in radius = 0.11475 mm