Roundness requirements
Thread Content
Are the roundness requirements for pressure vessels under internal pressure the same as those for those under external pressure?
It’s different. During the pressure increase and holding phase, the cylinder of the internal-pressure vessel will automatically assume a circular shape ； The failure mode of pressure vessels subjected to external pressures is stability failure; if their cross-sectional shape is not a standard circle, the loads acting on them are asymmetric, resulting in additional bending stresses in the vessel walls. The critical pressure of a cylinder under external pressure is related to the geometric parameters of the cylinder as well as the mechanical properties of the material. The relevant geometric parameters are the outer diameter, effective thickness, and design length; therefore, cylinders subjected to external pressure require higher strength than those under internal pressure.