chapter  25
Thick Cylinders
Pages 10

When the wall thickness of a pressure vessel such as a cylinder or pipe is greater than onetenth of the inside radius of the vessel, the meridional and circumferential (hoop) stresses cannot be considered uniform throughout the wall thickness, and the radial stress will not be negligible. At this point, the vessel will be considered to be a thick-walled cylinder, as in Figure 25.1.