Thin-walled Pressure Vessels
Thin-walled Pressure Vessels
Thin-walled Pressure Vessels
A pressure vessel can be described as thin walled when the ratio (about 10:1) of the inside radius to the wall thickness is sufficiently large so that the distribution of normal stress in the radial direction is essentially uniform across the vessel wall
The wall comprising a pressure vessel is sometimes termed the shell
Spherical Pressure Vessels
If the weights of the gas and vessel are negligible (a common situation), symmetry of loading and geometry requires that stresses must be equal on sections that pass through the center of the sphere.
Spherical Pressure Vessels
Typical sphere Free-body diagram
Spherical Pressure Vessels
There are no shear stresses on any of these planes, since there are no loads to induce them. The normal stress component in a sphere is referred to as axial stress and commonly denoted a .
Stress on spherical vessel
Cylindrical Pressure Vessels
Typical sphere
Cylindrical Pressure Vessels
Free-body diagram exposing long
PICTURE???
Spherical Pressure Vessels
Longitudinal Stress
Cylindrical Pressure Vessels
Free-body diagram exposing hoop
Spherical Pressure Vessels
Tangential or Circumferential Stress
Example 4.1
A standpipe with an inside diameter of 108 in. contains water, which has a weight density of 62.4 lb/ft3. The column of water stands 30 ft above an outlet pipe, which has an outside diameter of 6.625 in. and an inside diameter of 6.065 in.
Determine the longitudinal and hoop stresses in the outlet pipe at B.
If the maximum hoop stress in the standpipe at point must be limited to 2,500 psi, determine the minimum wall thickness that can be used for the standpipe.
Example 4.1