Stresses can be developed in a pressure vessel shell due to forces and moments that result from piping connections to nozzles. The magnitude of these forces and moments applied to a vessel are relatively insignificant and need not be considered for the design of a vessel. This is especially true for vessels designed according to Section VIII, Division 1, where extensive experience has shown that the required Safety Factor of 4 is sufficient to compensate for these relatively small loads without detailed analyses. Heavy equipment attached to nozzles (such as valves and bridles) should be supported to minimize the external loads acting on the nozzle.
The forces and moments attributable to piping connections can be calculated using the computer program CAESAR (see the Piping Manual), if it is suspected that they are high enough to affect the design of the vessel.
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