What is the purpose of a nozzle on a pressure vessel shell?

The purpose of a nozzle on a pressure vessel shell is primarily to provide a means for attaching various fittings to the vessel. Nozzles serve as access points through which fluids can enter or exit the vessel, allowing for the connection of piping, instrumentation, and other components essential for the vessel's operation. This can include connections for feed water, discharge lines, or the installation of instruments that monitor pressure, temperature, or level within the vessel.

Nozzles are designed to ensure that the integrity of the pressure vessel is maintained while allowing for the necessary functional connections. Their placement and specifications are critical because they must withstand the internal pressures and any potential external forces acting on the vessel.

In contrast, while connecting feed water piping, safety valves, or gauges may be functionalities associated with nozzles, the broader category of attaching fittings encompasses all these activities. Thus, defining the purpose of nozzles as relating to attaching various fittings accurately captures their role in the context of pressure vessels.