Terminology about pressure in pressure vessels

A pressure vessel is a closed container designed to hold gases or liquids at a pressure substantially higher or lower than the ambient pressure. There are many terminology about the pressure.

 

In pressure vessels, pressure refers to the force acting vertically on the unit surface area of ​​the vessel.

 

Working pressure refers to the highest pressure that may be reached at the top of the vessel under normal working conditions.

 

Design pressure refers to the set maximum pressure at the top of the vessel.

Note: Together with the corresponding design temperature, it is used as the basic design load condition of the vessel, and its value is not lower than the working pressure.

 

Calculated pressure refers to the pressure used to determine the thickness of the component at the corresponding design temperature. Note: It includes additional loads such as the static pressure of the liquid column.

 

Test pressure refers to the pressure at the top of the vessel when conducting a pressure test or a leakage test.

 

The maximum allowable working pressure MAWP is the maximum pressure allowed to be borne at the top of the vessel at the specified corresponding temperature. Note: This pressure is calculated based on the effective thickness of each pressure-bearing component of the vessel, taking into account all the loads borne by the component, and takes the minimum value. When the design document of the pressure vessel does not give the maximum allowable working pressure, it is considered that the design pressure of the vessel is the maximum allowable working pressure.