Allowable Working Pressure and Temperature

Several special terms are used to describe factors which affect the mechanical design of equipment. Some of these are discussed  

Operating Pressure and Temperature The operating pressure is the pressure at the top of a pressure vessel at which it normally operates. The operating temperature is the temperature that will be maintained in the metal of the vessel for the specified operation of the vessel. 

Design Pressure and Temperature The design pressure is the pressure used to determine the physical characteristics of the different components of the vessel. It usually is the sum of the maximum allowable pressure and the static head of the fluid in the vessel. The design temperature is the metal temperature coincident with the design pressure. 

Maximum Allowable Working Pressure (MAWP) The MAWP is the maxi mum gage pressure permissable at the top of a completed vessel in its operating position for a designated temperature. This pressure is the basis for the pressure setting of the pressure relieving devices protecting the vessel. 

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