MAWP of Vessel per ASME VIII; 

Maximum Allowable Working Pressure (MAWP) of the Pressure vessel is a Maximum Pressure of Vessel part at least, a strong will can be obtained by measuring the Pressure at the Top of the Vessel 

MAWP of Vessel per ASME VIII – Example; 

For example, the Maximum Allowable Working Pressure (MAWP) of the Vessel in Strength Calculation Sheet.

Further discussion on MAWP and Design Pressure: Design Pressure Vs MAWP (API, ASME)