What is MAWP?

Per ASME Section VIII-1 Appendix 3, MAWP (maximum allowable working pressure) is “the maximum gage pressure permissible at the top of a completed vessel in its normal operating position at the designated coincident temperature for that pressure.  This pressure is the least of the values for the internal or external pressure to be determined by the rules of Division 1 for any of the pressure boundary parts, including static head thereon, using nominal thicknesses exclusive of allowances for corrosion and considering effects of any combination of loadings listed in the code that are likely to occur at the designated coincident temperature.“