... .5+0.001DN)4) PFA (allowable operating pressure) is the internal pressure, exclusive of surge, that a component can ... in permanent service5) PMA (allowable maximum operating pressure) is the maximum internal pressure, including surge, that a component can ... Dimensional checks (Thickness & Dia. testing)7) Hydraulic test (Pressure test)8) Internal lining (Thickness testing)9) External coating ( ...