Practical solutions for corrosion control/materials performance problems in petroleum refineries can be obtained with the help of electrochemical, thermodynamic software. These include: (a) water washing to mitigate corrosion and fouling caused by ammonium salts in process streams, (b) determining whether equipment is operating in “Wet-H₂S” service and (c) estimating the intrinsic corrosivity of the aqueous phase in aqueous/liquid hydrocarbon two phase systems when the aqueous phase is present at levels on the order of 0.1 - 0.01%. These three examples are discussed in this review article.