This paper describes a roller coaster ride of corrosion and subsequent fouling in a Refinery MDEA system. The accelerated corrosion was first initiated by addition of caustic and the following up and down corrosion rate was a result of operating conditions imposed by increased sour crude charge, fouling and mis-application of MDEA. System variables that were controlled during this period included equipment metallurgy, the addition of caustic to neutralize heat stable salts (HSS), ion exchange to remove HSS and sodium, amine circulal ion rate, reboiler steam rate and the injection of corrosion inhibitor.