In a Refinery Condensate Splitting Unit, the lighter Feed hydrocarbon is distillated into Liquified Petroleum Gas, Naphtha, Kerosene, Light & Heavy Gas Oil and Atmospheric Residue. Operating philosophy of this unit is similar to that of Crude Distillation unit but without a desalter. The Pre-flash Column has two stage overhead system, and the Main Fractionator column has Single stage overhead system. Perennial corrosion was experienced in the Main fractionator Overhead fin fan cooler tubes in the form of thinning/pitting due to HCl & Amine/Ammonium chloride salt corrosion. Ionic Equilibria modelling of the overhead systems was carried out to estimate the Ionic Dew point, Water Dew point and Salt point of the overhead systems. The modelling helped to identify that improper neutralizing amine (NA ) injection location in Pre-flash overhead system, inadequate wash water flow, incompatible amine formulation and feed quality as the major contributor for the corrosion in the overhead system. Based on this study location of NA injection was modified, Wash water injection rate was optimized, and amine formulation was changed to have lower salting point. Finally, an Integrity Operating Window [IOW] was established to increase the reliability of the overhead systems in this unit.