A method for inhibiting corrosion on internal metal surfaces of an overhead condenser of a crude distillation unit in which hydrocarbons, water and amine hydrochlorides condense, the method includes adding to the overhead condenser an amine composition in an amount and at a rate sufficient to maintain the pH of water condensate in the condenser above a pH of about 5, the amine composition made of a mixture of four amines wherein the amines are monoethanloamine, methoxypropyl amine, morpholine and cyclohexylamine present in a weight ratio ranging from about 25:30:25:20 to about 30:40:15:15. Further, a system and method assess the corrosion rate and optimize the dosage of neutralizing amine composition during the operating conditions of overhead condensing system.