Corrosion in crude distillation unit overhead lines is primarily caused by hydrochloric acid at the dew point. Various other contaminants including air, organic acids, H2S, NH3, tramp amines, HCN, mercaptans, phenols, etc. also play a role in overhead corrosion. Mitigation strategies include process solutions such as wash water systems and temperature control, and chemical solutions including amine-based neutralizers and film-forming inhibitors. Despite implementing these strategies, corrosion is invariably observed in the overhead system. Conventional “non-volatile” filmers rely on free liquid to cover the metallurgy. However, the complex nature of overhead geometry and fluid flow make complete metal coverage challenging. This necessitates a different strategy to achieve protection. Here, we present a first of its kind Vapor Phase Corrosion Inhibitor (VPCI) for protecting overhead systems. Several VPCI candidates were studied in the lab for performance, volatility, and risks (emulsification, pentane solubility, amine salt fouling, thermal stability). Promising VPCI was field trialed in several refineries.