Volatile corrosion inhibitors (VCIs) were originally developed by Shell for the military during the last world war. Their effectiveness and ease of application attracted early users. Over the years, the field of usage has increased to cover water treatment, electronics, packaging, process industries, seasonal lay-up, coatings, reinforced concrete, and metalworking fluids. Technologically advanced treatment programs were designed for boilers, cooling towers, heat exchangers, and deaerator systems. A new class of VCIs has been developed in harmony with the concern for the environment. These new chemicals are classified as ambiodic type of inhibitors and inhibit cathodic and anodic
electrochemical reactions. They offer excellent protection to metals and at the same time they have a very low impact on the environment and are safe to use. These newly developed treatment programs provide three-phase corrosion protection:
1. in the water phase
2. in interphase between water/air
3. in the air/vapor phase