Corrosion Inhibitor-57 is an alkylpyridine quaternary ammonium chloride used to formulate corrosion inhibitors used in drilling, completion, production and water floods. A corrosion inhibitor is a chemical compound that, when added to a liquid or gas, decreases the corrosion rate of a material, typically a metal or an alloy. Inhibitors often play an important role in the oil extraction and processing industries, where they have always been considered to be the first line of defense against corrosion.