Carbon steel is, among other metals, the most vulnerable to weathering,including air and water.Unlike stainless steel, it does not have a natural covering layer of chromium oxides and hydroxides to protect it from corrosion.The passivation of carbon steel therefore intervenes artificially to cover the metal to allow its use in different contexts.Carbon steel alloys in the industrial context are used in a wide variety of contexts. Normally, carbon steel requires a protective coating that can be given by painting or galvanic coating treatments.When this is not possible or practicable, a chemical passivation is performed that is always preceded by a pickling, mechanical or chemical action. Passivation treatment is mainly carried out on products such as prefabricated pipes or bars, inside tanks, exchangers or valves.