Passivation is a chemical process used to protect metal against oxidation, it involves immersing the metal in a bath of electrolyte in order to form a protective layer of oxidation, or applying chemical products such as oils, waxes, alkaline substances, etc.
In this case, steam is not only useful for cleaning/degreasing the surface, but also as a vehicle for applying the specific passivation products.
The sequence below illustrates how a powerful jet of pure steam behaves when it encounters a surface covered with a thin layer of rust. Attention! As a rule steam does not eliminate rust, the purpose of this sequence is to give an idea of the efficiency of steam if used correctly in the passivation process, together with the correct products.