The action is by oxygen and water on a clean surface. It is our policy to passivate the SUS 316L and SUS 316LN austenitic SS tanks with 14% by volume cold Nitric acid. It is also our policy not to include hydrofluoric acid in a passivation solution. Hydro-flouric acid is a pickler which removes chromium and nickel along with heat hardened scale, it NOT a passivator. The concentrated acid you get on board in 200 litre drums is usually 68%. Contact time for Nitric acid is 2 hours.
Mineral salts can come in varieties. They are inorganic salts and include phosphate, calcium, chloride, sodium and potassium. One of the most common mineral salts is iodized salt. Iodine is essential to the function of the body as an iodine deficiency can be problematic.
Salt is a mineral composed of sodium and chlorine. Neither can exist alone in natural form. Together, they form the chemical compound that is sodium chloride. To geologists, salt is known as halite. Salt is a crystal of the isometric system, meaning it is usually cubic and perfectly symmetrical. Pure salt crystals are colorless, although a pile of them will appear to be white. Impurities in the crystals may cause salt to be various shades of yellow, red, blue or purple.