With the increased use of high-temperature operations, the chemical and petroleum process industries need an economical, efficient, heat transfer medium that is between steam and direct-fire heating.  Sodium nitrite can be mixed with nitrate salts to create a molten salt bath.  It has a low melting point, high heat transfer rate, is stable at high temperatures, and is non-corrosive to steel.  The salts are used for indirect heating and cooling or as quenching baths in the annealing of iron and steel.