The salts that are most frequently present in crude oil are calcium, sodium and magnesium chlorides. If these compounds are not removed from the oil, several problems arise in the refining process. The high temperatures that occur in downstream of the process could cause water hydrolysis, which in turn allows the formation of corrosive hydrochloric acid. A crude oil desalter is an equipment used in petroleum refineries to remove inorganic salts, water and sediment from the incoming petroleum crude oil feedstock before it is refined. The salt is dissolved in water in the crude oil, not in the crude oil itself. The desalting is usually the first process in crude oil refining.