Materials Selection for Use in Hydrochloric Acid

Hydrochloric acid (HCl) is an important mineral acid with many uses, including the pickling of steel, acid treatment of oil wells and chemical cleaning and processing. This acid is extremely corrosive and its aggressiveness can change drastically depending on its concentration, the temperature and contamination by oxidizing impurities. One of the most commonly encountered oxidizing impurities is the ferric ion. In general, stainless steels cannot tolerate aggressive HCl solutions, hence the need to use corrosion-resistant nickel-based alloys. A part of this study focused on the role of alloying elements on the corrosion performance of commercial nickel-based alloys C-276 (UNS N10276), C-22 (UNS N06022), C-2000 (UNS N06200), Alloy 625 (UNS N06625), Hybrid-BC1 (UNS N10362) and B-3 (UNS N10675)) in HCl solutions, with and without the presence of oxidizing impurities (ferric ions). Aggressive HCl solutions can also be used to simulate the critical crevice solution. Therefore, another aspect of this research is to investigate the role of alloying elements in Nickel-based alloys on the inhibition of crevice corrosion. In the present study various standard corrosion test methodologies, conservative electrochemical techniques, and a range of surface analytical tools have been utilized.