Corrosion of materials in hydrochloric acid solutions

Hydrochloric acid solutions, particularly at elevated temperature, are very corrosive media and cause rapid corrosion of the majority of metals, steels, and alloys, and also chemical breakdown of many nonmetallic materials. Under laboratory conditions in 2% hydrochloric acid solution at 20–25°C the corrosion resistance is studied for specimens of steels 12Kh18N10T, 10Kh17N13M3T, alloy 06KhN28MDT, and titanium VT1-0, and also in 20% hydrochloric acid solution at 95–100°C for specimens of nickel-molybdenum alloys N70MFV-VI (EP814A-VI), alloy N65M-VI (EP982), titanium-palladium alloy 4200 (Ti–0.2%Pd), zirconium, and tantalum, as well as nonmetallic materials, i.e., fluoroplastic, glass, porcelain, faolite, graphite, polypropylene, cross-linked polyethylene, acrylic plastic, silicon carbide composite, and vinyl plastic. The test duration is 1000 h. In 2% hydrochloric acid solution at 20–25°C high resistance is exhibited by titanium VT1-0, alloy 06KhN28MDT, and corrosion-resistant chromium-nickel-molybdenum alloy 10Kh17N13M3T, from which it is possible to manufacture equipment and engineering pipelines in contact with low-concentration hydrochloric acid solutions operating at ambient temperature. In hydrochloric acid solution with a weight concentration of 20% at 95–100°C high resistance to uniform and local corrosion is exhibited by zirconium and tantalum, and the rate of corrosion penetration for alloy N70MFV-VI (EP814A) is 0.447 mm/yr, for alloy KhN63MB it is 1.441 mm/yr, for alloy KhN65MV it is 13.931 mm/yr, and for alloy 4200 it is 3.403 mm/yr. Of the nonmetallic materials, alongside fluoroplastic, high chemical resistance is exhibited by polypropylene, and cross-linked polyethylene.