Abstract
Nickel-chromium-molybdenum (Ni-Cr-Mo) alloys are used in the chemical processing industry for very aggressive conditions. They have a long history of use in acids such as hydrochloric (HCl) and sulfuric (H2SO4) over a range of concentrations and temperature. Selection of the appropriate Ni-Cr-Mo alloy for a given environment is not always straightforward. This paper compares the corrosion resistance of three common highly corrosion-resistant alloys in several acid solutions. The corrosion resistance of UNS N102761, UNS N06022, and UNS N06059 were measured in four environments. The solutions used were 10% HCl at 40 0C, 35% HCl at 50 0C, 20% H2SO4 at the boiling point, and 85% H2SO4 at the boiling point. Additionally, the effect of chloride on sulfuric acid corrosion was investigated in a boiling solution of 5% H2SO4 with 2000 ppm of chloride. The results show that the ranking of these alloys relative to corrosion resistance is dependent on the specific environment.
