The corrosion behaviour of metals and alloys in hot phosphoric acid

Abstract

The presence of excess quantities of phosphoric acid in a process stream led to severe corrosion in a Type 316L stainless steel (T316L S.S.) reactor and in associated piping. The pipes were steam‐jacketed and the reactor was heated with Dowtherm. Laboratory tests, which were carried out using 75% phosphoric acid at temperatures of 200° and 250°C, confirmed the high corrosion rates on T316L S.S. and determined the rates for thirty‐nine other metals and alloys. Copper alloys (particularly cupro‐nickels) and high nickel alloys (particularly Ni‐28Mo) demonstrated much better resistance than T316L S.S, as did the following pure metals: platinum, tantalum, molybdenum and silver. Ferrous alloys, zirconium, lead, titanium and aluminium were found to have extremely high corrosion rates.

Citation

Smith, F.N. and Van Droffelaar, H. (1991), "The corrosion behaviour of metals and alloys in hot phosphoric acid", Anti-Corrosion Methods and Materials, Vol. 38 No. 5, pp. 4-6. https://doi.org/10.1108/eb007292