CORROSION IN AN AQUEOUS HYDROGEN-SULFIDE, AMMONIA, AND OXYGEN SYSTEM

Rotating cylinder experiments demonstrated that corrosion rates of ste el exposed to oxygenated aqueous solutions containing hydrogen sulfide (H2S) and ammonia (NH3) were dependent upon pH, the presence of oxyge n (O-2), H2S concentration, and flow. Corrosion was more severe than e xpected based upon a review of published reports considering systems a t relatively low ammonium hydrosulfide (NH4HS) concentrations and abov e pH 6. Dependence of carbon steel (CS) corrosion rates on pH and the impact of O-2 was strong, but only prior to reaction between H2S and O -2. The influence of H2S concentration was unexpected in that neutral, 1 mM solutions were more corrosive than neutral 10 mM solutions in sh ort-term tests and on a sustained basis.