Abstract Scope |
In industries handling carbonaceous gases, the high temperature corrosion mechanism called “metal dusting” can cause unforeseen plant shutdowns and high additional costs. One of the major challenges is the prediction of the corrosion process onset. A high risk of metal dusting is indicated by a high carbon activity a<sub>C</sub> of the gas. However, gases with similar a<sub>C</sub> do not always cause similar metal dusting attack. To develop a better understanding of the influence of the gas components, commercial Ni-base alloys (e.g. Alloy 601, 602 CA) were exposed to five different gas mixtures containing CO, CO<sub>2</sub>, H<sub>2</sub>, and H<sub>2</sub>O with constant a<sub>C</sub>. Tests were performed at 620°C and 18 bar. While protective oxide scales formed in some gases, severe metal dusting attack was observed in others. The outlet gas composition was determined using mass spectroscopy. Based on oxide scale formation and metal dusting attack, reactions defining the corrosion mechanism are proposed. |