The key factors that influence metal dusting in industrial applications are examined and examples ff metal dusting failures in both crude and catalytic reforming units are presented. The results of these investigations are compared with the currently proposed metal dusting mechanisms. The findings from the failures indicate that for the low alloy steels in the above processes, localised environmental conditions dictate whether metal dusting will occur or not. In the catalytic reformer tubes examined here it is apparent that temperature has a major influence on the location and appearance of the damage.