Damage caused by oxidation and carburisation at a valve of a dehydrating unit

The seal of an air injection valve, which is employed in a pertochemical pl ant and consists of the stainless steel F 321 H and Co-based alloys, serves as an example for the corrosive damage due to oxidation an carburization. Using the interference coating metallography according to Pepperhoff along with SEM-analyses, corrosion products have been identified and the damage h istory has been reconstructed. The article discusses the different states a nd mechanisms of oxidation and catastrophic carburization which resemble me tal dusting.