Abstract
Metal dusting has been studied for over fifty years. To more clearly understand the mechanism, and to obtain results more quickly, the process conditions studied in the laboratory were simplified from the industrial conditions that caused the metal dusting failures to occur. Although these laboratory tests were successful in outlining the basic mechanism for metal dusting, predictions about alloy resistance based on these academic studies have not proven to be accurate for all plant conditions. Multiple papers published at NACE and elsewhere have pointed to the important role that steam can play in changing alloy response to metal dusting environments. The work described in this paper follows up on a 2009 NACE publication by Hoffman, et al, which described plant results showing that stainless steels are more resistant to metal dusting than nickel-based alloys under high steam, low temperature syngas conditions. The current paper describes laboratory scale work that reproduced these plant results under controlled conditions equivalent to the process conditions found in the plant. These carefully controlled studies confirm that under the right conditions, stainless steels can have superior metal dusting resistance as compared with nickel-based alloys. Results are discussed for UNS N08810, UNS 06601 and UNS S31000 at 10500F (5660C) in flowing syngas containing greater than 23% steam.
