Caustic Stress Corrosion Cracking of 304 SS Incinerator Material

Abstract Under high temperature services such as in waste incinerating systems, failure can occur due to obscure reasons that are not directly related to process parameters. Although, the chosen material for the incinerator may be well suited, deposits in the system and some constituents of the process steam may synergistically react to form aggressive species, which may initiate failure of the material. The downcomer of an incinerator suffered sever cracking and loss of quenching water. Analysis, interestingly, revealed that the observed caustic stress corrosion cracking (CSCC) was not directly related to process parameters; rather, it was the results of the unexpected reactions of process constituents. Thus, an understanding of the factors that may lead to such scenario may help in extending the service life of the incinerator components. In this paper, a case study is presented to provide an insight into the mitigation strategies to circumvent the failure of an incinerator downcomer that had failed due to the presence of a caustic soda by-product that led to local stress corrosion cracking.