Determining Reliability Over Time for Stainless Steels Susceptible to Chloride-Induced Stress Corrosion Cracking

Abstract

Failure of corrosion-resistant materials due to chloride-induced stress corrosion cracking (SCC) continues to threaten long-term plant operations and component integrity. A probabilistic model was developed to address the degradation of austenitic stainless steel components from chloride-induced SCC in order to help plant owners make guided run, repair, replace, and inspect decisions. Consistent with observations in the literature, the SCC probabilistic model assumes the presence of stress, a corrosive environment, and susceptible material and further assumes that pitting corrosion is a precursor to SCC. The probability of exceeding a wear allowance and through-wall penetration from SCC can be determined by calculating the following: pit initiation and progression to a stable pit, the conditional probability that SCC becomes dominant over pitting, and the crack growth rate as a function of the crack tip stress intensity factor. This paper illustrates the probabilistic model’s sensitivity to key stressors of chloride-induced SCC.