Failure analysis of cracked connecting piece of BFW preheater

It was reported that the stainless steel elbow connecting two heat exchangers cracked within two months of service. Analysis revealed that a number of cracks nucleated in the vicinity of the weld and propagated radially. Microstructural and fractographic analyses suggest that the failure was due to stress corrosion cracking (SCC). High concentration of KOH in the process gas was responsible for the SCC. A detailed analysis of the failure is presented in the report