Corrosion behaviour of 304L stainless steel in nitric acid condenser

The aim of this paper is to present the failure analysis of a nitric acid condenser. After five years of service, significant localized thinning of the shell wall was detected. The nominal thickness of 12 mm had been locally reduced to 3.5 mm. The investigation included chemical composition testing using a spark Optical Emission Spectrometer, light microscopy, SEM imaging, SEM/EDS analysis, and an assessment of operating conditions. The results revealed that the wall thinning was caused by intergranular corrosion, resulting from the material entering a transpassive state under the given operating conditions. The findings highlight the need to select higher-grade materials for such applications and to implement more stringent temperature monitoring in areas susceptible to corrosion.