Analysis of a heat exchanger coil tube in a petrochemical reactor after fire

Abstract

The paper is focused on the estimation of the remaining service life of a centrifugally-cast stainless steel heat exchanger tube component which was exposed to high temperatures during a fire incident. Detailed microstructural analyses and tensile tests were carried out to evaluate the metallurgical condition of the tube. The microstructure of the exposed steel was compared to its as-cast counterparts. Coarsened precipitates and secondary precipitation were observed at the grain boundaries. The tensile properties of the specimen exposed to the fire were impaired and the steel was therefore not recommended for further use. The coarsening of the grain boundary precipitates was caused mainly by short-term high-temperature exposure of the steels during the fire.