Failure analysis of a fan blade holding assemblement, installed on the cooling tower of a power plant

Abstract

Abstract Cooling towers are important heat exchangers in power generation industry comprising of centrifugal fans which are used for cooling purposes. The present research investigates the failure occurred on the fan blade supporting system, installed on the cooling tower of a power plant. Τhe tower is consisted of twenty fans. Their blades are supported onto a hub by “U” shaped holders. These specific fitments frequently undergo damages increasing plant downtimes as well as the risk of accidents. The study comprises of historical data recording, macroscopic examination, hardness measurements and chemical analysis of three failed components. Moreover, the microstructure and fracture surface morphology of failed components are thoroughly analyzed. Conclusions are presented regarding the failure mechanism and its propagation mode. Holders were totally break by low cycle fatigue. Improper material selection and poor design are mainly responsible for the repeated damage. Practical recommendations were delivered to avoid similar failures.