Investigations of Failure Mechanism and Structural Integrity of a Hydro-Energetic Component

Abstract

Hydro-energetic equipment and installations are part of a national energy system. Age and their wear, lack of implementation of the risk-based inspections on the structural integrity of components and a proper risk management system can lead to unexpected in-service failure, which causes temporary disturbances in electricity distribution networks and financial losses. Paper presents the structural integrity analysis of the cause of failure of a spindle from a hydro-aggregate. For the material characterization, tensile tests, notch impact tests, hardness tests and non-destructive visual and magnetic particle tests (NDT) were performed. The experimental program also includes complementary investigation for chemical and structural analysis using Energy-Dispersive X-ray spectroscopy (EDX) and Scanning Electron Microscopy (SEM) techniques to assess the quantity and dispersion of elements in different areas of the fractured surface to highlight the particularities of material degradation. Connecting the inspections results leads to an in-depth understanding of the components failure mechanisms, which allows increasing the safety level in operation of the installations by adopting specific measures for avoidance of similar failure. From analysis and experimental results of this study, overload by shock in operation, particularly low steel toughness and non-metallic aligned or clustered inclusions are shown to be the main reason of spindle failure.