Integration of multiple failure mechanisms in a life assessment method for centrifugal pump impellers

Abstract

Methods in predictive maintenance are frequently confronted with limited applicability to realistic scenarios. The available approaches are often used for a single design, requiring an entirely new analysis for a slightly different case. A solution for this issue could be using a physical model. However, physical models focus on one unique failure mechanism, while, in a practical application, several mechanisms are typically active at the same instant. This work proposes and demonstrates a new methodology that combines different failure mechanism into an integrated life prediction model. Failure Modes and Effects Analysis is used to identify the different failure mechanisms that occur in a component simultaneously. Physical and empirical models are then analyzed and modified to be implemented in a realistic case of a centrifugal pump impeller applied in a maritime environment. As erosion, cavitation, and corrosion are the main failure mechanisms of an impeller, the combination of them quantifies the degradation increment during different types of pump operation. The proposed methodology is compared with traditional failure rate models and an established cavitation model that uses an aging factor to cover other failure mechanisms. In conclusion, it is demonstrated that the proposed methodology is more sensitive and reliable in describing the degradation process for a wide range of operating conditions, since all the mechanisms are considered.