Estimation of the useful life of a gate valve subjected to impact erosion

In the oil and gas industry, the flow control is particularly complex in fields with sand production because, when the solids impinge against the inner walls of a valve, removal of material can occur. This phenomenon, referred to as impact erosion, can result in loss of performance or even failure of the device, and, threfore, it is a serious concern to engineers. In this contribution, the useful lifetime of a gate valve subjected to impact erosion is numerically investigated. However, as a preliminary activity, a prototype of the device was exposed to an abrasive water-sand mixture in a slurry flow loop at the Hydraulic Laboratory of Politecnico di Milano. The experiment allowed clear identification of the valve components most subjected to erosion. The numerical simulations were performed following the well-established procedure in which the liquid-solid flow is simulated by an Eulerian-Lagrangian model and, afterwards, a single-particle erosion correlation is applied to each particle-wall impingement. On the grounds of an early study of this research group, the definition of the computational model was made by carefully accounting for the possible influence of its many sub-models and parameters on the wear estimates. Afterwards, the research was developed in four stages. Firstly, the numerical reproduction of the laboratory experiments, which yielded predictions of the erosion hotspots locations in agreement with the observations, gave strength to the reliability of the erosion prediction model. Secondly, the most important variables affecting the erosion of the valve were identified; this allowed setting up a number of virtual experiments, thereby collecting a large dataset of wear estimates. Thirdly, the functional dependence of the erosion of the valve upon the above identified variables was assessed based on the obtained results. Finally, the useful lifetime of the valve was inferred from the output of the numerical simulations and, with the aid of theory and engineering experience, a simple interpolatory formula of practical use was developed for its estimation.