Cost Effective Manufacturing and Optimal Design of X-Stream Trims for Severe Service Control Valves

Control valves are used under severe service conditions for a wide range of applications. These valves are installed with X-Stream cage trims in order to control the flow rate and the pressure drop within the valve. The X-Stream cage trims have a specific capacity rating, commonly known as Flow Coefficient (or Cv). These values of the X-Stream are important as far as customer’s requirements are concerned as are other features of the trim like reduction in erosion via velocity control and the prevention of cavitation via controlled pressure let-down.
The X-Stream is a complex geometry part and is traditionally manufactured using a process called electric discharge machining. This is considered a relatively expensive and time consuming process and as a result control valves industry has been extensively reviewing other methods of manufacture. A process known as selective laser melting has been identified as a high potential for cost reduction and competiveness for the business, however early tests have seen issues during the manufacturing process and significant reductions in the Cv of the X-Stream.
This study reviews the SLM method of manufacture and evaluates improvements in performance of the X-Stream when reviewing the process of manufacture and the design of the X-Stream component. Extensive flow loop testing of X-Streams have been carried out to calculate Cv of the trims. Then, Computational Fluid Dynamics based techniques have been incorporated to find out the same. The results have been compared and validated. Further tests at higher pressures of water have been conducted to evaluate Cv at severe service conditions
This report includes details of the test procedures, CFD modelling and full set of results for each flow condition and the effect of manufacturing constraints like surface roughness on the final Flow Coefficient (Cv) and other performance characteristics to improve the potential for SLM specifically for application with X-Stream.