Application of diamond to enhance choke valve life in erosive duties

As part of a LINK surface engineering project, a consortium of universities, hard materials suppliers, valve manufacturers and end users have investigated the incorporation of CVD diamond into choke valves to enhance valve life in erosive duties. Diamond was applied to regions of the valve trim and tested under full scale conditions in a high pressure valve loop test facility and compared with standard uncoated tungsten carbide trims. The valve trims were tested with a 60 bar pressure drop and a flow rate of 7.5 l s−1 using water–sand slurry containing 1% (w/w) solids with a mean diameter of 194 μm. The results show that valve seats and plugs with a partial coverage of CVD diamond exhibit 50–60% greater resistance to damage caused by sand particle impingement. Moreover, it is felt that further improvements are attainable with subtle improvement of the design of the trim and coating processes to allow complete coating of critical components with complex design.