EROSION IN CHOKE VALVES - OIL AND GAS-INDUSTRY APPLICATIONS

This paper describes predictions of erosion depth in pressure reduction valves (chokes) caused by solids and large amounts of droplets. Solid and droplet erosion data for WC (tungsten carbide) with 6% Co and 6% Ni and polycrystalline diamond (PCD) have been transformed into correlations. These correlations have been coupled with particulated fluid flow models to determine the erosion depth due to solids and droplets. One solution to the solids erosion problem in chokes is to reduce the impact angle of the solids and/or apply PCD as target material. For needle chokes particulated flow calculations and experiments have demonstrated that small impingement angles can be achieved. The incubation period against droplet erosion of PCD is 4-5 times longer than for WC-6%Co. The erosion rates, however, are similar. Even if computations indicate that small droplet velocities may be achieved in the commonly used chokes (if no closure of ports by steel debris), experiments are required to verify the actual exposed areas in the choke (by soft material experiments) as well as the angular dependency indicated by rotating arm experiments.