The erosion of butterfly valves by particle-laden fluid flows is a common problem that affects the safety, production, and economy of many industrial processes. Using COMSOL Multiphysics software, a numerical study of the erosion wear by solid particles on butterfly valve discs was carried out. For the pipe/butterfly-vale system created, the Navier-Stokes equations of laminar flow were solved. The effect of flow Reynolds number, disc apertures of 70 and 90 degrees, and two different disk geometries were analyzed. The particles were modeled using a Lagrangian approach and assuming a one-way interaction with the fluid. Additionally, in this study different particle Stokes numbers (St) were utilized ranging from 0.05 to 20.0. The lowest erosion rates were found for Stokes number less than one, as a consequence of the fluid forcing the particles to move away from the disk. On the other hand, for very large Stokes numbers, the erosion rates tend to plateau because the particles maintain their initial trajectories without major perturbation from the flow. In this case, the erosion depends on the particle entry conditions. It was noticeable that, at Stokes numbers close to 1, the erosion rates transition from their low values to the highest values.