Erosion, caused from solid particles is one of the most important problems of oil and gas industries. Presence of solid particles of sand, metal oxides and catalysts result in erosion and rupture in process equipment. Thus, prediction of erosion rate for preventing probable hazards is of paramount importance. With improvements of numerical methods and emergence of computational fluid dynamics, using CFD simulation as a reliable substitute for experiment in prediction of erosion rate has been taken into consideration. So, in current thesis, process of erosion caused from suspended solid particles in the gas distribution network has been simulated using CFD with Oka erosion model, at operational conditions of gas distribution network of Kerman city in winter. Stream of gas-solid, has been taken into consideration as a dilute stream and in accordance to distributed phase model. Interaction of particle-wall with the restitution coefficient model of Grant-Tabakoff has been simulated. Solid particles obey from non-uniform distribution of Rosin-Rammler and their volumetric fraction is lower than 10%. Thus, the interaction of particle-particle has been neglected. Turbulent stream has been simulated using k-? (Realizable). Erosion rate, in terms of rate of reduction of thickness of the wall has been predicted in 10, 20 and 30 m/s velocities and four geometries: short radius elbow, long radius elbow, direct stream tee and side stream polyethylene tee with 1in diameter. For validating the results of simulation and correction coefficients of angle functionality in the Oka’s erosion model for solid particles of dark powder and polyethylene wall, grid convergence index has been used. The results of simulation show that rate of reduction of thickness of the wall in the two long and short radius elbows are equal to each other for velocity of 10m/s. Upon increasing velocity of the fluid, rate of reduction of thickness of the wall for the short radius elbow reduces more than long radius elbow. By comparing pattern of erosion for two cases of uniform and non-uniform particle size distribution (Rosin-Rammler), in the long radius elbow, it is observed that uniform distribution of particle size concentrated erosion in the middle part of elbow curve. However, for the non-uniform particle size, the erosion pattern has increasing trend from beginning to the end of elbow. Also, functionality of corrected angle predicts the highest rate of erosion for non-uniform size distribution to occur at impact angle of 17 o . Keywords : Oka’s erosion model, Elbow, Tee, Polyethylene, Computational Fluid Dynamics