The commonly used practice for controlling sand erosion in gas and oil producing wells is to limit production velocities following the provisions of American Petroleum Inst. (API) RP14E. This guideline contains a procedure to calculate a threshold velocity, the flow velocity below which an allowable amount of erosion occurs. While providing the advantage of computational ease, the approach has some disadvantages. One is that, while many factors influence the erosion rate, API RP14E includes only one factor, the density of the medium. Thus, such factors as flow geometry, type of metal, sand size, and Reynolds number are not accounted for. Another disadvantage is that API RP14E does not specify the tolerable amount of erosion, in terms of loss of wall thickness. A method is presented to overcome these disadvantages by (1) accounting for many of the physical variables in the flow and erosion processes and (2) including a way to predict the maximum penetration rate for sand erosion. The capabilities of the method are evaluated by comparing pre dieted penetration rates with experimental data found in the literature. In this paper, the method is applied to calculate threshold velocities. The computational procedure allows an allowable amount of erosion to be specified in mils per year for elbows, tees, and direct-impingement geometries. Threshold flow-stream velocities are calculated for carrier fluids of crude oil, water, and methane at elevated pressure. Resulting threshold velocities are presented for a range of sand sizes, pipe diameters, sand production rates, and methane pressures. Results show that threshold velocities for single-phase gas flows are much lower than those for single-phase liquid flows.