The concentration of the sand inside the flowlines can directly affect the magnitude of erosion in various pipelines and pipe fittings components. The erosion models available in the literature suggest that the relationship between erosion and sand concentration is linear. Furthermore, some authors believe that for a volume concentration of sand approximately below 0.75% by volume (corresponding to about 2% by mass in liquid), the effects of sand concentration on the rate of erosion are minimal. However, one could ask how this limitation on the amount of sand concentration varies in various geometries as the local concentration at the location where the sand particles are impacting can change within a flow geometry and how this can affect the maximum local erosion rates. Therefore, the sand concentration distributions inside a vertical pipe and two elbows in series for liquid-solid and liquid-gas-solid flows are examined in this investigation by CFD simulations and experimentally. Experiments are performed in a facility with two vertical pipe sections (101.6 mm reducing to a 50.8 mm inner pipe diameters) and immediately after the first and second elbows (50.8 mm inner pipe diameter) from the inner to the outer diameter of the elbows. The concentration distributions are associated with erosion measurement results in both the first and the second elbows. Finally, the CFD simulations of the corresponding experiments in liquid-sand and liquid-gas-sand flows are conducted and compared with the experimental erosion patterns and magnitude as well as various concentration distributions.