Predicting erosion resulting from the impact of solid particles such as sand is a difficult task, since it is dependent on so many factors. The difficulty is compounded if the particles are entrained in multiphase flow. Researchers have developed models to predict erosion resulting from solid particles in multiphase flow that account for a variety of factors. However, no model currently accounts for the flow orientation on the severity of erosion. This work provides three sets of experimental results that demonstrate pipe orientation can have a significant impact on the amount of erosion for annular flow. A semimechanistic model to predict erosion in annular flow is also outlined that accounts for the upstream flow orientation.