Comparative Study of Erosion in Elbows and Cushion Tees and Implications for Modeling and Geometry Selection

Cushion tees are used in mining and oil and gas transportation pipelines to reduce erosion compared to elbows. However, the effectiveness of this approach is under investigation as pipeline failures due to solid particle erosion have also been found in the field with the use of cushion tees instead of elbows. With a large amount of erosion data collected at the Erosion/Corrosion Research center at the University of Tulsa, CFD models can be calibrated and then used for predicting erosion in elbows and cushion tees for conditions that are seen in the field. Therefore, as the first step of the present work, CFD model is validated with various experimental data for erosion in elbows covering a wide range of process conditions from single phase flow to multiphase flow. Experiments are also conducted to investigate erosion characteristics in cushion tees under multiphase flow conditions and used as benchmark for calibrating the CFD model. Afterwards, the validated CFD model is applied to simulate erosion in both elbows and cushion tees under various flow conditions to unveil the maximum erosion ratio for the two geometries, which provides insights of erosion resistance capability of the geometries. The present work has greatly extended the CFD model to predict erosion in large pipe diameter pipes which are often used in the field. Finally, the obtained information can be used to draw an erosion resistance envelope for the geometries as a function of Stokes number and/or other related process parameters. Thus, presenting a comprehensive reference for engineering modeling, design, and geometry selection and provides a valuable tool for engineering design and prediction under complex conditions.