Elbows in series are commonly encountered in various piping systems on oil and gas subsea platforms. In numerous oil and gas fields, solid particles are entrained with produced fluid causing solid particle erosion of these elbows. Therefore, solid particle erosion was examined in two standard ID 3-inch (76.2 mm) elbows in series. The distance between the two elbows is twice the pipe diameter (2D). Firstly, paint removal studies were performed to identify the location of the maximum erosion in the second elbow with superficial gas (air) and liquid (water) velocities of 31 m/s and 0.1 m/s, respectively, using 300 and 75 μm particle sizes. Secondly, erosion measurements were conducted in two standard stainless-steel (SS316) elbows with 25, 75, and 300 μm particle sizes. The results of the erosion measurement in the annular flow condition were compared with the gas-solid flow with a gas velocity of 31 m/s and particle sizes of 300 and 75 μm. The paint removal experimental studies showed that the location of the maximum erosion changes with changing the particle sizes in the second elbow. The erosion measurements showed that the erosion ratio (2nd elbow/1st elbow) in gas-solid is higher than in annular flow conditions by a factor of 14.25 and 5.8 with 75 and 300 μm particle sizes, respectively. Also, Computational Fluid Dynamics (CFD) simulations were performed for gas-sand flow conditions with 31 m/s gas velocity to study the effect of particle size on erosion in the investigated elbows. The CFD results over-predicted the erosion ratio (2nd elbow /1st elbow) by a factor of around 2.1 and 2.4 for 75 and 300 μm particle sizes, respectively.


In the oil and gas industry, solid particle erosion is a common challenge in pipelines, flowlines, and fitting components such as elbows. Elbows have been widely used to change the flow direction in industrial flowlines. When erosion occurs due to the impact of solid particles, it leads to significant financial and environmental threats. Different parameters influence solid particle erosion in elbows, including particle size and shape, particle concentration, flow regime, gas and liquid superficial velocities, and pipe material properties.1 In the case that elbows are installed in series, the flow field, and the erosion rates on the second elbow are affected by the first elbow and the distance between the elbows. The effects are magnified when the distance between the two elbows is short.

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