Effect of sand content on erosion–corrosion of a 90-degree horizontal elbow

Purpose The purpose of this study to characterize the erosion–corrosion characteristics of a 90° horizontal elbow under different sand content conditions. This study aims to reveal the effect of sand content in liquid–solid two-phase flow on the erosion–corrosion of the elbow and to provide theoretical guidance for the protection against erosion–corrosion of elbows under such conditions. Design/methodology/approach A pipe flow test device was used to study the effect of sand content on the erosion–corrosion of a 90° horizontal elbow. The weight loss method was used to quantify the erosion–corrosion rates at different locations of the elbow under different sand content conditions. Electrochemical tests were used to characterize the electrochemical properties of different locations on the elbow, and surface analysis techniques were used to examine the erosion–corrosion morphology of the elbow. Findings This study reveals that the erosion–corrosion rates, electrochemical characteristics and surface morphologies on the inner surface of the 90° horizontal elbow are significantly influenced by sand content. As the sand content increases from 0% to 1.25%, the arc radius of the electrochemical impedance spectrum noticeably decreases, while the erosion–corrosion rates and maximum pit depths increase substantially. The surface morphology transitions from sheet-like structures to more severe pit and groove formations. When the sand content increases from 1.25% to 2.5%, the reduction in the arc radius is minor, and the changes in erosion–corrosion rates and maximum pit depths are less pronounced, though still present. Surface morphologies continue to develop in greater depth, with an increase in the number of pits and grooves. In liquid–solid two-phase flow, the areas of severe erosion–corrosion are mainly at the bottom of the horizontal elbow and on the outside of the elbow outlet. Overall, this study highlights that sand content is a significant factor in accelerating erosion–corrosion, with higher sand concentrations leading to more extensive damage on the elbow surface. Originality/value This study investigates how sand content affects the erosion–corrosion of a 90° horizontal elbow. It characterizes the erosion–corrosion rates, electrochemical properties and surface morphologies at various locations of the elbow, revealing the underlying mechanisms by which sand content influences its erosion–corrosion behavior.