Investigation of abrasive wear in contact load-dominated slurry flows using a Toroid Wear Tester

Abstract

Friction loss in slurry pipelines transporting coarse (settling) particles are governed by two mechanisms: Coulombic and kinematic friction. The Coulombic (sliding bed) friction component produces a highly abrasive condition that results in significant wear at the pipe invert and produces asymmetric thinning of the pipe wall. In this paper, an experimental investigation was carried out to study abrasive wear under Coulombic friction-dominated slurry flow conditions. Experiments were conducted in a laboratory-scale apparatus known as the Toroid Wear Tester (TWT) using narrowly-sized coarse particles (0.125–4 mm) suspended in three different carrier fluids (μf: 1–5.12 mPas, ρf: 998–1103 kg/m3). The friction loss attributable to the presence of the coarse particles was obtained from torque measurements made during each test. Visualization experiments were used to establish contact load-dominated (sliding bed) slurry flow conditions based on the ratio of flow velocity to the particle terminal settling velocity i.e. V/v∞. Abrasive wear experiments were then conducted with the TWT operating under full contact load conditions. It was found that the measured wear rates correlated with the magnitude of the Coulombic shear stress. The most important outcome of this study is the demonstrated potential to predict actual slurry pipeline wear rates from TWT experiments.