Hydrodynamic and temperature effects on the flow-induced local corrosion rate in pipelines

When a flow enters a pipeline or goes over an obstacle, a new boundary layer is developed and produces a local corrosion rate that is greater than the average corrosion rate. Equations are developed to calculate this local flow-induced corrosion rate. The calculated local corrosion rate varies from a fraction of mm/year to 1.27 mm/year (50 mils/year), depending on the temperature, velocity, and location of the flow. The calculations also show that the maximum local corrosion rate occurs at a short distance from the edge of the pipe entrance. The wavy appearance of erosion-corrosion failure on metal surfaces can be explained by the boundary layer theory and the convective mass transfer of ferrous ions.