In carbon steel piping systems handling fluids containing water and dissolved CO2, under a range of conditions, an FeCOs (iron carbonate) scale can form on the pipe wall and provide a measure of protection against CO2 corrosion. If the fluid also contains sand, particles of sand impinging the pipe wall can remove the protective scale or prevent it from adhering to the pipe wall. Without the scale to protect the pipe, CO2 corrosion can progress at an accelerated rate. This process is referred to by many as “erosion-corrosion”. Whether erosion-corrosion occurs and how severe it will be depend on environmental factors such as pH and temperature, and on how erosive the conditions are, i.e., the “erosivity”. Factors that determine erosivity include fluid properties, flow parameters, and sand conditions.