The paper presents the diagnostic code for on-line erosion calculation which makes it possible to determine the real distribution of erosion rate along separate tubes of boiler convective tube banks, therefore leading to better identification of erosion hazardous areas. The influences of changes of operating parameters like steam output, pulverized coal quality and size distribution have been determined. Presented code allows adjusting the load distribution of the steam generator and selection of the coal type, which ensure acceptable erosion intensity. The code can be also used for optimization of coal mills operation.