Study on scale formation and corrosion behavior of heat exchanger steel 20 at different temperatures

This study investigates the scaling and corrosion behavior of steel 20 of cooling water in two locations: oil depot working area and living quarters. Furthermore, it explores the effect of temperature on scaling rate and corrosion rate. Through static scaling test and dynamic scaling prediction, the scaling effect of water quality is analyzed. The results show that the scaling degree of two water quality conditions is different with the change of temperature. The water scaling initiates at 60 degrees C in the living quarters, while a slight amount of scaling occurs when the temperature reaches 75 degrees C at working area. Through the utilization of open circuit potential, polarization curve analysis, scanning electron microscope (SEM) imaging and X-ray diffraction, the corrosion potential, corrosion rate, macroscopic and microscopic corrosion samples, as well as corrosion products of steel 20 were comprehensively examined. It was found that, in the temperature range of 30 -50 degrees C, the corrosion rate of steel 20 in the working area showed a linear trend with water temperature, while the corrosion rate in the living quarters exhibited an exponential function trend with temperature. Considering the combined impact of scaling and corrosion on heat exchanger performance, if the operating conditions can exceed 40 degrees C, the water quality within the working area poses minimal risks and operational pressure to the heat exchanger. Therefore, it is more suitable as a cooling water source compared to that in living quarters.