Corrosion and scaling of the galvanized steel pipe in flowing geothermal water

By immersion testing in flowing system and static system, the corrosion and scaling behavior of galvanized steels were studied. The corrosion potential, weight, microstructure of the samples and the concentration of scale ions contained in both kinds of system were also investigated. The results showed that the corrosion process was considered to be the main process on the surface of the sample soaked in the flowing system. The weight of the sample gained rapidly, but the concentration of Ca²⁺ and Mg²⁺ in the water didn't change any more after soaked for 77 h. The main process of the sample soaked in the static system was scaling. The weight gained slowly, and the consumption of Ca²⁺ and Mg²⁺ continued even at the end of the experiment, indicating that the scaling was still kept on in this system. The corrosion potentials of samples in both systems were also different from each other. In addition, the flowing geothermal water could wash the surface of the samples, which made deposition of the scales more difficult and even affected their morphology.