Abstract:

Steel pipe corrosion and scaling is a universal problem during the exploitation and use of geothermal resources. Scanning electron microscopy (SEM), energy dispersion spectrometry (EDS), X-ray diffraction (XRD), and electrochemistry test were used to characterize and investigate the scaling and corrosion behaviors of galvanized steel and 304 stainless steel pipes in a simulated geothermal water environment (Chinese central plain geothermal water). Results indicated that the scale formed on the 304 stainless steel pipe consisted of a needle-like substance and its main components were CaCO3 and MgCO3. The corrosion and scaling morphology of the galvanized steel pipe consisted of a ball-like substance and a needle-like substance with main components of Zn(OH)2, ZnO, and CaCO3. Corrosion and scaling often appeared simultaneously and acted synergistically during the formation and growth of the crystal nuclei and they prevented further corrosion of the galvanized steel pipe in geothermal water.

Key words: Geothermal water, 304 stainless steel pipe, Galvanized steel pipe, Scaling, Corrosion