Corrosion Characterization at Surface and Subsurface of Iron-Based Buried Water Pipelines

Abstract

Water pipe surface deterioration is the result of continuous electrochemical reactions attacking the surface due to the interaction of the pipe surface with environments through the time function. The study presents corrosion characterization at the surface and sub-surface of damaged ductile iron pipe (DIP) and galvanized steel (GS) pipes which served for more than 40 and 20 years, respectively. The samples were obtained from Addis Ababa city water distribution system for the analysis of corrosion morphology patterns at different surface layers. Mountains 8.2 surface analysis software was utilized based on the ISO 25178-2 watershed segmentation method to investigate corrosion features of damaged pipe surface and to evaluate maximum pit depth, area, and volume in-situ condition. Based on the analysis maximum values of pit depth, area and volume were 380 m, 4000 m2, and 200,000 m3, respectively, after 25% loss of the original 8 mm thickness of DIP. Similarly, the pit depth of the GS pipe was 390 whereas the maximum pit area and volume are 4000 m2 and 16,000 m3, respectively. In addition, characterizations of new pipes were evaluated to study microstructures by using an optical microscope (OM), and a scanning electron microscope (SEM) was used to analyze corrosion morphologies. Based on the SEM analysis, cracks were observed at the sub-surface layer of the pipes. The results show that uniform corrosion attacked the external pipe surface whereas pitting corrosion damaged the subsurface of pipes. The output of this study will be utilized by water suppliers and industries to investigate corrosion phenomena at any damage stage.

Multi-parameter optical fiber sensing of humidity, CH4, CO2, and corrosion

“…8 Corrosion is an electrochemical process where the metallic substance in the natural gas transmission pipeline (e.g., Fe in carbon steel pipe) generally undergoes oxidation alongside the reduction of aqueous protons in the presence of certain electrolytes. [10][11][12] The condensed water in natural gas in contact with CO2 and H2S creates an acidic environment which initiates and sustains corrosion. 4,6,12 Studies have shown that the corrosion rate has been found to be proportional to the amount of water content inside the pipe.…”