Study the causes of pitting corrosion in carbon steel water pipeline at the site of advanced chemical industries complex

There are many factors that affect the pitting corrosion of carbon steel (Q235A) some of them are related to the pipeline material such as material chemical composition specifications and other related to water specifications such as water temperature, pH of the water, and chemical and physical specification of water. In this study, the investigation was done for both water quality and materials of pipelines (Q235A), four samples from on a piece of same rolled sheet welded pipe(carbon steel (Q235A) were prepared and tested for chemicals composition, microstructure, roughness, and thickness, the test results shown that no difference observed for all results only on one sample have difference roughness value near to the welded joint, these test applied for 4 pieces took from one pipe to check the effect of rolling of these pipes that can cause dissimilarity .which enhance corrosion rates. Then the water quality was investigated for temperature 45C, pH equal to 9, chloride, TDS, and water pressure, the test result showed that the temperature of the water was 45 C pH 9 and contain chloride with a concentration quite enough to initiate pitting. From the collected data this study specified the causes of pitting corrosion in the studied area of water pipelines and summarized in the flowing, this pipelines exposed to high pressure than the required, and temperature of water reach over 45C in summer, and chloride iron have the main contribution on pitting corrosion of these pipes.