Mitigating Corrosion Challenges in Water Filtration Plants: a Case Study on Pitting Corrosion in 304 Stainless Steel Headers and the Transition to HDPE Solutions

Abstract This study investigates the causes of premature pinhole leaks in a 6.4 Million Gallons per Day (MGD) water filtration plant that utilizes 304 stainless steel feed headers. The leaks, predominantly occurring around welds on the 8-inch headers, were found to result from pitting corrosion, which was exacerbated by microbial activity and environmental factors. Laboratory analyses revealed significant iron oxides or rust formation, microbial-influenced corrosion (MIC), and extensive pitting, indicating compromised weld integrity. The formation of manganese dioxide when exposed to strong oxidizing agents such as chlorine or sodium hypochlorite, and the presence of chloride ions identified via EDS analysis further aggravated the corrosion. To address these issues, the study recommends replacing the corroded stainless steel pipes with High-Density Polyethylene (HDPE) pipes, implementing a monitoring program for early corrosion detection, and conducting microbial testing to manage MIC risks. These measures are proposed to enhance the plant's reliability, operational efficiency, and the longevity of its infrastructure. Understanding the formation of manganese dioxide and its impact on corrosion is crucial for developing effective management strategies in water treatment facilities.