Metallographic Investigations of the Premature Corrosion Failure of Steel Seam-Welded Galvanized Cold Water Pipes

Abstract

A premature corrosion failure in seam-welded galvanized steel cold water pipes was reported to occur after just 18–24 months in service. The aim of the present work was to investigate the causes of this premature corrosion of pipes, through metallographic investigations. This work comprised chemical analyses, visual examination of internal surfaces of pipes and microstructural examinations of the corrosion perforation regions (pitting corrosion areas) using optical and scanning electron microscopy with energy-dispersive x-ray analysis. The investigations showed that failures resulted from incorrect installation—pipes were installed with yellow brass ball valves. When mixed with yellow brass, galvanized steel triggers dezincification and results in electrolytic action when combined with nonferrous metals, such as copper and brass.