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Effect of metallurgical factors on steel pipe corrosion in water distribution systems DOI:10.15199/28.2018.1.6

  1. INTRODUCTION A large number of parameters affect pipe corrosion in water distribution systems, including water quality and composition, flow conditions, biological activity and corrosion inhibitors, as discussed in Ref. [1]. Improper water chemistry has been found to be the direct cause of the premature deterioration of zinc-coated steel pipes in water distribution systems [2÷6]. In some cases, the direct cause of perforations found in hot water steel pipeline systems has been identified as the polarity reversal of the zinc coating, which is driven by the high temperature of the water in the system due to thermal treatment for Legionella removal [7]. However, verification of the metallurgical quality of steel pipes should not be neglected, considering their premature deterioration when used in water distribution systems. In this study, the causes of failure of a black welded pressure steel pipe (the most commonly used steel pipe for sprinkler systems) and a zinc-coated welded steel pipe (used in potable water distribution systems) were investigated. 2. EXPERIMENTAL Macroscopic pictures of the investigated samples that were cut from the failed steel pipes are shown in Figure 1. According to the information obtained from the pipe users, both were to be made of S195T steel and meet the EN 10255 standard requirements. Metallographic specimens (cross-sections) were prepared from the leakage locations and their vicinities. In both cases, the leakage locations (pit corrosion) occurred in the area of the seam weld. For the zin[...]

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