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Effects of pH, chloride, bicarbonate, and phosphate on brass dezincification
Author(s) -
Zhang Yaofu,
Edwards Marc
Publication year - 2011
Publication title -
journal ‐ american water works association
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.466
H-Index - 74
eISSN - 1551-8833
pISSN - 0003-150X
DOI - 10.1002/j.1551-8833.2011.tb11438.x
Subject(s) - brass , alkalinity , zinc , bicarbonate , phosphate , chloride , corrosion , leaching (pedology) , inorganic chemistry , chemistry , halide , galvanic corrosion , solubility , metallurgy , copper , materials science , environmental science , biochemistry , organic chemistry , soil science , soil water
Plumbing failures associated with brass dezincification have recently been reported in some areas of the United States, prompting research to identify the interplay between water chemistry and dezincification propensity. This research identified a critical pH range (8–9) at which “meringue” dezincification was problematic. In addition, the authors have refined interpretation of the classic Turner diagram by attributing beneficial effects to higher alkalinity rather than hardness (or temporary hardness). Among other findings, chloride exacerbates the dezincification propensity of water (high galvanic current/ voltage and zinc leaching) by increasing zinc solubility and decreasing pH at brass surfaces in galvanic couples to copper pipe, leading to increased weight loss and formation of corrosion products. Inhibitive effects of orthophosphate dissipated after around 100 days, calling into question the long‐term efficacy of phosphate inhibitors in mitigating brass dezincification.