Effect of Changing Water Quality on Galvanic Coupling (PDF)
- Author(s): Boyd, Glen R.; Reiber, Steven H.; McFadden, Matthew S.; Korshin, Gregory V.
- Publications: Journal - American Water Works Association
- Issue Date: March 2012
- Volume / Number: 104, Number 3
- Page(s): E136-E149
- DOI: http://dx.doi.org/10.5942/jawwa.2012.104.0038
- Product Number: JAW_0075566
Non-Member Price: $0
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Two galvanic pipe-loop couples (lead-copper and lead-bronze)
were exposed to controlled changes in water quality (disinfectant,
pH, alkalinity, and phosphate) and monitored for changes in lead
and copper release. In addition open circuit potential (OCP)
profiles were measured along the junction of dissimilar metals to
determine the extent of the zone affected by galvanic coupling.
Grab sampling results showed changes in water quality caused
transient (short-lived) increases in lead and decreases in copper
that corresponded to the galvanic action of lead on the other
coupled metal. OCP measurements indicated that the galvanic
effect on corrosion potential can induce a shift of up to 600 mV.
The extent of the galvanically affected zone was limited,
penetrating no more than a few inches from the juncture along
the surface of each pipe. Additional testing confirmed strong
effects of external versus internal coupling on the OCP profiles
in the galvanically affected zone.
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