Desktop studies accurately predict trends in corrosion by‐product release.
Utility experiences were examined to assess the reliability of solubility models and decision trees in forecasting control of lead (Pb) and copper (Cu) corrosion by‐products. Such approaches cannot quantitatively predict effectiveness of corrosion control. For example, even the best‐fit solubility models explain only about 35 and 18 percent of the quantitative variation in 90th percentile Cu and Pb release, respectively. However, the decision trees and solubility models are qualitatively consistent with utility experience and are thus useful when promising water quality changes are identified to mitigate corrosion by‐product release. Utility experiences confirm that an optimal alkalinity range (20–40 mg/L as CaCO3) exists for Pb corrosion control above pH 8.5, a higher mass ratio of chloride to sulfate tends to worsen Pb by‐product release, and detectable color can signal a natural organic material content that may adversely affect compliance with the Cu action limit.
Little is known for certain about the factors that initiate or propagate blue water, a perplexing copper corrosion problem.
Extensive effort has been expended by utilities, consultants, and scientists to better understand factors causing outbreaks of blue water, a rare problem that occurs in relatively high pH drinking water. This work synthesizes information about initiation factors, remedial measures, and theories. Although chlorine is an effective remedial measure, little is known for certain about factors that initiate or propagate blue water.
Sulfides can accelerate the corrosion of copper pipe and elevate concentrations of copper in drinking water.
The presence of sulfides in potable water increases copper pitting and the release of copper corrosion by‐products. After 3 h of stagnation in a copper pipe, the average by‐product release of a synthetic drinking water that contained sulfides was 8.0 mg/L at pH 6.5 and 4.4 mg/L at pH 9.2. These concentrations represented a 5‐ and 50‐fold increase compared with water without sulfides. Sulfide‐induced corrosion problems might be ameliorated by removal of sulfides from the water, mechanical removal of the sulfide scale, chlorination, or deaeration. However, in the laboratory only mechanical removal of the sulfide scale and removal of sulfides from water were effective within a month. Utility case studies strongly support a relation between sulfides and increased copper corrosion problems.
NOTICE Th is document contains information of a preliminary nature and was prepared primarily for internal use at the Oak Ridge Notional Laboratory . It is subject to tevision or correction and therefore does not represent a final report .
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.