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This powerpoint presentation begins by providing background information on pitting corrosion of copper pipes. A case study is presented of a large water utility in Florida that experiencedwidespread pitting corrosion in copper plumbing. Initially, the community started orthophosphate addition andpH change to mitigate problem in 2003, but switched to 50:50 ortho-polyphosphate blend inSeptember 2005. The objective was to determine how phosphate treatmentimpacted the surface of copper pipes that wereremoved from a real distribution systemthat experienced localized corrosion. Analytical methods included: solids analysis;Scanning Electron Microscopy; morphological and phase contrast; Energy Dispersive Spectroscopy;elemental composition; X-ray Diffraction; and, mineralogy. Results of orthophosphate impact indicated:lack of detection one year into treatment; below EDS detection;carry-out issues;dose consistency; and,accumulation rate. Results of polyphosphate impact and/or orthophosphate impactindicated: measurable increase of P with treatment time;localized concentration of P coating cap; displacement of Si;migration; and,mineral precipitation ispossible over time.

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Edition: Vol. - No. Published: 11/01/2007 Number of Pages: 7File Size: 1 file , 430 KB