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Document Type

Thesis - University Access Only

Award Date

2013

Degree Name

Master of Science (MS)

Department / School

Civil and Environmental Engineering

First Advisor

Delvin E. DeBoer

Second Advisor

Christopher Schmidt

Abstract

Household systems use copper pipe as the plumbing material due to the excellent characteristics of the pipe such as easy installation and low cost. However, copper pipe is subject to corrosion despite being categorized as corrosion resistant. Pitting corrosion of copper pipe has occurred in several systems across the nation, and a body of research has occurred to identify the causes and remediation of pitting corrosion. This thesis presents the results of investigations into the potential causes and remediation of pitting corrosion that occurred in the premise plumbing of a small proportion of customers in a regional water system. Water quality factors and electrical grounding factors were investigated as potential causes of pitting corrosion. In order to determine causes of corrosion, investigations were conducted at corroded and non-corroded locations (control locations). Water samples were analyzed both on site and in the lab for: pH, alkalinity, sulfate, chlorine residual, and ammonia. Electrical current flow to ground was also measured at all the locations. The water quality results indicated no definite relationship between the plumbing material and a drop in pH. However, a drop in pH was always accompanied by a low disinfectant residual in the first draw sample and significant nitrate and nitrite concentrations as compared to the flowed water samples. Chloride and sulfate

concentrations did not differ between the control and corroded locations. However, the high content for both of the compounds in all the water samples could contribute to corrosion, as suggested in the literature. The measured electrical current flow to ground was higher in corroded locations as compared to the control locations, suggesting that grounding of electrical systems to the copper plumbing could be contributing to corrosion. Surface analysis of the pipes and microscopic analysis of the tubercles further revealed sulfur and oxygen to be the main component in the tubercles. A combination of water quality factors and high ground current were observed as potential factors contributing to corrosion.

Library of Congress Subject Headings

Pipe,Copper--Corrosion
Plumbing
Water quality
Electric currents--Grounding

Description

Includes bibliographical references (pages 129-133)

Format

application/pdf

Number of Pages

252

Publisher

South Dakota State University

Rights

In Copyright - Educational Use Permitted
http://rightsstatements.org/vocab/InC-EDU/1.0/

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