External Corrosion in Distribution Systems

O'Day, D. Kelly

doi:10.1002/j.1551-8833.1989.tb03289.x

Cited by 10 publications

(6 citation statements)

References 5 publications

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“…It has been established that the 'corrosiveness" of a soi1 is affected by properties such as soi1 type, pH, resistivity and sujphate reducing bacteria (Romanoff 1964, O'Day 1989Robinson 1993). However, the real world influence these soi1 properties have on cast-iron water main corrosion is not as well understood.…”

Section: Introductionmentioning

confidence: 99%

The role of soil in the external corrosion of cast iron water mains in Toronto, Canada

Doyle¹,

Seica²,

Grabinsky³

2003

Can. Geotech. J.

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External corrosion is a major factor contributing to the deterioration of cast iron water mains; it weakens the pipe wall, which increases the risk of failure. External corrosion is a function of the interaction between the pipeline and the soil that surrounds it. The aggressiveness of soil towards cast iron is affected by soil properties such as resistivity, pH, and the presence of sulphate reducing bacteria. Water main sections and accompanying soil samples were collected from locations across Toronto within the framework of a comprehensive research project over a 2 year period. After careful examination of the effect of each of the soil properties, it appears that soil resistivity has the largest effect on the observed maximum average pitting rate. Limitations to the practical application of the American Water Works Association soil corrosiveness scoring system are also presented. A preliminary spatial analysis of the data indicates that water mains in the district of Etobicoke have had a higher average rate of external corrosion than those in the district of Toronto. Microbiological corrosion could be an aggravating factor in the district of Etobicoke, since areas exhibiting increased levels of sulphide concentration were identified in soils that had originated from this district.Key words: water mains, external corrosion, soil properties, Toronto, cast iron, pipes.

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Section: Introductionmentioning

confidence: 99%

The role of soil in the external corrosion of cast iron water mains in Toronto, Canada

Doyle¹,

Seica²,

Grabinsky³

2003

Can. Geotech. J.

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“…It has been reported by many researchers that pipe failure varies with pipe age in accordance with a bathtub curve (Andreou et al 1987;Kleiner and Rajani 2001;Singh and Adachi 2013). Environmental factors such as precipitation, soil conditions, frost and traffic loading, and the quality of external groundwater have been identified as factors contributing to the failure rate of pipes in water networks (O'Day 1989;Rajani and Zhan 1996;Kleiner and Rajani 2001;Kimutai et al 2015). Generally, low temperature and rainfall tend to increase pipe break rates (O'Day 1982;Brander 2001;Kimutai et al 2015).…”

Section: Causes Of Pipe Breaksmentioning

confidence: 99%

Field Data–Based Methodology for Estimating the Expected Pipe Break Rates of Water Distribution Systems

Ghorbanian

Guo

Karney

2016

J. Water Resour. Plann. Manage.

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Presented in this paper is a field data-based probabilistic approach to quantifying the expected pipe break rates of water distribution systems. Uncertain demands and variations in the roughness of pipes during their service lives are described as random variables. Sample values of these random variables are generated and input to a distribution system model to determine the resulting minimum and maximum pressures in Monte Carlo simulations. Based on an estimated break rate-maximum pressure relationship, the sample maximum pressures obtained from a Monte Carlo simulation are transformed into a sample of break rates, and the expected pipe break rate can subsequently be determined. The sample minimum pressures are used to gain a better understanding of the distribution network. This probabilistic approach is used for a part of the City of Hamilton's network in Ontario, Canada. The results show that the frequency of low-pressure events is very small, but a higher minimum pressure criterion would inevitably increase expected pipe break rates. Local field data collection is necessary to use the proposed methodology. Savings resulting from reduced pipe break rates justify costs associated with data collection.

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“…Galvanic corrosion Stops galvanic current Less noble metal (e.g., iron main) no longer serves as sacrificial anode to more noble metal (e.g, copper service line) Ferguson & Nicholas, 1991;Gehring et al, 2003;Horton, 1995;O'Day, 1989;Rajani & Kleiner, 2003 Thawing of frozen pipes in cold environments None Electrical currents cannot be used to thaw pipes connected with dielectrics Nelson, 1976 Grounding to prevent electrocution and meet plumbing code…”

Section: Benefit Of Dielectric Hypothesized Detriment Of Dielectric Rmentioning

confidence: 99%

“…There have also been concerns that placing a dielectric between copper service lines and iron distribution mains to prevent galvanic corrosion of iron might hinder cathodic protection of the valuable copper service lines and increase copper failure rates (Horton, 1995;Ferguson & Nicholas, 1991). Obviously, any potential benefit of preventing galvanic corrosion must be weighed against a more rapid localized attack of the iron mains at copper service line connections; however, no cost-benefit analysis of these tradeoffs has ever been conducted (Gehring et al, 2003;Rajani & Kleiner, 2003;O'Day, 1989). Finally, in at least some cases, installation of dielectrics on lines carrying alternating/direct stray currents can induce corrosion and cause ele-vated iron, lead, and copper in water (Bell & Duranceau, 2002;Horton, 1995).…”

mentioning

confidence: 99%

Issues associated with use of dielectrics in drinking water systems

Clair¹,

Edwards

2014

Journal AWWA

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Performance of dielectric configurations to reduce corrosion while meeting electrical codes in premise plumbing was examined and ranked as follows: bridged plastic pipe section > dielectric nipple > dielectric union > brass nipple ≈ dielectric spacer. When dielectrics were bridged with a grounding strap, the primary factor affecting galvanic performance was separation distance between the anodic and cathodic metal; however, some dielectrics offered other important advantages such as greater corrosion allowances (i.e., wall thickness) or reduced likelihood of clogging as a result of scale buildup (i.e., higher cross‐sectional flow area). Although bridged dielectrics do not completely stop galvanic corrosion, they can dramatically reduce galvanic corrosion while maintaining electrical continuity (satisfying electrical grounding requirements) between pipe sections.

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External Corrosion in Distribution Systems

Cited by 10 publications

References 5 publications

The role of soil in the external corrosion of cast iron water mains in Toronto, Canada

The role of soil in the external corrosion of cast iron water mains in Toronto, Canada

Field Data–Based Methodology for Estimating the Expected Pipe Break Rates of Water Distribution Systems

Issues associated with use of dielectrics in drinking water systems

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