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

Abstract

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.

Methods to Evaluate Corrosion in Buried Steel Structures: A Review

“…Corrosion is the degradation of the steel that ends up causing the failure of the infrastructure [3,4]. It is an essential factor in the design phase of such infrastructures, not only for its implications in structural resistance but also for its importance in economic calculation, as it implies costly maintenance in the phase of exploitation [5,6].…”

Study on the Soil Corrosivity towards the Buried-Structures in Soil Environment of Tanglaphant-Tribhuvan University Campus-Balkhu Areas of Kirtipur

“…It has been reported that soil resistivity has the largest effect on the observed maximum average pitting corrosion rate on the surface of the buried-pipelines (Schashle & Marsh 1963). Many buried-structural materials, such as galvanized water supply pipelines, natural gas and crude oil pipelines have been corroded by soils all around the world (Levlin 1992, Doyle 2000, Doyle et al 2003, Rim-rukehand & Awalefe 2006, Alhazzaa 2007, Shamsuri 2010. It has been reported that the aggressiveness of soil towards the drinking water supply pipeline used in Toronto city of Canada was affected by soil properties such as resistivity, pH and the presence of sulphate-reducing bacteria (Doyle et al 2003).…”

Investigation on the soil corrosivity towards the buried water supply pipelines in Kamerotar town planning area of Bhaktapur, Nepal

“…The buried-pipelines used to supply the drinking water; natural gas and crude oil have been affected by corrosive nature of soil s all arou nd the world [5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21][22][23][24]. Wh en a f ailure of water suppl y buried−pipelines occurs, there is a high degree of environmental and economic consequences.…”