Improving pipe failure predictions: Factors affecting pipe failure in drinking water networks

Our plain-English summary of Improving pipe failure predictions: Factors affecting pipe failure in drinking water networks, by N.A. Barton, T.S. Farewell, S.H. Hallett, et al (Water Research, 2019).

The study

• Authors: N.A. Barton, T.S. Farewell, S.H. Hallett, T.F. Acland
• Journal: Water Research
• Published: 2019;164:114926
• Type of article: Review
• Cited by: 33 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

To reduce leakage and improve service levels, water companies are increasingly using statistical models of pipe failure using infrastructure, weather and environmental data. However, these models are often built by environmental data scientists with limited in-field experience of either fixing pipes or recording data about network failures. As infrastructure data can be inconsistent, incomplete and incorrect, this disconnect between model builders and field operatives can lead to logical errors in how datasets are interpreted and used to create predictive models. An improved understanding of pipe failure can facilitate improved selection of model inputs and the modelling approach. To enable data scientists to build more accurate predictive models of pipe failure, this paper summarises typical factors influencing failure for 5 common groups of materials for water pipes: 1) cast and spun iron, 2) ductile iron, 3) steel, 4) asbestos cement, 5) polyvinyl chloride (PVC) and 6) polyethylene (PE) pipes. With an improved understanding of why and how pipes fail, data scientists can avoid misunderstanding and misusing infrastructure and environmental data, and build more accurate models of infrastructure failure.

Copyright © 2019 Elsevier Ltd. All rights reserved.

In plain English

This article is a review written for data scientists who build statistical models to predict failures of drinking water pipes. It is an engineering paper and does not study asbestos-related disease. The authors summarised international research on why pipes fail, covering iron, ductile iron, steel, asbestos cement, PVC and polyethylene pipes. Their summary drew on input from industry professionals and on failure records from a UK water network operator. In that operator's data, collected between 2005 and 2018, asbestos cement pipes made up 7,259 km of a 37,560 km network and accounted for 14,053 of 58,018 recorded failures. These pipes failed more often in summer. The authors attributed this mainly to ground movement and said circumferential breaks made up about 75% of their failures. The review described uneven distribution of asbestos fibres in the cement as the main manufacturing defect. It also reported that UK manufacture of these pipes stopped in 1986. The authors concluded that failures are more likely in older, less resilient pipes in aggressive soils under extreme, unstable conditions. They noted that operational data remain inconsistent and incomplete.

We wrote this plain-English summary from the full article with the help of AI, and a second AI model checked each sentence against the article. It is not the authors' wording; the abstract and the article are their own account.

What the study did and found

• Design: Review of existing international literature on causes of drinking water pipe failure, illustrated with network failure data supplied by a UK water utility
• Who was studied: Drinking water pipes, not people: published studies from several countries, plus one UK utility provider's network data (37,560 km of pipe, 58,018 failures) collected between 2005 and 2018
• Exposure: Pipe material and the factors that make pipes fail, including asbestos cement (AC) water pipes. The fibre type in the asbestos cement is not named. Other factors covered were joints, coatings, manufacturing defects, corrosion, age, diameter, weather, soil and water pressure.
• Main results:
  • In the utility provider's data, asbestos cement pipes made up 7,259 km of network and had 14,053 failures, out of a total of 37,560 km and 58,018 failures
  • In the utility provider's data, asbestos cement pipes, and to a lesser extent PVC pipes, had higher failure rates in summer, while iron pipes had their highest failure rates in winter
  • In the utility provider's data, failure rates for asbestos cement pipes peaked for pipes installed during the 1940s to 1960s
  • The authors summarised that asbestos cement pipes largely fail in summer because of differential ground movement, with circumferential failure as the most common mode at approximately 75% of all failures
  • Citing earlier work, the review described two main types of chemical attack on asbestos cement pipes: lime leaching and sulphate attack. It said lime leaching can eventually leave a soft material in which the cement no longer binds the asbestos.
  • Citing an earlier source, the review reported that UK manufacture of asbestos cement pipe ceased in 1986 because of negative health perceptions of asbestos in building materials
• The authors' conclusion: The authors concluded that pipe failures are more likely in older, less resilient pipes in aggressive soils where weather and operating conditions are extreme and unstable. They said modellers should check their data inputs against known failure mechanisms.
• Limitations the authors state:
  • Operational data, such as water pressure, are still inconsistent and incomplete across large networks; pressure is largely modelled rather than measured
  • In the authors' experience, consistent and reliable operational data over long periods are the most difficult to obtain

Topics

Medical terms in this study, explained in our Lexicon: Asbestos-Cement.

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