Experiences with a non-failure based condition survey of ductile iron pipes in the water supply system of Vienna

Daniela Fuchs-Hanusch, Markus Günther, Franz Weyrer

Publikation: Beitrag in Buch/Bericht/KonferenzbandBeitrag in einem KonferenzbandBegutachtung

Abstract

Water distribution pipe condition information is mainly collected during the repair process of reported or detected leaks. In the contrary, less is known about the deterioration processes themselves. A reason for this is, that data collection of different stages of deterioration either is technically impossible (e.g. inside inspection of small diameter pipes) or expensive (e.g. inside inspection of large diameter pipes). For ductile iron (DI) pipes, the main failure cause is outside
corrosion. Corrosion is a process that can be easily observed if the pipe is subsequently uncovered. In 2009 Vienna Water Works therefore started a condition survey based on a questionnaire, which was filled each time a DI pipe is uncovered because of (small) construction sites. As Vienna’s water distribution, system consists of 60% ductile iron pipes with 3 different coating systems the condition evolution of theses pipes is of high interest for future rehabilitation planning. So far, 754 condition records were collected and statistically analysed.
The results of the significance tests have shown that a specific condition state of a pipe is by chance with less than a 5% probability for pipes with different coating systems, for pipes with previous failure and for pipes at different ages. This means these factors are statistically highly significant and hence were incorporated into the model building process. Although it is well known that the surrounding conditions can have significant influence on corrosion, the collected data in Vienna did not allow to derive any interrelationships between surrounding
material and the deterioration state so far. At the moment the model allows to predict the percentage of ductile iron pipes with different coating systems and with or without previous failure being in a specific condition state at specific ages. For Vienna the model has shown that at an age of 40 years 45% of bitumen coated pipes but only 25 % of zinc bitumen coated pipes are expected to be of class 3 (strong corrosion) if they belong to the category “pipes with previous failure”. In a next step it is planned to implement information from soil investigations into the analyses as well. Such soil investigations are made in the fore field of many
construction sites in Vienna and are collected by the municipality. The continuous
analysis of non-failure based condition data helps Vienna Water Works to
improve rehabilitation prioritization, especially because the analyses have shown
that pipes, with previous failure nearby, have a high probability to be in a bad
condition as well.
Originalspracheenglisch
TitelWater Loss
Seiten19-19
PublikationsstatusVeröffentlicht - 2014
VeranstaltungIWA Water Loss 2014 - Wien, Österreich
Dauer: 30 März 20143 Apr. 2014

Konferenz

KonferenzIWA Water Loss 2014
Land/GebietÖsterreich
OrtWien
Zeitraum30/03/143/04/14

Fields of Expertise

  • Sustainable Systems

Treatment code (Nähere Zuordnung)

  • Application

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