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

Failure analysis and assessment on the exemplary water supply network

Pipe failures in water distribution systems can have a serious impact and hence it’s important to maintain the condition and integrity of the distribution system. This book presents a whole-life cost optimisation model for the rehabilitation of water distribution systems. It combines a pipe breakage number prediction model with a pipe criticality assessment model, which enables the creation of a well-constructed and more tightly constrained optimisation model. The pipe breakage number prediction model combines information on the physical characteristics of the pipes with historical information on breakage and failure rates. A weighted multiple nonlinear regression analysis is applied to describe the condition of different pipe groups. The criticality assessment model combines a pipe’s condition with its hydraulic significance through a modified TOPSIS. This model enables the optimisation to focus its efforts on those important pipes. The whole life cost optimal rehabilitation model is a multiple-objective and multiple-stage model, which provides a suite of rehabilitation decisions that minimise the whole life cost while maximising its long-term performance. The optimisation model is solved using a modified NSGA-II. The utility of the developed models is that it allows decision makers to prioritize their rehabilitation strategy in a proactive and cost-effective manner.

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Deterioration and Optimal Rehabilitation Modelling for Urban Water Distribution Systems

Predicting pipe failures using statistical modelling benefits from detailed knowledge of the conditions and circumstances which influence such failures Incorporating this knowledge into model building improves failure predictions In this study, we model weather, soil and hydrogeological variables in a generalized additive model for five common pipe materials separately, using partial dependence plots to understand the partial effects of each variable on pipe failure We show how severe temperatures are associated with high pipe failure Cold temperatures and air frost and their interaction with soils represent the key factors for pipe failures during the winter for metal pipes Warm temperatures, high soil moisture deficit and soil movement results in higher pipe failures in asbestos cement pipes during the summer Warm temperatures, ground movement and soil wash out, and water demand are key factors for polyvinyl chloride pipe failure during the summer Frost is a key factor influencing polyethylene pipes during winter An understanding of the physical principals concerning pipe failures can enable the development of more accurate models, guiding network management plans to help reduce asset leakage through appropriate interventions

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Using generalized additive models to investigate the environmental effects on pipe failure in clean water networks

Soil deformation is believed to play a crucial role in the onset of failures in the underground infrastructure. This article describes a method to generate a replacement-prioritisation map for underground drinking water pipe networks using ground movement data. A segment of the distribution network of a Dutch drinking water company was selected as the study area. Failure registration data comprising 868 failures registered over 40 months and geographical network data were obtained from the water utility. Ground movement was estimated using radar satellite data. Two types of analyses were performed: cell and pixel based. For the cell-based analysis, asbestos cement (AC) pipes exhibited the highest failure rates. Older AC pipes were also shown to fail more often, whereas failure rates for PVC were the lowest. For the pixel-based analysis, ground movement was demonstrated to play a role in the failure of all materials combined. Therefore, a replacement-prioritisation map for AC was generated which combined g...

Pipe failure predictions in drinking water systems using satellite observations

This paper presents and discusses the significant role played by joints in the failures registered in drinking water distribution networks. The three most important failure mechanisms related are presented and a procedure to detect them through the visual measurement of the gap between pipes inside a joint is proposed. The procedure is proved to be a valuable source of information on joint condition after the assessment of a 600-m DN500 PVC pipe.

Ilse Pieterse

Papers

Failure mechanisms and condition assessment of PVC push-fit joints in drinking water networks