Combining Criticality Analysis and Failure Rate Assessment to Plan Asset Management in the Water Supply System of the Province of Ferrara
Autor: | Emilio Caporossi, Alessio Benini, Daniele Giunchi, Claudio Meoli, Claudio Anzalone, Francesco Maffini, Giancarlo Leoni |
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Rok vydání: | 2009 |
Předmět: | |
Zdroj: | Water Distribution Systems Analysis 2008. |
DOI: | 10.1061/41024(340)49 |
Popis: | In recent years Italian water utilities have gone through a restructuring process which focus is on processes optimization. Nowadays, the industry is still seeing many mergers and cost-reduction strategies taking place. Due to low tariffs, the Italian Water Industry has very limited economic resources that need to be spent optimally. In this framework, the importance of optimal asset management is increasing: as the budget is limited, an asset-specific knowledge is required “to choose exactly the right assets, to optimize maintenance activities and to refurbish and replace the selected assets at just the right times in a cost-effective manner” (Wu, 2006). This paper introduces the methodology that was developed to reach this objective by HERA, combining the results of a criticality analysis, performed through a detailed hydraulic model, with a Mean Time To Failure analysis based on pipe bursts-leaks data collected during a six-year period and processed in a GIS software. The water supply system serving the province of Ferrara (2420 Km of mains) was chosen for the application of the methodology as it is characterized by a high level of leakage (ILI = 11). The hydraulic model was implemented using accurate data from GIS, SCADA and billing systems to reproduce the complex dynamic behaviour of the water network. The model was calibrated against a set of flow/pressure data obtained from an ad hoc survey and historical SCADA information. The criticality analysis has been performed through an automated simulation process where each segment of the network was considered as out of service for a length of time. Several factors were considered, such as the system demand deficit caused by each segment outage, the number of critical customers (hospitals, schools, etc.) not supplied, traffic disruption along significant roads, possible ingress of contaminations at sub-atmospheric high points, etc. and the consequences of failure were determined. In order to calculate the risk related to each asset failure the likelihood of failure must be defined. Therefore, geo-referenced data on pipe and fittings failures in the 2000-2006 period were gathered and compared to the available information on materials, diameters, age, traffic load, thus determining the Mean Time To Failure for each segment of the network and the probability associated. Multiplying the consequence of failure by the likelihood of failure, the risk index related to each segment was calculated, thus allowing the prioritization of asset maintenance and replacement. |
Databáze: | OpenAIRE |
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