Stochastic optimization of water pipes for optimal replacement strategy

In a pipeline system, aging of the pipeline due to a variety of internal and external factors reduces its functionality as a water supply system and increases the risk of pipe failure. Failure of aging pipelines leads to greater social and economic damage, thus through proper repair and replacement, the pipeline systems must be managed to ensure safe water quality and structural performance. In this study, the authors propose a methodology for estimating the replacement time to minimize the life-cycle cost of the pipeline systems. It is assumed that failures in the pipeline system are classified into break and destruction. The occurrence probabilities of break and destruction in a pipeline were estimated using the competing deterioration hazard model. The time to break and destruction are explained by using the exponential hazard model and Weibull hazard model, respectively. The optimal replacement strategies are estimated using life-cycle cost approach. In order to evaluate the applicability of the proposed methodology in this study, an empirical analysis was carried out with the actual data of the pipeline system of S city, Korea.