In this paper, the reliability of transients due to pump trip as a powerful tool for the pre-localization of anomalies in real pipe systems is tested. The examined pipe system is part of the one supplying the city of Milan, Italy and is managed by Metropolitana Milanese SpA (MM). The characteristics of such a system can be considered as intermediate between those of classical transmission mains and distribution systems because of its several branches. A Lagrangian model simulating pressure wave propagation is used to evaluate the pipe pressure wave speed – associated with a genetic algorithm – and to locate possible anomalies – associated with wavelet analysis. The results of the diagnosis of the pipe system are corroborated by repairs executed by MM in the area where possible anomalies have been pre-localized.

This paper concerns the use of Transient Test‐Based Techniques (TTBTs) for fault detection in a long transmission main. It reports the results of two series of transient tests executed in a real and operating pipe system. Because of the complexity of the investigated pipeline that includes several stubs, different pressure wave generators were used at both the end sections. Precisely, transients were caused by a pump shut‐down and the Portable Pressure Wave Maker device. The analysis of the results shows that, according to the characteristics of the transient tests and the investigated system, only a part of the system can be explored properly from a given generation point. The proposed test procedure allows overcoming the negative effect of a change in the initial and boundary conditions. In fact, contrary to laboratory, in a real system, it is quite impossible to repeat tests in the same flow conditions. The success of the survey—with two leaks detected with a good precision—confirms the potential of the TTBTs for fault detection in real systems.

In recent decades transient test-based techniques (TTBTs) have been used for fault detection in transmission mains. Within TTBTs, the direct transient analysis (DTA) allows the identification of the defects directly by analysing the pressure signal. A possible DTA procedure is based on the analysis of the damping of the pressure peaks. In this paper, it is shown that the pressure decay in a polymeric leaky pipe depends exponentially on leak size and location and the pressure at the leak. It is also shown that, for a given transient, the same damping of the pressure peaks may result from different pipe systems (e.g. with a leak of a different size in a different location).

Since the 1990s, pressure waves propagating in pressurized pipes during a transient event have been re-evaluated both in the laboratory and in real systems as a way to obtain information about location and size of leaks. However, a systematic analysis of the obtained results has not been offered yet in the literature. In this paper, a review of the available experimental data concerning the use of transient tests for leak identification in pressurized pipe systems is presented. The selected data are examined with regard to the main features (categories) influencing the transient response of a leaky pipe system: layout, modality of transient generation, material, diameter, pre-transient pressure and flow condition, inserted pressure wave, and leak characteristics. Moreover, for each of such categories, possible specific issues to address for future research are proposed.