The detection of leaks in pipeline transportation systems is a matter of serious concern for operators, who pursue the integrity of their assets, the reduction of losses and the prevention of environmental hazards. Whenever a hole occurs in a pressurized pipeline, the corresponding leakage of fluid exiting the conduit is characterized by a turbulent flow and a peculiar acoustic noise, whose characteristics depend mainly on the size of the hole itself. This study shows that both the presence and the size of such a leaking hole can be successfully detected, either by exploiting the pressure transients (e.g., the acoustic noise internally recorded by hydrophones) generated by the fluid exiting the pipe, or by considering the corresponding vibrations (e.g., acceleration signals) propagating along the external shell of the conduit. To this purpose, several experimental campaigns of acoustic noise generation have been performed using multiple calibrated nozzles (from 0.1" to 0.25") on a 16” ID connection pipeline in a fuel tanks area located in Italy. Detection and classification procedures are proposed to control the presence of leakages, using pressure and vibration signals. Lastly, we demonstrate the possibility of estimating the size of the hole, which is shown to be proportional to the ratio between the leaking flow rate and the absolute pressure drop within the pipe itself.
Jet noise characterization for advanced pipeline leak detection
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