Advanced Leak Detection Applications for Pipeline Integrity Management Using Vibroacoustic Technology

Abstract The paper addresses the integrity monitoring of critical infrastructures as fluid filled transportation pipelines by developing a pilot full scale application of Advanced Leak Detection (ALD) monitoring system. The objective of the ALD system is to improve performances with respect to single separate LD system, in different scenarios in terms of sensitivity, localization accuracy, and robustness. Three Leak Detection methods have been evaluated which rely on different physical principles, though independent, and could interact with one another through cross-links data at core level. The Advanced Leak Detection system has been developed over an already existing technological platform based on vibroacoustic sensing, which includes flowmeters, pressure sensors, and accelerometers using acquisition units distributed along the pipeline routing, and processing computers with software suite. Leak Detection sub-systems are based on i) Advanced Negative Pressure Wave for detection and localization of fluid transients; ii) RTTM-Compensated Mass Balance for detection of imbalance in the fluid mass transportation; iii) Acoustic Noise for detection and localization of existing or slow-opening leaks. The integration of different Leak Detection sub-systems can take place at various levels: cross-check of measurements, cross-link of computed fluid-dynamic quantities, merge of alarms associated to the same physical event. The Advanced Leak Detection pilot system has been deployed and validated on liquid fuel transportation pipeline 40 km long, managed by Eni SpA in North Italy. Several controlled spill-tests (i.e., with distinct size, area, shape), including spillages simulating both short-duration and slow-opening cracks, have been performed in both pumping and shut-in operational conditions to calibrate the ALD system and to assess the performances. The amount of spilled product has been measured for each test by means of a calibrated weight scale. The ALD system proved to be able to detect and localize both quick and slow-opening leaks with a good sensitivity, specificity, and precision. In addition, Leak Detection alarms contain estimates of outflow rate and hole size: accuracy and alarm response time are assessed in the paper. In conclusion, the ALD system has been validated on fuel transportation pipeline by Eni as compliant with the technical requirements and is currently deployed in operations. The novelty of the pilot ALD system lies in the integration of Leak Detection methods at the core level, that allow to exchange information, calibration and synergically contribute to provide robust, sensitive, accurate and informative Leak Detection alarms.