The paper describes the principles and trial results of a new pipeline leak detection system based on the detection of the rarefaction pressure waves associated with a leak. A unique method is used to differentiate leaks from false alarms. The method is based on the analyses of tri-dimensional pressure maps proved successfully in more than 100 real leak trials on 5 different pipelines carrying water, crude oil, jet fuel and on 2 different multi-product multibatch pipelines. The trials were carried out successfully with the pressure sensors spaced between 3 km to 200 km. Operation conditions include severe transients, steady state, shut-in conditions and slack-flow. The results show sensitivity better than 1% of nominal flow for all the tests, and the detection of very small leaks which are better described in terms of a few litres.
The system was further developed for use in hydro-testing of buried pipelines. This new application of the technology has proven to be an excellent tool for the detection and location of existing leaks, leaks which were already present before the installation of the LDS system. This feature also works in flowing lines allowing the detection of existing leaks and very slow opening leaks which makes it perfect for the detection of pipeline theft and for the retrofitting of LDS systems in general.