Pipeline Leak Detection in Noisy Environment

One of the safest ways for transporting fluid materials, such as natural gas, petroleum products, water etc., is the use of pipelines. However, a major problem in pipeline systems is the occurrence of leaks, which result in many environmental problems, dangerous accidents and financial loss. For this reason, many leak detection techniques have been developed over the past years. In this paper, an Acoustic Emission (AE) method for the detection and localization of a leak in a pipeline is presented. The AE method employs the use of acoustic sensors mounted on the external surface of the pipeline, which receive acoustic signals created due to the existence of a leak. The localization of the leak can be achieved by determining the time difference between the moments that such an acoustic signal arrives to two adjacent sensors. Two ways for calculating this time difference are presented in this paper: the Threshold Surpassing technique and the Time - Frequency Analysis technique. Moreover, acoustic measurements on metallic rods and on real pipelines in the field are presented. Based on these measurements, several results are obtained, concerning the localization of cracks in the pipelines, as well as, the spectral contents of the ambient noise in the field.