Contents I. Introduction
Leaks in distribution gas pipeline are a critical problem which gas companies typically encounter. In underground low-pressure distribution, often water from the surroundings enters into the pipeline, causing blockage. This is known as ‘water ingress’ problem. Replacing existing pipeline under problems is rather costly and troublesome. For gas pipelines, when leak occurs, gas escapes into the environment, resulting in cooling of the surrounding area due to the Joule-Thomson effect. Commercial distributed temperature sensing (DTS) system with appropriate operation method could be a solution as it can achieve a resolution of 0.05°C. This paper describes the application of DTS technique for gas leak detection. The remainder of the paper is organized as follows. Section II describes the background knowledge, characteristic and measuring principle of the DTS technique. The evaluation procedures of temperature change due to Joule-Thomson effect have been proposed in section III. Section IV shows the calculation results of temperature drop when methane leaks from gas pipeline under different gauge pressures. The test setup for low gauge pressure of 2 kPa is shown in Section V, followed by conclusions in section VI.
