The Development Of Urban Heat-supply Pipeline Magnetic-thermal Comprehensive Testing Instrument

Although China is a great consumer to heat supply, its application of heat supply technology is still relatively behind. The inferior bury process and complex geographic condition not only give rise to a higher frequency of aging urban heat-supply pipeline web, but also prevent citizens from having a normal daily life. Currently, the specific testing instruments for the leakage location of urban heat-supply pipeline are not common in China. In this paper, a non-excavation testing instrument based on infrared temperature measurement method and micro-magnetic technology was proposed, which provides technical support for the leakage detection of urban heat-supply pipeline. The cost of test and maintenance will be decreased, and the accuracy of the leakage detection will be improved by using this instrument.In this paper, the principle of infrared temperature measurement method and micro-magnetic technology was explored after making a discussion on the reasons for the malfunction of urban heat-supply pipeline. Then through theoretic analysis, the feasibility of non-excavation, in-service inspection test which is based on infrared temperature measurement method and micro-magnetic technology has been identified. Three typical conditions of directly buried heat-supply pipe were analyzed subsequently by experiments. Its leakage characteristics were further established. And the leak signal and non-leak signal were distinguished. After that, through field investigation and consultation of relating materials, the testing method and the necessary function of the instrument were proposed with reference to real testing environment. The testing instrument was designed and developed with consideration of testing field environment. And its final framework and testing procedure was formed after repeated improvements and experiments.At last, a series of field tests were conducted by the testing instrument in Beijing, Wuxi( Jiangsu Province), Hohhot(Inner Mongolia Municipality) and some other places. After testing and analyzing, the leaking site was located and then verified by excavation. The results show that it is of high reliability to locate leaking sites and the correct rate can reach over 90% by using the instrument developed in this paper when testing the leakage of directly buried urban heat-supply pipe. The deviation between locating leaking place and real leaking place is less than 20 centimeters from the direction of pipeline.In this study, a new test method was proposed for the leakage of urban heat-supply pipeline, and the corresponding instrument was developed. Multiple practices proved that it is of high accuracy to use the instrument to locate the leakage of urban heatsupply pipeline. The test process has many advantages such as non-excavation, inservice inspection, rapid positioning, low-cost etc. And the instrument also has good adaptability to different road conditions above the pipeline, thus it can adapt to a majority of leakage detection of buried heat-supply pipeline.