LEAKAGE DETECTION OF PIPELINE

PURPOSE:To ensure reference pressure to be used when detection accuracy is improved by utilizing pressure difference, without using a special means or management. CONSTITUTION:The pressure in a pipeline L1 and a pipeline L2, which are in the proximities to each other, are formed into a first pressure by closing cutoff valves CV1 and CV3 of the both ends of the pipelines L1 and L2. The pressure difference between the pressures in the two pipeline is measured by closing a cutoff valve CV2 between the respective pipelines, so as to determine a first rate of change in the pressure difference. The pressures in the both pipelines are forcibly formed into a second pressure which is different from the first pressure by opening the cutoff valve CV2 between the respective pipelines L1 and L2. The pressure difference between the pressures in the two pipelines is measured by closing the cutoff valve CV2 between the respective pipelines, so as to determine a second rate of change in the pressure difference. Leakage in a region for leakage detection is detected based on the comparison between the first rate of change in the first pressure difference and the second rate of change in the second pressure difference.