Today the need for pipeline leak detection is clear and numerous different systems are commercially available. Most of these systems use measurement of flow, pressure and temperature; these systems are called ‘internal systems’, since no extensive hardware along the pipeline has to be installed. This paper starts with an overview of the most commonly used internal systems and a summary of the (dis)advantages of each system.
A software demo is used to explain why leak detection is more then just installing a flowmeter at inlet and outlet. The demo will, for example, show that flow is very transient during start-up of a pipeline and thus limits the minimum detectable leak rate of most internal leak detection systems. Unfortunately start-up is also the phase where most of the spontaneous pipeline leaks occur, after all pressure is increased during start-up.
Based on the aforementioned demo it will be shown why PipePatrol E-RTTM (KROHNE’s high-end system) maintains it’s sensitivity during transient condition, where more basic systems, such as PipePatrol Statistical (KROHNE’s basic system), have to raise the limit for the minimum threshold. A consideration will be made what system should be used for which application. High-end systems allow faster detection of smaller leaks, but can only do so if the SCADA system provides sufficient information.
The two most widely used principles for leak localization, the gradient intersection and the wave propagation method, will be explained using actual data from a 31 km long liquid pipeline. It will be clarified how the SCADA refresh rates influences the accuracy of the leak localization.