The aim of leak detection and leak location is the limitation of losses and possible environmental damage in case of a leak, especially with hazardous products. The recognition of a leak, the knowledge of its leak rate and its location should lead to preassigned action taken by the operating personnel. A basic requirement for that is a reliable leak detection system that provides a well-defined detection threshold, which mainly depends on the metering precision of the instrumentation and the performance characteristics of the process data acquisition. On this basis it provides a well-defined response within an appropriate period of time and unique behaviour on operational intervention. A properly calibrated LDL system is a valuable assistance to the operating personnel. It is sensitive and at the same time shows a low false alarm rate.
The pillars of deterministic leak detection (LD) and leak location (LL) for pipelines are: measuring technology, communication and SCADA technology, and the application of hydraulic and thermodynamic laws. Any leak detection system that uses process data – no matter if based on deterministic methods or not – faces the same limits with respect to the achievable performance characteristics. Sensitivity, response time and cumulated leakage volume are the most important performance characteristics to be discussed here. The focus of this paper is on liquid pipelines.
An important advantage of deterministic methods for leak detection and leak location (LDL) for pipelines compared to statistic and other methods is the possibility to predict the performance characteristics of the deterministic LDL system already before its implementation. This will be demonstrated by three examples of predicted results compared to data obtained from field experiments. Vice versa the deterministic approach enables us to specify the requirements of the instrumentation, communication system and SCADA components to obtain the requested sensitivity and accuracy of the LDL system. This is last but not least an important aspect for choosing an economically feasible solution for each pipeline.