DOW OLEFINVERBUND GmbH operates a network of ten pipelines for the transport of raw materials and products to and from their production plants in Eastern Germany. Raw materials such as naphtha, condensate and liquid gas as well as products such as styrene, ethylene, propylene or butadiene are transported in the network. The pipelines have a total length of more than 1200 km (745 miles). In accordance with the requirements of the Technical Guideline on Pipelines (Technische Regel für Rohrfernleitungen - TRFL), two continuously operating and independent methods for detecting leaks were required for these pipelines.

A Safety Integrity Level (SIL) assessment - the required effectiveness of safety systems based on the probability of tolerable incidents that can occur within a number of processing demands - was provided in the scope of an overall qualitative and quantitative risk assessment service by the German TÜV. The hazardous classification of the transported fluids requires that the Leak Detection System (LDS) meets the Level 1 safety requirements of IEC EN 61508.

In order to meet the needed Safety Integrity Level, a specific methodology and set of activities were developed. For LDS implementation, a work package was installed in the context of a general facility control system rehabilitation project. The LDS was engineered, installed, put into operation and approved with respect to the SIL 1 requirements under the supervision of the German TÜV.

Up until recently, an LDS was not normally considered a component of a Safety Instrumented System (SIS). However further activities in this area have now begun. The development of the methodology and corresponding practical steps, together with the certification of these steps, are the main benefits of our work.

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