Distributed fiber optic temperature sensing system is a unique tool for the detection and accurate localization of small ammonia or LNG (Liquefied Natural Gas) leaks on pipelines that can reach ten kilometers or more. Such distributed temperature sensing (DTS) systems have the advantage of being easy to deploy over long pipeline sections and have been shown to detect leakage events with good accuracy and reliability. This paper will present the experience gathered from ten ammonia and seven LNG leak detection installations, including examples of real accidental leaks that were detected using the fiber optic system. Reliability and availability data based on the use of the ATTS (Automated Trip Testing System) will also be presented along with information on the rate of undesired alerts and results of a SIL 2 rating analysis. Based on those field experiences, we finally formulate recommendations on the installation of the sensing cable, the alarm settings and the deployment process, to guarantee reliable results while reducing interference with day-to-day plant operations.
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