The concern of the pipeline industry and general population for a safe and green environment is higher than ever. This highlights the need for efficient leak detection to prevent environmental catastrophes and operational disruption. Therefore, accurate techniques to detect and locate very small leaks that could develop into larger leaks are a valuable asset for the construction of key pipelines. External pipeline leak detection systems based on distributed fiber optic sensing emerge as the most appropriate solution for automatic detection and localization of very small leaks.In the case of the Kinosis pipeline system, two 11km Electrically Heat Traced Pipe-In-Pipe (EHTPIP) pipelines have been built between the Nexen Long lake upgrader and Nexen Kinosis SAGD facilities. The fiber optic sensing cable is directly in contact with the EHTPIP external surface. These pipelines carry Produced Emulsion and Boiler Feed Water at temperatures as high as 120°C and 150°C respectively. The fiber optic distributed sensing system provides temperature feedback information to the operator, not only in operation and in case of a leak but also when the Electrical Heat Trace system is turned on; in this case, the monitoring system can detect and locate overheating problems and/or signs of heating failures.In the case of a leak, the outer temperature of the pipeline will increase; this will automatically be detected and monitored by the DITEST temperature monitoring system and will trigger an alarm to the Nexen LONG LAKE upgrader SCADA system for that specific location.Furthermore, the combination of fiber optic distributed monitoring with the PIP technology enables to detect and locate a leak in the inner pipeline at a very early stage, therefore avoiding any environmental damage (the leak is still contained by the outer PIP tube) and giving time to the pipeline operator to plan a sectional replacement.© 2014 ASME