Significant financial and environmental consequences often result from line leakage of oil product pipelines. Product can escape into the surrounding soil as even the smallest leak can lead to rupture of the pipeline. From a health perspective, water supplies may be tainted by oil migrating into aquifers. A joint academic-industry research initiative funded by (Pipeline and Hazardous Materials Safety Association) PHMSA(1) has led to the development and refinement of a free-swimming tool which is capable of detecting leaks as small as 0.01 L/min (0.03 gallons) in oil product pipelines. The tool swims through the pipeline being assessed and produces results to the end user at a significantly reduced cost compared to current leak detection methods. Above Ground Markers (AGM’s) capture low frequency acoustic signatures and digitally log the passage of the tool through a pipeline. A tri-axial accelerometer system gives the odometric position of the ball, and has the accuracy of standard instrumented pigs. Several other types of sensors like temperature, and pressure, are also present in the ball and collect useful data.