Analysis of FBG sensors data for pipeline monitoring

Pipelines for oil distribution may affect the environment when natural disasters such as landslides and earthquakes damage the infrastructures. Besides natural causes, illegal extraction of oil from the pipelines can produce significant environmental damage and sometimes loss of lives from explosions. During the spill, the fuel flow of the main stream theoretically reduces, but this variation is within the normal flow fluctuation and so it is not possible to detect this illegal activity using fuel flow measurements. Transducers based on Fiber Bragg Grating (FBG) sensors are very attractive for pipeline monitoring. In two previous works we proposed a new transducer for increasing the sensitivity of FBG sensors to detect illegal activities on the pipelines (drilling). In fact FBG sensors attached directly on the surface of the pipe are not capable to detect strain variations induced by a drill. This paper reports an update on the experimental results obtained on a real size pipeline and a theoretical study aimed to explain why a surface attached sensor does not work.