L51925 Detection of Anomalies in Coated Pipelines Using Long Range Ultrasonics

Long-range guided wave pipeline inspection is claimed to be able to inspect ranges of well over 30 meters (100 Feet) in either direction (i.e. total inspection >60 Meters or 200 Ft.) from a single position. In terms of inspected meters per measurement and cost per meter this technique can be a fundamental improvement from conventional methods for pipeline inspection. For inspection of hard-to-access locations it offers a good on-stream screening alternative by being able to image the pipe section from an easier-access location. Examples of inaccessible locations are road-, railway-, river-, dike- and other crossings. Excavating the pipeline for inspection at these locations is expensive and the potential cost savings of a technique like long-range pipeline inspection are attractive. The objective of this project was to combine theory, modeling and experimental/operational elements in order to be able to handle the more complex situations as found at buried sections of pipelines, more specifically bitumen coating. Laboratory and field experiments supported by modeling and developing an approach to inspect a coated pipe configuration are parts of this work in order to get both reliable and practical knowledge. Another important part was the evaluation of the different transducer and equipment concepts available and establish their merits. In the project the propagation and reflection of guided waves was modeled and simulated for relevant situations. Two suppliers, SwRI and PiL, were involved in laboratory trials and field trials both to confirm the modeling and obtain a clear view of the practical aspects in operation and the actual capabilities of their systems. Modeling resulted in a formula providing estimates for the reflectivity of defects. Using scaling rules these were compared to data obtained in the laboratory trials.