Small diameter pipelines have been historically very difficult to inspect with In-line Inspection (ILI) tools, especially using the MFL technique. Small diameter pipelines are challenging because they leave ILI system designers little space to fit the required system components of an ILI tool. In addition, many small diameter pipelines were designed and built without any consideration for ILI tool passage.
Recent advancements in microprocessor computational power, memory density, sensor technology, engineering design/modelling software, and rare earth magnetic technology have allowed an inspection system to be developed to inspect these small diameter pipelines.
This paper will describe several case studies and lessons learned about doing 1st time, MFL inspections of previously unpiggable, small diameter, pipelines.