|The inspection and monitoring of non-piggable pipelines is a prime technological gap in fuel network integrity management. Over the past decades, various non-destructive evaluation techniques have been developed and some of them have been marketed as new tools for inspecting unpiggable pipelines, including aboveground non-contact techniques such as tomography technology (MTM) and inline inspection techniques such as Explorer ILI robotic technology.
Research and industry experiences around use of inspection techniques for unpiggable pipes have been described in reports and papers scattered in the academic and industry literature, with various claims on the performance of these techniques. Currently the advantages, disadvantages, limitations and principles of these inspection techniques are often not well understood by the pipeline industry. This lack of knowledge would affect the correct selection and application of techniques for inspecting critical non-piggable pipelines.
This project provided a review on the current status and performance of these techniques by conducting an extensive review of the academic literature and an industry survey, and by comparing and analysing results from different sources. Major findings and conclusions from this study include:
- Up to the present time, there is no single tool or technology that could meet all requirements for reliably inspecting unpiggable pipelines. Direct assessment, including external corrosion direct assessment (ECDA) and internal corrosion direct assessment (ICDA) are still the most realistic approach to assessing the condition of unpiggable pipelines. The accuracy and reliability of ECDA and ICDA could be increased through the implementation and the combined use of some new inspection tools, corrosion monitoring probes, and data analytics techniques.
- Various non-destructive unpiggable pipeline evaluation technologies, in particular innovative ‘pigging-like’ devices and aboveground inspection tools, have been developed over the past decades. Based on industry survey and literature review several tools such as pigging-like ILI tools based on magnetic flux leakage (MFL) and spectrum XLI platform aboveground tool are highly recommended to be considered to be added to ECDA and ICDA toolboxes for assessing unpiggable pipelines conditions.