In-line inspection methods and tools for oil and gas pipeline: A review

Corrosion, mechanical damage, cracking, and deformation are the main factors that threaten pipeline integrity and transportation safety, potentially leading to serious accidents and economic losses. Therefore, ensuring safety and implementing effective pipeline integrity management (PIM) is crucial. In-line inspection (ILI) has been widely recognized as an effective approach for maintaining pipeline safety by accurately identifying and quantifying defects. This review summarizes the current state of research on ILI methods and tools. It also examines the applicability of traditional ILI techniques such as Magnetic Flux Leakage (MFL), Eddy Current Testing (ECT), Ultrasonic Testing (UT), and Alternating Current Field Measurement (ACFM). Additionally, the review analyzes the adaptability of emerging methods, including Acoustic Resonance Technology (ART), Direct Magnetic Resonance (DMR), Short Range Distance (SRD), and multi-physical field coupling methods. And the work describes the latest development of these methods in terms of application fields, limitations, inspection capabilities, etc. Furthermore, the key method of traditional MFL-such as problem formulation, tool development, and data processing are analyzed. Using the small-diameter pipeline (DN < 6-inch) MFL ILI system as a case study, the challenges and potential research directions for the development of small-diameter MFL tools are explored. The review concludes by suggesting areas for further improvement, which would benefit the advancement of ILI methods and tools in the field.