Any accident on Oil and gas pipelines can have extremely severe consequences. Magnetic flux leakage (MFL) inspection is commonly used to detect corrosion defects in pipelines at an early stage. However, many pipelines in real-world applications operate under low pressure, low flow conditions, or exhibit significant geometric deformations. In such cases, deploying MFL tools may be infeasible or pose a high risk of tool stuck. After years of research, an in-line inspection (ILI) technology based on the principle of permanent magnetic disturbance has been developed to effectively address these challenges.

This novel inspection tool offers several distinct advantages. Unlike conventional MFL tools, it does not rely on large permanent magnets, making it significantly lighter and more compact. As a result, it requires minimal backpressure and exhibits excellent pipeline passage capability. When integrated with a caliper sensor and an IMU module, a single inspection can simultaneously perform pipeline geometry assessment, IMU mapping, and metal loss detection on the internal pipeline wall. This tool is only less sensitive to external metal loss defects.

The inspection tool demonstrates high sensitivity to capture small defects and exhibits tolerance to sensor lift-off. Through extensive research and development, particularly with the design of specialized sensors and a segmented structural configuration, the tool can accurately detect pinhole defects as small as 5 mm in diameter within a certain range of sensor lift-off. This capability makes it particularly effective in identifying illegal oil taps. The technology has been recognized by major industry players such as PetroChina and China National Pipeline Corporation (PipeChina). It has been widely adopted in China, with an accumulated inspection track record of 15,000 km to date.