Several difficult to inspect scenarios of pipeline integrity are not related to problems in piggability or operational issues in general but rather stem from the inability of current ILI inspection technology to address certain relevant types of defects. This is in particular the case for pipe types that standard intelligent pigs are not designed for. These pipe types comprise but are not limited to pipes lined or clad with different materials. These pipe types are found in different areas of the industry and still represent a major gap in the process of gathering suitable data for pipeline integrity assessment.

The paper will review typical persisting problems in the detection of defects in several types of pipes. Drawbacks of the state-of the-art inspection technologies like Magnetic Flux Leakage (MFL) or Ultrasonic Technologies (UT) are explained. The driver for the development of the ILI technology were CRA (Corrosion Resistant Alloy) clad and MLP (Mechanically Lined Pipes) pipes often used in an upstream sour service environment. Eddy current technology in combination with magnetisation of ferritic steel components can effectively allow for the detection of defect types previously undetectable. Eddy current parameterization allows for proper adjustment of the tool capabilities without having to modify the hardware.

The development stages of the inspection technology are described together with the design of the ILI tool. Suitable steps of verification are set-up and executed. Applications of the technology to various related circumstances like heavy wall gas lines and concrete coated lines are discussed.