Quantitative characterization of liner collapse in bimetal composite pipe structure using magnetic saturation PECT equipped with a new signal processing algorithm

The bimetal composite pipe structure is a kind of pipe structure made of carbon steel outer structural pipe and stainless steel liner functional pipe, which is widely used in the field of natural gas transportation and storage. However, the bimetal composite pipe structure will inevitably appear liner collapse in the service process, and the non-destructive testing (NDT) of which is an important as well as difficult issue. To overcome the difficulty of liner collapse detection in bimetal composite pipe structure, this paper proposes a magnetic saturation pulsed eddy current testing (MSPECT) method equipped with a new signal processing algorithm. The signal processing algorithm can adaptively extract the feature called “late correlation coefficient”. Firstly, the principle of the proposed method is introduced. Then, the simulation is conducted to show the possibility using MSPECT method for the detection of liner collapse in bimetal composite pipe structure. Following, the experimental platform of MSPECT is built. Finally, four types of experiments, the comparative experiments, collapse detection validation experiments using plate specimens, quantitative collapse degree detection experiments using plate specimens and collapse detection validation experiments using industrial pipe specimens, are thoroughly conducted to systematically verify the effectiveness and superiority of the proposed method.