Development and application of new technologies and equipment for in-line pipeline inspection

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In-line inspection is one of the most effective technical measures to ensure the safety of oil and gas pipelines. However, the extensive application of oil and gas pipelines of high-carbon steel, large diameter, high pressure and high flow rate in recent years brings about new challenges to in-line inspection. In this paper, we investigated the engineering application of new technologies and equipment, including the in-line inspection technology based on electromagnetic detector array, the extremely low frequency transient weak signal detection technology and new in-line inspection equipment. Then, the new technology and equipment of electromagnetic detector array were developed by applying the active emission and receiving of electromagnetic signal to inspect the metallic defects. Finally, noisy signals were inspected on the basis of Duffing chaotic oscillator, and thus the inspection of extremely low frequency signals in the noise was realized. In addition, the new method and equipment of extremely low frequency transient weak signal detection were developed and verified in actual inspection engineering. And the following research results were obtained. First, the in-line inspection technology based on electromagnetic detector array uses the synergetic effect between DC exciting magnetic field and high-frequency exciting magnetic field, so a perturbation response can be realized even by small signal excitation. Second, with the introduction of a novel compressive sampling of acquisition information composition, the speed bottleneck of in-line detector is broken through, and a new world record of the inspection speed of the electromagnetic detector array is set up, i.e., 8 m/s. Third, under the condition of high-speed movement, the received signals of in-line detector are weak and temporary while tracking and positioning outside the pipeline. And by virtue of the extremely low frequency transient weak signal detection method based on chaos, this technical bottleneck is broken through, and the signal-to-noise ratio (SNR) of transient weak signal in the process of real-time inspection is decreased below −10 dB. In conclusion, the superior performance of these new equipment has already been verified in the inspection engineering of in-service oil and gas pipelines. These research results will provide technical and equipment support for the safe operation of domestic main oil and gas pipelines.