Magnetic leakage pipeline detection

Development status and improvement strategies of pipeline inspection technology and management
Pipeline defects have always been the main factor leading to pipeline failure, and identifying various types of pipeline defects through internal inspection technology has become a widely recognized practice both domestically and internationally. In order to further promote the development of internal inspection technology and improve management level, a systematic review was conducted on the inspection technology capabilities and development history of typical pipeline internal inspection technology service companies at home and abroad. The problems faced by oil and gas pipelines such as circumferential weld defects, crack defects, pinhole corrosion defects, and limitations of internal inspection technology under pipeline stress were analyzed. The existing problems in internal inspection technology management were summarized from three levels: government, pipeline enterprises, and internal inspection service providers. A multi-dimensional strategy was proposed to solve the limitations of pipeline internal inspection technology, providing reference for the future development and management level improvement of internal inspection technology in oil and gas pipelines.

It is widely recognized at home and abroad to detect and identify various pipeline defects through internal inspection technology. This technology can effectively control the failure frequency of oil and gas pipelines within a stable range. For example, in recent years, the failure frequency of oil pipelines under the jurisdiction of China Petroleum Pipeline Co., Ltd. has been controlled at 0.4 times/(103 km · a), and the failure frequency of gas pipelines has been controlled at 0.1 times/(103 km · a). At present, pipeline inspection technologies mainly include magnetic flux leakage detection, ultrasonic thickness detection, ultrasonic crack detection, geometric detection, and centerline detection (Inertial Measurement Unit, IMU). For weld defects in in-service pipelines, two main detection methods are currently used: magnetic flux leakage and ultrasonic testing.
The leakage magnetic detection technology mainly uses local magnetization of the tested specimen and magnetic sensors such as Hall devices to detect changes in the leakage magnetic field [1]. Based on the measured leakage magnetic field signal, defects can be identified, and it is widely used in the detection of oil and gas pipelines [2-3]. For crack defects, ultrasonic crack detectors are mainly used internationally, but only for internal inspection of liquid pipelines [4]. Ultrasonic crack detection uses an ultrasonic probe to emit ultrasonic waves at a certain angle, which return to the crack surface and record the data. Due to the directional nature of the crack surface, when the ultrasonic propagation direction is parallel to the crack surface, the reflected signal is usually not received, and the crack detector cannot detect the crack defect. Therefore, most crack detectors only target cracks in specific directions, such as cracks parallel or perpendicular to the axis [5-6]. There are few application cases of ultrasonic crack detectors in the detection of circumferential weld cracks, and the detection accuracy and evaluation methods for microcracks in circumferential welds are not yet clear.
In the past decade, pipeline inspection technology has made significant progress, especially in sensor technology, magnetization technology, and signal algorithm optimization technology, which have given rise to technologies such as three-axis high-definition magnetic leakage detection, ultra high definition magnetic leakage detection, and electromagnetic ultrasonic detection. With the rapid growth of demand for pipeline internal inspection, the number of institutions engaged in research and service of internal inspection technology at home and abroad is also increasing