Lateral Pipeline Buckling Detection via Demagnetization and Interior Magnetic Measurement

Abstract

Thermal buckling of subsea pipelines often occurs and seriously threatens pipeline safety. The spherical detector (SD) can realize quasi real-time detection of pipeline buckling owing to its low blockage risk and convenient launch-retrieval deployment. Vertical buckling can be judged by the rolling speed of the SD, while lateral buckling can only be judged by the interior magnetic fields. However, irregular magnetic remanence of the pipeline seriously hinders the magnetic detection of lateral buckling. To against this problem, this paper proposes a method of detecting the lateral pipeline buckling via demagnetization and interior magnetic measurement. It is experimentally demonstrated that demagnetization can remove most of the remanence of the pipeline and make the interior magnetic fields more regular and uniform; After the pipe is demagnetized, both severe and weak lateral bucklings can be sensitively indicated by the single or double peaks of the interior magnetic fields measured by the SD. The interior magnetic fields are also experimentally demonstrated capable of indicating the first and recurring weak buckling through comparing with the previous detection data.

Crosspoint Localization of Spiral and Girth Welds of Spiral Steel Pipelines

“…This method also has some drawbacks that are not related to spiral weld localization, but related to pipeline defect detection. The SD can only detect the existence of spiral weld and girth weld, as well as large deformation and vibration of pipeline [30][31][32], but cannot detect weld defects and local corrosion defects of pipe wall, especially the upper side, left side, and right side which are far away from the SD. This is because that the diameter of the SD is smaller than the diameter of the pipe, the SD cannot contact the pipe wall.…”

“…The SD has been used in the detection of magnetic anomalies in pipelines, and can identify girth welds from the measured magnetic signals, but cannot identify spiral welds [30]. Afterwards, the structure of SD was optimized to achieve fixed-axis rotation by adding a tungsten disc as counterweight to improve the quality of detected signals [31][32]. However, the existing SD is still unable to locate the crosspoint of spiral and girth welds.…”

Investigation of the kinematics behavior of spherical detector with different diameter ratios in oil pipelines

“…On the other hand, because the pipeline is too long and opaque, it is not easy to observe the flow state of the spherical IOP Publishing doi:10.1088/1742-6596/2730/1/012028 2 detector inside the pipeline, and it has become a major problem to analyze the motion and mechanical properties of the detector in the pipeline. It is found that when the Reynolds number Re is in the range of 100 to 350, the wake structure of the sphere is very similar to that of the isolated sphere in free flow when the sphere is rolling forward [10] . Krishnan et al [11] simulated the thermodynamics and hydraulics of the sphere under the constraint of the pipe boundary and studied the influence of the diameter ratio on the drag coefficient and the Nusselt number under the condition of the diameter ratio α < 0.5 and the Reynolds number Re < 500.…”