Lateral Pipeline Buckling Detection via Demagnetization and Interior Magnetic Measurement

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.