Monitoring Experiment of Electromagnetic Interference Effects Caused by Geomagnetic Storms on Buried Pipelines in China

The electromagnetic interference effects on buried pipelines induced by geomagnetic field are monitored for the first time in China, including geomagnetically induced current (GIC) and pipe-to-soil potential (PSP). It is of great significance for studying the influence of geomagnetic storms on pipeline corrosion and protection in mid-low latitudes. In order to monitor the GIC and PSP simultaneously, a monitoring experimental scheme is proposed. The monitoring data are obtained at Changyi oil transportation station (36°30'N, 119° 30'E) and Xiligu cathodic protection station (36°42'N, 119°12'E). For comparison, the geoelectric field data are acquired from the geomagnetic observatory near the monitoring stations. Based on the monitoring result and theoretical consideration, the effectiveness of potentiostat and the influence of GIC on the pipeline is evaluated by analyzing the correlation between the monitoring data and the geoelectric field data. The monitoring data show that the pipeline GIC maximum is 7.88 A caused by the magnetic storm commencing suddenly and the PSP positive offset of the two monitoring points exceeds the limit required by relevant standards. The GIC maximum is 3.98 A caused by the magnetic storm commencing gradually, and the PSP offset exceeds the standard when the potentiostat is cut off. The results of our research indicate that the geomagnetic storms can also cause serious corrosion of pipelines in the middle and low latitudes; the larger the distance between insulating flanges is, the stronger the corrosion situation of pipelines will be; the greater the variation rate of geomagnetic disturbance is, the more serious the corrosion of pipelines will be. Because the protection range of the cathodic protection station is limited and the response performance of the potentiostats is varied in different areas, medium or small geomagnetic storms can also cause serious corrosion even if the pipeline is protected by the potentiostat.