Field readings of induced AC voltage and AC current density from test points along a pipeline are regarded as an indicator of corrosion risk and personnel hazard caused by AC interference from collocated powerlines. Field data also provides the foundation to develop predictive modeling for AC mitigation design. A major technical challenge during modeling often results from unavailable current loads of collocated powerlines. This report introduces our experience regarding this situation and provides a solution option. It is demonstrated that current loads can be estimated via simulating the field reading profiles. The model based on the estimated current loads is applicable in AC mitigation design.
Pipeline corrosion may result from alternating current (AC) interferences from various sources, for example, high voltage AC (HVAC) transmission lines collocated with pipelines. AC mitigation is necessary to minimize corrosion risk, as well as personnel hazard, if intensity of AC interferences, normally characterized as AC induced voltage and current density, exceeds certain thresholds[1,2]. Field readings of AC induced voltage and AC current density obtained from test points along a pipeline are often regarded as indicators of such risks. Technically, a predictive modeling simulation of AC interference is a necessary step to determine the severity of interference for the length of the pipeline and the level of AC mitigation necessary to reduce interference risks. Current loads of powerlines and soil resistivity along the pipeline route are two of the most important inputs for modeling simulation. Other key parameters within the modeling analysis, such as pipeline coating status and pipeline and powerline separation and spatial alignment can be achieved from the pipeline operator, determined from field collected data and measured from GIS systems. The impact of these parameters on intensity of AC interferences are often compared to those of current loads and soil resistivity.
