Abstract
Pipeline networks are increasingly paralleling overhead AC power lines, as more pipelines are laid in energy corridors or are built to carry gas into gas powered generating stations. As a consequence, there is an increasing requirement to quantify the damage AC corrosion may be causing to these pipelines. Although pipeline operators routinely monitor AC current densities at test posts along pipelines interfered with by AC, it has not been possible to correlate these current densities with metal loss and hence the AC corrosion rate. Although repeat in-line inspection (ILI) will give an indication of the AC corrosion rate, the costs associated with running ILI vehicles at a high enough frequency becomes expensive, not least due to the requirement to reduce gas flows during this operation. An alternative approach is to use corrosion monitoring devices based on electrical resistance (ER) probes. This paper describes a field trial intended to investigate the response of one suppliers ER probe to the effects of AC voltages and induced currents onto a pipeline known to be experiencing high levels of AC interference. The paper discusses the electrical parameters being monitored and the importance of these parameters in terms of the AC corrosion rate.
