The traditional instant-off survey is time-consuming and will not provide information on the continuous evolution of the pipeline instant-off potential. This paper presents results from a small- and large-scale test of a remote-controlled GPS time-synchronized remote monitoring system, that is capable of capturing the instant-off potential at every logger position, when synchronized with a rectifier interrupter unit. Additionally, the loggers have a built-in line-current measurement module, that allows for detection of changes in the CP consumption in between logger positions, allowing for detection of 3rd party coating damage incidents. Finally, the loggers are capable of full AC/DC interference analysis with associated ER probe corrosion rate measurements.
There are several ways to validate the performance of a cathodic protection (CP) system for buried pipelines.1 Over the years, pipeline networks and their corrosion challenges have become increasingly complicated, not least due to the many sources of both AC and DC interference that affects CP operation.2 Also, the various measurement techniques that can be applied to test CP effectiveness has increased over the years. Finally, the sheer number of buried pipeline miles has been constantly increasing. Some of the challenges of modern pipeline CP operation are:
• Increasing complexity of pipeline networks
• Increasing number of corrosion challenges
• Increasing number of measurement techniques to perform (and interpret!)
• Increasing number of buried pipeline miles to cover for technicians
• Requirements for measurement/test frequency
It is only logical that operators are turning towards remote monitoring. Especially where AC and DC interference is present, since the corrosion conditions can change on hourly, daily, weekly or yearly basis. Such changing conditions would be almost impossible to investigate in detail with manual measurements, especially when considering the number of measurement positions that needs to be covered on hundreds of miles of pipeline. Figure 1 illustrates the infrastructure of a remote monitoring system for cathodic protection.