What is remote monitoring in cathodic protection
Remote monitoring enables detailed evaluation of the effectiveness and correct behaviour/operation of the cathodic protection system elements. With this type of monitoring we can obtain measurements every second, 24 hours a day, 365 days a year. This allows us to detect anomalies and malfunctions related to damage or deterioration of cathodic protection system components. As well as to capture information that we would lose with traditional field measurements, since it only reflects a snapshot of a specific moment in time.
By instance, measurements obtained with remote monitoring devices may suggest that the cathodic protection rectifier has been switched off, or that the anode resistance of the impressed current anode has increased. Also, we can assume that a damage has occurred to the unidirectional drains which fail to interrupt the flow of the drained current when it changes direction.
The importance of checking the correct operation of the cathodic protection system
Checking that the cathodic protection system is working properly is not only a requirement of international standards; it also helps to reduce risks in pipelines. This helps to extend their useful life and avoid possible explosions, or the risk of environmental contamination. These may be caused by spills or fires, or from any event that may arise from damages in the pipeline itself.
With remote monitoring, it is possible to verify the efficiency of the entire cathodic protection system with important savings in terms of both money and time, as the personnel traveling to the measuring points to collect the data is significantly reduced.
Remote monitoring makes it possible to collect and analyze data from the devices installed in the field from any point and at any time, as they communicate with the SCADA management software via wireless. It is therefore possible to collect remotely the necessary data, the required measurements and to receive alarms in real time and on a daily basis. Normally, we get this information once a month and, in the case of small companies, once a year or every three years.
The collection of data in real time, as well as the notification of alarms in the event of failures or abnormal situations existing in the cathodic protection system, makes it possible to promptly plan corrective maintenance operations (to be combined with periodic maintenance operations). This enables to maintain the efficiency of the cathodic protection systems and bring the situation back to normal operating conditions.
Getting the best results with remote monitoring
To identify anomalies or possible failures of system elements, it is important to be aware of what the remote monitoring device is measuring. For example, in cases with high stray currents, an analysis of the Eon potential may not be sufficient. In fact, this provides incomplete or sometimes misleading information; it therefore becomes necessary to measure the IRFree potential by carrying out the instant-off (Eoff) measure by means of a coupon.
The correct selection and installation of the coupon is essential to obtain the best results. This means choosing a coupon with the appropriate shape, size, type and material and installing it correctly with respect to the active part of the reference electrode and the tube. Under these conditions, the Eoff measure of the coupon can bring the IR component to zero; it is therefore possible to consider the Eoff very close to the IRfree value.
What are the advantages of remote monitoring
Remote monitoring helps operators involved in cathodic protection analysis to better evaluate the operational status of cathodic protection and cathodic protection devices (rectifiers, drains, reference electrodes, etc.).
The possibility of comparing the On and Off potential and the polarization current can lead to very significant analysis, such as the:
- Evaluation of stray currents;
- Effectiveness of cathodic protection;
- Some considerations on the evolution of the pH.
Carrying out the instant-off potential on the coupon, allows remote monitoring to move from a general assessment of effectiveness to a detailed assessment on at least all selected test stations. The selection of the measurement stations is very important to obtain the best information. In this way, resources and efforts can be focused on real needs and possible threats of corrosion can be more easily identified and investigated.
In conclusion, it becomes necessary to have remote monitoring devices to measure the Eoff of the coupon. The best choice is a device with an integrated solid state switch to control the connection between the pipe and the coupon.