The digitalization of cathodic protection for pipeline integrity management

Content in this blogpost originates from the article: ‘The digitalization of cathodic protection for pipeline integrity management.’ The article can be retrieved underneath.

A pilot in which rectifiers and tests posts have been outfitted with remote monitoring sensors.

Menno van Os NAM-UIO/T/SDP, Marinus NesNAM-ITZ/CCE, Paul Mignot (Withthegrid) [Team from left to right]

Background

Cathodic Protection (CP) is an important barrier against external corrosion of carbon steel pipelines and needs to be managed properly to ensure pipeline integrity. Historically, monitoring CP has been a manual and labor-intensive process. Periodic field inspections and measurements are followed by desk analysis. New digital solutions have enabled remote monitoring and direct analysis of results. This article describes the steps that NAM has taken to digitalize its Cathodic Protection management process.

Introduction

All carbon steel pipelines within NAM (see Figure 1) are protected by means of Cathodic Protection. This is
done by about 120 rectifiers which are inspected every 2 months. In addition, on- and off-potentials are
measured at all CP tests posts every year. Both activities are carried out by CP specialist Hommema.
For many years NAM has been using a custom MS access-based software tool called CP-Station to
support this process. In 2020 the decision was taken to streamline IT and phase out this custom system. Incombination with applying remote monitoring solutions for Cathodic Protection a digitalization
project was started together with Hommema and Withthegrid.

Figure 1: Geographical overview of the NAM pipelines in the northern part of the Netherlands
Figure 1: Geographical overview of the NAM pipelines in the northern part of the Netherlands

Cathodic Protection remote monitoring

By placing remote monitoring sensors at rectifiers or in test posts it is possible to obtain real-time insight into the performance of Cathodic Protection. This provides multiple benefits:
– Direct notification of outages
– Fewer manhours required for inspection
– Improved asset integrity
– Longer asset lifetime
– Reduced CO2 emissions


For Production Unit North, a pilot has been carried out, in which a subset of rectifiers and test posts have been outfitted with remote monitoring sensors (see Figure 2).

Figure 2: Cathodic Protection remote monitoring
Figure 2: Cathodic Protection remote monitoring

The system comprised of:

  • Sensors placed at rectifiers
  • Sensors placed at tests posts
  • An online cloud application

By having sensors at both these locations it is possible to obtain a detailed overview of the CP performance.
With thresholds defined on Voltage DC (see Figure 3) direct alerts are created in case the measurements
exceed their integrity operating window.

Figure 3: Rectifier measurements
Figure 3: Rectifier measurements

The sensor at the rectifier site includes a relay. This makes it possible to remotely turn off the rectifier for
works or for specialist measurements. Turning of a rectifier is often a time-consuming step prior to starting
any works. This is because the rectifier can be located far away from the works site. In addition, sometimes
switching the rectifier back on is forgotten leaving the pipeline unprotected longer than necessary. With remote monitoring the rectifier is turned off and on remotely and forgetting to turn it back on becomes
highly unlikely.

Another function is the possibility to interrupt the rectifier in a custom On/Off pattern (see Figure 4). In
this example a 2/3 second on – 1/3 second off cycle is selected to carry out DCVG measurements on the
pipeline.

Figure 4: Cathodic Protection Command for DCVG switching.
Figure 4: Cathodic Protection Command for DCVG switching.

By combining the switching possibility at the rectifier site, it is possible to take off-potential measurements at
a test post (which does not have a coupon in the soil). This function takes 30 consecutive measurements at
100 ms intervals simultaneously at the rectified and the test post. This results into a full depolarization curve as
shown in Figure 5. From this graph the off-potential can then automatically be selected and analyzed
whether it meets the performance standard criteria.

Figure 5: Cathodic protection depolarization curve
Figure 5: Cathodic Protection depolarization curve

Digitalizing manual measurement process

In addition to remote monitoring the manual measurement process has also been digitalized. This
was necessary because of the phase out of the CP 58 station software. For test posts and rectifiers where no
sensors are installed manual measurements are still required.


For this an online application is used. This application shows the electrical CP system which differs from a
pipeline system. For example, a rectifier can protect several different pipeline sections.


The online application works on mobile and tablet and enables CP specialists to directly enter their
measurements in the field. In close cooperation with Hommema, specialized CP functionality has been
added to the application.

Figure 6: Manual measurements from cathodic protection from mobile
Figure 6: Manual measurements for CP from mobile.

In order to maintain the measurement history all historical CP data have been imported into the online
application.

IMS Integration

With the phasing out of CP station and the implementation of the CP tool Withthegrid an
integration with Shell’s global Integrity Management System IMS is now possible. In the current phase
integration will be done using data exports. In the future, however, this can be done through an API.

Figure 7: Cathodic protection process
Figure 7: Cathodic protection process

Conclusion

This project has realized a successful phase out of CP Station software together with the implementation of
remote monitoring solution for CP. NAM now has all the required CP data readily available in IMS and up
to date, while its CP contractor Hommema is able to utilize modern digital solutions and work in a more
efficient way.

Key success factors

  • Having a software solution that can deal with
    manual measurements and remote monitoring at
    the same time
  • Linking with NAM systems including MyMaps and IMS
  • Excellent collaboration between all parties involved: NAM, Hommema, Withthegrid

Key Learnings

Real-time insights into Cathodic Protection improve asset integrity. Remote monitoring connected with a CP
software solution Withthegrid provides many operational benefits both for asset owner and CP specialists.

Acknowledgements

The authors would like to greatly acknowledge Hommema and Withthegrid for their contributions to
this article and for their role in the successful realization of this project.