Gas CP Subnetwork Controllers

[EdwardBlair]

Hi -

Unless I'm misinterpreting things, it looks like the only devices defined as subnetwork controllers for CP subnetworks in the UPDM are test points.   I would have thought anodes and/or rectifiers would be considered subnetwork controllers as well.

Am I missing something?  (As is often the case)

Thx,

Ed

[RobertKrisher · Accepted solution]

As always, I defer to @TomDeWitte on all Gas and Pipeline matters, but this is my understanding based on my time spent implementing cathodic protection in GIS for gas utilities.

From an electrical perspective, you are correct that it would make sense to model the rectifier (source) or anodes (sink) as subnetwork controllers. However, from a regulatory perspective each zone is considered a cathodic structure and is typically associated with a set of specific test points. Because of this many of these gas companies already have a database that lists out the structures and test points for each cathodic structure, which makes it easier to create and validate this information in the utility network, as well as integrate it for compliance purposes.

For more information on the compliance side of things, read Tom's One Source of Truth for Cathodic Protection.

For more general information on how CP works, read Tm's Understanding Cathodic Protection for GIS & IT Professionals.

@EdwardBlair you probably already know all the info in those two articles, but others reading this comment or post in the future may benefit from the information.

[EdwardBlair]

Hi Robert -

Thanks for the detail here.   This is a pretty interesting perspective.  We would not be defining the subnetwork based on the commodity (in this case, electrons) source or sink, but rather based on our measurement of that commodity at locations along the subnetwork.

Kind of like considering line monitors as subnetwork controllers for an electric distribution system.

I suppose if a gas company implementing this model has a different view, they could define rectifiers/anodes as sources, true?

Thanks again,

Ed

[JSchroeder]

Hi Ed. It is an interesting topic that you are inquiring about. It might help to understand whether the use of Test Points as Subnetwork Controllers causes issues in your situation, possibly you are not modeling Test Points, or if you are only exploring alternatives?

I do believe that you should be fine to alter your tier to include rectifiers and anodes as controllers. The CP tier is a bit different from the system or pressure tiers in that we are not tracing upstream or downstream, but tracing to find the connected CP features.

In this way, it makes sense to have a Test Point modeled as a subnetwork controller because it seems that these should always be used, whether it is a galvanic or impressed current system, and were not chosen for any logical reason such as a device that is 'controlling' anything related to CP.

I would love to hear more about your use case.

[EdwardBlair]

Hi J -

Thanks for the comment.

I'm not sure that using Test Points as subnetwork controllers will actually be a problem for us.   We have them connected to test lead wires and service pipes in our network.  And initial testing in at least one CP zone shows expected results.

I only asked because, as you mentioned, test points don't 'control' anything as do other subnetwork controllers and wanted to make sure I understood the model correctly.

Ed

[RobertKrisher]

@EdwardBlair Customers often adapt the model to suit their requirements. In the case of rectifiers/anodes, because the Domain Network is defined as being source-based and because anodes aren't always physically connected to pipes you'll likely want to use rectifiers as sources (see article 2 for examples).

I have seen some customers use the existing tier to manage this, foregoing the importance of test points. I have also seen one customer add a new tier so they could trace and manage the electrical conductivity of the cathodic protection system separate from the regulatory requirement.

It comes down to what are the requirements that you are trying to solve with your GIS and what configuration best meets that need. This is why I linked to the first article, because it lays out the requirements and business case for the original design and configuration of cathodic protection in the UPDM model.