Correctly assemble a pipe system the first time
By Tom Coolidge and Tom DeWitte
As a little kid, I loved playing with Tinkertoys. Tinkertoys were the sticks and sprockets which allowed my imagination to create and assemble all kinds of wonderful things. I could create chairs taller than myself to allow my favorite teddy bear to have a throne to sit upon. The only limit to what I could assemble was my imagination.
Safety and performance considerations do not permit hazardous liquids and gas pipe systems to be assembled in the same kind of easy and carefree manner. Rather, those considerations compel a strict adherence to design and engineering standards and specifications developed through centuries of experience and technical research. At a fundamental level, there are necessary technical restrictions of many kinds. For instance, the type of fitting or device that can be connected to a specific type of pipe. The classic example is that a plastic coupling cannot be connected to a metallic pipe segment. Another example is that a plastic fusion cannot be used to connect two metallic pipe segments. And, the list of fundamentals goes on and on.
Your pipe network data definition needs to be as complete and precise as the real world it models. A rule base as detailed and exacting as the standards and specifications which govern pipe network construction is key to making sure you get this right.
This leads to the question I am going to explore in this blog; How does an implementer of the Utility Network assemble this rule base?
With the January 2018 release of the Utility Network Management Extension, and ArcGIS Pro version 2.1, a new set of capabilities is being provided to Esri hazardous liquids and gas customers. These new capabilities provide enhanced abilities for improving the quality control of a pipe system through an enhanced rule base. These new capabilities also include new administration tools to help administrators assemble and manage a set of rules to assist the ArcGIS mapper in correctly creating and maintaining the as-built representation of what was installed in the field.
What kind of Rules can I Define
Technically there are five types of rules in the Utility Network rule base. The five type of rules are: Junction-Junction Connectivity, Junction-Edge Connectivity, Edge-Junction-Edge Connectivity, Containment, and Structural Attachments.
-Junction to Junction Connectivity: Defines which device or fitting features can be connected to each other. For example a metal coupling can now be directly connected to a critical valve.
-Junction to Edge Connectivity: Defines which lines can be connected to a device or fitting feature. For example a Plastic Tee can connect to a polyethylene distribution pipe.
-Edge to Junction to Edge Connectivity: Defines which type of device or fitting is allowed to connect two types of edge features. For example a bare steel service pipe can connect to a coated steel distribution main with a steel 3-way tee.
-Containment: Defines which line, device, or fitting features can be contained by a specific type of container. For example a compressor is contained within a compressor station.
-Structural Attachments: Defines which structure junctions can be connected to a device or fitting. For example a pipe hanger can connect to a weld feature. This weld feature denotes the location along a pipe segment where the pipe hanger is welded to the pipe.
Let’s dig deeper into the connectivity rules.
You mean I can connect two point features without an edge?
That is correct. The utility network continues to support spatial coincidence as a means of defining connectivity. But it adds a new capability to define a logical connection between two device and/or fitting features. No more fictitious pipe segments needed to connect a valve to a tee.
A great example of the value of supporting junction to junction connectivity is the wellhead. The wellhead diagram shown above is essentially a collection of valves and fittings. There are no pipe segments in the core construction. With the utility network’s new capability to define a logical connectivity association between two point features, such as a flange and a tee, the ArcGIS system can now take a significant step forward in correctly representing this complex assembly.
I could never do that with my tinker toys.
What criteria can I use to define a connection rule?
With the geometric network a connectivity rule was based on a two-value composite key. The two values were the name of the featureclass and its subtype value. Although this technically worked, it was difficult to meet the needs of pipe systems. With the utility network, the composite key has been expanded to a four-value composite key. This four-key composite key is based on the name of the featureclass, its subtype’s value (ASSETGROUP), ASSETTYPE value, and its terminal connection. With this expanded composite key, it is now possible to define the following connection:
UPDMDEVICE : Valve : Critical : All can connect too UPDMJUNCTION : Tee : Metal 4-Way : All
Thanks to this expansion of pipe asset descriptors to define valid connections between assets, it is much easier to define rules in terms engineers and GIS professionals understand. For example, metal tees can only connect to metal pipe segments or other metal fittings and devices.
How are these rules created and managed?
The utility network uses an inclusionary method for defining connectivity rules. This means anything not explicitly defined is invalid. Put another way, once a single connectivity rule is defined, you are committed to the task of defining all valid connections allowed between the pipe system assets.
Administration of the utility network rule base is accomplished within the ArcGIS Pro desktop application using the Geoprocessing tools to be available with ArcGIS Pro version 2.1. Within the Pro Geoprocessing panel is a toolbox named: Utility Network Tools. Within the Utility Network Tools toolbox is a toolset named: Administration. This toolset contains two tools which are used to create and manage rules: Add Rule and Delete Rule. Additionally these tools can be run as python commands. The use of python scripting to create and manage your rule base is significant. Now administrators of publicly traded companies can more easily comply with Sarbanes-Oxley data management requirements. A python script created and tested in the development environment can easily be given to the administrator of the testing or production environment. Allowing that administrator to exactly recreate the rule base which was created or modified in development.
That Sounds like a Lot of Rules
Yes, for most pipe systems, there will be several thousand unique valid combinations of connectivity between your pipes, devices, and fittings. To simplify the task of defining the rule base, Esri is providing a base data model specifically for the hazardous liquids and gas industry. This core data model will come with over 4,000 rules already defined. Additionally this core data model will be embedded within the 2018 edition of the Utility and Pipeline Data Model (UPDM). This will further simplify the effort required to deploy the utility network for your pipe system.
How do these rules present to administrators and as-built mappers?
A lot of effort has gone into creating a utility network property page which is both complete and easy to understand. This property page will sub-group the rules into the five types previously listed. Within each sub-group every rule of that sub-group is listed. As shown in the screenshot, the rules are listed in a spreadsheet like layout. This makes for a very easy to read listing of the rule base.
A better rule base
With the release of the Utility Network Management Extension, you now have increased power to control the quality of detailed data defining your pipe network. This builds confidence in your GIS data being an authoritative “digital twin” of your real pipe network. Greater data confidence, in turn, leads to more confidence in your day-to-day use of that data in the performance of business tasks and workflows. Additionally, the administration of the rule base is significantly easier to assemble and manage than what was previously available within ArcGIS.