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When computing or validating a model, the following error message is generated for one or more pipes in the model:
"Pipe references deleted or inactive node"
Pipes in WaterGEMS and WaterCAD need to have two active end nodes in order for the program to validate and compute. If one of the nodes connected to an active pipe is inactive or removed from the model, the error message will be generated.
To resolve the issue, you need to make sure that all active pipes in the model have active end nodes on each end. Some adjustment to the active or inactive status of the elements will be likely.
The ultimate solution for the issue will be highly dependent on the model itself. Below are a couple of possible examples.
First, you may want to have the node that is being made inactive at a tee to the main pipe line. This can work especially well for hydrants. For instance, let us say that you have a model layout similar to the one below, where the hydrant is in the main pipe line. If you make the hydrant inactive, the pipes connected to it will generated the error message about the pipe referencing deleted or inactive elements.
Instead of having the hydrant in the main pipe line, you can model the hydrant at a tee, as shown in the screenshot below. A junction with no demand will be placed at the position where the hydrant was before. You can then make the hydrant and the new lateral pipe connecting the hydrant to the main pipe line inactive, and the model will compute without issue.
Second, instead of just making the nodes inactive, you can make the pipes and the nodes inactive. This will be common when the inactive node (or nodes) is part of a new addition. In such cases, all elements in the new addition will be inactive.
There may be times when new elements are placed within the main part of the model, instead of a new addition. For instance, you may have a new pump that you need to model as part of a proposed addition. You can place a pump on the model and split the existing pipes. But if you make just the pump inactive, the pipes connected to the pump will generated the above error message.
In the screenshot above, the pump is inactive. This setup will generate the error message "Pump references deleted or inactive node." Instead of making just the pump inactive, you will need to make some adjustments to the model layout.
For scenarios when the pump is inactive, you will need to create a new pipe connecting the reservior to the downstream elements. This new pipe will be active, while the two pipes directly connected to the pump will be inactive. You can see this setup in the screenshot below.
For scenarios that the pump is active, the opposite will be the case. The pump and the pipes connect to the pump will be active, while the other pipe will be inactive. See the screenshot below for this modeling case.
For more information on active and inactive elements, as well as the Active Topology Selection tool and Active Topology alternatives, please review the following support solution: Active Topology Management
Scenario and Alternative Management