Dynamo has "memory" of pipe. Won't update

[awilliams]

A screenshot of your graph would be helpful to see what nodes you are using. In any case, it sounds as if the node you are using to collect the pipes isn’t refreshing. This might help:

Dynamo Scripts not updating output functions when a change is made in Revit

This is because Dynamo doesn’t update many nodes unless an input changes, which is almost a requirement to develop scripts for large datasets. Adding a true/false, number slider input or other easily adjustable input in conjunction with a list.create and list.first item early in the graph will allow a toggle to force a refresh. I believe that Clockwork also has a node for this.