I have multiple 3d polylines that I am trying to create pipes from. If I have an existing pipe network set up is there a way to add pipes to it? Per the attached when I pick on a polyline to create it does not let it actually be created (it never gives me the option to pick "ok").
Based on the command line output, your parts list is not finding the part library. Make sure the Pipe Network Catalog is set correctly. Since the parts list has no valid parts, you are not being given the OK button.
Your parts list is fine, but in order to use those parts C3D must be able to locate the part catalog. Just for grins, I renamed the folder where my catalogs are saved. When I tried to create a network from a pline I first got a warning dialog and then I got the exact same command line output you did and the create pipe network dialog looked just as your image shows.
So, make sure the the correct folder is being pointed to using this: