You can create a tube and pipe assembly by adding runs in the context of a standard Autodesk Inventor assembly. The assembly file can be empty or contain an assembly model but must be a saved file. Typically all tube and pipe components, including any additional runs you create, are contained in the master runs assembly.
When creating the first run, determine the location in your workspace to store the master runs assembly along with the first run. Continue to determine the location of each subsequent run, route, and flexible hose assembly (when the active flexible hosing style is defined to use subassembly). We recommend that you put all runs under the master runs assembly and hose assemblies under the corresponding parent run.