Use Revit Schedules with Conditional Formatting to check your model prior to exporting the .maj to Fabrication CAMduct.
Often times, people who are working in CADmep are finding out late that their deliverable needs to be in Revit. Here is a tutorial on how to import the unsupported patterns of CADmep into Revit.
Problem - When loading .dwg into Navisworks 2018, Fabrication elements are not displayed
In CADmep we used the command SL1 to isolate a service. Revit does not have a good isolation command so I wrote one using Dynamo, below is a link to download the script.