Configuring Revit to use your company database is an essential part of making the transition from "Design Build to Pre-Fabrication". Autodesk provides basic Imperial and Metric databases to use as a generic exchange. If you have already made an investment in a ITM Parts database you can make your exchanges between Revit and CADmep look exactly like your current ITM content models.
First the location of the Database folder for Revit 2017 and beyond. (C:\Users\Public\Documents\Autodesk\Fabrication 2017)
Next the sample path for ITM content parts. (C:\Users\Public\Documents\Autodesk\Fabrication 2017\Imperial Content\V3.04\Items\Imperial Content\*--*)