If you are a subscription member for Revit MEP, there is a new content extension you can download that includes new fittings for piping and duct. One important note and comment is that it does not follow the existing folder locations - for example, new pipe content was placed in a material folder a la ACAD MEP - in other words, look in the Gray Iron and Malleable Iron folders for the new fittings - but duct wasn't done the same way. Look for the new fittings in the existing duct folders. I'm assuming this will be reorganized again in the next release, so if it's doen around materials that would be fine. Move as you see fit - and make sure you put the lookup tables in the correct locations.
Here are the notes from the ReadME file:
The content contained in the RME 2009 Content Extension will not overwrite any of the default content that was originally installed by Revit MEP 2009. All of the Extension content is new and have names different from any of the original content names. When you install the Extension to the same location as your existing content, many of the new content families will install in folders that already exist. A notable exception is that all of the new pipe fittings have been re-organized to be grouped by material type rather than by category. The end result is that your original pipe fittings will remain as is (organized by category folders) and the new pipe fitting folders will be adjacent to those folders and organized by material type.
The fittings that are included in the RME 2009 Content Extension will not function properly if their associated lookup tables are not installed in the correct location. These lookup tables (.csv files) need to be installed in the same location as your current lookup tables.
The default installed location for the "LookupTables" folder is:
Windows XP: C:\Documents and Settings\All Users\Application Data\Autodesk\RME 2009
Windows Vista: C:\Program Data\Autodesk\RME 2009
If you are unsure where your "LookupTables" folder is located, you can find this information in the "Revit.ini" file. This file is located in the same folder where Revit MEP 2009 is installed. In this file, search for "LookupTableLocation". This will indicate where your lookup tables are installed.
LookupTableLocation=C:\Documents and Settings\All Users\Application Data\Autodesk\RME 2009\LookupTables
When you run the self-extracting ".exe" file to install the RME 2009 Content Extension, you will be prompted to choose a location to extract the content files. You should browse to the path indicated in your "Revit.ini" file, and stop one level above the "LookupTables" folder. In the example listed above, you should browse to and select the following folder:
C:\Documents and Settings\All Users\Application Data\Autodesk\RME 2009
This will ensure that the new lookup tables contained in the RME 2009 Content Extension will be installed to the correct location.
Alternatively, you could extract the new content to any location that you desire, and then manually move the contents of the newly extracted "LookupTables" folder to the correct "LookupTableLocation" location, as specified in the "Revit.ini" file.