Reposting on behalf of @SeckJ :
I've never agreed with the way Revit determines whether or not to place a flange (currently done in the Pipe Type Routing Preferences). If you are modeling a flanged piping system, it works fine because you will have a flange and each fitting/valve. However, if you are modeling a system with multiple connection types, it becomes difficult. For example, I recently modeled an aeration piping system that was primarily welded stainless steel. However, at each inline valve, flanges had to be placed at both sides of the valves. Since the majority of connection points were welded, I set the Flanges to <None> in the Routing Preferences. Therefore, at each valve, I had to pull back the pipe away from the valve, place a flange on the end of the pipe, and then drag the flange back to the valve to connect.
My idea is to move the Flange settings to the Pipe Accessory and Fitting family categories and remove it from the Routing Preferences. For example, create a setting within the Pipe Accessory family category in which the user can select the connection type, or merely provide a "Flanged Connection" checkbox. Then, regardless of the pipe type in which the valve/fitting will be placed, it will take on the setting within the family. This would allow a user to easily place flanged valves in welded pipe system. Another example of this situation is placing threaded valves in a soldered copper pipe system.
