Presently we can only "square cut" the pipe ends, then connect with a fitting when there is a change of direction. Some times we use the pipe to make the direction change. To do so, we will miter the ends and weld them together to provide the proper deflection. This would be beneficial to our piping layouts and estimates so we can track the total amount of pipe used/needed in the pipe system family. At present, we have a high amount of inaccuracy by using the "Miter Bend" fitting family, and the piping specifications are not carried through to the fitting. Please see sample
We see in the "Steel" and "Wall" Sections of Revit there is the ability to miter the shapes, so we know this is possible