Here are some pipe drawings sent from the company that bent these for us. It seems they measure from the very centre so just measure from your 3D sketch in the dead centre of each curve with angles attached.
I can't say all companies use this method but this was what they required.
thanks for your answer and sorry for my late reply.
I don't know if you have opened my file attached but if you open it you can see that the pipe got a 3d sketch which is not only in one plane.
Perhaps, do you have any drawings regarding pipes like mine?
I don't know about Mark but for I would still do it in the same manner but with an additional view.
In other words a drawing with one front view and one top view with the necessary center line measurements as well as angles, diameter, schedules, material etc.
Anyone in the business that knows his craft should have sufficient information with that without the need for you to break your head how they have to do it. If they don't then they should find a new profession.
The only caveat I have is that if the legs of the pipe become to small that they might have to resort to a weld.
Peter has written exactly what I would assume I would have to do. I'm afraid though that we don't have any pipes that bend in 3 dimensions so I don't have any drawings similar to yours. I would think multiple views should be sufficient but again I can't say exactly what they're looking for. I would agree with Peter statement.