Radius Elbow
To insert a radius elbow fitting, go to
Ribbon: 
Radius Elbow
Pulldown Menu:
You will be prompted to specify the duct on which a radius elbow is to be inserted.
Select duct or label to insert fitting at:
The Fitting Radius dialog box will appear.
- Â Radius: The radius multiplier for the fitting. This value will be multiplied by the width of the duct to determine the radius of the fitting.
Enter the radius of the elbow to be inserted and press the button. A radius elbow with the specified radius will be inserted on the drawing, as shown below.
Related Options
Radius for elbows: Sets the default value for the Radius field.