Although piping is concentric, you can specify the justification for the different sized piping.
The justification editor lets you align the tops, bottoms, or sides of pipes in a section of the system.
Edit panel
Control Point to select the end of the ductwork section that will be used as the reference for justification as indicated by an arrow that appears at the end of the branch. 
Each click alternately selects the starting segment or ending segment as indicated by an arrow at either end of the branch.
| Click... | to align to the... |
|---|---|
|
Top Left |
|
Top Center |
|
Top Right |
|
Middle Left |
|
Middle Center |
|
Middle Right |
|
Bottom Left |
|
Bottom Center |
|
Bottom Right |
Alignment Line, and select a reference line in the drawing area. This feature is most useful in a 3D view with Thin Lines selected and Visual Style set to Wireframe. It displays dashed reference lines at the edges and along the center of the faces of the reference pipe as shown. 
The piping shown here has been justified to the Top Center of the large segment connected to the tee.
