sweeping a Y-shaped line

[Anonymous]

This is my first project using autocad and it's been going smoothly so far.  I've run into a problem that I can't seem to solve or find information on.  I need to sweep a y-shaped design to draw a pipe that splits into two parts of equal diameter.  Any suggestions? 

Thanks

[Slawomir_]

This Y-shape entity is line? polyline? You have it predefined? or You have drawn it by Yourself?

I'm aware that this is not the best option, but it is simple:

1. draw new or pick existing curved polyline

2. MIRROR it along primary axis, so they would look like Y.

3. SWEEP both paths

4. UNION them.