Hello Shrinivas,
First, the autoplant components have to be converted to autocad solids. Then use the normal procedure to convert dwg to ACIS as you would any other autocad drawing. Please note though that the components will not be intelligent. It will only be a physical representation of the components for reference.
To create solids use the following procedure.
1. Start the autoplant model in autoplant piping.
2. Create a new layer called ACIS.
3. Set the ACIS layer to current.
4. Type in the command COPYASACIS.
5. Save the model.
Regards
Dinesh Solanki