HI !!

I want to open an AUTOCAD 3D file with dxf extension on CaesarII please can someone tell me how to proceed?

AutoCAD and CAESAR II do not directly speak to one another like CADWorx and CAESAR II. You can, however, export AutoCAD piping into a common pipe file format (pcf), which CAESAR II can import. Expect to have to do some rearranging, depending on the order in which the designer modeled the pipe.

It's possible to transfer AUTOCAD file to CADWORX than to Caesar II ?

No not really. The problem with a straight (plain) Autocad file is that there is no intelligence in the drawing. Any other software that might read the DWG file, or perhaps a DXF file, can't tell the difference between a line that represents a pipe versus a line that represents a part of the title block.

This is why you must use a piping package (a 3rd party application that sits on top of Autocad). There are several, but the most capable is CADWorx (granted I'm biased here, but it is the truth).