YES, there is a viewer "free of charge" for Smap3D P&ID projects and diagrams available.
This you can download with the following link:
Download Smap3D P&ID viewer english
This viewer with name PCschematic viewer and the version number 13.0 is compatible to the Smap3D P&ID versions 9.5 and 9.6.
It can installed and used as often you like.
This viewer can open, view and print all ".PRO" files of the versions listed above.