The exception was the 1998–99 season, which he spent with Kölner Haie of Germany's Deutsche Eishockey Liga. That season, Hartman also played three games for USA Hockey's qualifying squad which won a berth in the World Championships.
The exception to Hartman's usual team was his time playing with Kölner Haie of Germany's Deutsche Eishockey Liga during the 1998-99 season. He also played three games for USA Hockey's qualifying squad, which earned them a spot in the World Championships.