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.
In the 1998-99 season, Hartman was not part of his usual team but instead played with Kölner Haie of Germany's Deutsche Eishockey Liga.  He also participated in three games for USA Hockey's qualifying squad that secured a spot in the World Championships.