CATIA CAD software of course offers the possibility of export its own drawings and other files (including .catpart) to several other CAD vendor file types, for example IGES format (.igs, .iges). You can also find other 3rd party software capable of the same catpart to igs conversion, as well as some dedicated converters.
Open CATPART file Open IGS fileA CAD viewer program with conversion capabilities
A set of 3D modeling tools
3D CAD/CAM tool for product development
A CAD converter with huge format support
A CAD visualizaton, analyzation and translating system
A 3D CAD translation software
A dedicated CAD converter