It should be possible to convert CATPART files to 3DMAP format using CATIA CAD software from Dassault Systemes. Probably only some part of the data can be exported.
Convert CATIA part data to CATIA 3dmap file.
We have found one software suitable in our database for this conversion.
Microsoft Windows software - convert catpart to 3dmap on Windows
A PLM/CAD/CAM/CAE software suite
Convert from catpart file format
The table with program actions contains information about what each program is capable of doing with their files. This may be a good pointer for further searches for certain file conversions and help you find the converter you are looking for if our search result is insufficient for you. However, it is far from perfect and may sometimes show results which are not really usable because of the nature of the software handles the files. So a conversion that appears as possible, just because of matched actions, may in fact not be possible.