Rhino export igs file to ug nx precision setting

when i used rhino export igs file to ug nx, the adjacent of two face have a little space. i used the ug nx to sew them but i can’t turn them into entity. how can i fix the issue? i used ug nx 4.0 and rhino 4 sr9. anyone can help?

Hi JGAGAM - my guess is that it is a tolerance problem - what is the file tolerance in Rhino (Document properties > Units)?