Hi Michael,
thank you for your time!
If you read my last post you'll find that the coincident edges is not always the problem.
I can understand the connection between coincident parts but it is not my case. The body of the object it is in three parts but it is comprehensible their union. Other object do no have coincidence thru them!
I'll try to manipulate the IGES file to find some 'trick'.

Gianrico