Hy, I have a huge piping installations made in CATIA V5 R16 with piping and tubing design. How can I import in Caesar 2?

If CATIA can generate a PCF file, you can use the "\Tools\External Interfaces\PCF" option to import it.

I can save only with this formats: stp; session, igs, cgr, exe, hsf, stbom, txt and wrl. No PCF
In Catia you can generate drawing with ISOGEN...

ISOGEN works from a PCF file. Are you sure Catia can't generate this format?

CAESAR II can not import from any of the formats you mentioned above.