Patent ID: 8480135

Claim:
A tube fitting comprising: a fitting body comprising a cylindrical bore for receiving a tube end and a tapered mouth at one end of said bore; a drive member for threaded engagement with said body and having a ferrule drive surface; a first ferrule having a tapered first end that will extend into said tapered mouth of the fitting body and having a second end with a tapered recess that axially extends toward said tapered first end; a second ferrule having a tapered nose at a first end of said second ferrule that will extend into said tapered recess of said first ferrule; said second ferrule comprising a cylindrical interior wall that extends from the second ferrule first end to a second ferrule second end; said cylindrical interior wall comprising in a non-deformed condition a single circumferential recess that is axially spaced from said first end of said second ferrule and between said first end of said second ferrule and said second end of said second ferrule, and a first circumferentially continuous cylindrical portion of said cylindrical interior wall adjoining said first end of said second ferrule and a second circumferentially continuous cylindrical portion of said cylindrical interior wall adjoining said second end.