Patent ID: 8777276

Claim:
A tube fitting comprising: a body comprising a bore that is adapted to receive a tube end and a tapered camming mouth at one end of said bore; a nut that is adapted for threaded engagement with said body and having a ferrule drive surface; a first ferrule comprising a tapered first end that is adapted to extend into said tapered camming mouth of said body and a second end with a tapered recess; a second ferrule comprising a tapered first end that is adapted to extend into said tapered recess of said first ferrule and a second end having a ferrule driven surface that is adapted to engage with said ferrule drive surface; said second ferrule comprising a cylindrical interior wall of a bore that extends through said second ferrule; said cylindrical interior wall comprising in a non-deformed condition a single circumferential recess that is axially spaced from said tapered first end of said second ferrule and between said tapered 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.