Double bead tube fitting

A tube fitting comprising, in combination, a tube and a first threaded fitting member with a lateral first shoulder and adapted to threadably coact with a second threaded fitting member having a lateral annular second shoulder, said tube fitting comprising:

• a first outwardly deformed area of the tube wall near one end of said tube;
• a second outwardly deformed area of said tube wall outboard of said first deformed area;
• an annular bead as part of said second deformed area and extending at about 60 degrees relative to the longitudinal axis of said tube;
• a laterally inwardly U-shaped portion of said tube wall between said first and second deformed areas;
• said first threaded member surrounding said tube;
• and
• the end of said tube adapted to be received inside the second threaded member, whereby as the first threaded member is threaded into engagement with the second threaded member the annular second shoulder of the second threaded member is abuttable with said annular bead to axially compress said first and second deformed areas between the first and second shoulders and to radially inwardly compress said annular bead with the resistance to radially inward compression to establish a seal between said tube and the second fitting member against leakage of fluid pressure.

A tube structure adapted for use with first and second threaded fitting members having laterally extending first and second shoulders, respectively, said tube structure comprising:

• a first outwardly deformed area of the tube wall near the end of said tube;
• a second outwardly deformed area of the tube wall outboard of said first deformed area and including an outwardly extending annular bead of said tube wall;
• a laterally inwardly U-shaped portion of the tube wall between said first and second deformed areas;
• said annular bead extending at about 60 degrees relative to the longitudinal axis of the tube;
• and
• said annular bead and said first outwardly deformed area adapted to be engaged with longitudinal force by the second and first shoulders of the fitting members which tends to compress axially together said first and second deformed areas and the about 60 degree angle of the annular bead causing radially inward compression of said annular bead with the resistance to radially inward compression establishing a fluid-tight seal between said annular bead and the second shoulder.