Single flare tube and joint structure of single flare tube

A joint structure comprising:

• a single flare tube having a tube and a flare, the flare connecting at a flare rear end to the tube at a tube front end, the flare extending radially outward and forward from the flare rear end to form a radially outward extending part, the flare having a flare front end protruding and conically tapering forward from the radially outward extending part along an axis of the single flare tube, the flare extending rearward from the flare front end at an acute conical flare angle from the axis;
• a first connector member having a through-hole that receives the tube of the single flare tube;
• and
• a second connector member that couples with the first connector member, the second connector having a flare receiving surface extending rearward at a conical seal angle from the axis, wherein
• the acute conical flare angle is positive and less than the conical seal angle,
• a width of a narrow portion of an inner circumferential groove of the radially outward extending part of the flare is substantially zero and stays substantially zero when the single flare tube is pushed against and coupled with the flare receiving surface of the second connector member by fastening the first and second connector members together, and
• a radially inner diameter of the narrow portion of the inner circumferential groove is smaller than an external diameter of the tube.

A joint structure comprising:

• a single flare tube having a tube and a flare, the flare being connected at a flare rear end with the tube at a tube front end and extending radially outward along an axis, the flare extending rearward from a flare front end at an acute conical flare angle from the axis;
• a first connector member having a through-hole that receives the tube of the single flare tube;
• and
• a second connector member that couples with the first connector member the second connector having a flare receiving surface extending rearward at a conical seal angle from the axis, wherein
• the flare rear end of the single flare tube connects the tube to the flare smoothly and continuously along an outer perimeter of the single flare tube, a first curvature radius of the outer perimeter along the axis of a longitudinal cross-section of the single flare tube is smaller than a second curvature radius of the outer perimeter along the axis the longitudinal cross-section of the single flare tube, a point along the second curvature radius being at least as close to the axis as a point along the first curvature radius.