Pipe joint structure and air conditioner

A pipe joint structure formed to connect two pipes and comprising:

• a union connected to one of the two pipes, and including a male thread and a tapered outer circumferential surface;
• a flare nut including
• a female thread that is formed at one of axially opposite ends of the flare nut, and is fitted to the male thread,
• a through-hole that is formed in the other of the axially opposite ends of the flare nut, and allows the other of the two pipes to pass through the through-hole,
• a tapered inner circumferential surface that is formed between the female thread and the through-hole, and is located such that a flare portion of the other of the two pipes is sandwiched between the inner circumferential surface and the outer circumferential surface, and
• a first annular surface that is formed around the through-hole at the other of the axially opposite ends of the flare nut;
• a cylindrical sleeve configured to house the flare nut such that the flare nut is allowed to rotate and move forward and backward;
• a rotary ring having a second annular surface that faces the first annular surface, the rotary ring being attached to the cylindrical sleeve such that the rotary ring is allowed to rotate for the union;
• and
• a spring configured to press the flare nut toward the rotary ring,
• wherein at the second annular surface, a claw is formed in such a manner as to protrude toward the flare nut, and
• wherein the first annular surface includes an engagement surface that is formed in such a manner to face one side in a circumferential direction and a helically inclined surface that is adjacent to the engagement surface in the circumferential direction and formed helically in such a way as to incline and face the opposite side of the one side in the circumferential direction.