Pipe detachment preventing device for union nut pipe fitting

A pipe detachment preventing device for a union nut pipe fitting, comprising:

• a fitting body having a receiving portion which has an external thread on an outer surface thereof and into which a non-threaded pipe is inserted;
• a union nut which is screwed and tightened to the receiving portion with an annular rubber packing interposed therebetween;
• and
• a retaining ring composed of a pair of divisional components fixed to an outer-peripheral surface of the pipe by tightening means so as to be opposed to each other, wherein
• each divisional component includes
• a body portion along the outer-peripheral surface,
• an arm which is along an axial direction of the pipe and is provided with, at a distal end, a hook to be latched to the union nut, and
• a protruding portion provided with the arm and protruding outward from an end portion of the body portion,
• the protruding portion has at least a flange portion having a through hole through which the tightening means penetrates, and a wall portion extending from the flange portion,
• the wall portion is provided only at a side part along the axial direction of the flange,
• an end portion of the wall portion opposed to another divisional component is formed so as to protrude toward the other divisional component relative to end portions of the arm and the hook opposed to the other divisional component,
• when the end portions of the wall portions are brought into contact with each other, the end portions of the arms and the hooks do not contact with each other,
• the retaining ring has an elastically-deformable rubber member through which the tightening means is inserted and which is held between the flange portions opposed to each other,
• the rubber member forms a gap between the end portions of the wall portions when the pair of divisional components are coupled by the tightening means and latched to the union nut in a loose-fit state, and
• the tightening means is tightened until the end portions of the wall portions are brought into contact with each other and the gap disappears, thus causing a part of the rubber member to protrude out in the axial direction from the flange portion and tightening and fixing the pair of divisional components to the outer-peripheral surface of the pipe.