Fluid-tight pipe union

A fluid-tight union for reversably interconnecting first and second lengths of coaxial pipe, said union comprising:

• juxtaposed first and second annular fittings, said first and second fittings attachable to connection ends of said first and second lengths of pipe, respectively, said first fitting having a cylindrical body which, at one end thereof, incorporates a circumferential flange, said flange having a front and rear parallel faces which respectively face said second and first lengths of pipe, said second fitting having a circumferential shoulder adjacent a junction with said first fitting, said shoulder terminating in an inwardly-angled, overhanging circumferential step that faces away from said junction;
• a clamping collar comprised of arcuate segments, which are collectively sized to generally and coaxially surround both said first and second fittings, said collar incorporating, both an inwardly-angled clamping ledge that engages the overhanging step of the second fitting and at least one internal, inwardly-angled, spiral, circumferential thread spaced apart from said clamping ledge;
• and
• a retainer ring sized so as to be slidable over said first fitting, and rotatable against the rear face of said circumferential flange, said retainer ring incorporating external, spiral, circumferential threads that are angled away from the said flange, the external threads of said retainer ring engaging the internal threads of said clamping collar to draw the clamping ledge and engaged second fitting against the flange as the retainer ring is rotated in a thread engaging direction.