Fitting employing flexible plastic tubing with rolled back end

Claim 1

In a beaded plastic tubing joint, the combination comprising: a) relatively flexible polybutylene tubing having a rolled end portion forming a reversely turned bead, and b) relatively rigid annular structure at opposite sides of the bead and pressurizing the bead annularly and through the wall thickness thereof to form an annular seal, and to retain the bead in position, c) said structure including interconnected coaxial pin and box members having opposed shoulders at opposite sides of the bead, said shoulders effecting said pressurizing, the box member having an annular flange over which said bead is rolled, said flange forming one of said shoulders, said flange tapering toward an annular terminal which is convexly rounded in axial radial planes, said bead rolled over said terminal and extending frusto-conically to engage said one shoulder, said pin and box member opposed shoulders being differentially tapered to form a bulge in a portion of the pressurized bead that extends away from said flange terminal and away from the zone of closest approach of said shoulders.