Pipe joint locking ring and groove arrangement

In a snap-insertion pipe joint including a first synthetic resin pipe (1) having an enlarged, female receiving end (3) with a first circular groove (11) and a second circular groove (9) having side walls perpendicular to the pipe axis in its inner periphery, the first groove being closer to the end of the pipe than the second groove, a second synthetic resin pipe (2) having a male insertion and (6) with a tapered outer edge (5) and a third circular groove (7) in its outer periphery, the third groove having a side wall nearest the outer edge perpendicular to the pipe axis and a tapered opposite side wall (8), a packing ring (10) disposed in the first groove, and a locking ring (4) disposed in an annular space defined by the second and third grooves when the first and second pipes are assembled together, the improvements characterized by:

• (a) the locking ring being an endless or continuous ring of substantially rectangular cross-section and formed of a relatively rigid synthetic resin material, and
• (b) the normal or unassembled inner diameter of the locking ring being smaller than the outer diameter of the insertion end of the second pipe but at least 9/10 the diameter thereof.