Patent ID: 7270351

Claim:
A coupling for connection of a polymeric pipe, comprising: a hollow body having external threads and an inner surface, said body including an extended end portion having an end portion surface, said body comprising a polymeric material; a nut adapted to threadably engage said body external threads, said nut comprising a polymeric material, said nut having an internal cavity and at one end and internal threads co-operable with said body external threads, said nut including an integral hooked projection that extends from a nut transition region and over at least part of said body inner surface, said projection including a first inner surface generally parallel to said body inner surface and a second outwardly converging surface extending from the inner edge of said inner surface, said projection second surface having a first taper angle, said nut further including a recessed stop region that is disposed proximate said projection and configured to receive said body end portion therein, said recessed stop region having a recessed stop surface; and a deformable grip-ring having a first surface generally parallel to said body inner surface and having a second outwardly converging outer surface extending from said first surface, said grip-ring second surface having a second taper angle, said grip-ring including a plurality of radially inward barbs, wherein upon tightening of said nut, said body end portion engages said nut recessed stop region, whereby said body end portion surface is disposed proximate said nut recessed stop surface, and said nut second surface abuts against and exerts an inwardly directed radial force on said grip-ring second surface that is directed in longitudinal and radial directions, whereby said grip-ring is urged both radially and longitudinally into said body and said grip-ring exerts an outwardly directed radial force on said projection, and wherein engagement of said body end portion and said nut recessed stop region and said abutment of said nut second surface and said grip ring second surface provides an inwardly directed substantially radial resistive force that reinforces said projection and said nut transition region.