Joint for plastic pipe

Claim 1

An improvement in a joint for connecting a plastic pipe to fittings or metal pipes comprising: a hollow body member having an end portion, said body member having a bore extending at least through said end portion, a first counterbore terminating at its inner end in an inwardly extending annular shoulder surrounding said bore and terminating at its outer end in an outwardly extending annular shoulder, a second counterbore of a diameter greater than the diameter of said first counterbore and substantially equal to the outside diameter of the plastic pipe, said second counterbore extending outwardly from the annular shoulder of the outer end of said first counterbore and terminating in an outwardly facing and flaring frustoconicAl shoulder; an elongated rigid tubular sleeve element having one end portion fixedly secured in said first counterbore against axial movement relative said body member and the other end projecting substantially beyond the frustoconical shoulder of said body member, said tubular sleeve element having an exterior diameter substantially equal to the interior diameter of the pipe at least on the portion of the same received in the pipe and said tubular sleeve element having, on the exterior surface of the portion projecting beyond the frustoconical shoulder, an annular recess means of a substantial overall axial extent and uniform depth, said annular recess means terminating in oppositely disposed frustoconical inner and outer end walls at its overall axial extent, the outer juncture of said inner frustoconical end wall lying substantially in a projection of said frustoconical shoulder of said body member, the exterior surface of said sleeve element between the fixedly secured end of the same and the outer juncture of said inner frustoconical end wall defining with said second counterbore an annular chamber of substantial axial extent for snugly receiving an end portion of the plastic pipe; follower means including a nut threadedly received by said body member, said follower means having an inner diameter at least equal to the exterior diameter of the plastic pipe and a frustoconical inner surface opposed to and spaced from said frustoconical shoulder of said body member to define therebetween a variable volume annular compression chamber having an initial axial length greater than the overall axial extent of said annular recess means on said sleeve element; a noncompressible annular gasket seal made of a deformable material and having an axial cross section when relaxed generally complementary to said compression chamber prior to volume of the compression chamber being reduced and an axial extent greater than the axial extent of said annular recess means on said sleeve element; and means for limiting and tightening of said nut on said body member to a position where the frustoconical inner surface of said follower means reduces the volume of said compression chamber and where a projection of said frustoconical inner surface of said follower means extends through the outer junction of said outer frustoconical end wall of the said annular recess means on said sleeve element so that said gasket seal deforms the plastic pipe without extrusion into said annular recess to completely fill the same.