Patent ID: 7401821

Claim:
A bolt-ring for connecting stub end thermoplastic pipe having an end stub with a contact shoulder and an oppositely arranged end face, the bolt-ring comprising: a bolt-ring body having an outer vertical rim portion, an inner vertical rim portion and a web portion interconnecting the outer vertical rim portion and the inner vertical rim portion, the web portion having a plurality of spaced bolt holes therein which circumscribe a centerline of the bolt-ring body; the inner vertical rim portion, outer vertical rim portion and interconnecting web portion together forming a bolting-face for the bolt-ring on a top side thereof, the top side of the bolt-ring having a beveled and angular top surface, and wherein an opposite bottom side of the bolt-ring includes a contoured recess that reduces the material of the bolt-ring body and provides a variable cross sectional geometry; wherein the inner vertical rim portion includes a thumb region on the bottom side of the bolt-ring which contacts the contact shoulder of the pipe end stub in use, the thumb region including a bottom surface which is radially tapered so that it presents a beveled and angular bottom surface for the bolt-ring; wherein the plurality of spaced bolt holes provided in the interconnecting web portion each have a centerline which define a circular locus of bolt-hole centerlines, and wherein the beveled and angular top surface of the bolt-ring increases in dimension radially outward from the circular locus of bolt-hole centerlines and from the centerline of the bolt-ring body; and wherein the beveled and angular top surface, together with the beveled and angular bottom surface of the bolt-ring cause the bolt-ring to deflect under bolt-loading so as to come into parallelism with the pipe stub end faces to provide uniform and predictable load distribution on the end faces of the stub end and to be deformed by a predictable amount, such that the deformation imposes a spring load on the pipe stub end.