Patent ID: 7540540

Claim:
A pipe coupling comprising a pair of half members which have a half-ring shape on an x-y plane and a thickness along a z-axis, the half member comprising: a first end on which a circumferential groove is disposed, wherein the circumferential groove comprises a first groove surface and a second groove surface which are inclined over the x-y plane; and a second end on which a circumferential protrusion is disposed, wherein the circumferential protrusion comprises a first protrusion surface and a second protrusion surface which are inclined over the x-y plane, wherein the first groove surface and the second groove surface are inclined over the x-z plane in the same angle and direction as the first protrusion surface and the second protrusion surface, wherein the first end comprises a third groove surface perpendicular to the x-y plane between the first groove surface and the second groove surface, wherein the second end comprises a third protrusion surface perpendicular to the x-y plane between the first protrusion surface and the second protrusion surface, and wherein the third groove surface is inclined over the x-y plane in the same angle and direction as the third protrusion surface.