Abstract: A concave bearing surface for use with lugs of pipe coupling segments is disclosed. The concave bearing surface is positioned on the lug and surrounds an aperture which receives a fastener attaching the coupling segments together end to end surrounding pipe ends to be joined. Either the nut or the head of the fastener that engages the concave surface may be rotated to tighten the fastener. Engagement between the concave surface and the rotating member reduces the torque required to tighten the fastener and effect a stiff, fluid tight joint. A method of securing pipe ends using coupling segments with concave bearing surfaces is also disclosed.

Abstract: A coupling for joining pipe elements in end to end relation is disclosed. The coupling includes interconnectable coupling segments having connection members at opposite ends. The connection members are tightenable for drawing the segments toward one another and into engagement with the pipe elements. Each segment has a concavity positioned between inwardly projecting arcuate surfaces that engage grooves in the pipe elements. The concavities house a sealing member that extends circumferentially around the pipe elements. Angularly oriented surfaces are positioned adjacent to the connection members. The surfaces on facing segments engage one another and cause the segments to rotate in opposite directions about an axis perpendicular to the pipe elements. The concavities are angularly oriented with respect to the axis so that when the segments rotate, the cavities receive the sealing member without distorting it. A method of joining pipe elements end to end is also disclosed.

Abstract: A coupling for axially joining pipe ends together is disclosed. The coupling is divided into a pair of coupling portions which clamp around the pipe ends opposite one another. Each coupling portion has a pair of keys which engage circumferential grooves in the surfaces of the pipe ends. Each coupling portion has a free end with a V-shaped tongue extending therefrom and an opposite free end with a V-shaped recess. When clamped around the pipe ends, the V-shaped tongue on one coupling portion engages the V-shaped recess on the other coupling portion. The tongues each have an apex and the recesses each have a vertex which may be offset from the centerline of the coupling.