Abstract: A pipe element has a circumferential shoulder at one end. The shoulder has an outer diameter greater than the outer diameter of the pipe element. A groove is positioned adjacent to the shoulder. The groove has a floor surface with an outer diameter less than the outer diameter of the pipe element. A bead is positioned contiguous with the groove. The bead has an apex with an outer diameter greater than the outer diameter of the pipe element. A combination of roller tools is used to cold work pipe elements and impart a desired shape to the sidewall in one method of manufacture. In another method, a spin forming tool is revolved in an orbit of increasing diameter within the pipe element captured within a die.

Abstract: A mechanical pipe coupling is formed of segments attached end to end to surround a central space. Each segment has a circumferentially extending cavity facing the central space flanked by arcuate keys which project toward the central space. Two arcuate shoulder surfaces are positioned on each segment. The arcuate shoulder surfaces face the central space and are positioned in spaced relation on opposite sides of the cavity between the cavity and the arcuate keys. The arcuate shoulder surfaces are angularly oriented with respect to an axis perpendicular to a plane containing the segments. The coupling is used to couple pipe elements having a circumferential ring located at the ends of the pipe elements. The angular orientation of the arcuate shoulder surfaces provides flexibility to the joint. A method of joining pipe elements having circumferential rings is also disclosed.