A deformable mechanical pipe coupling is disclosed. The coupling has a plurality of interconnectable segments that straddle the ends of pipe elements to be joined. The segments have arcuate surfaces that engage outer surfaces of the pipe elements. The outer surfaces subtend an angle of less than 180 DEG and have radii of curvature greater than the radii of curvature of the pipe element outer surfaces. The segments have adjustably tightenable connection members for connecting the segments to one another. When the connection members are tightened, the arcuate surfaces deform and conform to the radius of curvature of the outer surface of the pipe elements.