A safety breakaway coupling for separating two lines in the case of excessive tensile forces between a first side and a second side of a coupling, comprising: - a first coupling half comprising a tubular housing and an automatically sealing fluid barrier in the interior of the housing, and having a first coupling side sealing tightly when engaged; - a second coupling half comprising a tubular housing and an automatically sealing fluid barrier in the interior of the housing, and having a second coupling side sealing tightly when engaged; - a series of ring segments having a cross-sectional shape for embracing the coupling sides engaged on each other; - a biasing element; - wherein at least one of the coupling sides has an oblique or conical surface (15, 25) inclined outwardly relative to the separation surface of the coupling, and wherein the ring segments each have at least one oblique or conical surface (31, 32) corresponding thereto in their embracing cross-sectional shape, which engages on the oblique or conical surface (15, 25) of the associated coupling side when the coupling halves are coupled; - wherein end flanges or collars (11, 21) having said oblique or conical surfaces are provided on the opposed coupling sides (11a, 21a), projecting beyond the perimeter of the respective tubular housing; - wherein the biasing element embraces the ring segments and resiliently urges the oblique or conical surfaces (31, 32) thereof against the oblique or conical surfaces (15, 25) of the end flanges or collars (11, 21); characterized in that - an expansion seal which is accommodated in a recess of the first end flange or collar cooperates with an axial annular projection of the second end flange or collar as a seal mating surface. - a first coupling half comprising a tubular housing and an automatically sealing fluid barrier in the interior of the housing, and having a first coupling side sealing tightly when engaged; - a second coupling half comprising a tubular housing and an automatically sealing fluid barrier in the interior of the housing, and having a second coupling side sealing tightly when engaged; - a series of ring segments having a cross-sectional shape for embracing the coupling sides engaged on each other; - a biasing element; - wherein at least one of the coupling sides has an oblique or conical surface (15, 25) inclined outwardly relative to the separation surface of the coupling, and wherein the ring segments each have at least one oblique or conical surface (31, 32) corresponding thereto in their embracing cross-sectional shape, which engages on the oblique or conical surface (15, 25) of the associated coupling side when the coupling halves are coupled; - wherein end flanges or collars (11, 21) having said oblique or conical surfaces are provided on the opposed coupling sides (11a, 21a), projecting beyond the perimeter of the respective tubular housing; - wherein the biasing element embraces the ring segments and resiliently urges the oblique or conical surfaces (31, 32) thereof against the oblique or conical surfaces (15, 25) of the end flanges or collars (11, 21); - an expansion seal which is accommodated in a recess of the first end flange or collar cooperates with an axial annular projection of the second end flange or collar as a seal mating surface.