Pipe coupling

A pipe coupling comprising two flanges which can be fixed to the ends of the pipes and a tightening device which bear on the flanges to sealingly connect the same, wherein the tightening device comprises an extensible member located between the end front faces of the flanges in such a way that said member can be fitted and removed without modifying spacing between said front faces and defining a passage providing a communication between the pipes, said tightening device further comprising at least one movable member controlling the increase of length of the extensible member to make it sealingly bear against the front faces of the flanges, the movable member further having terminal portions bearing on the rear face of the flanges to prevent the moving apart of said flanges during the increase of length of the extensible member, wherein the extensible member comprises at least two elements which move with respect to one another, each of them having a conical mating surface and the movable member comprises an intermediate portion having two opposite conical surfaces which bear against the conical mating surfaces so as to move the two elements of the extensible member away from one another when the movable member is radially displaced towards the axis of the flanges under the action of the tightening device wherein the extensible member also comprises a tubular member, whose internal diameter is substantially equal to the internal diameter of the flanges in order to define the said passage, the two movable elements being slidingly mounted on the tubular member in order to bring an O-ring into tight contact with the corresponding flange during the elongation of the extensible member.