Device for repairing damage or providing branchings on existing pipe installations

A device for repairing damage or providing branchings on a pipe, especially in existing underwater pipe installations, comprising a cylindrical metal muff which is longitudinally divided to form a pair of metal muff members which are dimensioned to be placed around and clamped to the pipe by clamping means, and sealing means provided between the muff and the surface of the pipe, wherein at least one of the muff members comprises a strong outer metal layer and a less strong inner metal layer, which layers are joined so as to form an intermediate closed volume between said strong outer metal layer and said less strong inner metal layer, said muff member being provided with means for supplying a hydraulic pressure medium to said volume, so that the volume when pressurized expands by movement of the inner layer, and the inner layer and the sealing means thereby are pressed to sealing engagement with the adjacent surface of the pipe.