The invention concerns a device for upper connection connecting two terminal endpieces (9, 10) of two submarine fluid transporting pipelines (2, 4) used in offshore hydrocarbon exploitation, a riser supported by at least one buoyant element (6) and a second pipe connecting the riser to a production and/or storage installation located at the surface, the device comprising an intermediate linking pipe (8) mounted mobile relative to the terminal endpieces of the riser and the second pipe between an operational position wherein it is connected at its two ends to said endpieces of the riser (2) and the second pipe (4) and an intervening position wherein its ends are disconnected from said endpieces (9, 10).