Abstract: An inflatable seal comprises a flexible active part and a rigid part which together define a chamber to be pressurized to place the active part in its operative position and to be evacuated to place the active part in its inoperative position, the active part being made from a composite material comprising an elastic material in which a wide deformable mesh of fibers of low extensibility is incorporated such that the active part has anisotropic elasticity and mechanical strength sufficient to withstand the differential pressures extend thereon in its operative and inoperative positions without the need for external reinforcements.

Abstract: A system for welding the ends of submerged pipes in a gaseous atmosphere at any depth comprises isolating the ends of the pipes by introducing obturators therein and then introducing the pipe ends into an open topped receptacle which is capped with an underwater personal carrying intervention unit. The closed receptacle is filled with gas and then a sleeve is positioned between the ends of the pipes and welded to the pipes.

Abstract: The ends of submerged pipes are connected using a receiver provided with two apertures through which the pipe ends extend, the receiver being adapted to form a watertight enclosure with an intervention unit and housing means for closing the ends of the pipes comprising two stoppers bearing seal means to be applied against the inner walls of the pipe ends and being maintained spaced apart by a first boom, the receiver including means for supporting a sleeve to be connected to the ends of the pipes and a replacement boom located in the sleeve, the connection being performed by introducing the ends of the pipes to be connected into the receiver through the apertures, at least one of the pipe ends being introduced by movement of the receiver relative thereto, closing the ends of the pipes with the stoppers, causing an intervention unit to descend on to the receiver, providing a watertight enclosure therewith, removing the water from the enclosure and placing it under atmospheric pressure, placing the receiver und