Abstract: In the welding of tubes with bevelled ends without heels or root-faces, all the weldings beads are made from the outside of the tubes with the tubes being in contact with local gap not exceeding 2 mm. The first and second welding beads are made both by the up-hill method and the down-hill method with the axis of the welding torches at the same inclination to the normal or the radius of the pipe and the accuracy of welding is improved by the use of mechanical guiding means for the welding means comprising at least one roller which bears on the bevelled ends of the tubes adjacent the welding zone.

Abstract: A method of 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: In a method of welding together two submerged pipe ends, the pipe ends are spaced apart and introduced through orifices into a receptacle by which they can be isolated from the surrounding medium. The spaced pipe ends are connected by a connection sleeve and after isolation are welded to the connection sleeve.

Abstract: Butt-welding apparatus for welding two pipes, e.g. for the shipboard welding of a laid pipe and a towed pipe, comprises a frame for receiving the pipe ends, means for securing the pipe ends relative to the frame and compensation means for causing movement of one pipe relative to the other to compensate for any shrinkage caused by the welding operation and by preheating the pipe ends to be welded.

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: In a method of welding together two submerged pipe ends, the pipe ends are spaced apart and introduced through orifices into a receptacle by which they can be isolated from the surrounding medium. The spaced pipe ends are connected by a connection sleeve and after isolation are welded to the connection sleeve.

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

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

Abstract: In the assembling and laying of an undersea pipe in which the already submerged pipe portion is suspended from a surface support, the end of the submerged pipe portion being supported on a variable inclination laying ramp, and a new pipe section is moved into alignment with the end of the pipe portion and fixed thereto, the submerged pipe portion is so suspended from the surface support that the tension in the pipe portion is maintained substantially constant irrespective of vertical movements of the surface support caused by the action of waves on the surface support.

Abstract: To enable the release and consequent recovery of a support float which supports a load, e.g. a pipe, as it is lowered to the sea bed, a marker buoy is lowered with the float to be released when the load reaches the sea bed, the marker buoy having an inflated flexible envelope which is trapped in a housing fast with the float and having an opening through which the float can escape only when it has been compressed to a predetermined extent under the effects of a predetermined hydrostatic pressure. The marker buoy is connected to the float by a cable and the float is released from the load either by operations on that cable, or on a release cable connected to the float, on appearance of the marker buoy at the water surface.

Abstract: A lip-seal for sealing the junction between two parts includes a body for mounting on one part, a sealing lip extending therefrom for application against the other part, and an inflatable chamber defined between the body, the lip and a diaphragm extending between, and connected to, the lip and the body, the arrangement being such that on inflation of the chamber the profile of the lip is modified so that it is moved away from the other part to permit the other part to be assembled with the one part without damage to the lip seal and without premature application of the lip to the other part.

Abstract: Apparatus for checking the bore and for plugging a pipe comprises a frame movable along the interior of the pipe, the frame carrying means for detecting a deviation in the bore of the pipe, means responsive to an overpressure of fluid in the pipe in a direction opposite to that in which the apparatus is intended to move, and a movable control part responsive to the detection of a deviation and of an overpressure for operating locking means for locking the apparatus relative to the pipe and sealing means for sealing the pipe.