Abstract: An external apparatus for butting two tubular elements 1, 2 to be welded together comprises two frames 8, 9 provided with means for the external gripping of the elements and which are connected by jacks 10, 11 for bringing the elements together and by a plurality of connecting and aligning means 14-19 each comprising a pair of members 20, 21 engageable one in the other with the interposition of an elastic means 22. The gripping means comprise a plurality of radial jaws 55-64 for gripping the tubular elements and carried by support rings each comprising three jaw holders 23-25 each in the form of a segment of a circle.

Abstract: In the positioning of an additional tubular element, e.g. a pipe section, on a tubular structure, e.g. a pipe-line in the course of immersion, where the end surfaces to be brought into contact are not in radial planes, the additional element is brought in alignment with the structure and at a short distance from the latter. The end surfaces of the element and structure are then brought into contact, the contacting ends are centered, and a compressive force is applied to them in such a way that the element can pivot about the point of contact between the element and the structure until its end surface is brought into complete contact with the end surface of the structure.

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.