Abstract: In a hydrocarbon production well in which effluent is activated by an activation pump installed in a production pipe in the well, a safety valve is disposed in the production pipe beneath the pump and is controlled for opening purposes by a control chamber which is provided with pressurized fluid present at the level of the pump. To this end an annular passage is provided inside the production pipe along a wall connecting the pump to the valve, the annular passage communicating at its ends with means for bringing it into communication with the pressurized fluid present at the level of the pump and the control chamber respectively.

Abstract: A process for tapping a region of a pipe placed on a sea bed utilizes a working platform which is installed vertically above the region of the pipe to be tapped, the platform being adapted to receive a support girder which can be lowered from the surface of the sea onto the working platform and be engaged therewith and then lifted off the platform. The platform is adapted to receive successively a plurality of modular tool-carriers provided with tools for carrying out a variety of operations on the pipe, the operations including concrete stripping, removal of anti-corrosion covering, transverse cutting, internal brushing, and making the longitudinal weld flush.

Abstract: The invention relates to an internal obturator for a pipe for use in separating two spaces inside a pipe. The obturator comprises a rigid hollow body comprising two end plates connected by a cylinder having a lesser diameter than the end plates between which an annular inflatable bladder of a jack is provided extending around the cylinder. The jack is inflated to apply a cylindrical wall against the inner surface of the wall of the pipe. The wall which is independent of the bladder of the jack may be connected by its ends to the end plates or may simply be inserted therebetween.

Abstract: The invention is concerned with a process for bringing a body of water into communication with a tunnel extending under the bed of the body of water. A cavity is excavated under the end of the tunnel adjacent the body of water, to a depth such that the volume of the cavity is at least equal to the volume of the ground forming the roof of the cavity and between the cavity and the bed of the body of water. The roof of the cavity is then collapsed and is received in the cavity.The invention is particularly useful in the connection of a pipe placed in the tunnel to an installation or pipe which is eventually immersed. For example a pipe may be provided on the bed of the body of water to be connected to a pipe in the tunnel, the connection being made after the cavity roof has been collapsed by introducing a pipe portion between the ends of the immersed and underground pipes.

Abstract: The invention relates to an internal obturator for a pipe, particularly for a hydrocarbon conveying pipe-line, which comprises a central core and a flexible inflatable sleeve surrounding the core, wherein the central core comprises a flexible casing filled with a hardenable material which is hardened after its introduction into the flexible casing. The hardenable material may be hardened before or after insertion of the obturator into a pipe.

Abstract: The characteristics of a weld made by electron beam welding are improved by introducing into the region of the pieces to be welded, which is subjected to remelting during welding, a material which is obtained by applying an arc welding process, or a process for remelting under slag, to a mild or slightly alloyed steel. The introduction of the material into the region of the weld increases the production of acicular ferrite which increases the tensile strength of the weld. The material may be introduced by providing a deposit of it over part or the whole of the surface of one or both of the pieces to be welded, by introducing a mass of it between the surfaces to be welded or as a filler wire.

Abstract: The invention relates to a device for injecting a liquid product, at a low flow rate, into the bottom of a hydrocarbon-producing well. The device comprises an injection valve and, above the injection valve, at least one settling tank through which the liquid to be injected must pass before arriving at the injection member.

Abstract: The present invention relates to a marine platform comprising a structure consisting of a lattice of tubular elements sealingly joined to one another. Pickups are provided on at least some of the tubular elements, to detect the passage of a fluid through the wall of an element. At a junction of one tubular element with another element whose interior space is monitored by a pickup, a backing plate is disposed in the one element facing the junction zone and sealed around the junction zone to define an intermediate space which is in communication with the interior space of the other element.

Abstract: The invention concerns the removal of a concrete covering applied to an underlying surface provided with an anti-corrosion coating, for example that of a hydrocarbon-conveying pipe.The coating is removed by making trenches in the concrete to divide it into removable elements, the trenches being made using a cylindrical milling cutter having a longitudinal diamond-faced toothing and provided with a central stud of tungsten carbide projecting axially from the end of the cutter. In use the stud contacts the surface to prevent the surface being damaged by the toothing on the cutter as the cutter is moved transversely across the surface. To initiate a concrete covering removal operation, a hole is first drilled through the covering perpendicular to the surface for receiving the stud. The cutter is then moved perpendicularly to the surface through the concrete with the stud projecting into the drilled hole and until the stud contacts the surface.

Abstract: An electron beam welding chamber for butt joining elongate members 1,2 extending longitudinally at the center of the chamber. The chamber comprises an envelope 7 defining the welding enclosure 6 and which rests on a fixed structure 8. The electron gun equipment 13 is provided within the envelope and is mechanically connected, by a withdrawable connection means 18 or by elastic connection means 24, 25, to the enclosure, clamping means 15 being provided for clamping the electron gun equipment relative to one of the elongate members. This invention is particularly applicable to the welding of the sections of a pipe to be laid on the sea bed.

Abstract: A welding chamber in which a vacuum is created for welding, using an electron beam, elongate pieces extending centrally of the chamber. The welding chamber is divided into a central sub-enclosure 41 for receiving the pieces 1, 2 to be welded and which is evacuated during welding, and a peripheral sub-enclosure 42 in which the welding means are located and which is permanently evacuated, the two sub-enclosures being separated by retractable sealing gaskets 12, 26, 27 which are retracted during welding to place the two sub-enclosures in communication.

Abstract: The characteristics of a weld made by electron beam welding are improved by introducing into the region of the pieces to be welded, which is subjected to remelting during welding, a material which is obtained by applying an arc welding process, or a process for remelting under slag, to a mild or slightly alloyed steel. The introduction of the material into the region of the weld increases the production of acicular ferrite which increases the tensile strength of the weld. The material may be introduced by providing a deposit of it over part or the whole of the surface of one or both of the pieces to be welded, by introducing a mass of it between the surfaces to be welded or as a filler wire.

Abstract: In a process for electron beam welding, the electron beam welding gun is controlled to maintain the power absorbed by the pieces being welded substantially constant. In a preferred embodiment the intensity of the electron beam transmitted by the pieces being welded, which corresponds to the power absorbed, is measured, compared with a preset intensity and the difference used to control the focussing current supplied to the gun to maintain the intensity of the transmitted beam constant.

Abstract: In a method of tracing a well drilling mud by determining the concentration of a tracer ion in samples of filtrate from a drilling mud which contains a predetermined concentration of the tracer ion, the improvement wherein the tracer ion is the acetate ion and is present in the drilling mud in a concentration of about 1.10.sup.-3 to about 5.10.sup.-2 ions per liter.

Abstract: To reduce the wear of surfaces of anti-friction devices or bearings, the surfaces are diamonded, e.g. by being provided with diamonds or by being the surfaces of diamond-containing concretions, and are lapped before use, substantially no further wear occuring after the surfaces have been lapped.

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 positioning of an assembly of work tools which are required to operate in the plane of the end face of a tubular structure, which is not necessarily orthogonal to the axis of the structure, a theoretical end face is determined by three sensing arms spaced apart by 120.degree., which, by an axial translatory movement followed by two pivotal movements about axes parallel to lines joining pairs of the arms, is brought into coincidence with the actual end face of the structure, then the plane of operation of the tools is brought into coincidence with the plane of coincidence of the theoretical and actual end faces.The work tools may for example be electron beam welding guns for welding an additional tubular element to an existing tubular structure.

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 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: Connecting means for connecting the ends of at least a pair of pipes, said pipe ends being immersed in water and one of the or each pair of pipe ends being mounted on a fixed structure and connected, e.g. to an oil well, and the other of the or each pair of pipes being mounted on a movable structure, e.g. a column, mounted for oscillatory movement relative to the fixed structure, comprises in respect of the or each pair of pipes a tube of a length greater than the maximum distance between the pipe ends and in a spiral and/or helical shape, wherein the tube is supported intermediate the ends thereof solely by means for correcting the buoyancy thereof to reduce the buoyancy to substantially zero.