Floating support comprising a device for the retention and securing of a subsea pipe

p0001The present invention concerns a floating support comprising a retaining device and maintenance of a subsea pipeline, in particular a pipe whose end is retained and kept in suspension in an inclined or vertical position at a floating support consisting of a laying vessel, and extends to the bottom of the sea, said retaining and holding device for performing the successive assembly of pipe sections end to end, preferably by welding the edge of said floating support or ship poses.

p0002The word "floating support" here refers to any movable floating assembly, including a vessel capable of allowing the installation of a pipe.

p0003More particularly, the invention applies in particular to the installation of a subsea pipeline consists of straight sections also called "oars" assembled together by butt welding on the ship, measuring generally 24 or 48 m, the pipe being thus asked by assembly and close down in near successive trains, each section or "train" itself can be made of several unitary pipe elements assembled by welding - usually land - to form a train.

p0004The present invention also relates to a floating support comprising a retaining device and holding for connecting and laying successive portions of an undersea pipe from said floating support.

p0005The invention thus applies to the continued suspension of substantially vertical pipe, but also to any type of pipe for conveying a fluid, an electric current, optical signals or information, including to rigid pipelines or flexible, umbilicals and power cables. It applies particularly to underwater pipes handled from a ship performing installation operations, including very deep water, ie about 1000 m deep and beyond.

p0006The present invention more specifically laying pipes consist of a set of coaxial pipes comprising an inner pipe and an outer pipe, especially underwater pipes for conveying hot or cold fluids, preferably underwater pipes for large depths. These coaxial pipes are called "Pipe In Pipe" or PIP, ie "driving in a pipe" in which an inner pipe conveys the fluid and a coaxial outer pipe to previous contacts with the environment, c that is to say water. The annular space between the two pipes can be filled with an insulating material or be evacuated of all gas.

p0007As part of a deep installations, subsea pipelines and assemblies underwater coaxial pipes are assembled earth elements of unit length, on the order of 10-100 m depending on load holding capacity the delivery system. Then they are transported out to sea on a laying ship. During installation, the unit lengths of the various elements of coaxial pipe assembly are connected to each other on the ship and as and when they arise in sea. It is therefore important that this connection can be achieved quickly and easily.

p0008To do this, use is made of connecting parts or connecting steel forgings are assembled to the ends of said assembly elements coaxial pipes to be assembled. The connecting piece at the downstream end of a first assembly element not yet assembled coaxial pipe being connected to the junction piece at the free upstream end of a second element coaxial pipe assembly already assembled downstream.

p0009More particularly a so-called junction forging to the end of a coaxial pipe element includes at each end of two arms of revolution comprising an outer branch and an inner branch forming a fork defining a said annular space, including a fork whose ends cylindrical fibers are assembled to the cylindrical ends of the outer and inner pipes, respectively, the other fork having its ends joined to the ends vis-a-vis of the joining piece of the other coaxial pipe element.

p0010These forged junction parts are also designed to strengthen the resilience of subject lines to significant bending during installation, especially in the connecting area of ​​two said successive unit lengths or successive trains, especially in the case of binding substance -surface, to give them a very high resistance to fatigue throughout the lifetime of the facility. Coaxial lines and such connecting pieces have been described in particular in<patcit id="pcit0001" dnum="FR2873427"><text>FR 2873427</text></patcit>.

p0011The pre-assembly of different parts of conduct on board the ship, then laying by step driving to the bottom of the sea by rowing assembly then dipping the pipe gradually as the trains are assembled, is traditionally, including for laying subsea to depths exceeding 1,000 m, or even greater than 2000 m from ship or floating support equipped with a tower, articulated or not, including handling means or grippers, for a so-called J-lay method in which the subsea suspension adopts a curved configuration between its attachment point on the surface at the ship level and point of contact with the seabed, said shape corresponding to the curve mathematics called chain for which the radius of curvature increases regularly from the bottom to the surface.

p0012This pose is called J-lay because the shape of the portion of pipe suspended between the ship and the point of contact on the bottom of the sea is treated improperly to form J. The J-lay is described in numerous patents including patents on behalf of the applicant <patcit id="pcit0002" dnum="FR2792991"><text>FR 2792991</text></patcit>, <patcit id="pcit0003" dnum="FR2793540"><text>FR 2793540</text></patcit> and <patcit id="pcit0004" dnum="FR2801088"><text>FR 2801088</text></patcit> among others.

p0013In these patents describes a laying ship fitted with a J-lay tower which allows the following operations:<ul><li>maintain steady the upper end of the tip of conduct already immersed Assembly suspended</li><li>down a new section of pipe or train, present in said upper end tip of said part of suspended pipe, the lower end of the so-called new part of driving or train,</li><li>firmly hold the ends of the line parts to be welded to said welding can be performed without risk of damage due to the various movements of the ship and the pipe portion immersed in suspension to the bottom of the sea, and finally</li><li>welding said parts of conduct.</li></ul>

p0014In the J-lay, the difficulty lies in the fact that all the above mentioned operations must be performed in one location located at the deck, so close to the lower end of the tower, and more, all operations must be executed in the shortest time because of the extremely high hourly operating cost of the installation vessel.

p0015Driving during assembly is generally maintained in the lower part of the J-lay tower by an external clamp system.

p0016The use of clamps with significant steel corners to secure the suspended pipe portion has the disadvantage of leaving traces on the outside of the pipe, especially damage to the anticorrosion coating. Many other types of clamps have been developed, primarily based on systems articulated toggle or cam lock, the engagement and disengagement of the clamp movements are often carried out by means of hydraulic cylinders.

p0017Such clamps are well suited when loads are low, but in the great depths, eg 2500 m, weight of the pipes can exceed 500 tonnes and it is necessary to ensure an extremely high level of safety regardless of the type of conduct during the splicing phase that can last 15 to 45 minutes per cycle, or in case of interruption of operations due to various reasons such as equipment or storm events, which can last several days. If one does not seek to preserve the integrity of the outer coating of the pipe clamps to significant corners as described above perfectly fulfill the function of retaining the pipe even though it has irregularities in diameter, but as long as said coating is fragile, this type of clamp can not be used.

p0018Many solutions have been developed to prevent damage to the outside of the pipes, but they are not adapted to extreme loads because they have the disadvantage of not providing a safe condition if triggered slip phenomena, which could create significant accidents, not only in material but also in personnel.

p0019In Patent <patcit id="pcit0005" dnum="FR2801088"><text>FR 2801088</text></patcit> the Applicant describes a clamp operating on the principle of friction involving the implementation of jacks arranged substantially perpendicular to the outer surface of the pipe and from the pinch.

p0020When the laying depth increases, the pipes have in general an increased linear weight since they must withstand the implosion because they are placed empty, that is to say the pressure inside the conduit is substantially atmospheric pressure, while the external pressure is substantially 100bars or 10MPa to 1000m deep. So not only the suspended length increases with depth, but also the thickness of the pipe, so its unit weight. The laying of voltages can then meet and exceed 1200-1500 tons or more, and friction clamps<patcit id="pcit0006" dnum="FR2801088"><text>FR 2801088</text></patcit> then have dimensions and too complex to reach a very high level of reliability in the operation of laying facilities. Moreover, the very large dimensions of such devices create a plug aware and swell considerably increased, requiring more power from the dynamic positioning of the ship whose position is to be maintained with high accuracy.

p0021In <patcit id="pcit0007" dnum="US6273643B"><text>US-6,273,643</text></patcit>Describes a system for holding and retaining the conduit in a tower, wherein the upper end of the pipe is rigidly attached to a fixed platform of the lower end of the tower and the inclination or curvature of driving below the rigid attachment of its upper end is controlled by a tubular structure device comprising a large number of so as to maintain the driving rollers substantially in the axis of the tubular structure.

p0022An installation of this type can generate nonuniform mechanical stresses at the junction driving around, which requires to provide safety factors with regard to the strength of the rigid joining parts and therefore costly junction mechanical parts .

p0023Thus the problem posed is to maintain tension a subsea Laying operation with a device and retention process and maintenance of conduct improved, simpler and less expensive to make and implement, while maintaining a level maximum reliability.

p0024To do this the present invention provides a floating support comprising a holding device and maintaining a subsea pipeline suspended from said floating support, the duct having a first forging of revolution welded to the upper end of said pipe forming an inner tubular conduit section having substantially the same diameter as that of said conduit, characterized in that the said retaining device and holding means comprises:<ul><li>a- a first said forging comprising a first peripheral radial protuberance on its outer surface, said first radial protuberance comprising underside a first contact surface of revolution,</li><li>b- at least one first latched collar removably around and against said first forging under face of said protrusion at said first contact surface of said first protrusion, said first contact surface cooperating in abutment on a second surface contact of revolution of said first collar, said first collar forming a second radial protuberance, preferably a second protrusion of revolution, of larger diameter than said first projection, said second protuberance being adapted to retain the gripping arm ends installed on said floating support and for raising and lowering said pipe in translation relative to said floating support substantially in the Z axis₁Z '₁ of said conduit at its upper end, and</li><li>c- a support means resting on a fixed platform crossing in a first pass through the pipe, said platform being integral with said floating support, said support means and said platform surrounding said pipe and directly or indirectly supporting said first collar, said first collar having a third surface of revolution contacting under said first collar and cooperating bearing directly or indirectly on said support means, said support means comprising means for load transfer and joint rotation (hereinafter hereinafter abbreviated as "articulation means in rotation") for guiding the inclination of the axis Z₁Z '₁ of said conduit at said upper end into a virtual cone angle 2α at the top of less than 10 °, preferably less than 5 ° with respect to an axis ZZ 'perpendicular to said platform, and providing a substantially uniform distribution of loads on all the said contact surfaces when said conduit has a non-uniform support on said contact surfaces and said support means, causing a so-called tilt driving.</li></ul>

p0025It is understood that:<ul><li>said first forging, the first collar, and the contact surfaces are the same axis corresponding to the axis of said upper pipe end, and</li><li>said means for load transfer and rotation in hinge joint allows free rotation of the Z axis₁Z '₁ of said first forging, first collar and said first, second and third contact surfaces in the boundary of the said cone of angle 2α at the top with respect to the ZZ 'axis perpendicular to said platform, and provides uniform load distribution and mechanical stress on said contact surfaces, and</li><li>said rotation joint means has a partial refocusing operation of the pipe when the latter is inclined relative to the axis ZZ '.</li></ul>

p0026The retainer and maintenance of the present invention is essentially to create a first protrusion or outgrowth located at the top of rowing or driving part installed, particularly in terms of forgings for assembling the driving parts, and least one said first collar supporting said first protrusion created by the forged workpiece, said first collar cooperating in abutment on a said articulation in rotation so that the transfer of charges at the interface between driving and holding device and maintaining is substantially isostatic throughout said revolution of contact surfaces of said retainer and maintain, whatever the respective movements of the vessel or said conduit, one vis-a-vis each other. Indeed, said means of pivot hinge makes it possible to evenly distribute the mechanical compression, shear and bending on all of said contact surfaces of said device according to the invention.

p0027It is understood that:<ul><li>said conduit is retained at said platform by said first contact surface of support revolution over said second contact surface on which it rests and the internal passage diameter of the first collar is smaller than the outer diameter of said first protrusion,</li><li>said first collar, said support means and said hinge means have one common axis of revolution ZZ 'corresponding to said axis of said retainer and maintenance, and corresponding to that of said first forging when said conduit and said device the invention in a position of minimum rest constraint,</li><li>said first projection is integral with said first piece and has forged by its geometry a sufficient thickness so that the level of compressive stress at the interface at said first contact surface is at an acceptable level, being understood that said stress is distributed substantially uniformly over the periphery of said first contact surface.</li></ul>

p0028But the implementation of said first collar minimizes the dimensions of said first projection which avoids excessive variation of inertia of said first forging. That said first projection cooperates with said first collar allows more generally prevent the implementation forging too large and therefore expensive and difficult to achieve and implement. Finally, the fact that said first protuberance is a forged piece portion confers greater mechanical reliability in terms of optimum transfer of load.

p0029This protuberance can transfer the load due to the weight of the pipe directly to the solid part, since a thickness of the forged part, which has the effect of transferring said load to both outer and inner pipes, thereby ensuring an optimal transfer of constraints within two coaxial pipes in suspension.

p0030The thickness of the projection is a function of the load to be supported which is a function of the length of the pipe and the outside diameter of the pipe, and therefore the depth of laying.

p0031More particularly, to depths of up to beyond 3500m, said first protrusion has a thickness of 10 to 50mm, preferably less than 30mm, more preferably from 15 to 25 mm corresponding to an increase of the maximum outer diameter of the protuberance relative to the diameter of the cylindrical surface of the main portion of said first forged from 20 to 100 mm, preferably less than 60mm, more preferably from 15 to 25 mm.

p0032Here, the term "thickness", the increase of the maximum radial distance that is to say the maximum radius of the outer surface of the forged component at said protuberance relative to the radius of the cylindrical surface of the portion current of the forging above and below the protrusion, which corresponds to half of the increase in the maximum outer diameter of the protrusion relative to the diameter of the cylindrical surface of the main portion of said first forged.

p0033Still more particularly, said second protuberance caused by a peripheral notch formed in the outer surface of said first collar.

p0034Advantageously, said rotary joint apparatus has a "self centering effect" of the pipe when the latter is inclined by movement of said floating support. It is understood that said self centering effect is to refocus the conduit so as to align the longitudinal axis of the pipe with the axis of said cone after a so-called tilt.

p0035In one embodiment, said support means is a support ring member secured to said floating support, resting on said platform, said support part having a first central through hole of larger diameter than said first protrusion and said means for load transfer and rotation in hinge joint allows free rotation of the axis of said first forging, first collar and said contact surfaces in the boundary of said cone angle 2α relative to the top to the axis ZZ 'of said support member and said first central passage opening.

p0036In one embodiment, said means for load transfer and joint rotation is a flexible hinge means comprising a laminated abutment of revolution comprising a plurality of elastomer layers interposed between rigid reinforcements, preferably metal, defining at rest of the same axis as the axis of revolution surfaces of revolution ZZ 'of said first forging, said support part and said first collar.

p0037Said elastomeric layers revolution surface may be frustoconical, annular, flat or shaped non-planar surface, such as an ellipsoidal shape section surface or parabolic or hyperbolic section, or preferably spherical section.

p0038Here, the term "truncated shape of revolution surface or ellipsoidal shaped section, parabolic or hyperbolic", an ellipsoidal surface of revolution respectively, parabolic or hyperbolic defined by two parallel section planes perpendicular to the axis of revolution.

p0039In particular, by the shape of the elastomeric layers of said laminated abutments of frustoconical or spherical shape, in particular in the case of laminated abutments of spherical section said spherical laminated abutments, the stresses and the strains generated at said laminated abutments and said forging are minimized, and to maintain or restore substantially coaxially said device according to the invention and said conduit.

p0040In a second embodiment, said charge transfer means and articulation in rotation and said support means are constituted by a plurality of hydraulic actuators, preferably at least three hydraulic cylinders uniformly distributed around said first passage of said platform and of said pipe, the cylinder body resting on said platform about said first passage through which the pipe, and the stems or pistons of said cylinders preferably having at their ends ball joints small free articulation in rotation, said ends of supporting cylinder rods directly or indirectly said third contact surface of said first collar, said body of cylinders being interconnected such that fluid exchange can occur between them to create a differentiated translation of said rods of the different cylinders, where a non-uniform support acts on said ends of cylinder rods.

p0041In a third embodiment, said support ring part and said means for load transfer by articulation in rotation comprises a mechanical ball consisting of two rigid parts, a lower part of revolution resting on said platform and an upper rotational part, said first collar resting directly or indirectly on said top piece, said bottom piece having an upper contact surface of concave spherical section cooperating by sliding with a complementary convex surface of spherical section constituting the bottom surface of said upper part of said support part , at least one of said concave and convex surfaces comprising an anti-friction coating, preferably a polymeric coating.

p0042It is understood that the axis of revolution of said upper body of revolution corresponds to the axis of said first forging, first collar and said first and second contact surfaces and the axis of said lower rotating part based on said platform corresponds to the axis of said cone of angle 2α at the top.

p0043It is understood that:<ul><li>said spherical concave and convex surfaces are centered in a point above the upper end of the pipe or of the holding device and holding device according to the invention on the same axis as that of the upper end of the pipe and said device and allow relative sliding of said complementary surfaces and cooperating in rotation with respect to each other slidably so that the inclination of said pipe remains in a cone with an apex angle less than 10 °, preferably less than 5 °, and</li><li>said third contact surface of said first collar comes to bear directly or indirectly on the said upper part.</li></ul>

p0044It is understood that said pivot hinge means described above allow the charge transfers substantially isostatically distributed over the entire periphery of said contact surfaces when load imbalance resulting from an inclination of the pipe occurs.

p0045however preferred for ease of manufacturing reasons and / or placed on the floating support, a means of resiliently flexible link type laminated abutment or preferably hydraulic type rotating hinge means with cylinders as described above.

p0046It is preferred to use a means of hydraulic type joint because, in this embodiment, it is not necessary to implement a so-called support piece on the floating support, independent of said articulation means in rotation, said means support including hydraulic cylinders is easier to implement and, where appropriate, remove the floating support.

p0047It is understood that the piston rods are arranged substantially parallel to said axis of revolution of the device according to the invention and perpendicular to said platform, and the piston rods of length may be relatively low, in particular less than 10cm, preferably less than 5cm, given the low allowed angular deviations.

p0048In a preferred embodiment, said first and second contact surfaces are frusto-conical surfaces of revolution are inclined relative to the Z axis₁Z '₁ said first forging, preferably a β angle of 30 to 60 °, preferably about 45 °.

p0049It is understood that said first and second tapered contact surfaces are entered into a cone having an angle at the top at the lower end of said cone, that is to say below said first and second contact surfaces

p0050More preferably, said third contact surface of said first collar is a frustoconical surface of revolution, preferably of substantially the same inclination as said first and second tapered contact surfaces.

p0051In another preferred embodiment, said first collar cooperates indirectly locked with said support means through a second collar removably around the outer surface of a portion of said first yoke including said third contact surface, said second collar including a fourth revolution contact surface on which said third contact surface of said first collar is supported, said second collar preferably having a maximum outer diameter and an inner diameter larger passage than the maximum outer diameter and respectively internal passage diameter of said first collar, said second collar having at the bottom a fifth revolution contact surface co-operating directly or indirectly supported on a sixth surface contact upper part revolution of said support means.

p0052More particularly, the diameter of the first passage opening of the pipe through said support part corresponds substantially to the diameter of the second through hole on said platform and is preferably greater than the internal diameter of said second collar.

p0053Preferably, the internal diameter of passage of said second collar is greater than the outer diameter of said first projection, so that if necessary, said pipe can be lowered after connection by removing only said first collar, without unlocking and removing said second collar support on said support part.

p0054It is understood that said revolution contact surfaces are surfaces extending over the entire periphery of the outer surface of the parts or collars involved.

p0055Also advantageously, the device according to the invention comprises a third locked collar around a lower part at least of a said second collar, said third collar comprising a seventh contact surface of upper revolution on which comes to bear said fifth surface contacting said second collar and an eighth contact surface of lower revolution from directly against said sixth upper contact surface of said support means, preferably said third collar having a maximum outer diameter and an inner diameter larger passage that the maximum outer diameter and the inner diameter respectively passage of said second collar.

p0056It is understood that:<ul><li>said second and third collars and fourth to eighth contact surfaces are the same axis corresponding to the axis of said upper pipe end, and</li><li>said means for load transfer and rotation in hinge joint allows free rotation of the axis of said first forging, first collar and said first, second and third contact surfaces in the boundary of the said cone having an angle at the top 2α relative to the axis ZZ 'perpendicular to said platform.</li></ul>

p0057The implementation of these different collars of increasing diameters is accompanied by implementing said first, second, third, fourth, fifth, seventh, eighth and sixth contact surfaces of said contact surfaces revolution of increasing area, thereby limit the dismantling necklaces required depending on the required flow diameter. Indeed, these removable components must withstand considerable loads of several thousand tonnes, which requires extremely massive and difficult elements to handle. Over the passage diameter is large relative to the outer diameter of the pipe, the more the bending forces within the said detachable collars are important, which requires considerable reinforcement. By doing this with multiple necklaces, whether to just go driving, the first collar has a diameter of slightly overpass that of the protrusion, which requires first necklaces of reasonable size that can remove and deliver each of assembly cycles an extra train. Whether to install an insulation protection around the pipe, in the assembly area, the passage diameter required will be more extensive and will then require disassembly and reassembly of the first and second collars each of cycles 'assembly. Finally, if one has to go bulky parts such automatic connectors or traction heads, we dismantle all clamps to ensure full bore. This necklace is extremely massive and heavy, and will be removed in exceptional occasions.

p0058Preferably, all of said contact surfaces comprise at least a portion of same frustoconical shape, that is to say in the same half-angle cone at the top, preferably 30 to 60 °, preferably about 45 °.

p0059Also advantageously, said first, second and, where appropriate third collars consist of several portions of the corner sections of the collar (s) round (s), said portions or angular sections of collars being locked together detachably or preferably only two adjacent portions being interlocked, the other parts being hinged together at each end so as to open after said collar removably unlocking.

p0060This embodiment facilitates the introduction and removal of said collars.

p0061The holding device and holding device according to the invention is particularly advantageous when said conduit is a coaxial pipe assembly of the PiP type and said first forging is a joining part to the end part of the coaxial pipe assembly to be assembled, said junction piece comprising the branches of the external and internal revolution defining two annular cavities, including outer and inner first branches are respectively welded to the ends of said outer and inner pipes of said portion of said assembly of two coaxial pipes, said first protrusion being formed on the external surface of a full-thickness area between the two annular cavities, and preferably said inner first branch being longer than said outer first branch.

p0062This latter feature facilitates the realization of welding of external welding seams at the ends of two inner and outer pipes.

p0063The present invention also provides a floating support including apparatus for connecting and laying successive portions of an undersea pipe from said floating support, preferably using a J-lay tower, wherein said platform on which said support means is located in the lower part of said tower perpendicular to the axis of said tower and said means for transferring loads and rotating joint allows said inclination in said cone axis corresponds to the axis of said turn.

p0064It is understood that:<ul><li>said second conduit portion is arranged above said first duct portion, and</li><li>the holding device and holding device according to the present invention is opened or released to allow the complete immersion of said undersea pipe after said joining of said first and second conduit portions, preferably by welding.</li></ul>

p0065The present invention also relates to a holding method and holding a pipe on a support according to the invention, characterized in that one performs the steps of:<ol><li>a) is welded to the upper end of said pipe one said forging comprising a said first protrusion, and </li><li>b) locks a first said collar bearing against said first contact surface of said first projection, and</li><li>c) is placed where appropriate, said third and second locked collars and bearing against a said support means secured to a said platform in the lower part of said lay tower J, and</li><li>d) a first down pipe portion having a said first forging with a said first protuberance at the upper end of said first duct portion, with said gripping arm to bear against said means support or, where appropriate, on said second or third collars, a first said collar being locked against said first protrusion, said gripper arm retaining said first collar, preferably on the underside of a said second protuberance.</li></ol>

p0066The present invention also relates to a method of joining two portions of pipe and installation at sea and connected to the pipe from a floating support including a J-lay tower according to the invention characterized in that it carries the following steps of:<ul><li>1- is placed where appropriate said third and second locked collars and bearing against a said support member secured to a said platform in the lower portion of said J-lay tower,</li><li>2- descending a first conduit portion having a said first forging with a said first protuberance at the upper end of said pipe of first party, using said gripping arm to bear against said support means or if any said third or second collar, said first collar being a locked against said first protrusion, said handling arms retaining said first collar preferably on the underside of a said second protrusion where appropriate, and</li><li>3- descending a second section of pipe having a said first forging with a said first protrusion at its upper end by means of said handling arm cooperating with said first latched collar around said first forging, to position the the lower end of said second conduit part preferably comprising a second junction piece forged or not said first protuberance, abutted with the upper end of said first forging at the upper end of said first conduit part and</li><li>4 is carried out preferably by welding connection of said first and second forgings, and</li><li>5- driving it falls somewhat connected with said gripping arms and unlocks and removes at least said first collar and</li><li>6 is lowered the line connected sea through the orifices of the first and second passage holes of said support means and said platform, respectively.</li></ul>

p0067Other aspects, features and advantages of the present invention will become clearer in light of the detailed description which follows, given by way of illustration and non-limiting with reference to the drawings in which:<ul><li>the <figref idrefs="f0001">1A</figref> represents a rowing laying vessel equipped with a J-lay tower;</li><li>the <figref idrefs="f0001">1B</figref> represents in side view a pipe down to the seabed and held in tension within said J-lay tower by the device according to the invention, not shown, and a ream held in the top portion of said tower J-lay, said string having approached said suspended pipe, to be assembled by welding;</li><li>the <figref idrefs="f0001">1C</figref> represents a side view of the two pipe portions being welded,</li><li>the <figref idrefs="f0002">2</figref> shows the detail of said first forging with its said first protuberance;</li><li>the <figref idrefs="f0002">3</figref> shows a side view of a variant of the holding device and holding device according to the invention comprising laminated abutments and first and second collars;</li><li>the <figref idrefs="f0002">3A</figref> shows a view from below of the device of <figref idrefs="f0002">3</figref> ;</li><li>the <figref idrefs="f0002">3B</figref> is the first open collar, unlocked;</li><li>the <figref idrefs="f0003">3C</figref> represents a side view of a second variant of the holding device and holding device according to the invention comprising laminated abutments and first, second and third clamps;</li><li>the <figref idrefs="f0003">Figure 3D</figref> shows in section and side view of the detail of said first forging with its said first protuberance cooperating with said first and second collars;</li><li>the <figref idrefs="f0004">4A-4B</figref> are side views of a variant of the device according to the invention having a mechanical spherical ball, said device being shown respectively in the axis and with an angle of inclination α;</li><li>the <figref idrefs="f0005">5</figref> is a side view of a variant of the device according to the invention comprising hydraulic cylinders coupled together.</li><li>the <figref idrefs="f0005">5A</figref> is a bottom view of the device of <figref idrefs="f0005">5</figref> ;</li><li>the <figref idrefs="f0006">6A-6E</figref> are side views of an assembly sequence of a new train to the pipe already laid and kept in the J-lay tower by means of the device according to the invention.</li></ul>

p0068The <figref idrefs="f0001">1A</figref> is a side view of a pipelaying vessel 20 equipped with a J-lay tower 23 variable inclination around its axis of rotation in the lower part of the tower 24. This vessel 20 enables the laying of a consists of assembled oar pipe sections and posed step by step, each train being itself consti killed several unit pipe elements welded together in general to earth, welding reams them are doing at the laying ship as will be explained below.

p0069The J-lay tower has in its lower part 24 at the welding station a retaining and holding device according to the invention, many variants are shown in <figref idrefs="f0002">figures 3</figref>, <figref idrefs="f0003">3C</figref>, <figref idrefs="f0004">4A</figref> and <figref idrefs="f0005">5</figref>.

p0070On the <figref idrefs="f0001">1A</figref> shows a driving underwater portion 10a providing the connection between the laying vessel and the seabed, the upper tip end is held firmly to the base of the lay tower J to using a retaining and holding device according to the invention.

p0071An additional train 10b to assemble at the upper end portion of the undersea pipe 10a suspended for subsequent raises, first of all based on the ship's deck. 10b train having 2 to 4 unitary pipe elements assembled by welding to each other and representing a length of 24 to 48m. A lifting beam 25 is able to support and raise said ream from its substantially horizontal position to the level of inclination of the tower in which it is transferred. At the top of the tower, the upper end 10b trainset equipped with said first connecting part as described below, is grasped by a gripping device 22 for moving the train in translation in the longitudinal axial direction ZZ ' the tower until another second or forged junction part 1₁ at the other end of the train 10b comes to be present in front of a said first junction piece forged one, the upper end immersed in the portion of pipe 10a being kept in suspension by a catenary shaped curve until its point of contact with the bottom of the sea.

p0072As shown in <figref idrefs="f0001">1B and 1C</figref>, Said second junction piece forged 1₁ at the lower end of the paddle 10b is welded to said first junction forging 1 to the upper end of the pipe portion 10a at the assembly plane XX and a welding station 24 in the lower part of laying tower in J. the tension of the upper end of the pipe is taken by means of a winch 26 connected to the gripper 22, the retaining and holding device according to the invention can be released to release the pipe which the upper end corresponding to the upper end of the cut 10b is then lowered in turn to the assembly plan for the assembly of a possible additional train, the retaining and holding device according to the invention is then reactivated to support the conduct and perform a subsequent cycle of connection.

p0073In the <figref idrefs="f0001">1B and 1C</figref>Depicts a train 10b and 10a of conduct constituted a PiP type of conduct of an internal pipe 10₂ and outer pipe 10₁ secured to said first junction part 1, said pipe 10a and second junction piece forged 1₁ at the lower end of the oar, the annular space between said inner and outer pipes being filled with an insulating material 10₃.

p0074Known manner and as described in <patcit id="pcit0008" dnum="FR2873427"><text>FR 2873427</text></patcit>, And as shown in the <figref idrefs="f0001">1B, 1C</figref> and <figref idrefs="f0002">2</figref>, Said first and second junction parts 1 and 1₁ are defined as follows:<ul><li>in a radial direction relative to a longitudinal axis ZZ 'of revolution of said workpiece, said parts are delimited by a cylindrical internal wall of substantially the same diameter as the main portion of said inner pipe 10₂And by a cylindrical outer wall of diameter substantially equal to the outer diameter of the main portion of said outer pipe 10₁and</li><li>in the longitudinal axial direction ZZ '<ul><li>the side of said junction piece assembled to the end of said outer and inner pipes of a said element of an assembly of at least two coaxial pipes, said outer and inner walls of said junction part form in longitudinal section of the first respective outer legs 11a and inner 12a substantially the same thickness as said outer and inner pipes 3 2 which they are intended to be assembled, said first 12a and 11a internal external branches defining a first annular cavity 13a, and</li><li>the opposite side of said junction forging assembled to another said junction part, itself assembled to the end of another assembly element of two coaxial pipes, said outer and inner walls form in longitudinal section of the second respectively external and internal branches 11b 12b, defining a second annular cavity 13b,</li><li>the bottoms of said first and second cavities 13a, 13b being spaced apart in said longitudinal direction ZZ ', so as to define a solid zone 13c of said junction forging in which said outer and inner walls form the outer and inner sides of the same wall cylindrical.</li></ul></li></ul>

p0075As shown in <figref idrefs="f0002">2</figref>, Said first forging 1 comprises at its full area 13c a first protrusion of the thickness (e) from 10 to 50mm, preferably from 15 to 25mm, corresponding to an increase of diameter of the surface of said forging relative the cylindrical intermediate portion by about 20 to 100mm, preferably from 30 to 50mm

p0076The <figref idrefs="f0002">3</figref> shows in section and side view of a holding device and holding device according to the invention a suspended pipe, the successful and holding device comprising a flexible means of ball joint type spherical laminated abutment, the aim is to release the rotation of the Z axis₁Z '₁ the upper end of the pipe with respect to the axis ZZ 'of the turn, thanks to the elasticity of the elastomer layers 6₁ said ball spherical laminated abutment.

p0077More specifically, in this first variant embodiment of a retaining and holding device according to the invention, a support member 5 or base shoe having a shape of revolution with a central orifice of a first passage 5a, substantially corresponds the diameter of the passage opening said second passage 22a of a platform 22 on which said support part 5 rests. Said platform 22 is disposed perpendicularly to the axis ZZ 'of the tower. These so-called first 5a and second passages 22a are intended to be traversed by the pipe 10 held in suspension by the holding device and holding device according to the invention. The support part 5 incorporates a hinge means flexible rotation 5₁ constituted by a laminated abutment 6 comprising a stack of elastomer layers 6₁ separated by rigid plates 6₂, Preferably steel, their shape is preferably spherical center O situated on the axis ZZ 'of the tower means when said flexible hinge is at rest. The laminated abutment 6 is surmounted by an upper portion 5₂ said supporting part, the upper outer surface comprises a said sixth surface 9a revolution contact of annular planar, or support surface on which a said fifth surface of revolution also contact 3b of flat annular form, under face of a second collar 3. the upper surface of the second collar 3 serves to support a first collar 2. the second clamp 3 is locked removably around the outer surface of a lower portion of said first collar 2, including a third contact surface 2c under said first collar 2 resting on said fourth revolution plane annular contact surface 3a of the upper outer surface of said second collar.

p0078The duct 10 comprises at its upper end a first junction forging 1 as described above, having on its outer surface a first protrusion 1a device that underside a first revolution of contact surface 1b of frustoconical shape corresponding to a inclination with respect to the Z axis₁Z '₁ the forging of a β angle of 30 to 60 ° preferably about 45 °, said tapered surface being flared upwards, that is to say with a virtual cone apex located below said frusto-conical surface. Said first collar 2 is locked removably around and against said first radial protuberance 1a of said first forging of revolution. More specifically, said first collar 2 comprising on its surface facing the central orifice a second surface 2b of the same frusto-conical shape revolution contact said first contact surface 1b on which it rests. Said second collar 2 comprises a second protrusion 2a forming a notch with the upper surface of the second collar 3 on which said first collar 2 cut in which the ends 21a of a gripper arm 21 can be accommodated under said first collar 2 so as to ensure retention of said upper pipe end when it is lowered along the axis ZZ 'until it bears on said second collier3.

p0079The laminated spherical stop 6 allows rotations by bending its upper portion 5₂ and therefore of the pipe 10 when the latter rests in support and in suspension through said first collar 2 and the second collar 3 on the upper part 5₂ said support part 5, these rotations corresponding to inclinations of the pipe at an angle of virtual cone with an apex 2α of less than 10 °, preferably less than 5 ° relative to the axis ZZ 'of the tower.

p0080On the <figref idrefs="f0002">Figures 3A and 3B</figref>, There is shown the different parts of 2₁, 2₂ and 2₃ said second collar 2 forming angular sections of circular collar, with a middle part 2₂ connected by a joint 25 to the end portions 2₁ and 2₃, Said end portions 2₁ and 2₃ being interconnected by locking means 2₄.

p0081These articulation means 2₅ and locking 2₄ enable laying the collar and lock on itself and its opening and removal if necessary, as explained below.

p0082The <figref idrefs="f0002">Figures 3A and 3B</figref> show the detail of an embodiment of a first collar 2, but the second clamp 3 and the other clamps described below are performed also according to the same principle in several parts hinged together angularly.

p0083Said first and second circular center hole collars can also be called "revolution flanges," given the fact that different collars are locked against each other.

p0084On the <figref idrefs="f0003">3C and 3D</figref>There is shown a second variant of the embodiment of a retainer and retaining device according to the invention with a support piece 5 comprising a laminated abutment. In this second embodiment, a third collar 4 is implemented. This third collar 4 is locked around a lower portion of said second intermediate ring 2. The second intermediate ring 2 comprises said fourth revolution contact surfaces 3a on which said third contact surface 2c under said first collar comes bearing, and said collar has partly below a so-called fifth revolution of contact surface 3b, which no longer cooperates this time directly with said sixth contact surface of revolution 9a in the upper part of the support part 5, but cooperates with a seventh upper surface of revolution contact 4a on which comes to bear said fifth surface 3b contact- said second collar. Said third collar comprises an eighth revolution underside contact surface 4b resting directly against said sixth contact surface 9a in the upper part of the support part 5.

p0085On the <figref idrefs="f0003">3C</figref>, Said fifth contact surface 3b on the underside of the second collar 2, seventh contact surface 4a in the upper part of the third collar 3, eighth contact surface 4b on the underside of the third collar 3 and sixth contact surface 9a in the upper part of the rigid support member 5 each comprise a middle portion of frustoconical shape of non-identical inclination. Said fifth contact surface 3b on the underside of the second collar and seventh contact surface 4a of the third collar 4 have flat annular portions driving side and vertical cylindrical external parties outside opposite side. Conversely said fifth surface of revolution 3b on the underside of the second collar 3 and sixth upper contact portion 9a in surface of the rigid part 5 have a vertical cylindrical part 9₁ the side of the inner pipe and a planar annular part 9₂ outside the opposite side.

p0086Said first collar 2 has an internal diameter slightly greater than the outer diameter of the main portion of said first forging 1 on the underside of said first protrusion 1a. Said third collar 4 under said second collar 3 has an internal diameter greater than the inner diameter of said second collar 3 itself larger than the inner diameter of the first collar 2. Conversely, the outer diameter of said second collar 2 is smaller than the outer diameter said third collar. This stack of said first, second and third collars present the interest of not having to disassemble-reassemble each train that collars for the required passage diameter. For the passage of very large parts, such as connectors or automatic pipeline terminations, the last necklace, piece of very high bending resistance capacity, very compact and very massive will be dismantled-rise occasionally, then the first collar, less cumbersome and less mass may be dismantled, reassembled without difficulty each installation cycle of a new train.

p0087On the <figref idrefs="f0004">Figures 4A and 4B</figref>There is shown a third embodiment of a retaining and holding device according to the present invention of the mechanical ball-joint type.

p0088This third variant differs from previous versions, by the structure of the support part 5 which is formed:<ul><li>a lower part or base part 8₁ resting on said platform and having a spherical concave upper surface 8₁was coated with a layer of antifriction polymer, preferably of Teflon, and </li><li>an upper part 8₂ constituting the upper part of the support part 5, having a lower surface 8₂b complementary convex spherical shape of the spherical concave shape of the upper surface 8₁in the lower part 8₁, Both concave and convex spherical surfaces having the same center O and being able to cooperate in rotation with sliding of said upper part 8₂ on said lower part 8₁. During rotation, the inclinations of the axis of the pipe of revolution 10 and the convex spherical surface of revolution lower 8₂ are substantially identical, an angle α relative to the axis of revolution of the spherical concave lower surface 8₁ or axis of revolution of said second passage 22a orifice, or longitudinal axis of the pipe 10 when the latter is at rest in abutment on said platform 22.</li></ul>

p0089Here, the term spherical surface centered in O a surface part of a spherical shell of the same sphere with center O located above said surfaces. It will be understood that said concave and convex spherical surfaces are concave side facing upwards and respectively convexity facing downwards.

p0090The articulation in rotation laminated abutment or mechanical ball as described above with a restraint device and holding device according to the invention allows to transfer to the supporting structure that is the platform 22 to the base of the tower of J-lay 23 all the forces resulting from an angular spacing of driving an angle α as shown in <figref idrefs="f0004">4B</figref>, And without creating bending stress in the XY plane perpendicular to the axis ZZ 'of the tower, at said first revolution frustoconical contact surface which thus constitutes an isostatic support in case of angular variation of the driving .

p0091On the <figref idrefs="f0005">5 and 5A</figref>There is shown a fourth alternative embodiment of a retaining and holding device according to the invention, which differs from the previous in that the 5 support means comprises hinge means rotatably 5₁ of hydraulic type.

p0092More particularly, the support means 5 is constituted by a plurality of hydraulic actuators, in this case as shown in the <figref idrefs="f0005">5A</figref>, <figref idrefs="f0004">4</figref> hydraulic cylinders 7 distributed at 90 ° about said second orifice passage 22a of the platform 22 through which the pipe 10. More specifically, cylinder 7 of the body₁ based on said platform 22 about said second through hole 22a and the rod or piston 7₂ said cylinders are arranged substantially parallel to the axis ZZ 'of the lap restraint and maintenance according to the invention, said pipe break whose ends support said eighth revolution of lower contact surfaces 4b under said third collar 4. In this case, the upper ends of said small ball articulation 7₃ constitute said sixth contact surface 9₁ in the upper part 5 of the support means.

p0093Said cylinders are preferably identical piston section and are then arranged at a constant distance from the axis ZZ ', so that the moment of force exerted by each of the cylinders relative to the axis ZZ' is constant . Similarly, one may remove one of the jacks of the ZZ 'axis, but its piston section should be reduced proportionately to maintain the same moment of the force exerted with respect to the axis ZZ': It then be necessary to increase proportionately the stroke of said cylinder, so the stem length, for it to allow the rotations of the assembly in said cone angle α.

p0094The different cylinder body 7₁ are interconnected 7₄ so that the oil exchange can take place as soon as a load imbalance appears on one of them. Thus, upon the occurrence of an inclination of the pipe at an angle α as described with reference to<figref idrefs="f0004">4B</figref>, The right cylinder sinks and drives the oil to the other actuators, so that the load remains uniformly distributed over the periphery of said supporting surface 1b first contact surface on the underside of the first protrusion, which may be the angular variations of the angle α. Thus, the actuators are not connected to any hydraulic power but all communicate between them via lines 7₄ thus ensuring the free transfer of the oil and to ensure the retaining and holding device according to the invention an isostatic support function.

p0095Initial filling of the hydraulic fluid in cylinder body is such that when the Z axis₁Z '₁ of the pipe coincides with the axis ZZ ', all the rods of the jacks are halfway. Shaft lengths of each of the cylinders is such that for maximum positive variation of the angle α (right), the right cylinder is in the lower stop and the left cylinder is at its upper limit. Similarly, for a maximum negative variation of the angle α (left), the right cylinder is in the upper stop and the left cylinder is in the low stop. Is advantageously limits the length of cylinder rods so as to limit rotation of the pipe in an angular cone with an apex 2α of less than 10 °, preferably less than 5 °.

p0096In the various embodiments of the rotating hinge means 5₁, It still has a self centering effect of the pipe.

p0097On the <figref idrefs="f0006">6A-6E</figref>Is shown in section and in side view the various stages of implementation of a retaining and holding device according to the invention. On the<figref idrefs="f0006">6A</figref>A first pipe portion 10a is descended to the gripper arm 21 from the top of the J-lay tower 23. To do this, said first forging 1 to the upper end of the first pipe portion 10a cooperates with said first collar 2 at said first protrusion 1a, so that the ends 21a of said gripping arms 21 can come crochet and retaining said second protrusion 2a of said second collar 2, and so the down pipe portion 10a. It is understood that said first collar 2 is locked on itself so that said first contact surface 1b on the underside of said first protrusion abuts against said first collar at a said second 2b upper contact surface said first collar. Said portion of conduit 10a can be lowered until it until said third surface 2c revolution contact under said first collar bears on said fourth surface contact upper revolution 3a of said second collar 3. Previously , said second intermediate ring or collar has been locked on itself and down into abutment on the upper inner surface of the third collar 4, itself resting on the upper part of a revolution of 5 support piece resting on the platform 22 as described above. Once the first pipe portion 10a rests on the support member 5 by means of said first, second and third clamps, as shown in<figref idrefs="f0006">6B</figref>, Gripping arms are released and a new ream or second pipe portion 10b provided at its upper end of a said first junction part forged 1 and at its lower end a connecting part without protrusion 1₁ is lowered again with the arm 21, and then close the upper end of said first portion 10a suspended at the holding device and holding device according to the invention as shown in <figref idrefs="f0006">6C</figref>.

p0098A welding machine 24 is then installed as shown in <figref idrefs="f0006">6D</figref> and welding is performed. All parties to conduct meetings is then raised a few tens of centimeters, which extracts the second collar 3 or intermediate ring and the upper collar and said first collar 1, freeing the passage down the pipe to the background over a distance corresponding to the length of the train for a new assembly cycle of the next train.

p0099The passage diameter of said second collar 3 is greater than the maximum outer diameter of the pipe, which leads down the line without any interference. In case of connector passage, anode or clamp to be installed on the periphery of the pipe, preferably removing said second collar 3 so as to leave a higher throughput.

p0100For example, a line of pipe-in-pipe kind posed by water depth of 2200m the following features. The outer pipe has a diameter of 403mm and a thickness of 23.8 mm, the inner pipe has a diameter of 254mm and a thickness of 27mm, the annular space of the driving pipe-in-pipe is 22 mm, which gives the forging a gap between its outer diameter and its inner diameter, that is to say a 72.8mm thickness in its main portion, at which value is added the thickness of the protrusion of 20mm. The resulting voltage of the catenary formed by laying course in the suspended pipe is 1200t approximately, which corresponds to a Von constraint resulting Updates in the conical plane 1b of 280MPa, which for a 450 MPa strength steel corresponds a working rate of 62% of the elastic limit. This high rate is acceptable from the point of view of safety thanks to the ball 5 which ensures a perfectly uniform distribution of the stresses on the entire periphery of the protrusion. This is also due to the fact that the faces in contact forgings and various clamps are machined to ensure proper load transfer and uniform levels of stress: we will exclude any gross surface area of ​​forge, or mediocre machining quality in terms of geometry or surface texture.