FR2624089A1 - FLEXIBLE JOINT FOR ANTENNA LINE OF PETROLEUM PLATFORM OF THE TYPE DIT A LINES TENDUES - Google Patents

Abstract

The present invention relates to a flexible articulation for a mooring line of a floating oil platform comprising a first laminated annular structure 20 with spherical symmetry. The flexible joint is characterized in that it further comprises a second laminated annular structure 30, also with spherical symmetry, with respect to a point which coincides with the center C of curvature of the first laminated structure 20, and which constitutes the center of curvature C of the flexible joint 40 as a whole, which second laminated annular structure 30 is secured to the end 10 of the taut line 1 and to the bottom 6 of the joint housing 2 and is composed, like the first structure laminated 20, of a plurality of elastomeric layers 22 alternating with curved metal layers 23 adhered to the elastomeric layers. Application to floating oil drilling platforms.

Description

i

  The present invention relates to an article

  flexible culation for anchoring line of a platform

  oil type said stretched lines.

  Such a platform is a floating-type operating or drilling platform that is moored to the seabed by means of tubular anchor lines (or rods) whose ends are hinged into hinge housings attached to connectors

  arranged at the bottom of the sea and in the columns of the platform.

  The set of lines is constantly subjected to tensile forces (hence the expression of platform with taut lines corresponding to the English expression "Tension Leg Platform", TLP) because of the floating character

of the oil rig.

  The articulation of the ends of each of the anchor lines enables them to follow the horizontal displacements of this one under the action of the waves and the

  winds, behaving like a deformable parallelogram.

  The essential element of each articulation is

  killed by an annular laminated elastomeric structure with spherical symmetry in which elastomeric layers alternate with

  curved metal layers, which justifies the name of ar-

  "flexible" articulation given to this type of articulation.

  The main functions of an elastic structure

  laminated tomatoes of the aforesaid type, in the context of

  Flexible culation, are: - transmission of tensile forces exerted by the anchor line, - authorization of angular (or conical) deflections of the anchor line caused by horizontal displacements of the floating platform on the surface of the sea, by limiting the moments of embedding,

  - transmission of side effects, at the level of

superior.

  Of course, the design of the laminated structure is conditioned by many parameters, such as solicitations, available space, environment, etc ...; but, in any case, the loads and deflections to which a laminated structure is subjected in each connector must be such that this structure

  works only in compression and shear.

  However, during the mechanical disconnection of the mooring lines, the laminated structure mentioned above is subjected to an undesired tensile force, which should be

to avoid not destroying it.

  The flexible hinge used for an anchor line in the prior art comprises a single laminated structure, with spherical symmetry, such as that represented by

  reference F in Figure 2 appended to the description of the pre-

  This laminated structure consists of elastomer layers alternating with curved metal layers, having the same center of curvature, and is integral with

  cover of a hinge box B attached to a connector

  E in the sea bed or at a higher connector

  located at the upper end of the anchor line.

  However, in this known type of flexible joints the tensile forces are manifested not only in

  when the system is disconnected, but also when

  normal and are limited (as can be seen in Figure 2 above) only by a metal ball R which is an axial abutment centered in the center of curvature of the flexible joint. This design is therefore far from satisfactory and further reduces the life of the joint because of the wear due to friction between the end of the anchor line and the ball joint. The object of the present invention is therefore to provide a flexible articulation for a mooring line of a floating oil platform, of the so-called extended line type, which better meets the requirements of the practice.

  flexible joints aiming at the same goal

  In particular, since the elastic joint is not subjected to any tension and limits the fatigue of the laminated structures, because its design makes it possible to control the transverse forces, the service life is substantially increased thanks to the elimination of any friction by metal-to-metal contact in the flexible joint, this joint presents a geometric center which coincides

  with the center of application of the efforts.

  The present invention relates to an articula-

  flexible method for mooring line of a floating oil platform, said platform with taut lines, comprising at each end of the line: a hinge housing of the corresponding end which is secured to a connector of fastened and bounded by: 20. a cover with a central opening

  the passage of the tense line and the

  gules thereof corresponding to the movements of the floating platform, a side wall, and 25. a bottom, this side wall and the bottom defining the enclosure of the box,

  said flexible hinge, located in said housing, allows

  rotating the corresponding end of the stretched line and comprising: a first spherically symmetrical laminated annular structure, with respect to a center of curvature located within the hinge housing, and disposed around the stretched line, which first laminated structure is secured to the end of the tensioned line and the cover of the casing and is composed of a plurality of elastomeric layers alternating with curved metal layers adhered to the elastomeric layers and having the aforementioned center of curvature, which flexible articulation is characterized in that it further comprises: a second laminated annular structure also with spherical symmetry, with respect to a point which coincides with the center of curvature of said first laminated structure and which therefore constitutes the center of curvature of the joint flexible as a whole,

  which second laminated annular structure is solid

  laughed at the end of the taut line and at the bottom of the bo

  of articulation and is composed, like the first structure

  laminate, a plurality of alternate elastomeric layers to bonded curved metal layers

to the elastomeric layers.

  According to a preferred embodiment of the articu-

  According to the invention, said second laminated annular structure is arranged, with respect to the center of curvature of the joint,

  on the same side where the first annular structure

laminated area.

  According to an advantageous arrangement of this embodiment, the bottom of the hinge box has a central tubular projection (axial) extending to

  the inside of the box in the direction of the lid of this

  ci, up to exceed the aforementioned center of curvature, and the end of the tensioned line has a recess (a concavity) in which is housed without contact a portion of said tubular projection, said second laminated annular structure being adhered between two annular metal parts whose first piece is fixed to said tubular projection, while the second piece is

  annular piece is attached to the end of the stretched line.

  According to a preferred embodiment of this arrangement, said first annular support piece of said second laminated annular structure is threaded around said tubular projection of the bottom of the casing and bears against a shoulder of the outer wall of this tubular projection, said shoulder being formed substantially at the center of curvature of the flexible joint. According to another advantageous embodiment of the flexible articulation according to the invention, said second laminated annular structure

  is arranged, with respect to the center of curvature of the

  on the opposite side to that where

  first laminated annular structure.

  According to an advantageous arrangement of this embodiment, the end of the tensioned line has a central (axial) tubular projection extending into

  direction of the bottom of the hinge box, until

  said center of curvature, and the bottom of the housing has a central opening in which is housed a portion of said tubular projection, said second laminated annular structure being adhered between two annular metal parts whose first piece is fixed to said tubular projection, while the second

  annular piece is attached to the bottom of the housing.

  According to a preferred embodiment of this arrangement, said first annular support piece of said second laminated annular structure is threaded around said tubular projection of the end of the stretched line and bears against a shoulder of the outer wall of this tubular projection. , said shoulder being arranged substantially at the center of curvature of

the flexible articulation.

  According to another preferred embodiment of the

  According to the invention, the height of the lateral wall of the hinge box is chosen according to a predetermined degree of prestress which is desired to be induced in said first

  and second laminated annular structures of the

flexible culation.

  According to another advantageous embodiment of the hinge according to the invention, said first laminated structure is secured to the cover of the hinge box by means of a part intended to

  to be recessed in the lid.

  According to yet another embodiment of the

  according to the invention, the elastomer layers

  each of said first and second annular structures

  laminates have different thicknesses.

  In addition to the foregoing, the invention

  other provisions, which emerged from the

  will be described in the following description.

  The invention will be better understood by means of

  additional description which will follow, which refers

  to the accompanying drawings in which: - Figure 1 is a schematic view of a floating oil platform, the so-called extended line type (TLP), namely a platform which is moored at the bottom of the sea by anchor lines articulated to

  their lower and upper extremities through

  connectors 2 attached to the bottom of the sea and the columns of the platform, respectively; - Figure 2, as already mentioned above, illustrates a flexible articulation of the prior art fixed to a connector E formed in the bottom of the sea and represented diagrammatically with cutaways, which articulation

  flexible is arranged inside an article cabinet.

  B and comprises an elastomeric annular structure

  laminated mother with spherical symmetry, F, and a ball joint R cooperating with the widened end of the anchor line

1;

  FIGS. 3 and 4 show a first embodiment of

  lisation. of the articulation of the invention, and differ essentially as regards the method of attachment to the cover of the hinge housing of one of the two laminated structures of which the flexible hinge is composed; Figures 5 and 6 show a second embodiment of the flexible joint

  according to the invention, and differ for the same

  mentioned in relation to Figures 3 and 4.

  It should be understood, however, that these drawings and the corresponding descriptive parts are given solely by way of illustration of the subject of the invention, of which they do not in any way constitute

a limitation.

  FIGS. 3 to 6 show one of the ends of one of the stretched lines 1 for docking a floating platform (not shown: see however FIG. 2)

  at the bottom of the sea, which is surrounded by

culation 2 of the end 10.

  The housing, which is attached to a connector (not shown

  However, see Figure 2), is delimited by:

  - a lid 3 provided with a central opening 4 allows

  both the passage of line 1 and the movements

  lairs thereof corresponding to the movements of the floating platform under the action of waves and winds, - a side wall 5, and - a bottom 6, the bottom and the side wall defining the enclosure 15 of the casing.

  Inside the housing 2 is housed an articu-

  flexible 40 or 50 (see Figures 3, 4 and 5, 6 respectively) for rotation of the end 10 and comprising: - a first annular structure lamifide 20 & spherical symmetry with respect to a center C, arranged around the

  line 1, which is adhered to the end 10 and the neck.

  vercle 3 of the casing 2 and which consists of a plurality of elastomeric layers 8 alternating with curved layers 9, preferably metal, adhered to the layers 8, the center of curvature of the laminated structure 20 as a whole and curved layers 9 in particular being defined by the point C, - a second spherical symmetrical laminated annular structure which is secured to the end 10 and to the bottom 6 of the hinge casing 2 and which consists, as the first laminated structure 20, of a plurality of elastomeric layers alternating with curved metal layers adhered to the elastomer layers, the center of curvature of the second laminated structure and its curved layers coinciding with the center of curvature C

  of the first laminated structure 20.

  FIGS. 3 and 4 differ from FIGS. 5 and 6 essentially in that in FIGS. 3 and 4 the second laminated structure 30 is, with respect to the center of curvature C, on the same side as the first laminated structure 20 , while in Figures 5 and 6 the second laminated structure 30a is

find on the opposite side.

  For this purpose, in Figures 3 and 4 the structure

  The laminated structure 30 is carried by a central (axial) and reentrant tubular projection 14 of the base 6 of the casing 2, whereas in FIGS. 5 and 6 the laminated structure a is carried by a central (axial) tubular projection.

  and protruding 24 from the end 10.

  Referring now more particularly to FIGS. 3 and 4, it should be noted that the second laminated structure 30, composed of layers

  elastomers 12 adhered to metal-curved layers

  lique $ 13, is adhered between two annular pieces 16

and 17.

  The piece 16 is threaded around the tubular projection 14 of the bottom 6 of the casing 2 and bears on

  a shoulder 18 of the outer wall of this protrusion tu-

  14.1a fixing the annular piece 16 at the bottom

  of the housing being obtained by bolts 19.

  The annular piece 17 is attached to the end 10

from line 1 by bolts 21.

  To allow the cooperation between the end and the tubular projection 14 a recess 25 (concavity)

  is formed in this end.

  With regard to FIGS. 5 and 6, it may be noted that the second laminated structure 30a, composed of elastomeric layers 22 adhered to metal curved layers 23, is adhered between two annular pieces.

26 and 27.

  The piece 26 is threaded around a tubular projection 24 of the end 10 of the line 1 and bears against a shoulder 28 of the outer wall of this tubular projection 24, the fixing of the annular piece 26

  at the end 10 being obtained by bolts 29.

  The annular piece 27 is fixed to the bottom 6 by

bolts 31.

  To allow the housing of the tubular projection

  24 of the end 10, as well as the second structure

  30, the base 6 of the hinge housing 2 is provided with a central opening 32 which is closed by all the elements 26, 30a and 27, in cooperation with

the end 10 of line 1.

  Whatever the positioning of the second laminated structure, 30 or 30a, with respect to the center of curvature C of the flexible articulation, 40 or 50, the first laminated structure 20 may be adhered to the cover 3 directly (see FIGS. and 5) or via a part 33 intended to be embedded in the cover 3 (see Figures 4 and 6), which facilitates the molding .. In general, the different

  The solutions shown in FIGS. 3-6 have inci-

  dence on the molding of parts and the assembly thereof. With regard to the preparation of the two laminated structures 20 and 30 (or 30a) prior to the assembly of the various parts of the joint according to the invention, it should be noted that the laminated structure 20 is molded directly and simultaneously on the end 10 of the tensioned line 1 and under the cover 3 of the housing 2, in the embodiments illustrated in FIGS. 3 and, or on parts 34 intended to be embedded in the housing cover, with regard to the modes of

  embodiment illustrated in Figures 4 and 6.

  The laminated structure 30 (or 30a) is molded

  between the two annular support and

16, 17 (or 26, 27).

  The various parts are assembled in the following order: embedding the lid 3 of the hinge box on the part 34, where this exists, - fixing the second laminated structure 30 or 30a

  at the end 10 of the stretched line 1 through the

  of the annular fitting piece 17 or 26,

  respectively, and - fixing the housing 15 of the hinge housing to the lid 3 thereof (by means of bolts 11) and to the annular fitting piece 16 or 27, respectively; during this operation, the two laminated annular structures 20 and 30 or 30a are subjected to a preload whose degree is adjusted according to the height of the side wall 5 of the casing 2 with respect to the axial encumbrance of the joint In practice, it imposes on the assembly a preload greater than the maximum tension induced in the first and / or in the second laminated structure 20 and 30 or 30a, the flexible joint and corresponding to the transmission of a force contrary to the normal direction of operation of the anchor line

  due to exceptional conditions (dismantling, handling,

  tion, etc.), but sufficient to damage one or the other of the laminated structures. In this way, the possible setting in traction of the whole, in particular

  during the mechanical disconnection of the anchor line ,.

  leaves the elastomer of the laminated structures in compres-

if we.

  It is easy to verify that the hinge according to the present invention meets the aims of the present invention and indicated above, in particular in this respect.

  concerning the control of lateral forces (or trans-

  versaux), the elimination of any metal / metal contact and any tension in the laminated structures of which it is composed. That being so, it is clear that the existence of transversal stresses causes the application of a torque - with respect to the center of curvature C - at each

  layer of the first laminated structure 20, which gives

  would be a lateral tilting of this structure

  stratified, and thus to instability of the system, if

  was not the second laminated structure, 30 or 30a, which provides the necessary stability by resuming (ie, transmitting) the transverse forces resulting from the

  combination of axial forces and angular deflections

  Therefore, it behaves like a laminar structure

"security".

  It should also be emphasized that the rigidities of the flexible joint as a whole are the sum

  rigidities of each component and that the stiffness

  of the second laminated structure, 30 or 30a, is of the same order of magnitude as the axial stiffness of the

first laminated structure 20.

  The contribution to the transmission of forces on behalf of the two laminated structures of the flexible joint according to the invention depends on the stiffness of each

  laminated structure. In the context of this invention

  it is recommended that: - for the ratio between the axial rigidities Ka1 and Ka2 of the first and second laminated structures, respectively, the following values: Ka1

\ K 1 00

  Ka2 with Ka1. 4.106kN / m, and - for the rotational rigidity Kr (ie, torsion and conical) values of the same order of magnitude per unit rotation angle, namely:

Kr. 150kNm / deg.

  As is apparent from the foregoing, the invention

  tion is not limited to those of its modes of

  tion and application that have just been described more explicitly; it embraces, on the contrary, all the variants that may come to the mind of the technician in the field, without departing from the scope or scope of the present invention. In particular, it must be understood that, for practical reasons,

  both ends of an anchor line, each equipped with

  one of the corresponding flexible joint, are not made in one piece with the anchor line, but that the structures shown in Figures 3 to 6 are related to the anchor lines themselves, to which they are fixed by any means appropriate,

preferably removable.

Claims (10)

  1.- Flexible hinge for a floating oil platform mooring line, said platform extended lines (TLP), comprising at each end (10) of the line (1): - a hinge housing (2) of the corresponding end   dante (10), which is secured to a single connector (E) of fixa-   and which is delimited by: a cover (31) provided with a central opening (4) allowing the passage of the stretched line (1) and the angular displacements thereof corresponding to the displacements of the floating platform a side wall (5), and at a bottom (6), this side wall (5) and this bottom (6) defining the enclosure (15) of the casing (2), said flexible joint (40, 50), housed in said   casement (2), allowing rotation of the corrugated end   corresponding to the stretched line (1) and comprising:   a first laminated annular structure (20) symmetrically   spherical section, with respect to a center of curvature (C)   killed inside the articulating box (2), and   placed around the stretched line (1), which first laminated structure (20) is secured to the end   (10) of the stretched line (1) and n (3) of the bo -   tier (2) and consists of a plurality of elastomeric layers (8) alternating with curved metal layers (9) adhered to the elastomer layers and having the aforementioned center of curvature, which flexible hinge is characterized in that it comprises in addition: a second laminated annular structure (30, 30a) also with spherical symmetry, with respect to a point which coincides with the center (C) of curvature of said first laminated structure (20), and which therefore constitutes the center of curvature ( C) of the flexible joint (40,50) as a whole, which second laminated annular structure (30, 30a) is secured to the end (10) of the stretched line (1) and the bottom (6) of the casing articulation member (2) and comprises, as the first laminated structure (20), a plurality of elastomeric layers (22) alternating with curved metal layers (23) adhered to the elastomeric layers.   2. Articulation according to claim 1, characterized in that said second structure has a minimum dimension (30).   arranged, relative to the curvature center (C) of the articu-   tion (40), on the same side where the first structure laminated annulus (20).   3. Articulation according to claim 2,   characterized in that the bottom (6) of the articula-   (2) has a central tubular projection (axial,   14) extending inside the casing (2) in direction   the cover (3) thereof, to exceed the aforesaid center of curvature (C), the end (10) of the stretched line (1> havinga recess (a concavity, 25) in which is housed non-contacting a portion of said tubular projection (14), and in that said second laminated annular structure (30) is adhered between two metal annular pieces (16, 17) whose first piece (16) is fixed to said tubular projection ( 14), while the second annular piece (17) is attached to the end (10) of the stretched line (1).   4. Articulation according to claim 3, characterized in that said first annular piece (16) for supporting said second laminated annular structure (30) is threaded around said tubular projection (14).   of the bottom (6) of the casing (2) and bears on a shoulder   (18) of the outer wall of this tubular projection (14), said shoulder (18) being formed substantially at the center of curvature (C) of the flexible joint (40). 5. Articulation according to claim 1,   characterized by said second annulled structure   The laminated web (30a) is arranged in relation to the center of contact (C) of this joint (50) on the side opposite to that where it is located.   said first laminated annular structure (20).   6. Articulation according to claim 5, characterized in that the end (10) of the tensioned line (1) has a central tubular projection (axial, 24).   extending towards the bottom (6) of the housing of   ticulation (2), to exceed the aforementioned center of curvature (C), the bottom (6) of the casing (2) .presentantune central opening (32) in which is housed a portion of said tubular projection (24), and in that   said second laminated annular structure (30a) is adhered   between two metal annular pieces (26, 27) whose first piece (26) is fixed to said tubular projection (24), while the second piece (27)   is fixed to the bottom (6) of the housing (2).   7. A joint according to claim 6, characterized in that said first annular piece (26) for supporting said second laminated annular structure (30a) is threaded around said tubular projection (24) of the end (10) of the line stretched (l) and abuts against a shoulder (28) of the outer wall of this tubular projection (24), said shoulder (28) being provided   substantially at the center of curvature (C) of the flexible articulation (50).   8. Articulation according to any one of the   1 to 7, characterized by the fact that the height of the   lateral wall (5) of the hinge box (2) is chosen   based on a degree of prestressing prefixed that is desired to induce in said first and second   laminated annular structures (20; 30, 30a) of the article flexible curing (40, 50).   9. Articulation according to any one of   Claims 1 to 8, characterized in that the layers   elastomers (8, 22) of each of said first and second laminated annular structures (20; 30, 30a) have different thicknesses. 10. Articulation according to any one of   Claims 1 to 9, characterized in that   first laminated structure (20) is secured to the neck.   (3) of the hinge housing (2) via   of a piece (33) intended to be embedded in the cover (3).