Stress-reducing clamping pad for a friction-based tube retention device

Abstract

Clamping pad for a friction-based tube retention device used in the subsea hydrocarbon production industry. The invention relates to a clamping pad (4) for a friction-based tube retention device (6) comprising a steel casing (8) in which a cavity (10) is formed, having a bottom (12) and two lateral edges (14). The cavity is filled with a flexible polymer material (16) in which are housed a plurality of gripping bars (18, 18a), each having a portion embedded in the flexible material and a portion protruding from it.The embedded portion of the lateral gripping bars (18a) closest to the two lateral edges of the cavity each has a different geometric shape from the other gripping bars (18) and each has a truncated, cylindrical lateral face (22a) so as to create a channel (C) of flexible material with a substantially constant width between the embedded portion of the lateral gripping bar and the lateral edge of the cavity. Figure for the abbreviation: Fig. 3.

Description

Title of the invention: Clamping pad with reduced stress concentrations for a friction-based tube retention device. Technical field

[0001] The invention relates to the general field of holding by friction a tube used in the subsea hydrocarbon production industry, in particular oil and gas.

[0002] One application of the invention relates to the securing of a pipeline for the underwater transport of fluids in a laying tower. However, the invention can also be applied to the laying of other tubes used in this industry, such as flexible hoses or umbilicals, or even submarine cables used in the fields of telecommunications and power transmission. Previous technique

[0003] Various methods are known in the subsea oil and gas industry for installing rigid and flexible pipelines at sea, such as S-laying, J-laying and coil-laying.

[0004] In each of these installation methods, the pipeline is suspended as a catenary between the laying vessel and the seabed, under the tension of its own weight. The weight of the catenary suspended between the laying vessel and the seabed is supported by a holding device in the laying tower on board the vessel, which applies a restraining force to the pipeline. When laying large-diameter pipelines in deep water, the holding device must therefore be sized to support a weight of several hundred tons.

[0005] One known solution consists of holding the pipeline by means of a plurality of clamps arranged one above the other in the pipeline laying tower, each clamp supporting a portion of the load acting on the pipeline. In these holding devices, each clamp is more precisely composed of several clamping pads uniformly distributed around the axis of the pipeline and actuated by cylinders to produce a radial load on the pipeline to be held.

[0006] There are various clamping pad architectures forming these grippers. Reference may be made, for example, to publications WO 2010 / 061280, US 3,778,094 and GB 1,506,407, which describe clamping pads comprising a rigid housing containing a deformable element and whose outer wall is concave with a radius of curvature substantially equal to the average radius of the tube to be held. The deformable element consists of a plurality of gripping bars extending along the longitudinal axis of the tube to be held. This deformable element thus presents a composite structure that allows it to adapt to variations in the cross-section of the tube to be held.

[0007] Although effective, it is necessary to reinforce the robustness of these clamping pads. In particular, the stress levels around the gripping bars closest to the lateral edges of the rigid housing are such that fatigue cracks may be observed in service. Description of the invention

[0008] The invention therefore aims to provide a clamping pad for a friction-based tube retention device which does not present the aforementioned disadvantages.

[0009] This objective is achieved by means of a clamping pad for a friction-based tube retention device used in the subsea hydrocarbon production industry, comprising a steel casing in which a cavity is formed having a bottom and two opposing lateral edges intended to extend along a longitudinal axis of the tube, the cavity being filled with a flexible polymer material in which are housed a plurality of gripping bars extending along the longitudinal axis of the tube and distributed between the two lateral edges of the cavity, and in which, according to the invention: - Each gripping bar has a portion embedded in the flexible material, and an exposed portion that is substantially flat to come into contact with an external surface of the tube, and - the embedded part of the lateral gripping bars which are closest to the two lateral edges of the cavity each have a different geometric shape from the other gripping bars and each have a lateral face opposite a lateral edge of the cavity which is truncated and cylindrical in shape so as to provide between the embedded part of the gripping bar and the lateral edge of the cavity a channel of flexible material having a substantially constant width.

[0010] The clamping pad according to the invention is notable in particular because the embedded portion of the gripping bars is rounded, which helps to mitigate the high stress concentrations in the flexible material at the interface with the casing. Furthermore, the lateral face of the two lateral gripping bars has a specific cylindrical shape with a given radius, calculated according to special rules, which further reduces the shear rate in the flexible material.

[0011] Indeed, since the lateral gripping bars have the greatest displacement relative to the neutral position (to reach the smallest and largest diameters in the range of tubes to be held), the provision of a flexible material channel of width constant between the edge of these bars and the tube helps to attenuate the shear rate in the lateral part of the bed of soft material.

[0012] This particular design of the lateral gripping bars relieves deformation of the soft material bed with the lateral gripping bars around the tube, which allows for better distribution of the radial load between the gripping bars and, consequently, increases the axial load capacity of the clamping pad. These modifications thus increase the robustness of the clamping pad.

[0013] Preferably, the embedded part of the gripping bars is rounded in order to reduce the shear rate of the flexible material.

[0014] Preferably, the gripping bars located between the two lateral gripping bars also have at least one anchoring notch in the flexible material on each of their two lateral faces. These anchoring notches improve the anchoring of the gripping bars in the flexible material.

[0015] Preferably also, the lateral gripping bars have at least one anchoring notch in the flexible material on their lateral face opposite the truncated lateral face.

[0016] These anchoring notches advantageously have a rounded profile.

[0017] Preferably, the two lateral edges of the cavity each have a partial cylinder shape which is concentric with the cylinder of the truncated lateral face of the embedded part of the lateral gripping bars.

[0018] The flexible material is advantageously glued to the internal faces of the cavity in order to ensure the retention of the lateral gripping bars.

[0019] The skid may further include a cylinder having a rod intended to be arranged in a radial direction to the tube and at the end of which the casing is mounted.

[0020] The invention also relates to a device for holding a tube by friction, comprising two clamping pads as defined above which are arranged opposite each other with respect to the axis of the tube.

[0021] The invention further relates to a device for holding a tube by friction, comprising three, four, six or eight clamping pads as defined above, said pads being spaced angularly apart from each other in a regular manner.

[0022] The invention also relates to the application of the device as defined above to the retention in a laying tower of a pipeline intended for the underwater transport of fluids. Brief description of the drawings

[0023] [Fig.1A] to [Fig.1C] Fig.1A, Fig.1B, and Fig.1C represent different configurations of a holding device according to the invention.

[0024] [Fig.2] Fig.2 represents a perspective view of a clamping pad of the retaining device according to the invention.

[0025] [Fig. 3] [Fig. 3] is a partial cross-sectional view of the clamping pad of [Fig. 2]. Description of embodiments

[0026] The invention relates to the retention by friction of a tube used in the underwater hydrocarbon production industry, in particular the retention in a laying tower of a pipeline intended for the underwater transport of fluids such as those shown in figures IA to IC.

[0027] Figures IA to IC show different possible configurations of a pipe support device in a laying tower.

[0028] The retaining device 2a of [Fig.1A] thus comprises six clamping pads 4 which are spaced angularly apart from each other in a regular manner around an axis XX of a pipe 6a having a diameter Da.

[0029] The retaining device 2b of [Fig.1B] also includes six clamping pads 4 which are spaced angularly apart from each other at regular intervals around an axis XX of a pipe 6b having a diameter Db (less than the diameter Da of the pipe 6a of [Fig.1A]).

[0030] Finally, the retaining device 2c of [Fig.1C] comprises three clamping pads 4 which are spaced angularly apart from each other in a regular manner around an axis XX of a pipe 6c having a diameter De (less than the diameters Da and Db of the pipes in Figures IA and IB).

[0031] Of course, it is possible to imagine that the retaining device according to the invention may alternately comprise four or eight clamping pads. Similarly, the clamping device could comprise several sets of three, four, six, or eight clamping pads that are offset from one another along the axis of the pipe.

[0032] According to the invention, as shown in Figures 2 and 3, each clamping pad 4 comprises a steel casing 8 in which a cavity 10 is formed.

[0033] The cavity 10 is provided with a base 12 and two opposing lateral edges 14 which are intended to extend along a longitudinal axis XX of the pipe. This cavity 10 is filled with a flexible polymer material 16, for example polyurethane, which is bonded to all internal faces of the cavity.

[0034] Inside this flexible material 16 is housed a plurality of gripping bars 18 which extend along the longitudinal axis XX of the conduit and which are distributed between the two lateral edges 14 of the cavity 10.

[0035] More specifically, all the gripping bars 18 of the clamping pad each have a (major) part which is embedded in the flexible material 16, and an emerged part which is substantially flat to come into contact with an external surface of the pipe 6. The embedded part of the gripping bars is glued to the flexible material 16.

[0036] According to the invention, the embedded part of the gripping bars 18 has a cross-sectional profile 20 which is rounded in order to reduce the shear rate of the flexible material.

[0037] According to the invention, the embedded part of the two lateral gripping bars 18a (namely those which are closest to the two lateral edges 14 of the cavity 10) each have a different geometric shape from the other gripping bars of the clamping pad.

[0038] More precisely, each of these two lateral gripping bars 18a has a lateral face 22a which is opposite a lateral edge 14 of the cavity.

[0039] According to the invention, this lateral face 22a has, in cross-section, a profile which is truncated and cylindrical in shape so as to provide between the embedded part of the lateral gripping bar and the lateral edge of the cavity a channel Ç of flexible material having a substantially constant width over its entire length.

[0040] Since the lateral gripping bars 18a have the greatest displacement from the neutral position to reach the smallest and largest diameter of the range of conduits to be held, the best way to mitigate the shear rate in the lateral part of the bed of soft material is to provide a channel Ç of constant width between the lateral face 22a of the lateral gripping bar and the lateral edge of the cavity.

[0041] Preferably, as shown in [Fig. 3], the two lateral edges 14 of the cavity 10 each have a partial cylindrical shape that is concentric with the cylinder of the truncated lateral face 22a of the embedded portion of the lateral gripping bars. Such a concentric arrangement between the truncated lateral face of the lateral bar, the lateral edge of the cavity, and the flexible material channel C between the two thus constitutes an optimal design for the lateral area of ​​the clamping pad.

[0042] According to an advantageous arrangement, the gripping bars 18, which are located between the two lateral gripping bars 18a, have at least one anchoring notch 24 in the flexible material on each of their two lateral faces 22. Advantageously, these anchoring notches 24 have a rounded profile.

[0043] According to another advantageous arrangement, the lateral gripping bars 18a have, on their lateral face 22b opposite the truncated lateral face 22a, at least one anchoring notch 26 in the flexible material. Advantageously, these anchoring notches 26 also have a rounded profile.

[0044] According to yet another advantageous arrangement shown in [Fig.1A], at least some of the clamping pads 4 of the retaining device may further comprise a cylinder 28 whose rod 30 is aligned with a radial direction ZZ to the conduit 6a and at the end of which is mounted the casing 8 of the clamping pad.

Claims

Demands

1. Clamping pad (4) for a friction-based holding device (2a-2c) for a tube (6a-6c) used in the subsea hydrocarbon production industry, comprising a steel casing (8) in which a cavity (10) is formed, having a bottom (12) and two opposing lateral edges (14) intended to extend along a longitudinal axis (XX) of the tube, the cavity being filled with a flexible polymer material (16) in which are housed a plurality of gripping bars (18, 18a) extending along the longitudinal axis of the tube and distributed between the two lateral edges of the cavity, characterized in that: - the gripping bars (18, 18a) each have a portion embedded in the flexible material (16), and an exposed portion which is substantially flat to come into contact with an external surface of the tube,and in that - the embedded part of the lateral gripping bars (18a) which are closest to the two lateral edges of the cavity each have a different geometric shape from the other gripping bars (18) and each have a lateral face (22a) opposite a lateral edge (14) of the cavity which is truncated and cylindrical in shape so as to provide between the embedded part of the lateral gripping bar and the lateral edge of the cavity a channel (C) of flexible material having a substantially constant width.,

2. Skate according to claim 1, wherein the embedded part of the gripping bars (18, 18a) is rounded in order to attenuate the shear rate of the soft material.

3. Skate according to any one of claims 1 and 2, wherein the gripping bars (18) located between the two lateral gripping bars (18a) have at least one anchoring notch (24) in the flexible material at each of their two lateral faces (22).

4. Skate according to any one of claims 1 to 3, wherein the lateral gripping bars (18a) have at least one anchoring notch (26) in the flexible material on their lateral face (22b) opposite the truncated lateral face (22a).

5. Skate according to any one of claims 3 and 4, wherein the anchoring notches (24, 26) have a rounded profile.

6. Skate according to any one of claims 1 to 5, wherein the two lateral edges (14) of the cavity (10) each have a partial cylinder shape which is concentric with the cylinder of the truncated lateral face (22a) of the embedded part of the lateral gripping bars (18a).

7. A pad according to any one of claims 1 to 6, wherein the flexible material (16) is glued to the inner faces of the cavity in order to ensure retention of the lateral gripping bars.

8. A skid according to any one of claims 1 to 7, further comprising a cylinder (28) having a rod (30) intended to be arranged in a radial direction (ZZ) to the tube and at the end of which the casing (8) is mounted.

9. A device for holding a tube by friction, comprising two clamping pads (4) according to any one of claims 1 to 8 which are arranged opposite each other with respect to the longitudinal axis (XX) of the tube.

10. A device for holding a tube by friction, comprising three, four, six or eight clamping pads (4) according to any one of claims 1 to 8, said pads being spaced angularly apart from each other in a regular manner.

11. Application of the device according to any one of claims 9 and 10 to the retention in a laying tower of a pipeline intended for the underwater transport of fluids.