JPS63235716A - Elastic unit, elastic load mechanism and offshore structure - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION (A) Field of Industrial Application The present invention relates to a resilient unit, in particular a resilient loading unit for an offshore tensioning leg platform, and a tensioning leg platform incorporating said resilient loading unit assembly; It is not limited only to this.

(b) In conventional technology tensioned platforms, the mooring lines serve to position the platform within predetermined limits relative to the seabed, while tension units are used to flow fluid between the seabed and the platform. It is necessary to be able to maintain tension within a predetermined range regardless of the movement of a single platform. It is important to maintain sufficient tension to ensure that there is no risk of damage to standpipes attached to the platform, and to prevent the tension from increasing to the point where damage occurs under adverse conditions. It is also necessary.

(C) Problems to be Solved by the Invention The present invention provides an elastic unit capable of responding to large movements while maintaining a load value within a predetermined range, and at least one such elastic unit. It is intended to provide a platform to handle the tensile loads of the riser.

(d) Means for Achieving the Object According to one embodiment of the present invention, an elastic unit is interposed between an inner rigid member, an outer fill rigid member, and between both of the rigid members, and and an elastic bearing assembly that moves each other in the axial direction in a restrained state, and the elastic bearing assemblies are arranged so that each set can receive a load and undergo shear deformation, thus responding to the applied axial load. A plurality of elastic bearing units are provided so that both rigid members can move relative to each other in the axial direction in the constrained state.

The resilient bearing assembly of the resilient unit includes an axial extension of a series of annular resilient elements, the resilient elements being arranged alternately with each support ring of the series of rigid support rings, and attached to the ring. Typically, a series of outer rings are arranged alternating with inner rings in the axial direction and are respectively joined to the outer and inner portions of the elastic element. The resulting bearing assembly has a generally cylindrical shape, and the joined interfaces are all generally cylindrical in shape, so that as a result of the axial load acting on the resilient unit, each resilient element , the shear load is mainly applied to each set.

The resilient unit may include a plurality of resilient bearing assemblies disposed in a preformed configuration between the inner rigid member and the outer rigid member, in which the bearing assemblies are in contact with each other. A pair of ends (typically both ends) of a continuous bearing assembly are connected to each other such that one of the inner and outer rigid members is in a surrounding relationship with respect to the other. When moving, loads are transferred from one bearing assembly to another, exerting a load on each set of bearing assemblies.

According to another embodiment of the invention, the elastic loading mechanism comprises an elastic unit of the invention, such that the elastic unit can act between one of the inner and outer rigid members of the elastic unit. Disposed boosting means and connecting means are associated, thus allowing greater relative movement of said connecting members through relative axial movement of the rigid members.

Preferably, the boosting means is a pulley system comprising at least one pulley rotatably secured to one of the inner and outer rigid members of the elastic unit.

The connecting means can be constituted in the end region of a gable or similar cable member of a pulley mechanism.

According to yet another embodiment of the invention, the present invention provides an elastic loading mechanism comprising an elastic unit, the elastic unit comprising a partially spherical or substantially spherical layer of elastic material positioned between complementary shaped rigid bearing surfaces. A pivot bearing is associated with the resilient unit.

The resilient pivot bearing may have an annular configuration to allow fluid flow.

The pivot bearing is fixed to one of the inner rigid member and the outer rigid member (the inner rigid member is preferable) of the elastic unit, or is formed integrally with the elastic unit, and is positioned substantially coaxially with respect to the elastic unit. can.

Alternatively, a resilient pivot bearing fixed to one rigid member of the resilient unit can be positioned eccentrically with respect to a longitudinal axis of the resilient unit. In this case, it is desirable to provide a plurality of (more preferably at least three) elastic units, and the rigid member of the pivot bearing is fixed to or integrally formed with the rigid member of each of the elastic units.

It is desirable that three or more elastic units are uniformly arranged around a central axis that coincides with the longitudinal axis of the elastic pivot bearing.

In accordance with yet another embodiment of the present invention, an offshore structure, such as a floating tow leg platform, is provided, in which a flexible riser attached to and extending from the ti structure has a resilient It is maintained in tension by the loading mechanism and/or the elastic unit of the invention.

A plurality of elastic loading mechanisms are associated with a single riser or similar attachment means, more preferably said elastic loading mechanisms are in the form of an elastic tensioning unit that exerts a tensile load on said rope.

If the elastic tube Iv1tR incorporates boosting means in the form of a pulley system, one end of the connection means constituted by the end region of a cable or similar line member may be attached to the standpipe or similar attachment means of the offshore structure. stick.

The pulley cable member can be directed to the attachment means via the pulley unit. In addition to guiding the rope member, the pulley unit, together with one or more corresponding pulley units with an elastic load v1 configuration, is configured to move axially relative to the offshore structure under the influence of the acting force of the elastic unit or other external force. The riser or similar attachment serves to position the means longitudinally when moving.

The pulley am may be provided with means for freely varying the length of the pulley cord between one end of the pulley cord fixed to one of the rigid members of the associated elastic unit and the connecting means.

(e) Examples Examples of the present invention will now be described in detail with reference to the attached page 1.

An offshore tension leg platform 10 with a support structure deck 11 is secured to the seabed by conventional mooring lines (not shown) secured to the periphery of the support structure deck.

A bundle of laterally spaced risers 14 extends from the seabed and is attached to the central portion of the platform through which gas and/or oil flows.

Each riser 14 is held in tension between the seabed and the platform support deck by four elastic tensile loading units 15. As shown in FIG. 2, the four tension units are arranged at substantially even intervals around the riser. These tension units will be explained in detail below.

Each resilient tensioning unit includes an inner rigid member capable of axial movement in a constrained manner relative to the outer rigid member by an interposed resilient bearing assembly. This inner rigid member is in the form of a metal support tube 16.
The upper end rotatably supports a pulley 17, hereinafter referred to as intermediate pulley. The outer rigid member is in the form of a cylindrical housing 18 having a cylindrical upper end cap 19 and a lower end cap 20. The support tube 16 extends through the central portion of each end cap 19, 20 so that each end collar 719, 20 acts as a guiding means to radially position the support tube relative to the housing.

The hole in the lower end cap 20 contains a fluid seal (not shown) that presses against the support tube to prevent fluid from inside the housing even when the housing and support tube move axially relative to each other. Prevent leakage. Although it is not envisaged that pressure fluid will be introduced into the housing, a fluid seal or a prisoner seal may be built into the hole in the upper end cap 19 to prevent foreign matter from entering.

Two pulleys 21 , 22 are associated with each tensioning unit and are mounted rotatably about respective axes fixed relative to the support structure deck 11 . In this embodiment, the pulleys are mounted to the upper end of the housing at diametrically opposed locations. The rotational axes of the two pulleys mentioned above are parallel to each other and to the rotational axis of the intermediate pulley 17. One of the two pulleys, the inner pulley, is a double groove guide pulley 21 that functions to radially position and guide the riser 14 relative to the deck 11, as will be explained below. The other of the two pulleys is a winch pulley 22 which is selectively rotatable under the action of an electric winch motor (not shown) and is provided with means for locking against rotation.

In the assembly shown, the three pulleys 17.21.22 associated with each tensioning unit are located in a common vertical plane, which is a plane orthogonal to the associated riser.

The support cable 23 has one end secured to the winch boot 22 and extends upwardly beyond the intermediate pulley 17.
It extends downward beyond the guide pulley 21. The other end is a connecting end, and is an annular connecting collar 2 fixed to the riser pipe at a position always below the guide pulley 21.
It sticks to 4.

The elastic bearing assembly 25 interposed between the support tube 16 and the housing 18 consists of eight identical annular elastic bearing units 26.
They are constructed by overlapping each other (see Figure 4). This stack receives a load for each set, undergoes shear deformation, and the support tube 16
is disposed such that it can easily move axially in a restrained manner relative to the housing 18.

Each elastic bearing unit 26 comprises an annular element 27 of elastic material interposed between and fixed to each radially inner rigid support ring 28 and radially outer rigid support ring 29.

The opposing surfaces of the support ring to which the annular elastic element 27 is fixed are each truncated conical and have an angle of inclination approximately equal to the longitudinal direction of the bearing assembly, which is perpendicular to the surface as viewed in FIG. There is. Corresponds to the fastening surfaces of the inner and outer support rings. One axial end face of the element 27 of zero elastic material is flat, which may include one or more frusto-conical sheet metal sleeves within the annular elastic element and inserted between the layers of elastic material; The other end surface assumes a truncated conical shape when no stress is applied to the material, as shown in FIG. A frusto-conical shape within the bearing assembly is such that when a compressive load is applied, resulting in a shearing action of the elastic material, the frusto-conical surface deforms towards a flattened shape (see Figure 1). Set the direction.

The bearing units 26 of the 8111 are kept spaced apart by four outer guide rings 30 and three inner guide rings 31 interposed between successive bearing units. Outer guide ring 30 and inner guide ring 31
are arranged alternately. Each guide ring has one for positioning a respective inner or outer rigid support member 28,29.
Pairs of cylindrical sealing surfaces 32, 33 and for preventing relative axial movement between the guide ring and the support ring supported by this ring when an axial compressive load is applied to the elastic bearing assembly. A pair of opposing radial contact portions 34, 3
5. Each outer guide ring 30 includes a radially extending fail-safe abutment 36 intermediate its axial end.
is provided, and for this reason one elastic bearing unit 26
If the inner support ring 2 of the bearing unit fails,
The load acting on 8 is directly transmitted through the outer guide ring 30.
It is transmitted to the outer support ring 29 of the next successive bearing unit.

In addition to the inner guide rings described above, the bearing assembly includes upper and lower inner guide rings 37,38. Each end guide ring has a cylindrical surface 39 and a radial abutment 40 that supports a single inner rigid support ring of an elastic bearing unit.

The upper end inner guide ring 37 is fixed to the support tube 16 in the axial direction, and the lower end inner guide ring 38 is in pressure contact with the lower end cap 20 and is supported by this cap 20. The remaining four inner guide rings and three inner guide rings are axially slidable relative to the cylindrical housing 18 and the support tube 16, respectively. To facilitate this activity, the sliding surfaces are provided with a low-friction material.

The housing 18 contains a viscous fluid such as oil,
This is to prevent rapid upward relative movement of the support tube 16 with respect to the housing 18 when the compressive load applied to the elastic bearing is suddenly released.

Furthermore, a stopper member (not shown) is fixed to the support tube located outside the housing and spaced downwardly from the lower end cap 20 to prevent the support tube from moving excessively upward relative to the housing. can do.

FIG. 2 is a plan view of the riser 14 supported by four resilient bearing assemblies 15, showing further details of the inner guide pulley described above. Each inner guide pulley 21 is provided with a cable positioning mechanism 41 at its shaft end,
A shallow guide groove 42 is provided adjacent to this groove 41 to contact and guide the outer surface of the riser pipe. The four bearing assemblies 15 are arranged symmetrically and are connected to the riser pipe 14.
They are arranged at approximately equal intervals around the center.
For this purpose, the riser in the region of the guide pulley is positioned radially with respect to the platform deck 11.

For convenience, the winch motor and winch pulley 22 are omitted in FIG. 2. The winch pulleys associated with the resilient bearing assemblies of the riser pipes (not shown) adjacent to the riser pipes shown in FIGS. 1 and 2 are supported in part, one above or below the other. They are positioned at different heights above the deck.

When using the tensile load unit 15 to apply a desired tensile load to the riser pipe 14, the winch motor is first spun up to shorten the free length of the cable 23, so that the bearing support tube 16 is pressed downward (but not very far) into the deformed state shown in FIG.

Thereafter, as a result of movement of the platform due to inclement weather, the resilient bearing unit may be further compressed into the approximately maximum deflection state shown in FIG. 1 or relaxed into the unloaded state shown in FIG. 3.

In another embodiment of the invention illustrated in FIG. 5, the platform riser tensioning unit is of substantially the same construction as described with respect to FIGS. 1-4, but
The difference is that a pair of auxiliary outer guide sleeves 50,51 are provided between the outer guide rings 52-55 and the inner wall of the cylindrical housing 18.

The upper part of the auxiliary guide sleeve 50 is secured to the uppermost outer guide ring 52 and extends downwardly from there to surround the next outer guide ring 53. The other auxiliary guide sleeve 51 is secured to the lowest outer guide ring 55 and extends upwardly from there to surround the next outer guide ring 54 . During the relative axial movement of the support tube and housing,
The axial movement of the two outer guide rings 53,54 is
Movement of one ring and/or a surrounding auxiliary guide and distributed between the auxiliary guide and the cylindrical housing.

One of the inner guide rings can be provided with an auxiliary guide, which extends axially and surrounds at least the other inner guide, thus allowing a relative axial sliding movement.

Figures 6 and 7 show a portion of an offshore structure having four resilient units of the invention and a mechanism for maintaining tension in the standpipe.

The riser 60 is positioned relative to the support deck 61 of the offshore tug platform by four resilient units 62 and resilient pivot bearings 63.

Four elastic support units are arranged around the riser pipe 60 at uniform intervals from the riser pipe 60, and the longitudinal axes of these units are parallel to each other and to the longitudinal direction of the riser pipe. It is.

Each resilient unit 62 (described in more detail below) has an outer rigid member in the form of a cylindrical housing sleeve 64 for support against the support deck, and an inner rigid member in the form of a steel support tube 65. Equipped with parts.

The support tubes 65 of the four elastic units 62 are mutually connected by a rigid spider unit 66 that acts as an outer rigid member of the pivot bearing 63. Yuko's spider unit has a concave annular bearing surface 6 that is partially spherical.
It has 7. This bearing surface 67 faces a partially spherical convex annular bearing surface 68 of an inner rigid support ring 69 secured to the riser 60 .

The partially spherical elastic bearing surface 6 facing the elastic material layer 70
7.68, and is joined to these bearing surfaces 67.68. The elastic layer can embed at least one partially spherical annular reinforcing layer, for example of sheet steel or fiber material.

Each elastic unit 62 acts as a load cell and comprises two substantially cylindrical intermediate rigid members 71 , 72 interposed between the housing sleeve 64 and the support tube 65 . Each of these intermediate rigid members includes a radially outwardly extending flange at one shaft end and a radially outwardly extending flange at the other shaft end. The intermediate members are connected to each other as a set, and the housing 64 and the support tube 65 are connected to each other by three coaxially arranged elastic bearing assemblies 76.

Each resilient bearing assembly 76 is constructed as described with respect to FIGS. 1 and 4 and is interposed with a rigid support ring so as to be loaded in pairs in such a manner that the resilient material shears. Equipped with an elastic bearing unit.

Inner bearing assembly 76 acts between tube 65 flange 73 and the inwardly directed flange of inner intermediate member 71 . The intermediate bearing assembly operates axially between the outer flange of the inner intermediate member 71 and the inner flange of the outer intermediate member 72. A third outer bearing assembly operates between the outer flange of the outer intermediate member and the inner end flange 74 of the housing 64.

When a tensile force is applied to the riser 60, each elastic load unit 62 deforms into the configuration shown in FIG.

Movement of the riser from the vertical direction or relative movement of the support deck 61 from the horizontal position is primarily accommodated by shear deformation of the resilient pivot bearings 63.

In another embodiment of the invention (described with reference to FIG. 10), the riser 60 is secured to the support deck of the tension leg platform by one elastic unit 80.

The elastic unit 80 is substantially the same as the elastic unit 62 described above.
However, the difference is that an inner housing 81 is used instead of the support tube 65. The inner housing 81 is formed with a ring 82 intermediate its ends, which provides a partially spherical convex annular bearing surface for a resilient pivot bearing 83. FIG. 10 does not show the elastic unit under axial load.

Still another embodiment of the present invention (described with reference to FIG. 11)
In this case, the riser is elastically secured to the pull leg platform by a resilient unit 90 which is substantially similar to the resilient unit 80 described above. This elastic unit 90
is different in that it is desired to be formed integrally with the bearing ring 92 at the upper end of the inner housing 91 rather than at the intermediate position in FIG.

[Brief explanation of the drawing]

Figure 1 shows the line 1-1 in Figure 2 under the load f condition.
FIG. 2 is a plan view of a portion of the offshore floating platform shown in FIG. 1; FIG. 3 is similar to FIG. 1 when no load is applied; 4 is a more detailed view of a portion of FIG. 3, FIG. 5 is a cross-sectional side view of a portion of an elastic unit according to another embodiment of the invention, and FIG. 7 is a plan view of FIG. 6, and FIG. 8 is a state in which no load is applied. 9 is a view of the elastic unit of FIG. 8 under load; FIGS. 10 and 11 are views of another offshore structure according to the invention; FIG. FIG. (Main code: visibility) 10...Tension leg platform 11...Deck 14...Rise pipe 15...
Elastic tensile load unit 16... Support tube 17... Intermediate pulley 18.
・Cylindrical housing 19... Upper end cap 20... Lower end cap 21
．． 22...Pulley 23...Support cable 24.
...Connection collar 25...Elastic bearing assembly 26...
- Elastic bearing unit 27... Annular element 28... Radial inner rigid support ring 29... Radial outer 0jq rigid support ring 30.31... Guide ring 32.33... Sealing surface 34.35.・Contact part 36...Fail safe contact part (4 people outside)

Claims (1)

[Scope of Claims] 1. An inner rigid member, an outer rigid member, and an elastic member interposed between the two rigid members to allow the two rigid members to mutually move in the axial direction in a restrained state. and a bearing assembly, wherein the elastic bearing assembly (2
The rigid member (1) is arranged to receive a load in series and undergo shear deformation, so that in response to the applied axial load the rigid member (1)
6, 18) are provided with a plurality of elastic bearing units (26) for relative axial movement in the constrained state. 2. A series of annular elastic bearing assemblies (25) arranged alternately with each of the support means (28, 29) of the series of rigid support means and joined to each of the support means (28, 29); Elastic unit according to claim 1, characterized in that it comprises an axial extension of the elastic element (27). 3. A series of outer rings (29) in which said series of rigid support means (28, 29) are mutually arranged with an inner ring (28).
according to claim 2, characterized in that the outer ring (29) is joined to the radially outer part of the elastic element (27) and the inner ring (28) is joined to the inner part of the elastic element (27). Elastic unit as described. 4. The bearing assembly (25) has a cylindrical shape, and all the joined interfaces have a substantially cylindrical shape, so that the axial load acting on the elastic unit causes the elastic elements (27) to mutually 4. The elastic unit according to claim 2, wherein the elastic unit receives a shear load primarily in series. 5. A plurality of elastic bearing assemblies (7) arranged in a telescoping configuration
6) is provided between the inner rigid member (64) and the outer rigid member (65). 6. A pair of ends of the continuous bearing assembly (76) are interconnected so that when one of the inner rigid member (64) and outer rigid member (65) moves relative to the other, one 6. The elastic unit according to claim 5, wherein the load is transmitted from one bearing assembly to the other bearing assembly, and the load is applied to each bearing assembly in series. 7. The elastic unit according to claim 6, characterized in that the phase-connecting ends of the continuous bearing assembly (76) are both ends. 8. An elastic unit according to any one of claims 1 to 7 is provided, acting between one of the inner and outer rigid members and the connecting means (24), so that the inner and outer rigid members (16) . 9. The boosting means has at least one wheel (17, 10. The elastic loading mechanism according to claim 8, further comprising: 21, 22). 10. Elastic loading mechanism according to claim 8 or 9, characterized in that the connecting means (24) are constituted by the end regions of cables or similar cable members (23). 11. The pulley mechanism guides the pulley cable means (23) and moves the connecting means (24) by the movement of the connecting means (24).
) to the mounting part (14) fixed to the mounting part (14).
An elastic load mechanism characterized by comprising a pulley wheel (21) for positioning in a direction substantially perpendicular to the direction of movement of the elastic load mechanism. 12. A pulley cable member (12) fixed to the connecting means and one of the inner rigid member (16) and the outer rigid member (18)
12. The elastic loading mechanism according to claim 9, further comprising means for changing the free length of the pulley cable member between one end of the elastic load mechanism. 13. An elastic pivot bearing comprising an elastic unit according to any one of claims 1 to 7 and comprising a partially spherical or substantially partially spherical elastic material layer (70) positioned between complementary shaped rigid bearing surfaces. 63). 14. The elastic loading mechanism according to claim 13, wherein the elastic member (70) is joined to the bearing surface. 15, the elastic pivot bearing (63) has an annular shape,
Claim 13 characterized in that fluid flow is allowed between the two.
Or the elastic loading mechanism described in 14. 16, the elastic pivot bearing (63) is connected to the elastic unit (80
16. The elastic loading mechanism according to claim 13, wherein the elastic loading mechanism is positioned coaxially with respect to the elastic load mechanism. 17. A plurality of elastic units (62) are provided, and the pivot bearing (63) is fixed to a rigid member (65) of each elastic unit (62) or formed integrally with the rigid member (65). The elastic loading mechanism according to any one of claims 13 to 15. 18. Connect the elastic unit (62) to an elastic pivot bearing (
18. The elastic loading mechanism according to claim 17, wherein the elastic loading mechanism is uniformly arranged around a central axis that coincides with the vertical axis of the elastic loading mechanism. 19. An offshore structure characterized in that the attachment portion (14) is maintained in tension by the elastic unit according to any one of claims 1 to 7 or the elastic loading mechanism according to any one of claims 8 to 18. .