GB2073842A - An Apparatus for Providing an Articulated Conduit Linkage - Google Patents

Abstract

An apparatus for providing an articulated conduit linkage comprising: a first body 14 and a second body 10 joined together by an articulated joint 12 including a first pivot means 32 defining a first axis for rotational movement of the first body 14 and second body 10 relative to each other, and a second pivot means 12 for angular movement of the second body 10 relative to the first body 14 about a second axis perpendicular to the first axis; a first conduit 18 extending through the first pivot means and through at least part of the first body 14, the said first conduit 18 having a first swivel 43 positioned for rotation about the first axis; a second swivel 48 positioned for rotation about the second axis; a portion of the first conduit 18 extending from the first swivel 43 to the second swivel 48. The apparatus is suitable for providing a conduit linkage between an offshore column 10 and a base 14 on the sea bottom. The apparatus may also be used for electrical cables. <IMAGE>

Description

SPECIFICATION An Apparatus for Providing an Articulated Conduit Linkage This invention relates to apparatuses by which a conduit, secured to two bodies which are connected together by an articulated joint, can by-pass the joint.

Many types of machines, apparatus and structural installations incorporate articulated joints to connect together non-rigidly two adjacent bodies when it is desired or necessary to have one or both of the bodies pivot with respect to the other body, or to a third body.

At times a conduit, such as a fluid conduit, must extend from or between, and be secured to, two bodies connected together by an articulated joint. Since the two bodies pivot with respect to one another at the articulated joint, it is essential that the conduit include a non-rigid yieldable section at, or in the vicinity of, the articulated joint which will not significantly interfere with the pivoting action between the bodies, There is much present interest in fluid conduit articulated joint by-pass systems by oil companies engaged in offshore exploration, development and production. This is because such endeavours often require the utilisation of a deep water offshore buoyant column or tower pivotally secured in place at its lower end by an articulated joint operatively connected to a base anchored to the sea floor.Oil or gas lines or conduits desirably run along the sea floor and then up the column to the column top. From the column top, the oil or gas lines extend to a ship moored to the column. The mechanism used to moor the ship can include an articulated joint at the column top so that the ship is free to pitch and roll relative to the column. Since a fluid conduit must often extend from the column top to the ship, it is necessary for the fluid conduit to include a means by which fluid can be conveyed from a conduit on the column past the articulated joint to a conduit on a ship mooring boom or yoke or to the ship itself.

U.S. Patent Specification No. 4,010,500 (Reid) discloses the use of a Cardan-type universal joint ("cardan" is a Registered Trade Mark) at the top and bottom of an offshore mooring column. This Patent Specification also discloses fluid coupling of a pipe from one side of the Cardan joint to the other side by passing a conduit or pipe elbow through hollow pins of the Cardan joint positioned 900 from each other. Conduit or pipe sections communicate with each end of the elbow through suitable fluid swivels so that pivotal movement of the column to the base, or the ship mooring yoke to the column, is unrestrained yet a fluid-tight coupling between conduit rections is achieved.

Because of the 900 bend which the elbow must make inside the Cardan joint disclosed in the Reid U.S. Patent Specification, the joint must be larger than that which is necessary to carry the axial, torsional and shear loads. Also, the sharp curve of the elbow inside the Cardan joint restricts the pipe size which can be used and the sharp curve can prevent passage of a pig through the elbow, thereby making it impossible to clean the elbow without disassembly of the pipes.

Furthermore, the Reid system is limited to conducting two flow lines or pipes from one side to the other side of the Cardon joint.

Other Patent Specifications disclosing various types of articulated joint by-pass conduit arrangements include U.S. Patent Specification Nos. 4,026,119 (Dotti) 4,029,039 (van Heijst); 4,165,108 (Saint-Palais); 3,641,602 (Flory); 3,984,059 (Davies) and 4,142,820 (Tuson) (which is similar to Reid, supra), According to the invention, there is provided an apparatus for providing an articulated conduit linkage comprising: a first body and a second body joined together by an articulated joint including a first pivot means defining a first axis for rotational movement of the first body and second body relative to each other, and a second pivot means for angular movement of the second body relative to the first body about a second axis perpendicular to the first axis; a first conduit extending through the first pivot means and through at least part of the first body, the said first conduit having a first swivel positioned for rotation about the first axis; a second swivel positioned for rotation about the second axis; a portion of the first conduit extending from the first swivel to the second swivel; and a portion of the first conduit extending from the second swivel into a supporting arrangement on the second body.

In this specification the term conduit is used to embrace fluid flow conduits and electrical cables.

Also the term swivels is used to embrace both fluid swivels and electrical slip ring swivels.

The first swivel is preferably inside the articulated joint. The second swivel can be inside or outside of the articulated joint. If the end of the second body has a yo ucture, in other words two spaced-apart elements or legs, rotatably connected to trunnions forming part of the second pivot means, the first pivot means can be inside the articulated connection, and the second swivel can be either inside or outside the ariculated connection. If the second swivel is inside the articulated joint, the second swivel is preferably between the spaced-apart rotating elements of the second pivot means.

The by-pass conduit arrangement of the invention is particularly useful on an offshore structure where the first body is a base secured to a seafloor, the second body is a column, the first pivot means has a vertical axis and the second pivot means has a horizontal axis intersecting the vertical axis. In such an apparatus the second swivel is unrestricted by the base and moves in unison with the column. In addition, the conduit portion between the two swivels is preferably so shaped as to rotate only around a vertical axis at the same rate as the column.

The invention also encompasses having two or more conduits by-pass an articulated joint by the use of a multiport swivel as the first swivel. A second conduit is operatively so connected to the multiport swivel as to extend therefrom to a third swivel outside the articulated joint, the third swivel being positioned for rotation about the second axis, with the second circuit extending from the third swivel into a supporting arrangement on the second body or column. A multiport fluid swivel which can be used is disclosed in U.S. Patent Specification No.

4,052,090 (Stafford).

If desired, piggable fluid swivels such as disclosed in U.S. Patent Specification No.

4,183,559 (Stafford et al) and U..U.S.....

Patennent Specification No. 4,174,127 (Carn et a/) can be used.

Although the invention is primarily directed to a fluid conduit articulated joint by-pass, the principles of the invention are equally applicable to an electrical conduit or cable by-pass using slip-ring electrical contacts in place of fluid swivels.

So that the invention may be better understooc and so that further features of it may be appreciated, various apparatuses in accordance with the invention will now be described by way of example with reference to the accompanying drawings, in which: Figure 1 is an elevational view of an offshore ship mooring column or tower secured to a base on a sea floor by an articulated joint or connection, with a conduit by-passing the articulated joint; Figure 2 is an enlarged vertical sectional view along the line 2-2 of the articulated joint of Figure 1, showing a first type of conduit by-pass of the articulated joint; Figure 3 is a vertical partial sectional view of the articulated joint of Figures 1 and 2, with a second type of conduit by-pass of the articulated joint; Figure 4 is a partial sectional view taken along the line 4-4 of Figure 3;; Figure 5 is a vertical partial sectional view of the articulated joint of Figures 1 and 2, with a third type of conduit by-pass of the articulated joint; and Figure 6 is a partial sectional view taken along the line 6-6 of Figure 5.

To the extent that it is practical, the same numbers will be used in the various views of the drawings to identify the same or similar elements.

With reference to Figures 1 and 2, an offshore column 10 (second body) has its lower end connected by an articulated joint 12 to a base 14 (first body) supported by the sea floor 16. A conduit 1 8 extends upwardly from beneath the sea floor 16, through the articulated joint 12.

The top of column 10 is connected to one end of a ship mooring boom 22. The other end of the boom 22 is suitably connected by a releasable and pivotable means to the bow of a ship 24.

Struts 26 extend downwardly from the boom 22 to a ballasted float 28 which maintains the boom above sea level when no ship is moored to the boom.

As shown in Figure 2, the base 14 has a conical upright support 30 around the top of which a sleeve bearing 32 fits snugly. A ring 34 fits rotatably around the sleeve bearing 32, and the sleeve bearing 32 is secured in place by a retainer 36. Axially positioned horizontal trunnion pins 38 have reduced inner ends which fit securely into holes in the ring 34.

Two identical legs 40 and 42 in a spaced-apart yoke-like arrangement project downwardly at the lower end of the column 10. Each of the legs 40, 42 has a hole at one end containing a sleeve bearing 44 held in place by a disc plate 46. The pins 38 remain stationary on the ring 34 when the column 10 pivots about the horizontal axis of the pins.

The base 14 has a hole 41 through which the conduit 1 8 runs. A first swivel 43 in the conduit 18 permits the conduit portion 45, made of three 900 elbows, in the conduit 1 8 to rotate when the column 10 rotates 3600 about a vertical axis. The conduit portion 45 extends to a horizontally positioned second swivel 48 which is axially aligned with the trunnion pins 38. An elbow 50 is communicatively connected to the swivel 48 and to a pipe 52 which extends upwardly in the column 10, through the boom 22 to the ship 24.

When the column 10 pivots on the pins 38, the elbow 50 swivels in the second swivel 48, thereby avoiding the application of a twisting torque to the conduit 18.

Figures 3 and 4 illustrate a second embodiment of the invention in which the articulated joint 12 is like that shown in Figure 2; therefore, the articulated joint structure will not be described again.

Extending upwardly from the first swivel 43 is a 900 elbow 54 which is mounted to rotate freely in the swivel. The elbow 54 is connected at its upper end to a horizontally positioned tee 56. A respective reducing 900 elbow 58 is joined to each end of the tee 56, and elbows 58 are in turn joined to respective elbows 62 which communicate with respective swivels 64. The swivels 64 are axially aligned with the trunnion pins 38. Respective elbows (1530)66 communicate with the swivels 64 and with conduits 68, which conduits extend up, and are attached to, the inside or outside of the column 10.

When the column 10, in the embodiment shown in Figures 3 and 4, rotates about a vertical axis, elbow 54 turns in the first swivel 43 (and carries with it all of the piping from it, up to and including conduits 68) without applying any twisting torque which might break the conduits.

However, when the column 10 pivots on the trunnion pins 38, conduits 68 move with the column and cause elbows 66 to swivel in the swivels 64 without breaking or damaging any of the elbows or other portions of the conduit. This is achieved by axial alignment of the swivels 64 with the trunnion pins 38.

It should be understood with respect to the embodiment illustrated in Figures 3 and 4 that only one elbow 58 need communicate with tee 56, in which case the other end of the tee is closed.

A third embodiment of the invention is illustrated in Figures 5 and 6. The articulated joint 12 in the apparatus illustrated in these figures is similar to that shown in Figures 2 to 4, so it will not be described again.

With reference to Figures 5 and 6, the conduit 1 8 communicates with elbow 70 which, in turn, communicates with a vertical conduit 72. The vertical conduit 72 has a swivel 74 joined to its top. An elbow (900) 76 extends from the swivel 74, in which it is swivel-mounted, to a 900 elbow 78 which communicates with another 900 elbow 80. A conduit portion 82 extends from elbow 80 to elbow 84 (also of 900) which is connected to a swivel 86. Swivel 86 and the trunnion pins 38 are axially aligned with each other. A conduit 88 is swivel joined to swivel 86 and extends upwardly through the inside or outside of the column 10, to which it is attached for support.

A second conduit 98 communicates with the lower portion 102 of a fluid swivel 100 which axially surrounds the vertical conduit 72 in a spaced apart position. The lower portion 102 of the fluid swivel 100 is stationary while the upper portion 104 is free to rotate about a seai 106.

A 90" elbow 106 communicates with the swivel upper portion 104 and with another 900 elbow 108. A further 900 elbow 110 is joined to elbow 108 and to a swivel 112. A conduit 114 joined to swivel 112 is directed upwardly inside or outside the column 10. Conduit 114 is attached to, and held in place by, the column.

The apparatus described with reference to Figures 5 and 6 provides means for two fluid conduits or lines to by-pass the articulated joint 12. Rotation of the column 10 about a vertical axis does not twist the conduits because the swivels 74 and 100 accommodate such a rotation. Furthermore, when the column 10 pivots on the trunnion pins 38, the swivels 86 and 112 permit such a movement and no adverse torque or twisting is applied to the components making up the articulated joint by-pass conduit apparatus.

Although Figures 5 and 6 show two fluid conduit by-pass lines, additional lines can by-pass the articulated joint by use of an appropriate multiport fluid swivel.

Even though the drawings illustrate the invention utilised to by-pass an articulated joint at the base of an offshore column, it should be understood that the invention is not limited to such a use. For example, an apparatus in accordance with the invention can be used equally well at the top of a column or in equipment quite different from that pertaining to offshore apparatus.

The foregoing detailed description has been given for clearness of understanding only, and no unnecessary limitations should be understood therefrom, as modifications will be obvious to those skilled in the art.

Claims (14)

Claims

1. An apparatus for providing an articulated conduit linkage comprising: a first body and a second body joined together by an articulated joint including a first pivot means defining a first axis for rotational movement of the first body and second body relative to each other, and a second pivot means for angular movement of the second body relative to the first body about a second axis perpendicular to the first axis; a first conduit extending through the first pivot means and through at least part of the first body, the said first conduit having a first swivel positioned for rotation about the first axis; a second swivel positoned for rotation about the second axis; a portion of the first conduit extending from the first swivel to the second swivel; and a portion of the first conduit extending from the second swivel into a supporting arrangement on the second body.

2. An apparatus according to claim 1 in which the first swivel is inside the articulated joint.

3. An apparatus according to claim 1 or claim 2 in which the second swivel is between spacedapart rotating elements of the second pivot means.

4. An apparatus according to any one of claims 1 to 3 in which the second swivel is outside the articulated joint.

5. An apparatus according to any one of claims 1 to 3 in which the second swivel is inside the articulated joint.

6. An apparatus according to any one of the preceding claims in which the first body is a base secured to a seafloor, the second body is a column, the first pivot means has a vertical axis and the second pivot means has a horizontal axis intersecting the vertical axis.

7. An apparatus according to claim 6 in which the second pivot means comprises spaced-apart trunnions, and spaced-apart downwardly extending legs at the base of the column are rotatably connected to the trunnions.

8. An apparatus according to claim 6 or claim 7 in which the second swivel is unrestricted by the base and moves with the column.

9. An apparatus according to any one of claims 6 to 8 in which the conduit portion between the two swivels can rotate only around a vertical axis at the same rate as the column.

1 0. An apparatus according to claim 4 in which the first swivel is a multiport swivel to which a second conduit is operatively connected, the second conduit extends therefrom to a third swivel outside the articulated joint, the third swivel being positioned for rotation about the second axis, and the second conduit extends from the third swivel into a supporting arrangement on the second body.

11. An apparatus substantially as herein described with reference to, and as shown in, Figures 1 and 2 of the accompanying drawings.

1 2. An apparatus substantially as herein described with reference to, and as shown in, Figures 3 and 4 of the accompanying drawings.

1 3. An apparatus substantially as herein described with reference to, and as shown in, Figures 5 and 6 of the accompanying drawings.

14. Any novel feature or combination of features described herein.