AU5886898A

AU5886898A - Tool for intercoupling of two subsea pipelines

Info

Publication number: AU5886898A
Application number: AU58868/98A
Authority: AU
Inventors: Per Olav Halle; Fredrik Witting
Original assignee: ABB Offshore Systems AS
Current assignee: Aibel AS
Priority date: 1997-01-28
Filing date: 1998-01-28
Publication date: 1998-09-08
Also published as: GB2335961B; NO306181B1; NO970368D0; BR9807014A; NO970368L; GB9916553D0; GB2335961A; WO1998036200A1

Description

TOOL FOR INTERCOUPLING OF TWO SUBSEA PIPELINES

The present invention relates to a tool for preferably remotely controlled hauling and coupling of a submarine conduit such as a pipeline to a complementary conduit mounted on a sea bottom based installation.

There is known several designs for carrying out such operations. Some designs include a pipeshaped open funnel and winch and cable means for axial hauling and pulling of the pipeline into the funnel, whereafter the pipeline is aligned and coupled to the sea bottom based installation.

With other designs are utilised tools including yoke means which can straddle and hold an end section of the pipeline to provide a hauling and a positioning of the pipeline in order to couple the same to a complementary conduit, pipeline or alike mounted on the sea bottom installation. There is also known adjustable tools mounted on a sea bottom installation to accommodate a final positioning and alignment of the pipeline to facilitate the coupling operations.

Some examples of the prior art are disclosed in Norwegian Patent 177648, US 1404207 and GB 2057082, AU 658239 and also applicant's pending Norwegian Application No. 952123. Since submarine conduits and pipelines of this kind may constitute heavy, frequently rigid structures which may be located in awkward positions on the sea bottom, at a distance from the bottom based installation, and therefore requiring tools with large power and stability in order to accomplish the hauling and coupling operations. Known tool constructions are further frequently hampered with the drawback that the pulling and alignment operations take place more or less simultaneously and not stepwise resulting in that large peak loads may occur with corresponding large demands to the tools used for the operations.

An important object for the present invention is to provide a new concept for pulling, positioning and coupling of submarine conduit and pipelines to each other and which will offer reduced demands to the physical dimensions and the tools required and which nevertheless can result in a more simple and quicker coupling procedure. A special object of the invention is to develop a tool which makes it possible to carry out a rotational and angular adjustment of the submarine conduit about its longitudinal axis, an operation which may be necessary especially in the case where the submarine conduit comprises a mantle enveloping two or more parallel submarine pipelines, conduits or alike positioned in a bundle and which shall be coupled to a complementary conduit bundle located on the sea bottom installation.

In accordance with conventional designs the attachment point for the pulling wire is positioned on a pre-selected point on the circumference of the pipeline or on the outside of the mantle thereon. Thereby the end section of the pipeline during the hauling and pulling will be forceably pivoted until the attachment point is located approximately on the top side of the end of the pipeline prior to that the same is pulled up into the coupling tool. However, since such pipelines frequently are rather rigid both lengthwise and transversally, the pulling require great power in order to straighten the pipeline and may still be problematic and even in pulled up position one cannot guarantee that the pipeline has been angularly positioned in the tool such that it safely can be angularly correct coupled to the complementary conduit mounted on the sea bottom based installation. In order to lessen the power required for hauling and positioning it is known to position the attachment point for the hauling wire on a freely rotatable ring or so called "bellyband" on the pipeline mantle such that the mantle and pipeline may undertake independent pivoting movements inside the "bellyband" during the hauling thereby reducing the required power but if this design one will not obtain a pre-selected angular positioning of the pipeline when in coupling po- sition in the tool.

A special object of the invention is to provide a pulling tool which in addition to the described object is equally well suited for pulling single pipelines, i.e. pipelines with no need for angular position before the coupling operation as well as for conduit or pipeline bundles requiring an accurate angular positioning be- fore being coupled to a complementary conduit or pipeline bundle mounted on the sea bottom installation. The tool unit in accordance with the invention for pulling and optionally angular positioning and coupling of an initially loose free end on a submarine conduit, for instance in position on the sea bottom, to a complementary conduit mounted on a sea bottom installation, is of the kind wherein the tool includes a downwardly open substantially U-shaped longitudinal yoke for receiving and positioning the submarine conduit in connection with the coupling, and includes further winch equipment mounted on the yoke or on a supporting frame in order to pull up the end section of the submarine conduit, means for axial movement of the submarine conduit in pulled-in position in the yoke for coupling the ends of conduits together, the end section of the submarine conduit encased in a mantle or jacket conforming to the transverse dimension of the yoke, and attachment means or fitting attached to the mantle for fastening a hoisting cable extending from the above mounted winch, and the invention is characterized in that the mantle on the end section of the submarine conduit at least along a part of its length is provided with non-circular cross-section presenting two opposed parallel side faces, the space between the side faces substantially corresponding to the space or distance between complementary parallel side faces in the U-shaped yoke, and in that the cross-sectional area of the mantle is substantially symmetrical about a central axis extending parallel with the parallel side faces, and in that the fitting point for the hoisting cable is positioned at the point along the circumference of the mantle between the two opposed parallel side faces of same, having into effect that the parallel side faces on the mantle will serve as an angular positioning and as a guide of the mantle during the hauling up into the yoke. A pulling tool in accordance with the invention can be utilised in connection with pipelines optionally provided with a mantle provided with a fixed hauling bracket or alike for the hoisting cable whereby the angular positioning of the conduit will be substantially accomplished during the forced directional upward pulling of the conduit thereby accomplishing a pivoting of the conduit, and also for the type of conduit mantles provided with an attachment point for the hoisting cable positioned on a freely rotatable ring or so-called "bellyband" such that the conduit or mantle thereon may undergo more or less free pivoting movements inside the "bellyband" during the hauling.

In an preferred embodiment of the invention wherein is utilised a rotational support or bellyband, it is preferred to design the hauling wire attachment point and the bellyband such that the pivoting is defined between two end positions presenting pivoting arch comprising about 90° corresponding substantially to the circumference between the respective parallel side faces on the mantle. Thereby one can during the hauling and hoisting of the conduit from a sea bottom position obtain a rough pivoting and thereby angular positioning of the conduit before the conduit is hauled up inside the tool prior to the further hauling up whereafter a possible forced pivoting of the conduit in a horizontal plain will take place and where finally an accurate angular position of the conduit will take place when the parallel side faces on the mantle are entering up into the corresponding parallel side faces in the yoke. The invention comprises further features which will appear from the following description wherein one embodiment for the invention shall be described in connection with the accompanying drawings, wherein

Figure 1 shows a simplified side view of a complete tool system in accordance with the invention for hauling positioning and coupling of a initially on a sea bottom located submarine conveyer, such as a pipeline illustrating the hoisting step of the operation,

Figures 2 and 3 show two simplified plan views illustrating two steps during pulling of the subsea conveyer,

Figures 4 a, b, c and d show schematic cross-sections through a under- water conveyer located on a sea bottom and illustrating the initial steps during the hauling procedure,

Figures 5 a, b, c and d illustrate four different steps illustrating the final or terminating part of the pulling and positioning of the pipeline or conductor to its final position in the U-shaped tool. Figure 1 is a side view illustrating a tool in accordance with the invention during the hauling of a submarine conveyer or pipeline 2 which is located on a sea bottom 3, frequently at some distance from the ROW supported tool which is mounted on a subsea installation 4. On the installation 4 is mounted a permanently installed subsea conduit unit 8 with coupling means 10. The operative ROV 12 seated on the support frame 14 is carrying a tool 16 which during the hauling and coupling operation is positioned on the installed bottom frame 4 or as shown on a support frame 6 in front of the stationary unit 8. The tool 16 in accordance with the invention is displaceably mounted in the shown embodiment on all together four squarely spaced supporting posts 18 the outer ends of which are anchored on frame 14 which is further attached to the support frame 6 on the bottom installation. The tool 16 slide forcrably on the posts 18 between a rear position and a front position in the frame 14 by means of not shown power cylinders or the like. On top of the tool 16 is mounted a drum winch 22 with a pulling wire or cable 24 which in operation extends down through the top wall of the U- shaped yoke 26 the design of which appear in detail from figures 5a-d. The winch 22 may optionally be mounted in the frame 14. The yoke 26 consists as shown of a downwardly open U-shaped clamp device which preferably is made in the shape of one single integral unit or optionally in the shape of two or more interlinked parts. The yoke has parallel side faces 28, 28 the upper ends of which are interconnected with a preferably arched top part 30 which in centre is provided with a suitable opening 32 for passing through the pulling wire 24. The lower parts 31 ,31 diverges outwardly in per see known fashion in order to facilitate the introduction of the submarine conduit or pipeline.

The operational mode for a tool in accordance with the invention shall in the following be described with reference to the accompanying drawings.

As mentioned the tool in accordance with the invention can be used for submarine conduits consisting of one single pipe or for submarine conduits comprising a mantle enveloping two ore more pipelines, cables or alike positioned in one single termination. By the use of the tool in accordance with the invention is accomplished the necessary rotational adjustment prior to the coupling to a complementary submarine conduit mounted on a sea bottom frame. Also in connection with submarine conduits consisting of one single pipeline the end section thereof must usually be provided with a mantle or termination as shown in the figures 1-3, firstly because the mantle diameter is adapted to the transverse opening of the yoke, and secondly in order to furnish the conduit with attachments 38 for the pulling wire. Furthermore such mantle or terminations 36 with a so-called "bellyband" 40 in the shape of an encircling support ring which may be arranged rotatable or not rotatable on the conduit mantle. In the case with single submarine conduits the bellyband 40 does not need to be rotatable but in most cases a rotatable bellyband is preferable to lessen the problems in connection with existing torsional tensions in the conduit during the hauling and positioning operations. In the position shown in figure 1 the submarine conduit will usually have an oblique position both in the vertical and the horizontal plane as shown in figures 1 and 2, but will during the further hauling up from the sea bottom be vertically positioned from an oblique position as shown in figure 2 into an aligned position as shown in figure 3 obtained by the diverted inlet sections 31 ,31 lowermost on the yoke as shown in figure 5.

The invention shall in the following be described in detail in connection with submarine conduits of the mantle type as shown in figure 4 and 5, usually enveloping two or more built-in conduits. In accordance with an essential feature of the invention the conduit mantle 36 is designed with non-circular cross-section and not circular cross-section, more particularly presenting two parallel side faces in mutual distance between which correspond to the distance or space between the parallel side faces in the yoke. The shape of the mantle appear best from figure 5. As shown the submarine conduit is encircled by a termination or mantle 36 provided with parallel side faces 42, 42, a spherical top section 44 and preferably with a somewhat extended section 46 at the other end, preferably ending into a substantially flat cross-sectional end face 48 (see figure 4c). The mantle is further preferably equipped with a pivotable bellyband 40 equipped with mounting means 38 for attaching a pulling wire 24. The bellyband is preferably such arranged that it may pivot freely inside a defined angle, preferably 90° from a centre position, but dependent on the actual type of conduit it may be suitable to reduce or expand the pivoting possibilities for the bellyband. Figures 4 a, b c and d illustrates the initial steps of the conduit in connection with the attachment of the pulling wire. Figure 4a shows a conduit terminal with a non-circular mantle 36 as described, and where the submarine conduit incidentally is positioned on a sea bottom with the wire mounting 38 on a pivotable bellyband pointing straight down into the sea bottom as shown in figure 4a. The bellyband is however provided with one or more auxiliary attachments in the shape of hook 50 on opposite side of the mantle, respectively. By means of a manipulating tool 52 on a ROV 12 the bellyband is moved 90° to the left, such that the mounting means 38 is accessible on the right side of the mantle as shown in figure 4b. Optionally one can use water jets or alike in order to expose the mounting hook. Thereafter the pulling wire 24 is pulled down by the ROV tool and is attached in the mounting as shown in figure 4c. Upon the end of this step the next step, the hauling may be initiated as shown in figure 4d. When the conduit is pulled up into position as shown in figure 1 it will be lifted up from the sea bottom simultaneously as existing torsional stretches in the conduit 2 will be continuously equalised by the pivoting of the bellyband. In the case with single pipelines having circular termination or mantle, the conduit can now be pulled directly up into top position in the yoke 26 as shown in figure 5d. In the case shown in figure 5 is however illustrated the case wherein the conduit mantle comprises several built-in conduits, cables or alike, and such a mantle must be rotationally positioned prior to proceeding with the inter-coupling.

Figures 5a, b, c and d illustrate the rotational adjustment accomplished by the invention during the hauling up into the yoke prior to the finalising adjustment of the submarine conduit. If the mantle for instance contacts the opposing side faces as shown in figure 5a, it will pivot to the left because the distance from the mounting point for the pulling wire on the mantle on the right side is shorter than the corresponding distance from the pulling wire to the yoke wall on the left side, due to the extension of the mantle on the left side as shown. Consequently the mantle will pivot as shown in figure 5b, such that the pivoting is substantially completed as shown. An accurate rotational calibration or adjustment will take place during the further hoisting up along the co-operating parallel side faces, in the yoke and on the mantle, respectively, as shown in figure 5c, having into effect that when the mantle has been pulled completely up to the top wall of the yoke, the rotational adjustment has been completed. The before mentioned limitation of the rotational movement of the bellyband to 90° between two end-positions will normally contribute to a smooth and problem-free angular positioning of the mantle. In a last step of the positioning of the conduit including the mantle the mantle is pulled completely up into longitudinal contact with the top wall of the yoke, having into effect that the submarine conduit is completely positioned and adjusted both angularly and longitudinally such that the longitudinal axis through the conduit runs flush with the axis through the complementary conduit mounted on the bottom frame such that the aimed inter-couple of the two conduits can be accomplished.

It will be understood that hauling and coupling of a submarine conduit by means of the tool and a system in accordance with the invention, the entire coupling operation takes place as a continuous procedure which however is divided into separate steps, such that the conduit is stepwise positioned and adjusted in different planes on different levels. The demand to optimal pulling forces and existing or inherent torsional tensions in conduits and tools will therefore be radi- cally reduced, before all necessary positioning and adjustment takes place prior to the final inter-coupling of the conduits. And it should be noted that the rotational adjustment of conduit bundles encircled in mantles through use of the invention will take place prior to that the conduit mantle and the termination is finally positioned in the yoke. When the submarine conduit has been pulled up into the position shown in figure 3, the tool is moved forwards along the posts 18 in order to position the coupling termination against the complementary conduit mounted on the bottom based frame. In order to provide the necessary supplementary force which can be required in order to clamp the mantle on the submarine conduit into complete contact with the top wall of a yoke, one can utilise a winch having pivotal mounting on the tool, and wherein the support and tool is provided with operating cylinders such that the final hauling can take place directly by the hydraulic cylinders and thereby reduce the necessary power rating of the winch.

It will be understood that many constructional details and the equipment can be altered without leaving the scope of the invention. Thus, one can utilise two separate pulling wires with two winches if desired, and in replacement of posts arranged through or along the yoke unit for the forward movement of the yoke this unit can be provided with roller means mounted in the frame 14 etc..

It is also possible to handle mantles or pipe terminations having various diameter by providing the yoke with laterally adjustable, but lockable sidefaces or side face sections with preservation of the mutual parallelity.

Claims

P a t e n t c l a i m s

1. Tool for hauling and angularly positioned coupling of an initially freely positioned end section of a submarine conduit to a complementary conduit or pipe end mounted on a sea bottom based installation, of the kind wherein the tool includes a downwardly open, substantially U-shaped gripper or yoke for reception and positioning of the submarine conduit tool in connection with the coupling operation, winch equipment (22) mounted on the tool frame for hauling and positioning of side end section of the submarine conduit (2), means for axial dis- placement of the submarine conduit in pulled-in position in the yoke in order to accomplish the inter-coupling of the ends of said two submarine conduits together, the end section of said submarine conduit (2) provided with an encircling mantle or termination adapted for the submarine conduit and the dimensions of the yoke, respectively, and in that a mounting fixture is provided on the mantle for s attachment of a pulling cable connected to the winch equipment (22), c h a r a c t e r i z e d in that the mantle on the end section of said first free pipeline at least along a part of its length is provided with a non-circular cross- sectional shape including two opposed parallel side face parts, the mutual spacing between which substantially corresponds to the space between said two par- o allel side faces in the yoke, in that the cross-sectional surface of said mantle is substantially symmetrical about a central axis extending parallel with said parallel side faces, and in that the mounting point for the pulling cable is located on the mantle on one of the two end parts of said mantle between said parallel side faces, having into effect that the parallel side faces of the mantle serves as a 5 guide and angular positioning of the mantle and thereby the submarine conduit during the hauling up into position in the yoke by means of the winch equipment.

2. Tool in accordance with claim 1 , c h a r a c t e r i z e d in that the cross-sectional area of the mantle of the sub- 0 marine conduit has a greater dimension in direction parallel with the parallel side faces than the dimension between said side faces.

3. Tool in accordance with claim 1 or 2, characterized in that the funnel in a cross-sectional view presents one in operational position downwardly directed opening with two opposed diverted side faces each of which constitute an extension of each respective parallel side face, and in that the distance between said diverted side faces at the opening end is larger than the greatest dimension or length of said cross-sectional area of said yoke.

4. Tool in accordance with claims 1 -3, characterized in that the mounting point for the pulling wire is located on the outside of one of the two end parts of said yoke and at the point along the symmetrical axis there-through, which end part of said mantle is adapted to be pulled up into contact with the uppermost top wall in said yoke.

5. Tool in accordance with claims 1 -3, characterized in that said conduit mantle is provided with a circular section located along the longitudinal extension of said parallel side faces on the mantle, upon which section is located a freely pivotable support ring or so-called bellyband, to which a bellyband is mounted said mounting point for the hoisting wire, the pivoting movement of said support ring or bellyband being defined between two end positions which are positioned respectively in the vicinity of an adjacent end of said parallel side faces on the mantle, respectively.

6. Tool in accordance with claim 5, characterized in that the mounting point on the pivotable support ring for said pulling cable may pivot along an arch of about 90┬░ between the end positions.

7. Tool in accordance with any of the preceding claims, characterized in that the side faces of said yoke (26) or at least a part of side faces (26) are arranged laterally adjustable and lockable, with preservation of the mutual parallel position, having into effect that said yoke can be adapted for angularly positioned hauling and coupling of submarine conduits provided with mantles having various cross-sectional dimensions.

8. Method to be used with a tool as defined in any of the preceding claims, wherein the submarine conduit or pipeline is provided with a mantle in accordance with the invention and initially for instance positioned on a sea bottom in vicinity of the tool furnished with a hauling cable which may be pulled out in order to be attached to an attachment point provided on said mantle, c h a r a c t e r i z e d in that the submarine conduit in a first step is hauled up into the opening of said yoke, thereafter the submarine conduit with said mantle by means of the hauling equipment is manipulated such that a preliminar pivoting of the non-circular mantle is accomplished, such that the end section of the submarine conduit with the fastening point can be hauled further up into the mantle, whereafter the hauling proceeds having into effect that said mantle is forceably pivoted about its longitudinal axis in that the parallel side faces on the mantle are guided between the parallel side faces in the yoke and subsequently is hoisted up to the top section of said yoke having into effect that the end section of said submarine conduit including the mantle is pressed into lengthwise contact with said uppermost part of said yoke, whereafter the yoke including said mantle on the pipeline is moved forward towards the submarine conduit mounted on the sea bottom installation having into effect that the first submarine conduit is angularly positioned relative to the submarine conduit mounted in the sea bottom based installation and can be coupled thereto.