End Connection Assembly and Method for Producing the Same

Abstract

An end connection assembly (200) for pull-in and coupling of a flexible tubular pipe to an inboard hub of a subsea structure using a tie-in tool, which flexible tubular 234 pipe comprises a plurality of superposed flexible layers (210, 214, 218) of metal materials and plastics materials, wherein the end connection assembly comprises an end fitting (202) which is connected to an end section (204) of the flexible tubular pipe in a sealed manner forming a termination of the flexible tubular pipe in which at least one layer of said plurality of flexible layers is anchored; an engagement surface (226a, 226b) for interacting with engagement means of the tie-in tool; and a collet connector assembly allowing releasable coupling of the end connection assembly to the inboard hub. The engagement surface is arranged in the end fitting radially outside of and circumferentially enclosing the at least one flexible layer.

Claims

1. An end connection assembly for pull-in and coupling of a flexible tubular pipe to an inboard hub of a subsea structure using a tie-in tool, the flexible tubular pipe comprising a plurality of superposed flexible layers of metal materials and plastics materials, the end connection assembly comprising: an end fitting which is connected to an end section of the flexible tubular pipe in a sealed manner to form a termination of the flexible tubular pipe in which at least one layer of said plurality of flexible layers is anchored; an engagement surface for interacting with engagement means of the tie-in tool; and a collet connector assembly for releasably coupling the end connection assembly to the inboard hub; wherein the engagement surface is arranged on the end fitting radially outside of and circumferentially enclosing the at least one flexible layer.

2. The end connection assembly according to claim 1, wherein the engagement surface is circular-cylindrical.

3. The end connection assembly (200) according to claim 1, wherein the end fitting comprises an annular recess for mounting of the collet connector assembly to the end fitting.

4. The end connection assembly according to claim 3, wherein the end fitting forms an internal body of the collet connector.

5. The end connection assembly according to claim 1, wherein the end fitting comprises: a first section which is connected to an outer layer of said plurality of superposed flexible layers in a sealed manner; and a second section which is connected to an inner layer of said plurality of superposed flexible layers in a sealed manner; wherein said engagement surface is arranged radially outside of and circumferentially encloses the inner layer.

6. The end connection assembly according to claim 5, wherein the first section is connected to the second section in a sealed manner enclosing at least one intermediate layer of said plurality of superposed flexible layers in an annular volume between the first section and the second section, and wherein said engagement surface is arranged radially outside of and circumferentially encloses the at least one intermediate layer.

7. The end connection assembly according to claim 6, wherein the at least one intermediate layer comprises armour formed by a pair of crossed armour plies wound in opposite directions.

8. A method of producing an end connection assembly for pull-in and coupling of a flexible tubular pipe to an inboard hub of a subsea structure using a tie-in tool, the flexible tubular pipe comprising a plurality of superposed flexible layers of metal materials and plastics materials, the method comprising: connecting an end fitting to an end section of the flexible tubular pipe in a sealed manner to form a termination of the flexible tubular pipe in which at least one layer of said plurality of flexible layers is anchored; at a location radially outside of the at least one flexible layer, providing the end fitting with an engagement surface for interacting with engagement means of the tie-in tool, wherein engagement surface circumferentially encloses said at least one flexible layer; and mounting on the end fitting a collect connector assembly for releasably coupling the end connection assembly to the inboard hub.

9. The method according to claim 8, wherein the step of connecting the end fitting to the end section of the flexible tubular pipe comprises the steps of: connecting a first section of said end fitting to an outer layer of said plurality of superposed flexible layers in a sealed manner; connecting a second section of said end fitting to an inner layer of said plurality of superposed flexible layers in a sealed manner; and connecting the first section to the second section in a sealed manner enclosing at least one intermediate layer of said plurality of superposed flexible layers in an annular volume between the first section and the second section; wherein the step of providing the end fitting with the engagement surface comprises providing the first section with the engagement surface; and wherein the step of mounting the collect connector assembly on the end fitting comprises mounting the collect connector assembly on the second section.

10. The method according to claim 9, wherein the second section of the end fitting is produced from a first sub-section and a second sub-section, and wherein the method comprises the steps of: connecting the first sub-section to the at least one inner layer; forming a first sub-assembly by connecting the first section to the first sub-section in a sealed manner, thereby enclosing the least one intermediate layer in an annular volume between the first section and the first sub-section; testing the integrity of the seal between the first section and the first sub-section; forming a second sub-assembly by mounting the collect connector assembly on the second sub-section; testing the integrity of the seal between the collect connector assembly and the second sub-section; and after said steps of testing the integrity of the seals, attaching the second sub-assembly to the first sub-assembly by attaching the second sub-section to the first sub-section.

11. The method according to claim 10, wherein the step of attaching the second sub-assembly to the first sub-assembly comprises joining the second sub-section and the first sub-section by welding.

Description

DESCRIPTION OF THE DRAWINGS

[0054] Following drawings are appended to facilitate the understanding of the invention:

[0055] FIG. 1 is a partial schematic cutaway view of a flexible tubular pipe;

[0056] FIG. 2 is a semi-axial view of a first embodiment of an end connection assembly according to the invention;

[0057] FIG. 3 is a semi-axial view of a second embodiment of an end connection assembly according to the invention;

[0058] FIG. 4 illustrates a procedure of connecting a flexible tubular pipe to an inboard hub of a subsea structure using an end connection assembly according to the invention and a first type of tie-in tool; and

[0059] FIGS. 5a-5d illustrates a procedure of connecting a flexible tubular pipe to an inboard hub of a subsea structure using an end connection assembly according to the invention and a second type of tie-in tool.

[0060] In the drawings, like reference numerals have been used to indicate common parts, elements or features unless otherwise explicitly stated or implicitly understood by the context.

DETAILED DESCRIPTION OF THE INVENTION

[0061] In the following, one or more specific embodiments of the invention will be described in more detail with reference to the drawings. However, it is specifically intended that the invention is not limited to the embodiments and illustrations contained herein but includes modified forms of the embodiments including portions of the embodiments and combinations of elements of different embodiments as come within the scope of the following claims. It should be appreciated that in the development of any such actual implementation, as in any engineering or design project, numerous implementation- specific decisions must be made to achieve the developer's specific goals, such as compliance with system and/or business-related constraints, which may vary from one implementation of the invention to another. Moreover, it should be appreciated that such a development effort might be complex and time consuming, but would nevertheless be a routine undertaking of design, fabrication and manufacture for the skilled person having the benefit of this disclosure.

[0062] FIG. 1 illustrates, in a cutaway view, an example of a flexible tubular pipe 10 for which the end connection assembly according to the invention is suitable to be adopted. The pipe 10 has a pipe axis C and comprises a plurality of superposed flexible layers provided radially one on top of the another, from the inside of the pipe to the outside. The inside of the pipe 10 forms an internal flow space for hydrocarbon fluid.

[0063] In the shown embodiment, the flexible tubular pipe 10 comprises, from the inside to the outside, an internal sealing sheath made of polymer material 12, a metal vault 14 formed by the helical winding at a short pitch of at least one metal wire in the form for example of a self-interlocked zeta wire, if necessary a hoop reinforcement 16 formed by a winding at short pitch of a rectangular wire, an anti-collapse intermediate wire 18, armour 20 resistant to axial tension in the longitudinal direction of the pipe and formed by a pair of crossed armour plies wound at a long pitch in opposite directions, and an external sealing sheath made of polymer material 22. The internal sealing sheath 12 is also referred to as pressure sheath. The external sealing sheath 22 is also referred to as external sheath. The metal vault 14 and the hoop reinforcement 16 form the pressure vault 14, 16 of the pipe 10. The main function of the pressure vault 14, 16 is to react the forces associated with the pressure of the fluid flowing through the pipe 10.

[0064] The pipe 10 shown in FIG. 1 is referred to as a smooth bore pipe since its first layer starting from the inside is a polymeric tube having a smooth internal surface. This type of pipe has an anti-collapse intermediate sheath 18 so as to protect the internal sheath 12 in the event of a loss of sealing of the external sheath 22. Specifically, when the pipe 10 is submerged, an accidental loss of sealing of the external sheath 22 causes flooding of the inside of the wall of the pipe. In this case, the seawater is stopped by the sealed intermediate sheath 18, the latter being able to react the hydrostatic pressure since it is supported by the pressure vault 14, 16. In this way, the hydrostatic pressure is not applied to the external face of the pressure sheath 12 and does not cause this sheath to collapse.

[0065] The end connection assembly according to the invention could also be applied to pipes referred to as rough bore pipes. These pipes have a metal carcass situated inside the pressure sheath 12. This carcass generally consists of a profiled and interlocked spiral metal strip, its main function being to react the forces associated with the hydrostatic pressure.

[0066] Reference is now made to FIG. 2, which illustrates, in a semi-axial view, an embodiment of an end connection assembly 200 according to the invention connected to a flexible tubular pipe comprising a plurality of flexible layers.

[0067] The end connection assembly 200 comprises an end fitting 202 which is connected to an end section 204 of the flexible tubular pipe 10 in a sealed manner. The end fitting 202 forms a termination of the flexible tubular pipe 10 in which the layers of the flexible pipe are anchored.

[0068] The end fitting 202 comprises tubular first and second sections 206, 208.

[0069] The first section 206 of the end fitting 202 is connected to an outer layer 210 of the pipe 10 in a sealed manner. The outer layer 210 may for example be an external sealing sheath 22 of the type previously discussed in relation to FIG. 1 and may be connected to the first section 206 by means of a first ring, or cannula, 212, crimping the outer layer 210 against an interior surface of the first section 206.

[0070] The second section 208 of the end fitting 202 is connected to an inner layer 214 of the pipe 10 in a sealed manner. The inner layer 214 may for example comprise an internal pressure sheath 12, a metal vault 14, a hoop reinforcement 16 and/or an intermediate wire 18 of the type previously discussed in relation to FIG. 1, and the inner layer 214 may be connected to the second section 208 by means of a second ring, or cannula, 216, crimping the inner layer 214 against an interior surface of the second section 208.

[0071] The first section 206 is connected to the second section 208 in a sealed manner covering at least one intermediate layer 218 of the pipe 10, which at least one intermediate layer 218, in the axial direction of the end fitting 202, extends in between the first and second sections 206, 208. In other words, the terminal end section of the at least one intermediate layer 218 is arranged radially outside of the second section 208 but radially inside of the first section 206. The at least one intermediate layer 218 may for example comprise an armoured layer 20 of the type previously discussed in relation to FIG. 1.

[0072] The first section 206 is connected to the second section 208 in a sealed manner by means of a threaded joint 220 and a pair of annular sealing rings 222.

[0073] At its free end, the second section 208 of the end fitting 202 comprises an annular recess 224 which allows a collet connector assembly (not shown in FIG. 2, but see FIGS. 5b-5d) to be mounted to the second section 208. As is known in the art of hydrocarbon production, processing and storage, a collet connector is used to provide a tight connection between two fluid carrying elements and comprises fingers arranged to grip a radially protruding flange or hub of an opposing fluid carrying element. The collet connector may be a KC-connector, e.g. a KC-4 connector, which is well known in the art.

[0074] At its outer surface, the first section 206 of the end fitting 202 comprises first and second engagement surfaces 226a, 226b which are arranged for interacting with engagement means, e.g. pull-in clamps, of a tie-in tool. Each engagement surface 226a, 226b is circular-cylindrical, allowing the engagement means access to the engagement surfaces 226a, 226b independent of the circumferential orientation of the tie-in tool vis--vis the end fitting 202. The engagement surfaces 226a, 226b are bounded by a radially extending annular surface 228a, 228b that prevent the engagement means from slipping or gliding in the axial direction of the end fitting 202 when the engagement means are in engagement with the engagement surfaces 226a, 226b.

[0075] In order to reduce mechanical stress on the end connection assembly 200, bending restrictors 234 may be attached to the end fitting.

[0076] When producing the end connection assembly 200, the end fitting 202 is connected to the end section 204 of the flexible tubular pipe in a sealed manner by attaching the inner layer 214 of the pipe to the interior of the second section 208 and arranging the at least one intermediate layer 218 such that it circumferentially encloses the axial end of the second section 208 facing the pipe end section 204. Thereafter, the first section 206 is connected to the second section, enclosing the at least one intermediate layer 218, and the annular volume 230 between the first and second sections 206, 208 in which the at least one intermediate layer 218 is housed is filled with a resin which, when cured, fixes the intermediate layer or layers 218 in their intended positions. The collet connector assembly (not shown in FIG. 2, but see FIGS. 5b-5d) is then attached to the second section 208, after which the integrity of the seal between the end fitting 202 and the end section 204 of the pipe, and also between the end fitting 202 and the collet connector, is tested.

[0077] According to an alternative embodiment of the end connection assembly 200 (see FIG. 3), the second section 208 of the end fitting 202 is produced from a first sub-section 208, which is connected to the inner and intermediate layers 214, 218 and the first section 206 as is discussed above, and a second sub-section 208, to which the collet connector assembly is attached. This allows the end section 204 of the pipe, the first section 206 and the sub-section 208, on the one hand, and the sub-section 208 and the collet connector assembly, on the other hand, to be assembled and tested independently of each other, which may be beneficial for logistical reasons. When the integrity of the seals of the two sub-assemblies thus formed have been tested, sub-section 208 can be attached, e.g. welded, to sub-section 208 to form the final end connection assembly. In FIG. 3 such an alternative embodiment is disclosed, showing a weld joint 232 at the interface between sub-sections 208 and 208.

[0078] The procedure of connecting a flexible tubular pipe equipped with one of the above-described end connection assemblies to a subsea structure using a tie-in tool may vary depending on which tie-in tool is used.

[0079] With reference to FIG. 4, the procedure using the tie-in tool marketed as ROVCON generally comprises the steps of: [0080] using a Remotely Operated Vehicle (ROV) 300, docking the tie-in tool 302 to the end connection assembly 200 by bringing engagement means (not visible in FIG. 4) of the tie-in tool 302 into engagement with the engagement surfaces 226a, 226b; [0081] using the ROV 300 to operate the tie-in tool 302, bringing the end connection assembly 200 into alignment with an inboard hub 306 of the subsea structure 308, pulling in the end connection assembly 200 to the inboard hub 306, and bringing the collet connector of the end connection assembly 200 into locking engagement with the inboard hub 306; and [0082] releasing the tie-in tool 302 from the end connection assembly 200 by bringing the engagement means to release the grip of the engagement surfaces 226a, 226b.

[0083] With reference to FIGS. 5a-5d, the procedure using the tie-in tool marketed as UCON generally comprises the steps of: [0084] connecting the tie-in tool 302 to the end connection assembly 200 by bringing engagement means (not visible in FIGS. 5a-5d) of the tie-in tool 302 into engagement with the engagement surfaces 226a, 226b of the end connection assembly 200; [0085] bringing the tie-in tool 302 with attached end connection assembly into alignment with an inboard hub 306 of the subsea structure 308 (see FIG. 5a), [0086] using a stroking tool 310, pulling in the end connection assembly 200 towards the inboard hub 306 (see FIG. 5b, where the collet collector assembly 312 of the end connection assembly and the inboard hub 306 are shown in sectional views), [0087] bringing the collet connector 312 into locking engagement with the inboard hub 306 (see FIG. 5c); and [0088] releasing the stroking tool 310 from the tie-in tool 302 (see FIG. 5d).

[0089] In the preceding description, various aspects of the apparatus according to the invention have been described with reference to the illustrative embodiment. For purposes of explanation, specific numbers, systems and configurations were set forth in order to provide a thorough understanding of the apparatus and its workings. However, this description is not intended to be construed in a limiting sense. Various modifications and variations of the illustrative embodiment, as well as other embodiments of the apparatus, which are apparent to person skilled in the art to which the disclosed subject-matter pertains, are deemed to lie within the scope of the present invention as defined by the following claims.