OA17033A - Method of connecting a flexible line to a structure of a fluid operating installation and associated connection device. - Google Patents

Abstract

This method includes providing a flexible line (18) and a bend limiter immobilized axially around the flexible line (18) via a releasable immobilization mechanism (46). It involves the partial insertion of the flexible line (18) through a rigid hollow member (40), immobilization of the curvature limiter on the rigid hollow member (40) and deactivation of the releasable immobilization mechanism (46 ). The releasable immobilizer (46) is deactivated regardless of the movement of the flexible line (18) relative to the bend limiter.

Description

The present invention relates to a method for connecting a flexible line to a structure of a fluid operating installation, comprising the following steps:

- supply of a flexible line and a curvature limiter Axially immobilized around the flexible line by means of a releasable immobilization mechanism;

- Partial insertion of the flexible line through a rigid hollow member integral with the structure;

- immobilization of the curvature limiter on the rigid hollow member;

- deactivation of the releasable immobilization mechanism;

- displacement of the flexible line relative to the curvature limiter in the hollow rigid member, the curvature limiter remaining substantially fixed axially with respect to the hollow rigid member.

Such a method is implemented in particular in installations for the exploitation of hydrocarbons through a body of water, comprising for example a rigid structure fixed to the seabed, an oscillating structure secured to the seabed or a a floating structure such as a surface naval support, a semi-submersible platform, a vertical floating column, or a ship.

The flexible line to be connected to the structure is for example a rising flexible pipe for transporting fluid, designated by the English term “riser”. The term “flexible pipes” means those described in the normative documents published by the American Petroleum Institute (API), API 17J and API RP 17 B and well known to those skilled in the art. More generally, the flexible line can be a composite bundle of the "bundle" type, a set of umbilicals or electric cables.

A method of the aforementioned type is implemented during the installation and connection of the flexible line to the surface structure.

To this end, to reduce the risk of damaging the structure and the flexible line, it is known practice to immerse the flexible line in the body of water under the structure at the surface, and to raise it up to the connection area located on the surface structure using a winch. Such a connection is designated by the English term "pull-in".

The flexible line is guided on the structure by introducing it through a rigid hollow tube integral with the structure, oriented vertically, which constitutes a protective sleeve. The hollow tube is for example of the “1-tube” or “J-tube” type.

At the top outlet of the tube, the flexible line is connected to the surface installation.

In order to avoid damaging the flexible line, in particular under the effect of the agitation of the water liable to cause it to come into contact with the structure, it is known practice to engage around the flexible line, a suitable curvature limiter. locally imposing a radius of curvature greater than the minimum radius of curvature that the flexible line can occupy.

In the remainder of the text, the term “curvature limiter” is understood to mean both curvature limiters consisting for example of articulated rigid elements called “vertebrae”, curvature limiters constituted for example by molded plastic blocks, as well as combinations of these elements.

A curvature limiter is for example arranged around the flexible line near its upper end to cooperate with the hollow tube during insertion of the flexible line into the tube.

To this end, firstly, the curvature limiter and the flexible line are moved together towards the lower end of the hollow tube until the limiter is partially inserted into the hollow tube. Then, in a second step, the flexible line is moved upwards with respect to the curvature limiter to move it up through the hollow tube for its connection to the surface structure.

During this second phase, the curvature limiter is kept motionless in translation in the hollow tube by fitting and / or fixing by means of clamps.

WO 98/23645 describes a method using a single winch to pull the flexible line and the curvature limiter by temporarily securing the curvature limiter to the flexible line using a breakable pin.

When raising the bend limiter to the Lower end of the hollow tube, the bend limiter and the flexible line move together. Then, the bend limiter is attached to the lower end of the tube. Sufficient upward traction is then applied to the flexible line to break the breakable pin to allow upward movement of the flexible line relative to the bend limiter.

Such a process is not entirely satisfactory. Indeed, to allow the release of the flexible line relative to the curvature limiter, it is necessary to locally move the line relative to the curvature limiter to cause the breakage of the frangible pins. Such displacement results from the application of an upward pulling force on the flexible line. Such force can deteriorate driving.

In addition, the method is complex and requires great reliability of the mechanical parts inserted between the flexible line and the curvature limiter.

An object of the invention is to obtain a method of connecting a flexible line to a structure of a fluid operating installation which is simple and reliable to use, with a very limited risk of damage to the line. flexible.

To this end, the invention relates to a method of the aforementioned type, characterized in that the releasable immobilization mechanism is deactivated independently of the movement of the flexible line relative to the curvature limiter.

The method according to the invention can include one or more of the following 10 characteristics, taken alone or in any technically possible combination:

- the releasable immobilization mechanism comprises a retaining member integral with one of the flexible line and the curvature limiter and a movable engaging member, suitable for being placed in an engaging configuration of the member retainer, the deactivation step comprising moving the movable member from the engagement configuration to a retainer release configuration, independent of movement of the flexible line.

- The releasable retaining mechanism comprises an actuator, preferably a hydraulic actuator, the actuator being controlled during the deactivation step to allow the passage of each movable member from its engagement configuration to its release configuration.

- the releasable immobilization mechanism comprises a cage for retaining the movable member, and during the deactivation step, the actuator moves the retaining cage between a first position for holding each movable member in the setting configuration engaged, and a second position, in which each movable member is able to pass into its release configuration.

- the flexible line comprises at least one support flange, the curvature limiter comprising a retaining flange applied to the support flange when the releasable immobilization mechanism is activated, the releasable immobilization mechanism maintaining the flange of support applied to the retaining flange when the curvature limiter is immobilized on the hollow rigid member, the bearing flange being free to move relative to the retaining flange after deactivation of the releasable immobilization mechanism.

The hollow rigid member comprises at least one retaining collar, the curvature limiter comprising at least one member for pre-fixing on the collar, the engagement 35 of the curvature limiter on the hollow rigid member comprising the engagement of the pre-fixing member on the collar.

- The method comprises, after the step of deactivating the releasable immobilization mechanism, the final fixing of the curvature limiter on the hollow rigid member by means of at least one fixing member.

The subject of the invention is also a connection device, intended to be mounted on a structure of a fluid operating installation, comprising:

- a flexible line;

- a hollow rigid member intended to be fixed to the structure, the flexible line being intended to be engaged through the hollow rigid member;

- A curvature limiter engaged around the flexible line, the curvature limiter being intended to be immobilized axially on the hollow rigid member;

- an axial immobilization mechanism releasable from the flexible line on the curvature limiter;

characterized in that the releasable immobilization mechanism is able to be deactivated independently of the displacement of the flexible line with respect to the curvature limiter.

The device according to the invention may include one or more of the following characteristics, taken in isolation or in any technically possible combination:

- the releasable immobilization mechanism comprises a retaining member integral with one of the flexible line and the curvature limiter and a movable engaging member, suitable for being placed in an engaging configuration of the member retainer, the movable member being movable from the engagement configuration to a retainer release configuration regardless of movement of the flexible line.

- The releasable retaining mechanism comprises an actuator, advantageously a hydraulic actuator, the actuator then being controllable to allow the passage of each movable member from the engagement configuration to its release configuration.

- the releasable immobilization mechanism comprises a cage for retaining the movable member, and the actuator can be controlled to move the retaining cage between a first position for maintaining each movable member in the engagement configuration and a second position in which each movable member is able to pass into its release configuration.

- the flexible line comprises at least one support flange, the curvature limiter comprising a retaining flange applied to the support flange when the releasable immobilization mechanism is activated, the releasable immobilization mechanism maintaining the flange of support applied to the retaining flange when the curvature limiter is immobilized on the hollow rigid member, the bearing flange being free to move relative to the retaining flange after deactivation of the releasable immobilization mechanism.

the hollow rigid member comprises at least one retaining flange, the curvature limiter comprising at least one member for pre-fixing to the flange.

- The device comprises at least one member for fixing the curvature limiter on the collar capable of axially immobilizing the curvature limiter with respect to the collar.

The invention will be better understood on reading the following description, given solely by way of example, and made with reference to the accompanying drawings, in which:

• Figure 1 is a schematic view, taken in section along a vertical median plane, of a fluid operating installation comprising a first connection device according to the invention;

• Figure 2 is a partial sectional view, taken along an axial plane, of the flexible line intended to be mounted on the installation of Figure 1, provided with a curvature limiter connected to the line by a mechanism of releasable immobilization;

- Figure 3 is a view similar to Figure 2, during a first step of implementing a connection method according to the invention;

- Figure 4 is a view similar to Figure 3, during a second step of the connection method according to the invention;

- Figure 5 is a view similar to Figure 3, during a third step of implementing the connection method according to the invention, the releasable immobilization means having been deactivated.

- Figure 6 is a partial perspective view of the releasable immobilization means, in an activated configuration, and

- Figure 7 is a view similar to Figure 6 in a deactivated configuration; and

- Figure 8 is a partial view similar to Figure 4 illustrating a variant of the prefixing member.

FIG. 1 illustrates an installation 10 for operating fluid according to the invention. This installation 10 is for example intended to collect a fluid, in particular a hydrocarbon taken from the bottom 12 of a body of water 14, or to transfer this hydrocarbon to a transport vessel.

The installation 10 comprises a structure 16 floating on the body of water and a connection device 17 according to the invention comprising a flexible line 18 intended to be connected to the structure 16.

The body of water 14 is for example a lake, a sea or an ocean. The depth of the body of water to the right of the floating structure 16 is for example between 15 m and 3000 m.

The floating structure 16 is for example a surface naval support, a semi-submersible platform, a floating vertical column, or a ship.

As a variant, the structure 16 is a fixed rigid structure of the “jacket” type or an oscillating structure secured to the seabed.

The structure 16 has an upper surface 22 on which is advantageously mounted a maneuvering winch 24 of the flexible line 18 and a manifold 26 (“manifold” in English) suitable for connecting one end of the flexible line 18.

The winch 24 advantageously comprises a single deployable cable 28 for the traction of the flexible line 18.

The flexible line 18 is, in the example shown in Figure 1, a flexible tubular pipe 30 for transporting fluid internally delimiting a fluid circulation passage. This pipe is also called a riser or "riser", and is intended to connect a collection assembly (not shown) located on the bottom 12 of the body of water to the manifold 26 located on the surface 22 of the floating structure 16.

As a variant, the flexible line 18 is for example a composite bundle of the umbilical or “Integrated service umbilical” (ISU) or IPB type well known to those skilled in the art and described in the normative documents published by the American Petroleum Institute (API ) API RP 17 B section 4.3.4. Alternatively, the flexible line 18 can be a bundle of electric cables.

The pipe 30 has, at its upper end 32, a head 33 for connection to the working line to the cable 28.

As illustrated in Figure 2, the head 33 comprises a connection sleeve 34 attached to the upper end of the conduit 30 and an eyelet 35 for inserting the lower end of the working line to the cable 28. The eyelet 35 is advantageously mounted to rotate on an upper part of the sleeve 34 about a circulation axis AA * of line 18, corresponding to the longitudinal axis AA * of line 18.

The head 33 further comprises a lower bearing flange 36 extending transversely with respect to the longitudinal axis A-A *.

The pipe 30 is for example unwound and submerged in the body of water 14 from a surface laying vessel and is stored on the bottom 12 of the body of water 14, then the end of the pipe 30 (section not placed on the seabed) is abandoned on the bottom 14 via an abandonment cable.

In addition to the flexible line 18, the connection device 17 comprises a hollow rigid tube 40 for guiding and protecting the tubular line 18, integral with the structure 16, a local curvature limiter 42 of the line 18, engaged around the line 18 away from the upper end 32, and an assembly 44 for fixing the curvature limiter 42 to the lower end of the hollow rigid tube 40.

According to the invention, the device 17 further comprises a releasable mechanism 46 for axially immobilizing the curvature limiter 42 on the flexible line 18.

In the example shown in Figure 1, the hollow rigid tube 40 is a straight tube of the "1-tube" type. Alternatively, the tube 40 is a "J-tube" which has a vertical straight upper part and a bent lower end.

The tube 40 comprises a hollow vertical sleeve 50, integral with the structure 16, and a lower end flange 52 located at the lower end of the sleeve 50.

The sleeve 50 defines an interior passage which opens into the body of water 14 at the lower end and which opens at its upper end in the vicinity of the upper surface 22 of the structure, above the body of water. 14.

The end flange 52 is submerged in the body of water 14.

In this example, the curvature limiter 42 comprises, from bottom to top in FIGS. 2 and 3, a rigid lower assembly 62 and an articulated upper assembly 64, attached to the flexible lower assembly 62.

The flexible lower assembly 62 comprises a stiffening block 66 and an intermediate flange 68 for fixing to the hollow rigid tube 40.

The lower block 66 is for example molded from a plastic material such as polyurethane. It has a tapered shape converging downwards.

The intermediate flange 68 is attached to the top of the block 66. It has a peripheral rim which projects radially away from the axis A-A ’relative to the stiffening block 66.

The articulated upper assembly 64 comprises a plurality of tubular vertebrae 70A, 70B assembled axially end to end by means of annular collars 71 (visible in FIG. 2).

The lower vertebra 70B is fixed on a bracket 72 carried by the intermediate flange 68.

The vertebrae 70A, 70B are movable slightly relative to each other between a linear configuration along the A-A 'axis and a slightly curved configuration relative to the linear configuration.

The block 66, the flange 68 and the vertebrae 70A, 70B internally define a central lumen 76 for the circulation of the flexible line 18 which defines the axis A-A 'of circulation of the line 18 in the curvature limiter 42, coincident with the local longitudinal axis of line 18.

In block 66 and in vertebrae 7QA, 70B, lumen 76 is of cross section substantially the same as the outer cross section of line 18.

The blocks 66 and the vertebrae 70A, 70B thus locally impose on the flexible line 18 a radius of curvature greater than the minimum radius of curvature that the flexible line 18 could occupy.

The curvature limiter 42 further comprises an upper retaining flange 73 intended to receive in abutment the lower bearing flange 36 integral with the flexible line 18.

The top flange 73 projects radially from the top assembly 64. A through opening 73A is provided through the top flange 73 to accommodate the immobilization mechanism 46.

As will be seen below, the curvature limiter 42 is movable between a disassembled position shown in Figure 2, in which it is placed away from the hollow rigid tube 40, and a position mounted on the hollow rigid tube 40, shown in Figures 1 and 5, in which the intermediate flange 68 of the limiter 42 is fixed to the lower end of the flange 52.

The fixing assembly 44 comprises members 75 for pre-fixing the curvature limiter 42 on the rigid hollow tube 40 and members 76 for definitive fixing of the curvature limiter 42 on the hollow rigid tube, visible in FIG. 5.

The pre-fixing members 75 are arranged at the periphery of the intermediate flange 68. They are mounted to be able to move radially relative to the intermediate flange 68, between a radially contracted hooking position on the hollow rigid tube 40 (Figures 2, 4 and 5) and a radially separated docking position on the tube 40 (Figure 3). The radially contracted position forms a rest position.

In this example, the pre-fixing members 75 are formed by hooks mounted to rotate at the periphery of the flange 68 about respective axes B-B ’perpendicular to the axis A-A *.

As illustrated in Figure 4, the pre-fixing members 75 are intended to engage around the end flange 52 of the tube 40 to rest on an upper surface of this flange 52 and thus axially retain the limiter. curvature 42 preventing its axial displacement downward.

The pre-fixing members 75 do not oppose the upward axial displacement of the curvature limiter 42 relative to the tube 40.

The definitive fixing members 76 are able to keep applied against one another the intermediate flange 68 of the curvature limiter 42 and the flange 52 of the hollow rigid tube 40. These members 76 are able to axially immobilize the curvature limiter 42 up and down along the AA * axis with respect to the hollow rigid tube 40.

The fasteners 76 are formed, for example, by screw / nut systems inserted through the flange 68 and the collar 52 to keep them applied against each other.

As illustrated in FIG. 2, the releasable immobilization mechanism 46 comprises a retaining member 80 carried by the flexible line 18 and an engagement assembly 81 mounted on the curvature limiter 42.

Referring to Figures 6 and 7, the engagement assembly 81 includes a plurality of movable engagement members 82 for engagement around the retainer 80. The engagement assembly 81 further comprises an outer cage 84 for retaining the movable members 82 and a support piston 85 for the cage 84.

The immobilization mechanism 46 also includes an actuator 86, shown schematically in Figures 6 and 7, intended to move the outer cage 84 to allow the release of the movable members 82.

The retaining member 80 is formed by a rod, preferably a threaded rod, which projects downwardly through the flange 73.

When the head 33 of the flexible line 18 is pressed against the top flange 73, the retainer 80 is inserted through the through opening 73A in the top flange 73 and protrudes downward beyond the top flange 73 to be received in the engagement assembly 81.

The engagement assembly 81 is for example a segmentable nut. Such a segmentable nut is for example marketed under the name “HYDRAQUICK” by the company <HYDRATIGHT ”.

It is mounted under the upper flange 73. The cavity 88 of the cage 84 opens up opposite the through opening 73Λ

The movable members 82 are formed by disjoint threaded segments movable radially between a retracted configuration of engagement of the retainer 80, shown in Figure 6, and a deployed configuration of release of the retainer 80, visible in figure 7.

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The cage 84 is movably mounted along the axis C-C 'of the support piston 85 between a distal position for retaining the movable members 82 and a distal position for disengaging the movable members 82. It defines an internal cavity 88 for receiving the moving parts 82.

In your distal position, your cage 84 externally covers your movable members 82. It maintains each movable member 82 in its engaging configuration and prevents each movable member 82 from moving radially towards its release configuration.

In the proximal position of the cage 84, the movable members 82 are uncovered radially outwards and are free to move radially towards their release configuration.

The actuator 86 is for example a hydraulic actuator suitable for being connected to the cage 84 in order to cause its displacement between your distal position and the proximal position. The actuator 86 is for example carried by a remotely controlled vehicle (ROV) and reversibly connectable to your cage 84.

Alternatively, actuator 86 is a mechanical actuator.

The releasable immobilization mechanism 46 is suitable for being controlled between an activated configuration of axial immobilization of the flexible line 18 with respect to the curvature limiter 42, shown in FIGS. 2 to 4, and a deactivated configuration for releasing the line. flexible 18.

The immobilization mechanism 46 is suitable for being deactivated independently of the displacement of the line 18, in particular without having to exert a tensile force on the line 18, by a simple command of the actuator 86.

In the activated configuration of the mechanism 46, the cage 84 thus occupies its distal position covering the movable members 82 on the outside. The movable members 82 are maintained in their retracted configuration. They are suitable for engaging the retainer 80.

In the deactivated configuration, the actuator 86 has moved the cage 84 to its proximal position to radially uncover the movable members 82.

The movable members 82 are capable of moving radially towards their deployed configuration to release the retaining member 80.

A method of connecting the flexible line 18 to the floating structure 16 will now be described.

Initially, the curvature limiter 42 is engaged around the flexible line 18 and is immobilized axially on the flexible line 18 via the immobilization mechanism 46.

To this end, the pipe 30 is introduced through the rigid lower assembly 62 and the articulated upper assembly 64. The head 33 of the flexible line 18 is placed in contact with the curvature limiter 42. The lower flange 36 carried by the flexible line 18 is advantageously applied against the upper flange 73 carried by the curvature limiter 42.

Releasable immobilizer 46 is placed in its activation configuration. The retainer 80 is introduced through the lower flange 73 of the curvature limiter 42 and through the upper flange 36 present on the head 33.

The retainer 80 then protrudes beyond the lower flange 73 downwards. The free end of the retaining member 80 is then introduced into the internal cavity 88 of the cage 84 between the movable members 82.

The movable members 82 then occupy their contracted configuration in engagement with the retaining member 80.

In this configuration, the curvature limiter 42 is fixed axially on the flexible line 18. The curvature limiter 42 and the flexible line 18 are then movable together by being fixed one on the other.

The assembly formed by the flexible line 18 and the curvature limiter 42 is then immersed in the body of water 14.

When the line 18 is to be connected to the manifold 26 of the structure 16, the winch 24 is activated to lower the cable 28 through the hollow rigid tube 40, then to connect the lower end of the cable 28 to the connection head 33.

The line 18 and the curvature limiter 42 are then placed under the end flange 52 of the hollow rigid tube 40, away from it.

Then, the winch 24 is activated to raise the cable 28 towards the upper end 56 of the hollow rigid tube 40. The rise of the cable 28 causes the joint displacement of the flexible line 18 and of the curvature limiter 42 towards the collar 52. When of this movement, the curvature limiter 42 is partially introduced into the rigid tube 40.

As illustrated by FIG. 3, when the upward movement of the flexible line 18 continues, the pre-fixing members 75 come into contact with the peripheral edge of the flange 52. This causes their radial displacement towards their visible separated position. in Figure 3.

When the upward movement of the line 18 continues, the free ends of the pre-fixing members 75 pass above the collar 52 and are returned to their contracted position to rest against the upper surface of the collar 52. The curvature limiter 42 then rests on the hollow tube 40, while being held in position by the pre-fixing members 75.

Then, in a first variant, the fasteners 76 are put in place. The intermediate flange 68 of the curvature limiter 42 is then applied against the lower surface of the flange 52 and the fasteners 76 are inserted between the flange 68 and the flange 52 to ensure the axial fixing of the curvature limiter 42 at the end. lower part of the hollow rigid tube 40.

This being done, the releasable immobilizer 46 is passed into its deactivated configuration. In this example, the actuator 86 is driven to move the cage 84 from its distal position, shown in Figure 6, to its proximal position, shown in Figure 7.

During this passage, the radial space located outside the movable members 82 is freed, allowing a radial displacement of each movable member 82, towards the deployed configuration. The retaining member 80 is then released from the movable members 82.

No tensile force is applied to line 18 to cause the switch to the disabled configuration. The line 18 remains fixed axially with respect to the curvature limiter 12 during the passage.

This being done, the flexible line 18 is free to move axially upwards with respect to the curvature limiter 42.

The deactivation of the immobilization mechanism 46 is therefore carried out independently of the movement of the flexible line 18, without it being necessary to apply a tensile force to the flexible line 18. This considerably limits the risk of damage to the flexible line. the flexible line 18.

In addition, the reliability of the release of the flexible line 18 is increased, since it is not necessary to have calibrated mechanical parts such as pins. Even if a local tensile stress accidentally applies to the flexible line 18, the releasable immobilization mechanism 46 is only released when the operator of the device 17 chooses, which helps to ensure reliability.

Then, the flexible line 18 is raised through the central opening of the curvature limiter 42 and through the circulation passage of the hollow rigid tube 40, to the collector 26. During this rise, the curvature limiter 42 remains stationary by compared to tube 40.

Then, the line 18 is connected to the manifold 26 to allow the circulation of fluid between the bottom assembly (not shown) and the structure 16 at the surface.

Alternatively, the step of installing the fasteners 76 is performed after the release of the immobilization mechanism 46, after the rise of the flexible line 18 out of the critical path of the operation.

In another variant, the pre-fixing members 75 are carried by the hollow rigid tube 40 and are for example mounted at the periphery of the lower flange 52 projecting downwards.

In yet another variant, the retaining member 80 of the releasable immobilization mechanism 46 is carried by the curvature limiter 42.

The engagement assembly 81 is then carried by the hollow rigid tube 40. In this variant, the retainer 80 protrudes upwardly from the upper flange 73 of the curvature limiter 42. It is introduced into a through opening formed in the lower flange 36 of the head 33 to pass through this flange 36, in order to be engaged with the movable members 82 in the internal cavity 88 of the cage 84.

The operation of this device 17 is similar to that of the device described above.

In the variant illustrated in FIG. 8, the fixing assembly 44 comprises a support 200 mounted at the periphery of the intermediate flange 68 and comprising a portion 202 projecting downwardly relative to the flange 68.

The axis B-B 'of rotation of each pre-fixing member 75 is mounted in the projecting part 202. The pre-fixing member has a longitudinal slot 204 receiving the axis B-B *. It is thus able to move longitudinally perpendicular to the axis B-B ’on a given stroke.

Such an arrangement further improves the mechanical strength and reliability of the fixing assembly 44.

Claims (14)

14 CLAIMS 1. - A method of connecting a flexible line (18) to a structure (16) of an installation (10) for the production of fluid, comprising the following steps: - provision of a flexible line (18) and of a curvature limiter (42) immobilized axially around the flexible line (18) by means of a releasable immobilization mechanism (46); - partial insertion of the flexible line (18) through a rigid hollow member (40) integral with the structure (16); • Immobilization of the curvature limiter (42) on the rigid hollow member (40); - deactivation of the releasable immobilization mechanism (46); - displacement of the flexible line (18) relative to the curvature limiter (42) in the hollow rigid member (40), the curvature limiter (42) remaining substantially fixed axially relative to the hollow rigid member (40) ; characterized in that the releasable immobilizer mechanism (46) is deactivated regardless of movement of the flexible line (18) relative to the bend limiter (42), and in that the releasable immobilizer mechanism (46) has a retainer carried by one of the flexible line (18) and the bend limiter (42) and an engagement assembly mounted on the other of the bend limiter (42) and the flexible line (18) , the engagement assembly being a segmentable nut. 2. - Method according to claim 1, characterized in that the releasable immobilization mechanism (46) comprises a retaining member (80) integral with one of the flexible line (18) and the curvature limiter (42) and a movable engagement member (82), adapted to be placed in an engagement configuration of the retaining member (80), the deactivation step comprising the movement of the movable member (82) from the engagement configuration to a release configuration of the retainer (80), regardless of the movement of the flexible line (18). 3. - Method according to claim 2, characterized in that the releasable retaining mechanism (46) comprises an actuator (86), preferably a hydraulic actuator, the actuator (86) being controlled during the deactivation step to allow moving each movable member (82) from its engagement configuration to its release configuration. 4. - Method according to claim 3, characterized in that the releasable immobilization mechanism (46) comprises a cage (84) for retaining the movable member (82), and in that during the deactivation step , the actuator (86) moves the retaining cage (84) between a first holding position of each movable member (82) in The engagement configuration, and a second position, in which each movable member (82) is adapted to pass into its release configuration. 5. - Method according to any one of the preceding claims, characterized in that the flexible line (18) comprises at least one support flange (36), the curvature limiter (42) comprising a retaining flange (68) applied to the backing flange (36) when the releasable immobilizer (46) is activated, the releasable immobilizing mechanism (46) keeping the backing flange (36) applied to the retaining flange (68) when immobilizing the curvature limiter (42) on the rigid hollow member (40), the bearing flange (36) being free to move relative to the retaining flange (68) after deactivation of the mechanism d 'releasable immobilization (46). 6. - Method according to any one of the preceding claims, characterized in that the hollow rigid member (40) comprises at least one retaining flange (52), the curvature limiter comprising at least one pre-fixing member ( 75) on the collar (52), the engagement of the curvature limiter (42) on the rigid hollow member (40) comprising the engagement of the pre-fixing member (75) on the collar (52) . 7. - Method according to any one of the preceding claims, characterized in that it comprises, before or after the step of deactivating the releasable immobilization mechanism (46), the final fixing of the curvature limiter (42) on the hollow rigid member (40) via at least one fixing member (76). 8. - Connection device (17), intended to be mounted on a structure (16) of an installation (10) for operating fluid, comprising: - a flexible line (18); * a rigid hollow member (40) intended to be fixed to the structure (16), the flexible line (18) being intended to be engaged through the rigid hollow member (40); - a curvature limiter (42) engaged around the flexible line (18), the curvature limiter (42) being intended to be immobilized axially on the hollow rigid member (40); - a mechanism (46) for releasable axial immobilization of the flexible line (18) on the curvature limiter (42); characterized in that the releasable immobilization mechanism (46) is adapted to be deactivated independently of the displacement of the flexible line (18) relative to the curvature limiter (42), and in that the releasable immobilization mechanism (46 ) has a retainer carried by one of the flexible line (18) and the bend limiter (42) and an engagement assembly mounted on the other of the bend limiter (42) and the flexible line (18), the engagement assembly being a segmentable nut. 9. - Device (17) according to claim 8, characterized in that the releasable immobilization mechanism (46) comprises a retaining member (80) integral with one of the 16 flexible line (18) and of the curvature limiter (42) and a movable engagement member (82), suitable for being placed in an engaging configuration of the retaining member (80), the member movable (82) being movable from the engagement configuration to a release configuration of the retainer (80) independent of the movement of the flexible line (18). 10. - Device (17) according to claim 9, characterized in that the releasable retaining mechanism (46) comprises an actuator (86), preferably a hydraulic actuator, the actuator (86) being controllable when to allow the passage of each movable member (82) from the engagement configuration to its release configuration. 11. - Device (17) according to claim 10, characterized in that the releasable immobilization mechanism (46) comprises a cage (84) for retaining the movable member (82), and in that the actuator ( 86) is controllable to move the retaining cage (84) between a first position for holding each movable member (82) in the engagement configuration and a second position in which each movable member (82) is able to pass into its release configuration. 12. - Device (17) according to any one of claims 8 to 11, characterized in that the flexible line (18) comprises at least one support flange (36), the curvature limiter (42) comprising a flange retainer (68) applied to the backing flange (36) when the releasable immobilizer (46) is activated, the releasable immobilizer (46) keeping the backing flange (36) applied to the flange retainer (68) when the curvature limiter (42) is immobilized on the rigid hollow member (40), the bearing flange (36) being free to move relative to the retaining flange (68) after deactivation of the releasable immobilization mechanism (46). 13. - Device (17) according to any one of claims 8 to 12, characterized in that the hollow rigid member (40) comprises at least one retaining collar (52), the curvature limiter (42) comprising at at least one pre-fixing member (75) on the collar (52). 14. - Device (17) according to any one of claims 8 to 13, characterized in that it comprises at least one member (76) for fixing the curvature limiter (42) on the collar (52) suitable for immobilizing axially the curvature limiter (42) with respect to the collar (52).