WO2015082275A1

WO2015082275A1 - Connection end-fitting of a flexible pipe with the armour threads anchored by trapping

Info

Publication number: WO2015082275A1
Application number: PCT/EP2014/075648
Authority: WO
Inventors: Fabrice DELEAU; Gerard Papon
Original assignee: IFP Energies Nouvelles; Technip France
Priority date: 2013-12-03
Filing date: 2014-11-26
Publication date: 2015-06-11
Also published as: GB2535925B; FR3014165B1; GB2535925A9; BR112016012426A2; GB2535925A; FR3014165A1; DK179648B1; BR112016012426B1; GB201609767D0

Abstract

The present invention relates to a connection end-fitting for a flexible pipe, in which the armour threads (4) are anchored by trapping between at least two jaws (7, 8). The jaws (7, 8) have more or less a tapered shape and are formed in such a way that the armours (4) have a continuous radius of curvature. In that way, the armour does not have any singular point in the end-fitting.

Description

CONNECTION TIP FOR A FLEXIBLE CONDUIT WITH ANCHORING OF WIRES

ARMOR BY COIN

The present invention relates to a connector for connecting a flexible pipe, in particular for transporting a fluid in a marine environment. It relates more particularly to a flexible pipe of unbound type ("unbonded" in English) used for the offshore exploitation of oil and / or gas fields.

These flexible pipes, generally tubular, formed of a set of different layers of concentric and superimposed weave wires, are said to be of unbound type when the armor and the layers have a certain freedom to move relative to each other. other.

These flexible pipes can satisfy, among others, the recommendations of the normative documents API 17J "Specification for Unbonded Flexible Pipe" and API RP 17B "Recommended Pratice for Flexible Pipe" established by the American Petroleum Institute.

In general, the constituent layers include sheaths of polymer material generally providing a sealing function, and reinforcing layers for the recovery of mechanical forces. These reinforcing layers are formed by windings of strips, metal son, various bands or profiles of composite materials.

Figure 1 illustrates a flexible pipe of unbound type used for the offshore exploitation of oil and gas fields. Such a flexible pipe generally comprises, from the inside to the outside, an internal carcass (1) consisting of an interlocked strip which serves to resist the crushing of the pipe under the effect of external pressure, a sheath internal pressure (2), a pressure vault (3) consisting of at least one metal wire of stapled form and wound helically with a short pitch, said pressure vault (3) serving to take up the radial forces related to the internal pressure at least one tensile armor ply (4) (four plies as illustrated in FIG. 1) formed of helical windings with a long pitch of threads, strips, metal or composite strips, said plies of armor ( 4) being intended to take up the longitudinal forces experienced by the pipe, and an outer sealing sheath (5) for protecting the seawater reinforcing layers.

The pipe illustrated in FIG. 1 is said to have a non-smooth internal passage ("rough-bore" in English), that is to say that the fluid flowing in the pipe is in contact with the internal carcass (1), said inner carcass ( 1) being indeed the first layer starting from the inside. However, the flexible pipe can also be smoothly internal ("smooth-bore" in English), in this case, the first layer of the pipe from the inside is an additional sealing sheath, for example polymer material.

The flexible tubular pipes comprise, at each end, a connection piece for connecting the pipes between them, or with terminal equipment. These tips must be made in conditions ensuring both a good connection and a good seal.

Indeed, the connection ends must perform several functions which are, in particular the anchoring of the tensile armor as well as the crimping and sealing of the free ends of the different sheaths, and in particular the crimping at the free end of the internal pressure sheath. An essential function of a rigid end of a flexible pipe is to transmit a tension force, and among the various layers that make up the hose, it is the layers of armor that take up this effort, therefore the anchoring of the armor conditions the static and fatigue resistance of the system.

An example of connection tip is described in particular in the patent application FR 2816389 A1. For this embodiment, the armor is folded and unfolded and the anchoring of the armor is made by means of an epoxy resin. The general shaping of the armor wires induces concentration factors due to the particular geometry and its local plastic and elastic deformations.

When the conditions of use are severe, the fatigue resistance of this system is not sufficient. Indeed, for this tip, the manufacture and realization (including folding / unfolding) induce in operation a significant stress of the son in an area near the entrance to the tip (at the detachment of armor); the wire is subjected to tensile stress, normal and transverse bending with a state of significant residual stresses.

To overcome this drawback, the present invention relates to a connector for a flexible pipe, for which the anchoring of the armor son is made by wedging between two jaws. The jaws have a substantially conical shape and are shaped such that the armor has a continuous radius of curvature. Thus, the armor does not have a singular point in the tip and ensures good resistance to fatigue. In addition, the required geometrical shape of the wires in the end piece is preferably close to its free form in order to avoid introducing maximum residual plastic and elastic stresses (in particular due to the folding / unfolding step). The device according to the invention

The invention relates to a connecting end of a flexible pipe, said flexible pipe being of the unbonded type and comprising in particular an inner pressure sheath and at least one layer of tensile armor wound around said pressure sheath, each of said traction armor plies comprising an end length anchored in said tip. The anchoring of each of said ends is achieved by wedging said end between two jaws so that said end length has no singular point, said jaws being disposed in said tip and being substantially conical.

According to the invention, said end length has a substantially continuous radius of curvature.

Advantageously, said jaws have a shape of a cone of revolution whose generatrix is substantially a straight line at an angle to the axis of revolution of said flexible pipe less than 20 °, preferably less than 10 ° and preferably substantially equal to at 5 °, an arc of a circle or a portion of ellipse, parabola or hyperbole or formed by two consecutive radii of curvature.

According to one embodiment of the invention, said flexible pipe comprises at least two traction armor plies wrapped around said pressure sheath, said ends of said traction armor plies being arranged one above the other and stuck between two jaws.

According to another embodiment of the invention, said flexible pipe comprises at least two traction armor plies wrapped around said pressure sheath, each end of said armor plies being stuck individually between two jaws.

Preferably, said flexible pipe comprises two plies of tensile armor wound around said pressure sheath and said tip comprises three jaws, among which an intermediate jaw in contact with each of said ends of said plies of tensile armor.

Advantageously, at least one of said jaws is moved by means of at least one threaded rod.

According to one aspect of the invention, at least one of said jaws is made of mild steel.

In addition, at least one of said jaws may include a polymer thickness at the contact with said end length of one of said tensile armor plies.

Preferably, said polymer thickness is made of an elastomeric material. Advantageously, one of said jaws is fixed on said tip or on one of the layers of said flexible pipe.

According to an alternative embodiment of the invention, at least one of said jaws is grooved for the pre-positioning of said end length of a sheet of tensile armor.

Advantageously, the clamping pressure exerted by said jaws on said end length is between 3 and 100 MPa, preferably substantially equal to 50 MPa.

In addition, the invention relates to a flexible pipe of the unbound type comprising in particular an inner pressure sheath and at least one layer of tensile armor wound around said pressure sheath. Said flexible pipe comprises at least one of these ends a connection tip according to the invention.

Brief presentation of the figures

Other features and advantages of the method according to the invention will appear on reading the following description of nonlimiting examples of embodiments, with reference to the appended figures and described below.

Figure 1, already described, illustrates a flexible pipe.

Figure 2 illustrates a sectional view of a nozzle according to a first embodiment of the invention.

Figure 3 illustrates a sectional view of a connection tip according to a second embodiment of the invention.

FIG. 4 represents a three-dimensional cross-sectional view of a connector end according to the second embodiment of the invention.

Figure 5 shows a sectional view of the second embodiment of the invention.

Figure 6 illustrates the forces exerted on an armor in a mouthpiece according to the invention.

Figure 7 illustrates a step prior to the manufacture of the tip according to the second embodiment of the invention.

FIG. 8 illustrates the sealing zones of the nozzle according to the second embodiment of the invention.

Figure 9 illustrates an embodiment of the jaws for the two embodiments of the invention.

Figure 10 illustrates the winding angle of a weave wire. Detailed description of the invention

The present invention relates to a connecting end of a flexible pipe, in which the rigid endpiece has the particular function of taking up the axial mechanical tension to which the flexible pipe is urged. For this, the invention consists in anchoring in the connection tip armor plies included in the flexible pipe, by pinching (pinching) the ends of the armor plies between jaws to make their hooks to the rigid part of the mouthpiece. According to the invention, the jaws are substantially conical and have a form of jamming so that the wire does not have a singular point in the tip to avoid soliciting the armor at their anchor. A singular point is a point of the armor for which the shape (three-dimensional trajectory) of the armor varies abruptly, that is to say a point for which the derivative of the form (trajectory) is not continuous. At a singular point, the armor is strongly constrained (stress concentration), which generates a reduction in static resistance and fatigue resistance. The singular points may be due to the shape of the armor (for example a discontinuity, or a reversal as described in the patent application FR 2816389 A1) or to the manufacturing process. An important angle formed by two line segments is an example of a singular point.

Indeed, an advantage of the invention is the progressivity of the anchoring which is possible by the pinch system and a geometry that does not have a singular point. This is possible with geometry having the following characteristics:

the geometry (three-dimensional) of the wire is continuous, the derivative of the average fiber of the armor wire being continuous,

the laying surface of the wire has no inflection point, the second derivative of the equation of the laying curve of the thread f (x) is always of the same sign, f "(x)> 0 or f "(x) <0.

FIG. 11 gives an exemplary embodiment of the geometry G of the armor wire in the anchoring, as a function of the depth of anchorage. This profile consists of two successive radii of curvature. In the case where the laying envelope of the wire is constituted by an assembly of surfaces connected in a tangent manner, the connections will induce jumps of normal curvature. However, these bending breaks generate an additional bending stress which must be limited. This stress will come to add to the tensile stress due to the normal stress of the hose. According to the invention, the stress Δσ generated by the jump of curvature AC _n must not be high, and preferably this stress does not exceed 10% of the maximum stress acceptable by the armor wire. current length (o _max = 0.55 σ _β , with σ _β the elastic limit of the armor wire). We can write the following relation: Ασ = Ε.-. AC _n with E Young's modulus, and e the thickness of the armor. To avoid over-stressing, bending jumps are minimal at the entrance of the anchor where the stress in the wire is maximum. It is possible to change the thread path of the current length with a minor modification of the local curvature of the armor wire. In addition, in the anchor, larger jumps of curvature are permissible as long as the over-stress does not exceed the maximum stress of the current length.

According to the invention not to present over-stress, the normal curvature of the wire in the anchor undergoes a sudden change in curvature. Advantageously, the variation of curvature AC _n of the armor wire in the anchor can be limited, preferably such that AC _n ≤ ^η ^ ^ with C _n expressed in mm ^-1 . flexible of diameter D and wound (armed) with an angle is expressed:

S in ² a

C "= 2 .---. This bend for hoses from 2 "(about 5.08 cm) to 20" (about 50.8 cm) armored between 20 and 55 ° is between: 4.6.10 ^"3 <C _n ≤ 26.10 ^{" 3} mm ^_1 .

For example, for a 4 "hose (about 10.16 cm) armed at 35 °, the curvature in current length is equal to C _n = 6.5.10 ^{" 3} mm ^" .1 Therefore, according to the criterion above , the variation of curvature must not exceed: AC _n ≤ 9A0 ^{~ 6} mm ^{~ 2} Advantageously, the jaws have a shape of a cone of revolution whose bases are substantially circular and whose generator may be a straight line, a bow of circle, a portion of an ellipse, parabola or hyperbola or formed by two consecutive radii of curvature.Thus, the trajectory of the armor wire in the tip may be a straight line, but is preferably a a curve between the geodesic (zero transverse curvature in the armor) and the loxodrome (constant arming angle), which allows for additional capstan dragging, thus the radius of curvature of the end length of the armor. armor is substantially continuous, which allows a good distribution of the stresses of the thread n of the anchor and which avoids the singular points in the tip (limitation of stress concentrations at a point of the end length). Indeed, this bit geometry makes it possible to have:

a progressive clamping pressure from the entry of the jaws to the final termination,

a progressive immobilization of the armor, and - good resistance to fatigue.

The level of tension in the armor yarn is progressively reduced by the load transfer due to friction between the yarn and the jaws.

Figure 10 shows the winding angle of a weave wire (4) on a tapered trunk. The armor wire (4) is thus wound on a conical trunk (jaws). The angle β between the tangent

(t) to the wire and the axis (A) of the conical trunk is preferably between 10 and 60 °. This winding makes it possible to press the wire against the surface of the conical trunk (creation of a normal force wire / jaw). The intensity of the normal force depends on the tensile force applied to the wire. Considering a coefficient of friction at the wire / jaw interface, a force is transmissible to the interface by friction (capstan effect).

Note that the grip length of the jaws can be quite reduced (between 100 mm and 500 mm).

According to an alternative embodiment of the invention, the cone angle (half-angle at the top) of the jaws is preferably between 2 and 30 ° and preferably substantially 5 °, in order to limit the radius of curvature of the armor.

The anchoring of the armor may be common (see first embodiment of FIG. 2) or non-common (see second embodiment of FIG. 3) to the two plies between two jaws (completely independent system). The remainder of the description and the figures are given for a flexible pipe which comprises a carcass, an inner sheath, a pressure vault, and two layers of armor, but the invention is suitable for all types of flexible pipes comprising at least one internal pressure sheath and at least one layer of tensile armor wound around the pressure sheath. In particular, the invention is suitable for all numbers of armor plies, in particular for four plies of armor. Advantageously, the plies of armor are arranged in pairs to have a balance in torsion since two plies of tensile armor are cabled in opposite directions.

For the first embodiment of the invention illustrated in FIG. 2, the flexible pipe is composed of the interior towards the outside of a carcass (1), of an inner sheath (2), of a roof of pressure (3) and two plies of tensile armor (4) and the plies of armor (4) are anchored in the tip (6) by wedging by means of two jaws (7, 8). The jaws (7, 8) are movable towards each other in the axial direction of the hose, so as to generate a clamping force for anchoring the armor (4). For this first embodiment of the invention, the armor plies (4) are arranged one above the other between the jaws (7, 8). Thus, the anchoring of the two layers of armor (4) is performed simultaneously. One of the jaws (8) is in contact with the cap of the tip (6) and the other jaw (7) is in contact with the inner layers (arch or sheath) of the flexible pipe. The jaws (7, 8) can slide on the internal parts (layers under the armor) or external (hood). Alternatively, one of the jaws is mechanically secured to the part that supports it by screw, thread, welding or by manufacture. Clamping of the jaws (7, 8) can be achieved by means of a threaded rod or a threaded ring or by any other similar means. Hydraulic pre-clamping can be used.

For the second embodiment of the invention illustrated from FIG. 3, the flexible pipe is composed of the interior towards the outside of a carcass (1), of an inner sheath (2), of a pressure vault (3) and two traction armor plies (4) and the plies of armor (4) are anchored in the end piece (6) by wedging by means of three jaws (7, 9, 10). ). The jaws (7, 9, 10) are displaceable in the axial direction of the hose into each other, so as to generate a clamping force for anchoring the armor (4). For this second embodiment of the invention, the armor plies (4) are arranged individually between two jaws: a first armor is wedged between a jaw (7) disposed on the flexible pipe and an intermediate jaw (9) and the second armor (4) is wedged between the intermediate jaw (9) and a jaw (8) disposed in the cap of the end piece (6). The jaws (7, 10) can slide on the internal parts (vault or sheath of the flexible pipe) or external (hood) or be integral with the part that supports it by screw, thread, welding or by manufacturing. This second embodiment therefore consists of dissociating the anchoring of each sheet to optimize the anchoring forces (two friction surfaces) and pinching each layer of armor in a jaw which allows the armor wire to have a radius continuous curvature of the running part at its hanging end.

Figure 4 is a three-dimensional view of this embodiment. It can be seen in particular the embodiment of the nozzle (6) in two parts: the hood (6a) ensuring the seal and the connecting flange (6b) for connecting the flexible pipe to a tip of another flexible pipe or with terminal equipment.

Clamping of the jaws (7, 9, 10) can be achieved by means of at least one threaded rod or ring or by any other similar means. Hydraulic pre-clamping can be used. FIG. 5 represents a variant of this embodiment of the invention, for which the common clamping of the jaws (7, 9, 10) is implemented by a threaded rod (1 1) passing through the three jaws. Alternatively, the clamping of the jaws (7, 9, 10) may be independent so as to separately perform the anchoring of the armor (4).

The three jaws of the second embodiment are presented as single-block pieces. However, to help the assembly by avoiding reworking machining, you can use multi-piece jaws (lengthwise cutting) to adjust the positioning of the armor by tightening.

The second embodiment of the invention can be adapted for flexible pipes with even numbers of armor: for each pair of armor plies, the anchoring is carried out by means of three jaws.

The jaws may be made of mild steel to provide plastic deformation at the contact surface to improve crimping. The assembly is then removable but the mild steel parts are to be replaced.

FIG. 9 illustrates an embodiment variant of the jaws according to the invention. In some cases, the steel / steel contacts can be avoided so as to limit the problems of corrosion and / or contact fatigue (fretting). A polymer thickness (13) may be installed between the armor wire (4) and the jaw (7, 8, 9, 10). The use of jaws with a polymer layer (13) limits the slippage at the interface with the armor son (4) because these jaws (7, 8, 9, 10) deform under stress. The thickness of this non-steel element (13) can be between 1 and 50 mm. The polymer may be chosen from elastomers.

To ensure the anchoring of the armor, it is possible to preform the armor before assembly.

A hydraulic clamping of the jaws can be provided to set up the assembly.

To improve the performance of the anchor, it is possible to increase the level of friction at the armor / jaw interface. For this, structural bonding and / or surface texturing may be used.

A surface of the jaws may be grooved to pre-position the armor wire. The non-grooved jaw is then mobile and allows crimping.

A prepositioning system for armor wires can be used when mounting the tip.

The clamping pressure exerted by the jaws on said end length of the armor wires is between 3 and 100 MPa, preferably substantially equal to 50 MPa, in order to ensure sufficient clamping without creating a concentration of stresses in the wires. armor.

According to an exemplary embodiment of the invention, the approximate dimensions of the invention are:

the overall length (total length) of the end piece is of the order 1 400 mm,

the diameter of the cover (6a) is 300 mm.

- The part of the anchor has a footprint of about 400 mm in length (in layers) and 250 mm in diameter. Pre-dimensioning example:

Figure 6 shows different forces involved during tightening. To carry out a pre-dimensioning calculation, the considered elements are:

- a cone / cone geometry (half-angle at the top) at 5 °.

- The armor is pinched between two flat jaws.

a coefficient of friction at the wire / jaw interface is 0.3 or a friction angle of 17 °.

- The jaw system is self jamming but this effect is not taken into account.

- the recovery of effort by capstan effect is not considered.

an anchor length of 300 mm.

- The wire width considered in contact is 10 mm to take into account the rounded corners.

a tensile force F _ten of 1000 kN.

The normal force F _N to be exerted on each side of armor ply is 1 666 kN (= 1000 / 0.3 / 2) to retain the armor by friction. The axial clamping force must be 145 kN (= 1666 x sin (17 ° + ⁵⁰ )). This clamping can be achieved by threaded rods, for example two M12 screws.

The elongation at the connection output can be estimated by considering a blockage at its end, if the maximum stress is reached, 1 200 MPa, then the maximum elongation

■ _/ ^a ad - 1200.300,,, " _{ί x} . . _x . . will be about 2 mm ⁽ = -≡ ^■ - =). The extension at the tip outlet will depend on

E 210000

the armor free length present in the mouthpiece (between the jaws outlet and the end of the mouthpiece). This distance is of the order of 400 mm, thus increasing the elongation at the tip end to about 4 mm.

This jaw system allows embedding the armor wire at its end and release it gradually. The friction force will allow to retain the wire over the grip length of the jaws and limit movement / elongation. In addition, the invention relates to a flexible pipe comprising at least one pressure sheath, at least one armor ply and at least one end piece as described above at one of these ends. By means of the nozzle, the flexible pipe according to the invention can be connected to another portion of flexible pipe or to a terminal equipment. For example, the constitution of the flexible pipe may be that of the flexible pipe of Figure 1. The flexible pipe according to the invention can be used in particular for the offshore exploitation of a petroleum and / or gas field. The flexible pipe according to the invention can satisfy, among others, the recommendations of the normative documents API 17J "Specification for Unbonded Flexible Pipe" and API RP 17B "Recommended Pratice for Flexible Pipe" prepared by the American Petroleum Institute.

The invention therefore has many advantages:

The specific geometry of the jaws (circular, elliptical, parabolic ...) allows a progressive blocking of the armor and to avoid any singular point (advantage compared to the current concept).

The anchor is adapted to provide good resistance under stress fatigue.

Armor does not require specific shaping (no folding / unfolding, hook). In addition, pre-forming the wires is not necessarily mandatory (simplification of the assembly). However, the preform may be an improvement route of the invention for reducing maximum stress or facilitating assembly.

For the second embodiment of the invention, the immobilization of the armor is made tablecloth by a sheet with a series connection which allows to clamp together with the same system.

Figure 7 illustrates a step prior to the assembly of the tip (6). The introduction of the cones (7, 9, 10) requires cutting the armor (4) to the appropriate length, the outer layers are the shortest which facilitates the preparation operation. A temporary armor immobilization collar (12) makes it possible to preserve the organization of the plies (4) for mounting. Preferably, it is then dismounted. The assembly of the connection tip (6) according to the invention is thus facilitated.

The system is removable. If mild steel jaws or if a structural bonding of the armor is used, dismantling requires specific tools and a change of some parts to reassembly.

The mechanical stress recovery of the invention is reinforced by the self-jamming effect of the cones and the capstan effect.

Whether by screwing with a torque wrench or by tightening with a hydraulic system, the invention ensures perfect control of clamping compressions, regardless of the operator Access to the sealing zones is not dependent on the anchoring technology. Indeed, Figure 8 shows the sealing zones (Ze) which are not dependent on the anchoring means.

Claims

claims

1) Connection end of a flexible pipe, said flexible pipe being of the unbound type and comprising in particular an inner pressure sheath (2) and at least one layer of tensile armor (4) wound around said pressure sheath (2), each of said traction armor plies (4) comprising an end length anchored in said end piece (6), characterized in that the anchoring of each of said ends is achieved by wedging said end between two jaws (7, 8, 9, 10) such that said end length has no singular point, said jaws being disposed in said tip (6) and being substantially conical.

2) A tip according to claim 1, wherein said end length has a substantially continuous radius of curvature.

3) tip according to one of claims 1 or 2, wherein said jaws (7, 8, 9, 10) have a shape of a cone of revolution whose generator is substantially a straight line at an angle to the axis of revolution of said flexible pipe less than 20 °, preferably less than 10 ° and preferably substantially equal to 5 °, an arc or a portion of ellipse, parabola or hyperbola or formed by two radii of curvature consecutive.

4) Nipple according to one of the preceding claims, wherein said flexible pipe comprises at least two traction armor plies (4) wound around said pressure sheath (2), said ends of said plies of traction armor ( 4) being arranged one above the other and wedged between two jaws (7, 8).

5) Nipple according to one of claims 1 to 3, wherein said flexible pipe comprises at least two plies of tensile armor (4) wound around said pressure sheath (2), each end of said plies of armor of traction (4) being wedged individually between two jaws (7, 9, 10).

6) Nipple according to claim 5, wherein said flexible pipe comprises two plies of tensile armor (4) wound around said pressure sheath (2) and said tip comprises three jaws (7, 9, 10), among which an intermediate jaw (9) in contact with each of said ends of said traction armor plies (4).

7) tip according to one of the preceding claims, wherein at least one of said jaws (7, 8, 9, 10) is moved by means of at least one threaded rod (1 1). 8) tip according to one of the preceding claims, wherein at least one of said jaws (7, 8, 9, 10) is made of mild steel. 9) tip according to one of the preceding claims, wherein at least one of said jaws (7, 8, 9, 10) comprises a polymer thickness (13) at the contact with said end length of one of said layers traction armor (4).

The tip of claim 9, wherein said polymer thickness (13) is made of an elastomeric material.

1 1) An end piece according to one of the preceding claims, wherein one of said jaws (7, 8, 9, 10) is fixed on said tip (6) or on one of the layers of said flexible pipe. 12) End piece according to one of the preceding claims, wherein at least one of said jaws (7, 8, 9, 10) is grooved for the pre-positioning of said end length of a layer of tensile armor ( 4).

13) Nozzle according to one of the preceding claims, wherein the clamping pressure exerted by said jaws (7, 8, 9, 10) on said end length is between 3 and 100 MPa, preferably substantially equal to 50. MPa.

14) Flexible duct of the unbound type comprising in particular an inner pressure sheath (2) and at least one layer of tensile armor (4) wound around said pressure sheath (2), characterized in that said flexible duct comprises at least one of these ends a connection piece (6) according to one of the preceding claims.