FR3079279A1 - DRIVING REINFORCEMENT SYSTEM AND MOUNTING METHOD - Google Patents

Abstract

The reinforcing system (10) of the wall (20) of a pipe comprises a rigid ring (30) and a seal (40) made of a viscoelastic material and constituting an expandable wedge, the seal being intended to be interposed between the ring and the wall and maintained in a state constrained by prestressing means (50; 60).

Description

PIPE REINFORCEMENT SYSTEM AND ASSEMBLY METHOD

The present invention relates to a pipe reinforcement system, in particular a flexible pipe.

A flexible pipe is for example used for pumping seawater. It then advantageously has a large diameter of a few meters.

The creation of a flexible pipe intended to operate under vacuum (the water column being sucked in instead of being forced back into the pipe), requires the use of rigid rings (also called "hoops") making it possible to maintain the passage section of the pipe, while the suction flow produces a vacuum tending to crush the pipe on itself.

So far, the problem of keeping these rings in position on the pipe has not been satisfactorily resolved.

Indeed, a mounting clearance must be reserved between the ring and the wall of the pipe to allow the introduction of the ring into the pipe, then its placement in its final position, while taking into account the manufacturing dispersions of these two components.

However, this assembly clearance is not compatible with the proper functioning of the pipe and the service life of the assembly. In fact, if this clearance has too great an amplitude, the ring will not be suitably held, and if it has an amplitude that is too low or even zero, contact between the ring and the wall risks leading to premature wear of the driving.

It is therefore necessary to master this assembly game.

It should be noted that attempts to build flexible, environmentally friendly seawater pipes have been unsuccessful.

The main resistance to the development of this technology is the mechanical resistance of the interfaces between the rings and the wall of the pipe under extreme environmental conditions (loading and fatigue).

The object of the present invention is therefore to solve this problem.

For this, the invention relates to a system for reinforcing the wall of a pipe, comprising a rigid ring and a seal made of a viscoelastic material and constituting an expandable wedge, the seal being intended to be interposed between the ring and the wall and maintained in a constrained state by means of prestressing.

The system according to the invention provides for interposing a seal between a ring and the wall. This joint incorporates a pair of expandable corners to be placed between the ring and the wall of the pipe. It makes it possible to make up for the play between components of the assembly and to transfer, by adhesion and visco-elastic deformation, the loading forces. The system according to the invention thus makes it possible to control the contact between ring and wall. It avoids relative movements while eliminating contact wear.

According to particular embodiments, the system includes one or more of the following characteristics, taken in isolation or according to all technically possible combinations:

- the joint results from the assembly of an upper half-joint and a lower half-joint, each half-joint having a substantially triangular section.

- The seal has come in one piece and has an upper portion and a lower portion, each portion having a substantially triangular section.

- a section of the joint has a first side shaped as an arc of a circle so as to be applied against the ring and a second side which is substantially rectilinear so as to be applied against a surface of the wall.

- the second side of the joint has a surplus of material.

- The prestressing means comprise a plurality of straps passing through orifices provided in the joint and provided with stops making it possible to maintain the application of a prestressing force of the joint capable of deforming it radially.

- The prestressing means further comprise a means of stiffening the pipe at a transverse plane for positioning the ring and the seal, the stiffening means being placed against a second surface of the wall opposite a first surface of the wall against which the seal is placed.

- The stiffening means is constituted by a belt applying a clamping force.

- The belt has stops projecting radially towards the joint and suitable for holding the joint axially.

The invention also relates to a method for mounting the previous reinforcement system, comprising the steps of: providing the ring with the seal; introduce the ring and the seal inside the pipe up to an installation point; and force the joint in the gap between the ring and the wall and maintain the stress applied to the joint by means of prestressing.

The invention and its advantages will be better understood on reading the detailed description which follows of a particular embodiment, given solely by way of nonlimiting example, this description being made with reference to the appended drawings in which:

- Figure 1 is an axial section of a pipe equipped with a plurality of reinforcement systems according to the invention;

- Figure 2 is an enlarged view of zone II of Figure 1 showing a section of a reinforcement system of Figure 1;

- Figure 3 is a section of a first embodiment of a joint of the reinforcement system according to the invention;

- Figure 4 is a section of a second embodiment of the joint of the reinforcement system according to the invention; and,

- Figure 5 shows schematically in the form of blocks the different stages of a method of mounting the reinforcement system of Figure 1.

FIG. 1 represents a pipe 1, equipped with several reinforcement systems in accordance with a preferred embodiment of the invention.

Line 1 is a cylindrical line around an axis A.

Line 1 has a wall 20 of circular cross section. The wall 20 has a reduced thickness and has an internal surface 22 and an external surface 24.

Preferably, the pipe 1 has a large internal diameter D1 (evaluated on the internal surface 22 of the wall 20), for example of around 5 meters.

In the envisaged embodiment, the pipe 1 is flexible, the wall being for example made of a woven material.

To reinforce the pipe 1 and in particular allow it to withstand the pressure differences, which are sometimes significant, which, when in use, are applied to its wall 20, the pipe 1 is reinforced by a plurality of reinforcement systems 10.

The reinforcement systems 10 are identical to each other.

Each reinforcement system 10 is arranged in a plane P transverse to the axis A.

As illustrated in FIG. 1, the reinforcement systems 10 are placed at an equal distance from each other along the central axis A of the pipe. Alternatively, the distance between two successive reinforcement systems is adapted, in particular in the vicinity of a portion of the pipe which will be bent during the use of the pipe.

Referring to Figure 2, a reinforcement system 10 consists of a rigid ring 30, a seal 40 interposed between the ring 30 and the wall 20 of the pipe, as well as means of prestressing the seal 40 to secure the ring 30, the seal 40 and the wall 20 by adhesion.

The prestressing means comprise a plurality of straps 50.

The prestressing means of the reinforcement system 10 further comprise a means of stiffening the flexible pipe at the level of the plane P for positioning the ring 30, constituted by a belt 60 placed on the surface of the wall 20 of the pipe, which is opposite to the surface against which the seal 40 is pressed.

In Figure 2, the ring 30 and the seal 40 being on the side of the inner surface 22 of the pipe, the belt 50 is placed on the outer surface 24 of the wall of the pipe.

The belt 50 is placed in the same plane P as the ring 30 and the seal 40, to apply a counter-reaction such as to allow the stress 40 to be placed under stress so as to generate friction forces that maintain the position of the ring 30.

The ring 30 has a circular section, the outside radius R3 of which is small compared to the diameter D1 of the pipe 1.

The ring 30 is preferably hollow to limit its weight.

The ring 30 is made of a rigid material, or at least having a rigidity making it possible to sufficiently reinforce the pipe 1 taking into account the intended application. For example, the ring is made of metal. This is for example a bent tube, the ends of which are welded to each other.

The outer diameter of the ring, D3, evaluated in the plane P, is less than the diameter D1 of the pipe 1 so as to provide a clearance. As will become apparent in the following description, the seal 40 causes this clearance may be chosen greater than the assembly clearance provided in the prior art. In other words, the outside diameter D3 of the ring 30 is chosen so as to guarantee that there is no point of contact between the ring and the pipe, when the ring is centered on the axis A. This facilitates mounting.

The joint 40 constitutes a prestressed corner.

The function of the seal 40 is to make up for the play existing between the ring 30 and the inner surface 22 of the wall 20. The ring 30 and the wall 20 therefore do not have to be manufactured with drastic tolerances. The joint 40 makes it possible to relax the dimensional constraints of manufacture of the various components of the assembly.

The seal 40 also has the function of generating, by contact, sufficient friction to keep the ring 30 in position in the pipe 1. This friction is generated on the one hand at the interface between the ring 30 and the seal 40 and on the other hand at the interface between the wall 20 of the pipe and the seal 40.

For this, the seal 40 is a semi-rigid seal, made of a viscoelastic material. For example, the joint is made by molding an elastomeric material. It has for example a hardness of 84 ShA.

The seal 40 is then deformed by axial compression by the straps 50 for stressing.

The seal 40 is O-ring around the axis A. It is preferably continuous and made in one piece. As a variant, it is made up of several angular sectors arranged regularly around the ring 30.

In the preferred embodiment, as shown in FIG. 3, the seal 40 is formed by the association, by means of the pretension straps 50, of an upper half joint 41 and a lower half joint 42. The upper and lower half-joints are symmetrical to each other with respect to the mounting plane P of the ring 30.

The section of the upper half-joint 41 has a substantially triangular shape so as to constitute a self-locking corner between the ring 30 and the wall 20 of the pipe 1.

The inner side 412 forms an arc substantially complementary to the portion of the surface of the ring 30 in contact with which it is applied. The inner side 412 thus has a radius R4 slightly smaller than the radius R3 of the ring in order to make up for the dimensional differences of the ring and to deform the material of the seal in order to improve the adhesion to the surface of the ring.

The outer side 414, intended to be applied against the inner surface 22 of the wall 20 of the pipe, is substantially rectilinear.

The angle a between the interior 412 and exterior 416 sides is chosen according to the desired adhesion. It is for example 15 °.

The outer side 414 advantageously has an extra thickness 416. This excess material is intended to be deformed radially outward when the seal is compressed by the straps 50. When the belt 60 is fitted, the force for tightening the belt will counteract this radial deformation, leading to compression of the material constituting the seal, and, consequently, to an increase in contact forces and therefore in friction forces, in particular between the seal 40 and the wall 20.

Advantageously also, the axial side 418 of the upper half-seal 418 is profiled to facilitate the flow of the fluid, circulating in the pipe 1, around the assembly consisting of the ring 30 and the seal 40 and so that the fluid in movement does not come off the joint 40 from the wall 20. Such detachment would result in the introduction of pollutants between the joint and the wall, causing premature aging of the pipe.

A similar description could be made for the lower half-seal 42, which has an interior side 422, an axial side 428 and an exterior side 424, the latter preferably being provided with a surplus of material 426.

The upper 41 and lower 42 half-joints are associated by the straps 50 arranged at regular intervals along the periphery of the ring.

The strap 50 passes through through holes 43 and 44 (Figure 2) provided in each half-joint.

The strap 50 is provided with a lower stop 52 capable of coming to bear and applying a force on the axial side 428 of the lower half-joint 42. The lower stop 52 is for example fixed near a lower end of the strap 50.

The strap 50 is provided with an upper stop 51 capable of coming to bear and applying a force on the axial side 418 of the upper half-seal 41.

The upper stop 51 is of the ratchet or wedge type so as to allow an operator, by pulling on the strap 50, to apply a force to the seal 40 then to lock the strap in position in order to maintain this force to wedge and constrain half joints 41 and 42 between the ring 30 and the wall 20.

The strap 50 advantageously goes around the ring 30 and its free upper end is attached by a clasp to the lower end of the strap.

FIG. 4 represents a second embodiment of the joint of the reinforcement system according to the invention, in which the upper and lower half-joints are now joined to each other by a median bridge 145. The seal 140 thus came in one piece. Advantageously, in this embodiment it is possible to do without the straps, which are then integrated into the material.

Preferably, the bridge 145 has a reduced thickness so as to be able to be crushed during the stressing of the seal 140 by the belt 60 and allow the approximation and consequently the jamming of the upper 141 and lower 142 portions of the seal 140 corresponding to the upper and lower half-seals of the embodiment of FIG. 3.

In FIG. 4, the axial sides of the seal 140 are not profiled, unlike the embodiment of FIG. 3.

The belt 60 is, in position, a cylinder whose height H corresponds substantially to the height of the seal 40 or 140.

The belt is for example made of a rigid material. Two half shells are associated, flange against flange, by means of bolts tightened to a tension equivalent to the maximum overpressure tolerable by the pipe during its operation.

The belt 60 is preferably made of a flexible material, for example a reinforced fabric. It has a tightening loop for tensioning the belt.

The belt 60 ensures the axial maintenance of the seal 40 by radial compression, increase in contact forces and consequently in friction forces. Advantageously, the belt 60 incorporates upper 61, lower 62 and middle 65 stops for axially enclosing each half-joint 41 and 42 and allowing the application, when the belt is tightened, of radial compression forces, avoiding axial deformations .

From a mechanical point of view, the belt 60 removes the stresses from the wall 20 which is sandwiched between the seal 40 and the belt 60. The belt 60 distributes the shearing of the material constituting the wall 20, in particular thanks the increase in contact pressure and the stops. The belt 60 makes it possible to eliminate the DRC (residual deformation after compression) linked to the aging of the polymer materials, in particular that of the seals.

Furthermore, the stops of the belt 60 make it possible to protect the seal from pollution in the event of overpressure in the pipe 1, by avoiding detachment of the seal which would be such as to allow the introduction of pollutants at the interface between the seal. and the pipe wall.

The mounting method 200 is shown diagrammatically in FIG. 5.

In step 210, before being introduced into line 1, the ring 30 is provided with two half-seals 41 and 42. They are held by the straps 50. They are arranged set back from the median plane P of l ring 30 in order to preserve a clearance allowing the mounting of the ring on the wall of the pipe.

In step 220, the wall 20 of the pipe 1 is deformed to have an elliptical section, the major axis of which has a length greater than the diameter D3 of the ring 30.

In step 230, the ring 30 is introduced inside the deformed pipe. It is introduced with a certain attitude relative to the axis A to increase the clearance with the wall and to be able to easily move it to its point of installation in the pipe.

In step 240, the ring is then straightened by pivoting to be placed in a plane P transverse to the axis A of the pipe 1, the latter having regained its circular conformation. A clearance exists between the ring 30 and the wall 20 of the pipe.

In step 250, once the ring in its final mounting position, the lower 42 and upper 41 half-seals are put in place by an operator using straps 50 and / or by using a hydraulic clamp in the shape of a "C", so as to force the seal 40 in the interval between the ring 30 and the wall 20.

Each half-joint is moved to come into contact with the ring 30 and the inner surface 22 of the pipe and thus make up for the play. Then, each half-joint is deformed viscoelastically by substantially axial crushing. This causes a radial deformation towards the outside of the joint, which also drives the wall 20 towards the outside. The positioning of the upper stop 51 of each of the straps 50 makes it possible to maintain this prestress.

The prestress applied is chosen to obtain adhesion of the joint at its two interfaces which is adapted to the hydrostatic pressure in the pipe. Advantageously, a grip reserve is produced by the excess material (s) 416, 426 provided on the outside of the seal 40.

In the case where the seal has come in one piece (case of the seal 140 in FIG. 4) and the wall is flexible enough to admit a radial deformation during the pivoting of the ring with its seal (zero play after pivoting), l step 250 can be omitted.

In step 260, the belt 60 is finally placed facing the seal 40 on the outer surface 24 of the wall 20 of the pipe. The belt 60 is then tensioned to generate a tightening force ensuring the operational maintenance of the ring and the seal against the wall.

This assembly is preferably hydraulic and automatic in order to limit human intervention.

Other embodiments of the reinforcement system are possible, in particular by placing the ring outside the pipe and the belt inside the pipe, or even by dispensing with the use of a stiffening belt.

A person skilled in the art will note that the seal eliminates the play necessary for the positioning in position of the ring inside the pipe. It makes up for the dimensional differences in the manufacturing of the components of the reinforcement system.

The corner effect of the joint guarantees friction grip on the one hand to the ring and on the other hand to the wall. According to this effect, an increase in the axial force leads to an increase in the radial force.

Furthermore, the seal allows a better distribution of the forces on the ring and therefore better buckling resistance of the ring.

The joint absorbs the movements of the ring and only a fraction of the corresponding energy is transmitted to the wall of the pipe. This improves the longevity of the wall.

The pre-tensioning straps ensure the positioning by viscoelastic deformation of the seal.

Furthermore, they join the upper half-joint and the lower half-joint in the first embodiment.

Tests have made it possible to validate the use of a joint operating on the principle of the expandable wedge and to confirm the advantage of this solution compared in particular to a solution by simple adhesion, that is to say with a cylindrical joint. of constant thickness, interposed between the ring and the pipe.

For a clamping force at standstill of 750 N, the loss of adhesion occurs above 2700 N with corner joint instead of 375 N with cylindrical joint (for a coefficient of adhesion tg = 0.5).

On average, a coefficient of 3 to 4 between the tightening force of the belt (radial force) and the axial strength of the ring is obtained.

The proposed solution is low-cost since it preferably combines a flexible fabric-based wall, a ring of the welded curved tube type and a molded elastomer seal 10.

Claims (10)

1. -Reinforcement system (10) of the wall (20) of a pipe (1), comprising a rigid ring (30) and a seal (40) made of a viscoelastic material and constituting an expandable corner, the seal being intended to be interposed between the ring and the wall and maintained in a constrained state by prestressing means (50; 60). 2. - reinforcement system (10) according to claim 1, in which the joint (40) results from the assembly of an upper half-joint (41) and a lower half-joint (42), each half -joint having a substantially triangular section. 3. - reinforcement system (10) according to claim 1, wherein the seal (40) has come in one piece and comprises an upper portion (141) and a lower portion (142), each portion having a substantially triangular section. 4. - reinforcement system (10) according to claim 2 or claim 3, wherein a section of the joint has a first side shaped in an arc so as to be applied against the ring and a second side substantially rectilinear so to be applied against a surface of the wall. 5. - reinforcement system (10) according to claim 4, wherein the second side of the seal has a surplus of material (416, 426). 6. - System according to any one of claims 1 to 5, in which the prestressing means comprise a plurality of straps passing through orifices provided in the joint (40) and provided with stops (51, 52) making it possible to maintain applying a prestressing force to the joint capable of deforming it radially. 7. - System according to any one of claims 1 to 6, wherein the prestressing means comprise a means of stiffening (60) of the pipe at a transverse plane for positioning the ring (30) and the joint (40), the stiffening means being placed against a second surface (42) of the wall (20) opposite a first surface (41) of the wall against which the joint is placed. 8. - System according to claim 7, wherein the stiffening means is constituted by a belt (60) applying a clamping force. 9.- The system of claim 8, wherein the belt (60) has stops (61, 62, 65) projecting radially towards the seal (40) and adapted to maintain the seal axially. 5 10.- A method of mounting a reinforcement system according to any one of the preceding claims, comprising the steps consisting in: - providing (210) the ring (30) with the seal (40); - Introduce (230) the ring (30) and the seal (40) inside the pipe to an installation point; 10 - force (250) the seal (40) in the interval between the ring (30) and the wall (20) and maintain the stress applied to the seal (40) thanks to the prestressing means (50; 60).