FR2616198A1 - System for assembling a metal end-fitting and a high-pressure composite material tube and applications particularly to equipment in the petrochemical field - Google Patents

Abstract

Device providing the permanent link between a metal end-fitting on the one hand and a composite material tube on the other hand, with a pipe subjected to a static pressure which may reach 150 MPa. The assembly is made up of a metal part forming a connection end-piece 7 and sealing end-piece 8, including a shoulder 2 on which the composite material 1 is used. A tubular anti-abrasion and anti-corrosion sleeve 6 set into the metal end-fitting and protected by a ring 9 at its end gives total insulation of the composite/metal joint aginst corrosive fluids which might circulate in the pipe.

Description

The present invention relates to a composite material / metal assembly system making it possible to use the composite materials in the transport of corrosive and / or abrasive fluids under static pressures up to 150 MPa.

The invention makes it possible in particular to interpose between the metal conduits, or a fluid circulating under very high pressure, a composite tube element which can in particular form part of a sensor intended to measure various properties of the fluid (viscosity, flow rate, density, etc ...)
One of the known problems of the prior art consists in the difficulty of producing composite material / metal connections capable of withstanding very high pressures for a long time. The invention solves this problem.

A particularly important application lies in the application to sensors of the petroleum and parapetroleum industry which must measure, as we know, the properties (viscosity, density, rheological parameters, etc.) of fluids circulating under very high pressures, and which can be corrosive (acids) and / or highly abrasive (cement slag).

According to the invention, there is between the composite material and the metal tube a metal end piece comprising a projecting shoulder at its end in contact with the composite material and a high pressure connection at its other end.

Figures 1 and 2 attached show a preferred embodiment of the invention, without limitation, in longitudinal section view in a plane parallel to the axis of conduit.

One of the essential characteristics of the invention resides in the projecting shoulder 2 around which the various plies of composite material are deposited by winding, in known manner.

The advantage of this structure is that it allows normal winding of the composite material while ensuring, for the first time in the industry, the resistance to tensile and torsional stresses between the metal tube (and the metal end piece) on the one hand. , and the composite tube on the other hand.

This eliminates the risks of deformation, leaks and ruptures which are common in attempts in the prior art.

Given the work pressures, we see that this advantage is absolutely decisive.

In the petroleum and parapetroleum industry, the drawbacks of the prior art have even more serious consequences (any interruption of work on a line entails a serious risk of poor treatment of the well, poor placement of cement, with sometimes irreversible consequences).

References have the following meaning 1. Wound composite material 2. Shoulder on metal tip 3. Metal tip 4. Circumferential fibers of composite material 5. Longitugin fibers of the composite material
P. Pressure exerted by the pumped fluid inside the
drove.

S. Duct section
F. Longitudinal tension forces due to pressure
R. Radius on shoulder AH. Angles of the inclined planes on the shoulder 6. Anti-abrasion / anti-corrosion sleeve 7. Weco type assembly system with a metal tube
high pressure not shown 8. High pressure seal 9. Protection ring 10. O-rings
FIG. 3 represents an embodiment of a sensor (11) for measuring properties of the fluid, measurements made through the composite material constituting the conduit (1).

FIG. 4 represents a very high pressure tube made of composite material, connectable at both ends, thanks to the application of the invention.

Figure 1 illustrates in detail the operating principle of the invention.

 When a high pressure P is applied inside the pipe, it creates a high tension F = PxS within the material of the pipe.

The longitudinal fibers (5) of the composite material partially take up this force. In the connection zone between the composite tube and the metal end piece 3, the shear forces at the interface between the two materials reach values such that no adhesive can be sufficient to hold the assembly together.

It is at this point that the achievements of the prior art are fragile. In the present invention, the tube made of composite material is wound around a shoulder (2) projecting from the metal end piece.

When a tensile force is exerted on the tube, any slippage must result in an increase in the diameter of part of the turns of the layer of circumferential fibers (4) of the composite material.

However, these fibers are made of material with a very high Young's modulus, this is particularly the case for glass, carbon or aramid fibers. It is therefore very difficult, if not impossible, to slide the assembly, either in tension or in compression, thanks to the shape of the shoulder 2 which has two planes inclined at the angles A, B.

To avoid breaking the longitudinal fibers by breaking off, we will take the precaution of defining well-chosen radii R at the shoulder.

Ultimately, the shape of the shoulder can be chosen in various ways but will preferably include a profile such that the diameter changes are not too "abrupt".

In another preferred winding mode, the fibers of the composite material will be wound in two symmetrical spirals (one left, the other right), the angle of the fibers relative to the axis of the conduit will be of the order of 50 to 600. We know that a pipe made of fibers wound in a spiral has an angle of Arctg (2) approx. 54,730 is virtually inexpansible under the effect of pressure forces.

Finally, it is possible to envisage carrying out the invention with a combination of more than 2 layers of fibers with orientations chosen from the examples cited.

Figure 2 specifies the embodiment of the invention. A sleeve 6 made of a material resistant to pumped fluids (corrosive or abrasive), which can in particular be polyurethane or polytetrafluoroethylene, has the function of protecting the composite material against chemical attack. It is known in fact that the resins binding the reinforcing fibers of the material can be dissolved by certain fluids, moreover the glass fibers are attacked by hydrofluoric acid.

 The sleeve 6 can be used to facilitate the manufacture of the tube. In fact, it can be used as a guide for winding the composite material over the metal end piece 2.

The metal part 9 associated with the joint 8 makes it possible to protect the end of the sleeve 6 against abrasion. The O-rings 10 ensure total sealing and thus prevent penetration under the effect of the pressure of aggressive fluids between the part 9 and the sleeve 6.

In this example, the end 7 of a high pressure female Ueco type connection has been shown. The WECO assembly system is well known, especially in the petroleum and oil services industry. It can however be replaced by any other system known to those skilled in the art capable of withstanding the very high pressures mentioned here.

FIG. 3 illustrates the application of the invention to the production of sensors connectable to high pressure lines.

 In this mode of application, the sensor (11) measures one or more properties of the fluid flowing in the composite conduit 1. The sensor will in particular be a flow meter, a densitometer, a conductivity measurement sensor, of known type and that it is needless to describe here in detail.

Finally, FIG. 4 represents a very high pressure pipe having at each end a Weco male and female type connection (respectively) connected to the pipe made of composite material thanks to the invention.

The advantage of using polymer-based composite materials for high-pressure hoses lies above all in the significant weight gain, allowing easier handling and the transport of a greater number of hoses by truck. For the industry, notably the oil and oil industry, this advantage is extremely important.

Claims (9)

1 - System for assembling a part with cylindrical symmetry in  composite material with a metal part, capable of  withstand very high internal pressures (150 MPa),  characterized in that the end (1) of the piece of material  composite integrates and at least partially covers a  metal end piece (3) of cylindrical symmetry comprising  one end a shoulder (2) with a diameter whose  section through a plane passing through the axis of symmetry has a shape  substantially trapezoidal (2) around which are  "wound" the reinforcing fibers of the composite material, and  what the other end of the metal end piece (3) has  a high pressure connection (7) for assembly with the part  metal to be connected. 2 - System according to claim 1, characterized in that the  composite material part and the metal end cap are  very high pressure tubes and in that the metal part to  to connect is either a very high pressure tube or a  very high pressure cap. 3 - System according to claim 1 or 2, characterized in that  the composite material at the interface with the nozzle  metallic (3) has at least one longitudinal ply (5)  reinforcing fibers oriented parallel to the axis and to the  minus a circumferential sheet (4) of reinforcing fibers  wound in substantially circular turns located in  planes substantially perpendicular to the axis of symmetry of the  system. 4 - System according to claims 1 to 3, characterized in that  the inner wall of the composite material tube is integral  a coaxial tube (6) for protecting the composite material  against aggressive fluids that can circulate in the  conducts, especially acids and abrasive fluids. 5 - System according to claim 4, characterized in that the  protective tube material is polyurethane, or  polytetrafluoroethylene, or the like. 6 - System according to claims l to 5, characterized in that  the composite material consists of a bonding resin  and reinforcing fibers which may be glass fibers,  carbon fiber or aramid fiber, or product  similar. 7 - Sensors, especially for the petroleum industry and  oil tanker, comprising a tube of highly composite material  high pressure in which the fluid circulates, some of which  properties are measured by the sensor, characterized in  that the composite tube has at its two ends a  assembly system according to claims 1 to 3.  8 - Tubes in high pressure composite material, connectable  between them to form a line of variable length,  compatible with very high internal static pressures  (150 MPa), characterized in that each composite tube  has at its two ends an assembly system according to  claims 1 to 3, male / male, female / female or  preferably male / female. 9 - Tube in high pressure composite material, connectable according to  claim 8, characterized in that the interior of the tube  composite has a protective tube according to the  claim 4 or 5.