WO2012072894A1

WO2012072894A1 - Paid-out rigid pipe with polymer sheath and method of manufacturing the paid-out rigid pipe

Info

Publication number: WO2012072894A1
Application number: PCT/FR2011/000614
Authority: WO
Inventors: Michaël MARTINEZ; Laurent Cangemi; Eléonore ROGUET; Tomasz Tkaczyk; Daniel Smith; Richard Ross
Original assignee: IFP Energies Nouvelles; Technip France
Priority date: 2010-12-01
Filing date: 2011-11-22
Publication date: 2012-06-07
Also published as: FR2968380B1; FR2968380A1

Abstract

The paid-out rigid pipe for the petroleum industry comprises a metal tube 10 made up of at least two lengths of tube assembled end to end by a weld 13. A layer of insulating material 11 covers the length of tube leaving the ends of the lengths free. An annular sleeve made of filling material 14 covers the metal tube that has no layer of insulating material. A polymer sheath 12 covers at least one portion of said annular sleeve made of filling material 14 to strengthen the steel tube 10 in order notably to increase the bending stiffness of the rigid pipe when it experiences deformations in the plastic domain of the steel tube 10.

Description

RIGID-CONDUIT DRIVE WITH POLYMER SHEATH AND METHOD OF

DRIVING MANUFACTURE

The present invention relates to the field of rigid-unwrapped pipes.

In the field of oil exploitation, rigid pipes are used to transport a petroleum effluent at sea. Such pipes can be assembled at sea, on laying vessels by welding end-to-end short sections (12 m or 24 m) of rigid pipes forming a rigid pipe of great length which is deployed at sea as and when it is assembled. Because the welds are made on board the laying ship, the speed of laying is slow compared to that of a method where the rigid pipe is deployed in great length without resorting to welds on the laying ship. According to this other method, called "lay-up" or "reeled lay method" in English, the rigid pipe is assembled on the ground by welding small sections of rigid pipe, then stored on the vertical wheel or coil of a laying boat. . At sea, the rigid pipe is unrolled from its storage reel, straightened out and deployed at sea. A rigid pipe, deployed according to the so-called uncoiling method, is commonly called a "rigid-unrolled pipe". A rigid-unrolled pipe described in particular in API17A is composed of a long, continuous and rigid metal tube.

Referring to Figure 1, after manufacture, the rigid pipe is wound on a wheel 2, also called drum or reel, storage. The wound pipe is conveyed to the place of use by ship 3. During laying, the pipe is unwound, inclined by the bend 4 on the laying ramp, then straightened by the straightening means 5. During these operations, the rigid pipe is energized which is applied by the tensioning means 6.

During winding operations of the pipe on a reel and straightening, the pipe undergoes deformations in the plastic field of steel. A slight variation in the stresses applied to the tube or a slight variation in the local stiffness of the tube can cause significant geometrical deformations, or even buckling of the tube. One usual way to prevent these risks is to apply sufficient tension by the means 6 on the pipe during the winding and unwinding operations, and during the straightening to keep the tube plated on the bending form. However, the power of the rigid pipe has disadvantages: increased ovalization, plastic elongation of the tube, efforts on the tools. The present invention proposes to reinforce the steel tube by a tube of polymer material to significantly increase the bending stiffness of the rigid pipe when it undergoes deformations in the plastic field of the steel tube. In general, the present invention describes a rigid-unrolled pipe, comprising a metal tube composed of at least two pipe sections assembled end to end by a weld. A layer of insulating material covers the tube sections leaving the ends of the sections free. An annular sleeve of filling material covering the metal tube without a layer of insulating material. The pipe is characterized in that a sheath of polymer material covers at least a portion of said annular sleeve of filling material, the sheath of polymer material having a bending stiffness at 2% of flexural deformation, said stiffness being at least two times greater than the bending stiffness of the metal tube sections at 2% of plastic flexural deformation.

According to the invention, the sheath of polymer material can form a tube, the thickness of the sheath being at least two times greater than the thickness of the metal tube, the polymer material having a Young's modulus of at least greater than 500 MPa and the polymeric material having a breaking strain of at least greater than 5%. The sum of the thickness of the annular sleeve of filling material and the thickness of the polymer sheath may be less than the thickness of the layer of insulating material.

Alternatively, the polymer sheath may cover a portion of the layer of insulating material on either side of the weld.

The polymeric material may be selected from polypropylene, polyamide and polyethylene.

The metal tube can be made of steel.

The insulating material may be chosen from polymeric, syntactic and non-syntactic foams.

The filling material may be chosen from solid polymers or in the form of foam.

the pipe can be wound on a drum, the metal tube undergoing plastic deformation in bending greater than 1%.

The present invention also relates to a method for manufacturing a pipe according to the invention, in which the following steps are carried out:

the at least two tube sections are provided,

the layer of insulating material is deposited on a part of the outer surface of each tube section, the ends of the sections remaining stripped,

the two pipe sections are joined by a weld to form the metal tube,

the annular sleeve of filling material is arranged on the part of the metal tube which does not have the layer of insulating material,

the sheath of polymer material is arranged around the filling material and at least on a part of the layer of insulating material.

According to the invention, the sheath of polymer material can be deposited by performing one of the following steps: the polymer material is injected into a mold forming an annular space around the pipe,

two half-shells made of polymer material are assembled around the rigid-unrolled pipe,

a strip of polymer material is wound helically around the pipe,

the polymer material sheath is extruded around the pipe. The pipe can be wound on a drum.

Other features and advantages of the invention will be better understood and will become clear from reading the description given below with reference to the drawings among which:

FIG. 1 schematizes a device for laying a rigid pipe unwound,

FIG. 2 represents a first embodiment of a rigid-unrolled pipe according to the invention,

FIG. 3 represents a second embodiment of a rigid-unrolled pipe according to the invention,

FIG. 4 represents the cumulative plastic deformation at the end of the winding operation of a rigid-unrolled pipe with and without a polymer sheath,

FIG. 5 represents a comparison of the bending moments of a metal tube and of a polymer sheath as a function of flexural deformation,

- Figure 6 shows a comparison of the tangent stiffness in bending of a metal tube and a polymer sheath according to the bending deformation. The rigid-unrolled pipes shown in FIGS. 2 and 3 consist of a rigid metal tube 10 of great length. They can be used to transport a petroleum effluent. The metal tube has typically a diameter of 6 to 18 inches and a thickness e1 of 0.3 to 1.8 inches. It is most often made of low alloy steel X40 to X80, stainless steel or duplex type steel. The tube 10 is composed of several sections assembled by welding. The weld 13 makes it possible to assemble two sections of the tube 10. The tube 10 is surrounded by a thermal insulation 11 in the form of a tube of thickness e2. The insulating material has a coefficient of thermal conductivity of less than 0.3 W / (mK). The insulating material preferably has a Young's modulus greater than 1000 MPa. For example, the insulating material may be a polymeric foam, for example a polypropylene, a polyurethane, a polymeric syntactic foam such as a polypropylene, a polyurethane or an epoxide, comprising glass beads, an elastomer such as rubber, or a gel consisting of a mixture of Kraton and iso-paraffin, kerosene and iso-polyurethane, or a silicone elastomer with a silicone oil. The ends of the sections constituting the tube 10 are devoid of the thermal insulation layer 11 to allow the welding operation.

Referring to Figure 2, a filler material 14 is disposed around the tube 10 at the weld 3 to obtain a continuity of the insulation along the length of the tube 10 after the welding operation. The filling material 14 forms a tube-shaped sleeve whose thickness e4 is smaller than the thickness e2 of the thermal insulation layer 11. In other words, the filling material 14 fills some or all of of the annular space devoid of the insulating layer 11. With reference to FIG. 2, the thickness e4 of the tube of material 14 is substantially equal to the thickness e2 of the layer of insulating material 11. In reference in FIG. 3 the thickness e4 of the tube of material 14 is smaller than the thickness e2 of the layer of insulation material 11. A filling material 14 is often chosen which is softer than the insulation material 11 for guarantee a good seal at the weld 13 and for greater ease of implementation. In other words, the filling material may have a lower Young's modulus, or even preferably two times lower than the Young's modulus of the insulating material. The Young's modulus of the insulating material may be less than 500 MPa, preferably less than 250 MPa. For example, the filler material 14 is polyurethane. The insulation layer then has a significant variation in stiffness at the weld 13, which leads, in the field of plasticity of the steel, to a significant variation in the stiffness of the pipe. This results in a concentration of stresses and plastic deformations in the steel, at the level of the weld 13, during winding and straightening.

To increase the strength of the rigid-unrolled pipe, the present invention proposes to strengthen the metal tube 10 by a sheath of polymer material.

The tube 10 thermally insulated by the layers 11 and 14 of Figure 2 is reinforced by depositing a polymer sheath 12 around the tube 10 at the weld 13. The polymer sheath 12 is deposited on the outer surface of the insulation layer 11 in FIG. 2, the sheath 12 covers the filling material and a part of the insulating layer 11, forming a tube of thickness e3 over an axial length L1. The axial length L1 may be between two times L2 and ten times L2, L2 being the axial length over which the filling material 14 extends on the tube 10. Alternatively, the polymer sheath 12 may be laid over the entire length of the tube. metal tube 10.

The tube 10 thermally insulated by the layers 11 and 14 of Figure 3 is reinforced by depositing a polymer sheath 22 around the tube 10 at the weld 13. The polymeric sheath 22 is deposited on the outer surface of the layer of filling 14 to fill the annular space devoid of insulating material, without exceeding the outer diameter of the insulating tube 11. In other words, the thickness e2 of the insulation layer 11 is greater than or equal to the sum of the thickness e4 of the tube of material 14 and the thickness e5 of the polymer sheath 22. In the case where the sum e2 = e4 + e5, the outer surface of the unrolled rigid pipe forms a cylinder of substantially constant diameter between the layer 11 and the superposition of the layers 14 and 22. The sheath 22 extends approximately along the length L3 separating the two layers of insulating material 11. The polymer and the dimensions of the polymer tube 12 and 22 are selected to significantly increase the bending stiffness of the entire rigid-unrolled pipe when the steel pipe is subjected to significant plastic deformation. According to the invention, a polymer sheath 12 or 22 is chosen so that, by the choice of the polymer and the dimensions of the tube, the sheath made of polymeric material has a bending stiffness at 2% of bending deformation at least twice, preferably at least three times, or even at least four times, greater than the bending stiffness of the metal tube at 2% flexural plastic deformation. In other words, when the pipe according to the invention undergoes a deformation which corresponds to 2% of plastic deformation in flexion of the metal tube, the polymer sheath is stiffer, twice, preferably 3 times or even 4 times, stiffer. that the plastically deformed metal tube (the comparison is made with respect to a portion of the metal tube that does not include welding). According to the invention, it is possible to choose a polymer which is stiff, for example a polymer whose Young's modulus is greater than 500 MPa, preferably greater than 700 MPa. An excellent value of the Young's modulus of the polymer being greater than 1000 MPa. Preferably the stiffness of the sheath 12 or 22 is greater than the stiffness of the insulating material, that is to say that the Young's modulus of the sheath polymer material is greater than the Young's modulus of the insulating material. According to the invention, it is possible to choose a polymer which is ductile, for example a polymer which has a deformation at break greater than 5%, preferably greater than 8%, at 20 ° C. at a strain rate of 2.10 ^-4. s ^"1 . An excellent value of the deformation at break of the polymer material being greater than 10% under the same conditions mentioned above. For example, a polymer of the family of polypropylenes, polyethylenes or polyamides is used to produce the polymer sheath 12 or 22. Preferably, the thickness of the polymer sheath 12 or 22 is greater than the thickness of the steel tube 21 or 10. Preferably, in the embodiment of Figures 2 and 3, the thickness e3 of the polymer sheath 12, respectively the thickness e5 of the sheath 22, is greater than twice the thickness e1 of the metal tube 1 . The polymer sheath 12 or 22 makes it possible to significantly increase the stiffness of the rigid-unrolled pipe when the metal tube of the pipe is deformed in the plastic field. As shown in the examples presented hereinafter, certain polymers have a much larger elastic range than steels, and their residual stiffness drops much less sharply at the time of plasticizing the steel. Consequently, the polymer sheath, which is well chosen according to the invention, has an initial stiffness in negligible flexion with respect to the bending stiffness of the metal tube when the rigid-unrolled pipe is not deformed. On the other hand, when the deformation of the rigid-unrolled pipe causes the deformation of the metal tube in the plastic domain, the bending stiffness of the metal tube decreases. The inventors have found that the flexural stiffness of the plasticized metal tube is then very low and that the bending stiffness of the metal tube drops dramatically well below the bending stiffness of the polymer sheath. The polymer sheath implemented according to the invention makes it possible to significantly increase the bending stiffness of the rigid-unrolled pipe when it is subjected to flexural deformations in the plastic region of the metal tube that composes it. The bending behavior of the rigid-unrolled pipe coated with the polymer sheath is then much more stable than a single metal pipe.

The rigid-unrolled pipe according to the invention makes it possible to reduce the geometrical variations (ovalization, residual curvatures, large plasticization zones) of the metal tube during winding and straightening operations and, therefore, to increase its limit loads (especially the resistance to external pressure due to lower ovalization) and its fatigue behavior. With equal geometric tolerance, the present invention makes it possible to reduce the voltage applied during the winding and straightening operations, and thus to reduce the forces on the tools. The thickness of the metal tube is often sized by the buckling resistance during winding, the present invention then makes it possible to reduce this thickness.

The rigid-unrolled pipe of Figures 2 or 3 can be manufactured according to the method described below. At least two sections of metal tube are manufactured.

The layer of insulating material 1 is deposited on the outer surface of the metal tube sections. For example, the layer 11 consists of a band wound helically around the section of the metal tube. Alternatively, the layer 11 is extruded on the outer wall of the section of the metal tube. The layer 11 covers the entire length of the tubes, except the ends of the sections which remain stripped in order to be able to perform welds.

The two sections covered with the insulation 1 are joined by a weld 13 to form the thermally insulated metal tube 10.

A filling material 14 is disposed on the part of the tube 10 that does not have the insulation 11 at the weld 13. For example, a mold is formed by placing a tubular sleeve over the weld 13, which makes it possible to close the annular space located between the tube 10 and the two insulating layers 11. The tubular sleeve has a cylindrical inner surface whose internal diameter is approximately equal to the diameter of the outer surface of the insulation 11. Then, the material is injected 14 in the closed annular space defined by the tube 10, the ends of the two layers of insulation 11 and the inner surface of said sleeve.

The polymer sheath 12 or 22 is placed on the filling material 14 and optionally on at least a portion of the insulation layer 11. Optionally, the polymer sheath 12 is disposed over the entire length of the metal tube 10 to form the rigid-unrolled pipe according to the invention.

The rigid-unrolled pipe is wound on a spool or a wheel.

The polymer sheath 12 of FIG. 2 or the polymeric sheath 22 of FIG. 3 may be arranged around the rigid pipe unwound according to the following techniques.

The polymer material is injected into a mold forming an annular space around the rigid pipe unwound at the weld 13. The polymer sheath is formed of two half-shells of polymer material which are assembled around the rigid-unrolled pipe, for example by welding the two half-shells with each other.

The polymer sheath is constituted by a strip of polymer material wound helically around the rigid-unrolled pipe. The strip may be hot rolled. One or more coiled strip thicknesses may be required to form the polymeric sheath.

The polymeric sheath is extruded around the rigid-unrolled pipe. The numerical examples presented below make it possible to illustrate the advantages and effectiveness of the polymer sheath to improve the stiffness of a rigid-unrolled pipe subjected to flexural deformations.

The behavior of a rigid-unrolled pipe according to the embodiment described with reference to Figure 2, was simulated by numerical calculation. The simulations were carried out for a unrolled rigid pipe provided with the polymer sheath 12 and for the same pipe devoid of the polymer sheath 12.

The dimensions of the rigid-unrolled pipe are presented in Table 1:

The materials of the rigid-unrolled pipe are presented below: Metal of the tube 10: steel XC 65 Young's modulus = 210,000 MPa

Insulating material 11: polypropylene foam, Young's modulus 1250 MPa

Filling material 14: solid polyurethane, Young's modulus

50 MPa W

11

Polymer 12: Solid Polypropylene, Young's Modulus = 1500 MPa, Fish Factor 0.36, Elastic Limit 50 MPa, Deformation at Break greater than 40%. The simulation consisted in observing the behavior of the rigid-unrolled pipe comprising a weld 13, when it is wound on a rigid wheel having a radius of 9.5 m. When the pipe is wound on the storage wheel, the steel pipe 0 undergoes a plastic deformation of 1%.

FIG. 4 shows the cumulative plastic deformation ECP in% at the end of the winding operation of the pipe rigid-unwound on the wheel, without polymer sheath 12 (dotted line curve) and with the polymer sheath 12 (curve in black). In FIG. 4, the cumulative plastic deformation is represented as a function of the position P in meter along the pipe, the weld being located at the 0 position. The simulation shows that the unrolled rigid pipe devoid of the polymer sheath 12 flames during the winding operation around the wheel, at the weld, it is not possible to wind all the pipe. On the other hand, the unrolled rigid pipe provided with the polymer sheath 12 does not flare and the localized forces in the weld 13 remain limited. The winding can be completed.

To evaluate the distribution of the stiffness of the structure of the rigid pipe-unwound between the metal tube 10 and the sheath 12, the bending behavior of the tube 10 and the sheath 12 were simulated separately.

The bending moments MF, in kN.m, are compared in FIG. 5, the dotted line curve corresponding to the steel tube 10 and the black curve corresponding to the polymer tube 12. In FIG. bending is plotted against EF flexural deformation in%. The polymer tube 12 has a larger diameter and a greater thickness than those of the steel tube 10. This is why, although the polymer is less stiff than the metal, the bending forces supported by the polymer tube are not negligible. compared to the steel tube. It is noted that the bending moment of the steel tube reaches a maximum at about 3.4% of the deformation of bending. At this point, the residual stiffness of the steel tube is no longer sufficient to counteract the reduction of the moment of inertia due to ovalization of the tube.

The residual stiffnesses in bending TRF, in kN.m, are compared in FIG. 6, the dotted line curve corresponds to the steel tube 10, the curve in black corresponds to the polymer tube 12. In FIG. 6, the variation of the residual flexural stiffness is plotted against EF deflection deformation in%. In FIG. 6, it can be seen that the stiffness of the steel tube 10 is very large at low deformation (less than 0.5%), then it drops very rapidly and becomes smaller than that of the polymer tube 12. The stiffness of the tube steel is so low for bending deformation greater than 0.6% that the stiffness of the structure of the rigid-unrolled pipe (steel pipe 10 + insulating layer 14 + polymer sheath 12) is practically based only on stiffness of the polymer sheath 12. For flexural deformations greater than 3.4%, the bending stiffness of the steel tube is negative, which means that the tube becomes unstable in bending if it is not stabilized by the sheath 12 .

Therefore, the simulations clearly confirm that the polymer sheath 12 makes it possible to increase the stiffness and the stability of the rigid-unwound pipe when it is deformed in the plastic domain of the steel tube 10.

Claims

1) Rigid-unrolled pipe, comprising a metal tube (10) composed of at least two pipe sections assembled end to end by a weld (13), a layer of insulating material (1 1) covering the tube sections leaving the ends of the free sections, an annular sleeve of filling material (14) covering the metal tube without a layer of insulating material, characterized in that a sheath of polymer material (12, 22) covers at least a portion of said annular sleeve in filling material, the sheath of polymeric material (12, 22) having a flexural stiffness at 2% of flexural deformation, said stiffness being at least twice as high as the flexural stiffness of the metal tube sections (10) to 2% of plastic deformation in flexion.

2) pipe according to claim 1, characterized in that the sheath of polymer material (12, 22) forms a tube, the thickness of the sheath (12, 22) being at least twice the thickness of the metal tube the polymeric material having a Young's modulus of at least greater than 500 MPa and the polymeric material having a deformation at break of at least greater than 5%.

3) pipe according to one of claims 1 and 2, characterized in that the sum of the thickness of the annular sleeve of filling material (14) and the thickness of the polymer sheath (12, 22) is less than the thickness of the layer of insulating material (1 1).

4) pipe according to one of claims 1 and 2, characterized in that the polymeric sheath (12, 22) covers a portion of the layer of insulating material (1 1) on either side of the weld (3) . 5) Conduit according to one of claims 1 to 4, characterized in that the polymeric material (12, 22) is selected from a polypropylene, a polyamide and a polyethylene. 6) pipe according to one of claims 1 to 5, characterized in that the metal tube (10) is made of steel.

7) Conduit according to one of claims 1 to 6, wherein the insulating material (11) is selected from polymeric, syntactic and non-syntactic foams.

8) Conduit according to one of claims 1 to 7, wherein the filler material (14) is selected from solid polymers or foam. 9) Pipe according to one of the preceding claims, characterized in that the pipe is wound on a drum, the metal tube (10) undergoing plastic deformation in bending greater than 1%.

10) A method of manufacturing a pipe according to one of claims 1 to 9, characterized in that the following steps are carried out:

the at least two tube sections are provided,

the layer of insulating material (11) is deposited on a part of the outer surface of each tube section, the ends of the sections remaining stripped,

the two tube sections are joined by a weld (13) to form the metal tube (10),

the annular sleeve of filling material (14) is arranged on the part of the metal tube which does not have the layer of insulating material,

the sheath of polymer material (12, 22) is arranged at least around the filling material (14). O 2012/072894

15

11) A method of manufacturing a pipe according to claim 10, characterized in that the sheath of polymer material (12, 22) is deposited by performing one of the following steps:

the polymer material is injected into a mold forming an annular space around the pipe,

a strip of polymer material is wound helically around the pipe,

the polymer material sheath is extruded around the pipe.

12) A method of manufacturing a pipe according to one of claims 10 and 11, characterized in that the winding the pipe on a drum.