CN211203158U

CN211203158U - Composite pipeline

Info

Publication number: CN211203158U
Application number: CN201921915985.5U
Authority: CN
Inventors: 马伊; 张志成; 梁文斌
Original assignee: China Energy Investment Corp Ltd; National Institute of Clean and Low Carbon Energy
Current assignee: China Energy Investment Corp Ltd; National Institute of Clean and Low Carbon Energy
Priority date: 2019-11-07
Filing date: 2019-11-07
Publication date: 2020-08-07
Anticipated expiration: 2029-11-07

Abstract

The utility model discloses a composite pipeline, composite pipeline includes: an inner layer made of a first material; the core layer is sleeved on the inner layer and is made of a second material; and the outer layer is sleeved on the core layer and made of a third material, the expansion coefficient of each of the first material and the third material is larger than or smaller than that of the second material, a first elastic buffer layer is arranged between the inner layer and the core layer, and/or a second elastic buffer layer is arranged between the outer layer and the core layer. According to the utility model discloses compound pipeline has advantages such as not layering under cold and hot in turn.

Description

Composite pipeline

Technical Field

The utility model relates to a pipeline field specifically, relates to composite pipeline.

Background

The pipeline, the road, the railway, the water transportation and the aviation jointly form five transportation modes of the modern society. Compared with the latter four, the pipeline has the advantages of easy laying, high transportation efficiency, low comprehensive cost and the like, and is an important mode for mass and low-cost transportation of gas, liquid and solid-liquid mixtures.

The steel wire mesh reinforced thermoplastic pressure-resistant pipeline is an important member in a pipeline family, and is widely applied to the fields of offshore oil exploitation, natural gas transportation, building water supply and drainage, mining water supply and drainage, chemical engineering and the like. However, due to the problem of steel wire corrosion, such thermoplastic pipes are very prone to failure, and the operation safety and the service life of the pipes are seriously affected.

The composite pipeline has excellent corrosion resistance, can effectively solve the corrosion problem of the steel wire mesh reinforced thermoplastic pipeline, and is an important development direction in the field of pressure-resistant pipelines.

SUMMERY OF THE UTILITY MODEL

The utility model aims at overcoming the problem that prior art exists, provide compound pipeline.

The present application is based on the discovery and recognition by the inventors of the following facts and problems: existing composite pipes comprise an inner layer, a core layer and an outer layer, the coefficient of expansion of the material used for the core layer being much smaller than the coefficient of expansion of the material used for the inner layer and the coefficient of expansion of the material used for the outer layer. Therefore, the existing composite pipe is very easy to delaminate under the cold and hot alternation, namely, the core layer is separated from the inner layer and the outer layer under the cold and hot alternation.

In order to achieve the above object, the present invention provides a composite pipe, including: an inner layer made of a first material; the core layer is sleeved on the inner layer and is made of a second material; and the outer layer is sleeved on the core layer and made of a third material, the expansion coefficient of each of the first material and the third material is larger than or smaller than that of the second material, a first elastic buffer layer is arranged between the inner layer and the core layer, and/or a second elastic buffer layer is arranged between the outer layer and the core layer.

According to the utility model discloses a compound pipeline has the advantage that does not laminate under cold and hot in turn.

Preferably, the first elastic buffer layer is associated with each of the inner layer and the core layer; and/or the second elastic buffer layer is associated with each of the outer layer and the core layer.

Preferably, a first bonding layer is arranged between the inner layer and the first elastic buffer layer; and/or a second bonding layer is arranged between the outer layer and the second elastic buffer layer.

Preferably, a third bonding layer is arranged between the core layer and the first elastic buffer layer; and/or a fourth bonding layer is arranged between the core layer and the second elastic buffer layer.

Preferably, a first groove is formed in the outer circumferential surface of the inner layer, a first part of the first elastic buffer layer is fitted in the first groove, a second groove is formed in the inner circumferential surface of the core layer, and a second part of the first elastic buffer layer is fitted in the second groove; and/or the inner peripheral surface of the outer layer is provided with a third groove, the first part of the second elastic buffer layer is matched in the third groove, the outer peripheral surface of the core layer is provided with a fourth groove, and the second part of the second elastic buffer layer is matched in the fourth groove.

Preferably, the cross-sectional area of the first groove increases in the outside-in direction, and the cross-sectional area of the second groove increases in the inside-out direction; and/or the cross-sectional area of the third groove increases along the direction from inside to outside, and the cross-sectional area of the fourth groove increases along the direction from outside to inside.

Preferably, the cross-sectional area of the first groove gradually increases along the direction from outside to inside, and the cross-sectional area of the second groove gradually increases along the direction from inside to outside; and/or the cross sectional area of the third groove is gradually increased along the direction from inside to outside, and the cross sectional area of the fourth groove is gradually increased along the direction from outside to inside.

Preferably, the first resilient cushioning layer is normally in compression and the second resilient cushioning layer is normally in compression.

Preferably, the inner layer is made of a thermoplastic resin, the outer layer is made of a thermoplastic resin, the core layer is made of a fiber-reinforced thermoplastic composite material, the first elastic buffer layer is made of at least one of a polyolefin hot-melt adhesive and a multipolymer polyolefin and/or the second elastic buffer layer is made of at least one of a polyolefin hot-melt adhesive and a multipolymer polyolefin.

Preferably, the thickness of the core layer is 0.5 mm to 50 mm, the thickness of the first elastic buffer layer is 0.05 mm to 5 mm and/or the thickness of the second elastic buffer layer is 0.05 mm to 5 mm.

Drawings

Fig. 1 is a schematic structural view of a composite conduit according to an embodiment of the present invention;

fig. 2 is a schematic partial structural view of a composite conduit according to an embodiment of the present invention;

fig. 3 is a schematic partial structure diagram of a composite pipeline according to an embodiment of the present invention.

Detailed Description

Reference will now be made in detail to embodiments of the present invention, examples of which are illustrated in the accompanying drawings. The embodiments described below with reference to the drawings are exemplary and intended to be used for explaining the present invention, and should not be construed as limiting the present invention.

A composite pipe 1 according to an embodiment of the present invention is described below with reference to the accompanying drawings. As shown in fig. 1-3, a composite pipe 1 according to an embodiment of the present invention includes an inner layer 10, a core layer 20, and an outer layer 30.

The core layer 20 is sleeved on the inner layer 10, and the outer layer 30 is sleeved on the core layer 20. In other words, the core layer 20 is disposed within the outer layer 30 and the inner layer 10 is disposed within the core layer 20. The inner layer 10 is made of a first material, the core layer 20 is made of a second material and the outer layer 30 is made of a third material. It will be understood by those skilled in the art that the first material, the second material and the third material are all known materials.

Each of the first material and the third material has a coefficient of expansion that is greater than or less than a coefficient of expansion of the second material. Wherein, a first elastic buffer layer 40 is arranged between the inner layer 10 and the core layer 20 and/or a second elastic buffer layer 50 is arranged between the outer layer 30 and the core layer 20.

When the expansion coefficient of each of the first material and the third material is greater than that of the second material, the amount of expansion of the core layer 20 is smaller than the amount of expansion of the inner layer 10 and the amount of expansion of the outer layer 30 when heated, and the amount of contraction of the core layer 20 is smaller than the amount of contraction of the inner layer 10 and the amount of contraction of the outer layer 30 when cooled.

By providing the first elastic buffer layer 40 between the inner layer 10 and the core layer 20, the inner layer 10 and the core layer 20 expanded when heated can compress the first elastic buffer layer 40 (i.e. the first elastic buffer layer 40 can absorb the expansion of the inner layer 10 and the core layer 20) so as to avoid the inner layer 10 from (excessively) extruding the core layer 20, and the first elastic buffer layer 40 can expand inward and outward when cooled so as to avoid the inner layer 10 and the core layer 20 from separating from the first elastic buffer layer 40, i.e. to avoid the inner layer 10 and the core layer 20 from separating from each other.

By providing the second elastic buffer layer 50 between the outer layer 30 and the core layer 20, which expand when heated, can compress the second elastic buffer layer 50 (i.e. the second elastic buffer layer 50 can absorb the expansion of the outer layer 30 and the core layer 20) so as to avoid the outer layer 30 from (excessively) extruding the core layer 20, and the second elastic buffer layer 50 can expand inward and outward when cooled so as to avoid the outer layer 30 and the core layer 20 from separating from the second elastic buffer layer 50, i.e. to avoid the outer layer 30 and the core layer 20 from separating from each other.

"heated" and "cooled" are to be understood in a broad sense. For example, after the composite pipe 1 at the normal temperature is heated, the process of returning the composite pipe 1 from the heated state to the normal temperature state may be a "cooling" process; after the composite pipe 1 at the normal temperature is cooled, the process of returning the composite pipe 1 from the cooled state to the normal temperature state may be a "heated" process.

Therefore, by providing the first elastic buffer layer 40 between the inner layer 10 and the core layer 20, the inner layer 10 and the core layer 20 can be prevented from being separated from each other by alternating cold and hot; by providing a second elastic buffer layer 50 between outer layer 30 and core layer 20, it is possible to avoid that outer layer 30 and core layer 20 are detached from each other under alternating cold and hot conditions.

When the expansion coefficient of each of the first material and the third material is smaller than that of the second material, the core layer 20 expands more than the inner layer 10 and the outer layer 30 when heated, and the core layer 20 contracts more than the inner layer 10 and the outer layer 30 when cooled.

By providing the first elastic buffer layer 40 between the inner layer 10 and the core layer 20, the core layer 20 and the inner layer 10, which expand when heated, can compress the first elastic buffer layer 40 (i.e. the first elastic buffer layer 40 can absorb the expansion of the core layer 20 and the inner layer 10) so as to avoid the core layer 20 from (excessively) extruding the inner layer 10, and the first elastic buffer layer 40 can expand inward and outward when cooled so as to avoid the core layer 20 and the inner layer 10 from breaking away from the first elastic buffer layer 40, i.e. to avoid the core layer 20 and the inner layer 10 from breaking away from each other.

By providing the second elastic buffer layer 50 between the outer layer 30 and the core layer 20, the core layer 20 and the outer layer 30, which expand when heated, can compress the second elastic buffer layer 50 (i.e. the second elastic buffer layer 50 can absorb the expansion of the core layer 20 and the outer layer 30) so as to avoid the core layer 20 from (excessively) extruding the outer layer 30, and the second elastic buffer layer 50 can expand inward and outward when cooled so as to avoid the core layer 20 and the outer layer 30 from breaking away from the second elastic buffer layer 50, i.e. to avoid the core layer 20 and the outer layer 30 from breaking away from each other.

According to the utility model discloses composite pipe 1 is through setting up first elasticity buffer layer 40 between inlayer 10 and core layer 20 and/or set up second elasticity buffer layer 50 between skin 30 and core layer 20 to can avoid under cold and hot alternation that inlayer 10 and core layer 20 break away from each other and/or skin 30 and core layer 20 break away from each other.

Therefore, the composite pipe 1 according to the embodiment of the present invention has the advantages of no delamination under the cold and hot alternation, etc.

As shown in fig. 1-3, in some embodiments of the present invention, composite pipe 1 includes an inner layer 10, a core layer 20, and an outer layer 30. Preferably, the inner layer 10 is made of a thermoplastic resin, the outer layer 30 is made of a thermoplastic resin, and the core layer 20 is made of a fiber-reinforced thermoplastic composite material. Since the expansion coefficient of the fibers is much smaller than that of the thermoplastic resin, the expansion coefficient of the fiber-reinforced thermoplastic composite is also much smaller than that of the thermoplastic resin.

A first elastic buffer layer 40 is provided between the inner layer 10 and the core layer 20 and/or a second elastic buffer layer 50 is provided between the outer layer 30 and the core layer 20. Preferably, the first elastic buffer layer 40 is made of at least one of polyolefin hot melt adhesive and multipolymer polyolefin, and the second elastic buffer layer 50 is made of at least one of polyolefin hot melt adhesive and multipolymer polyolefin.

In one specific example of the present invention, the thickness of the core layer 20 is 0.5 mm to 50 mm, the thickness of the first elastic buffer layer 40 is 0.05 mm to 5 mm, and the thickness of the second elastic buffer layer 50 is 0.05 mm to 5 mm. The structure of the composite conduit 1 can thereby be made more rational.

The first elastic buffer layer 40 and the second elastic buffer layer 50 with the thickness of 0.05 mm to 5 mm can better compensate the deformation of the core layer 20, the inner layer 10 and the outer layer 30 caused by thermal expansion and cold contraction. The inner diameter of the inner layer 10 is 10 mm-1500 mm, the thickness of the inner layer 10 is 1 mm-500 mm, the inner diameter of the outer layer 30 is 15 mm-1600 mm, and the thickness of the outer layer 30 is 0.5 mm-200 mm. Wherein the thickness is equal to half the difference between the inner and outer diameters. For example, the thickness of the outer layer 30 (outer diameter of the outer layer 30 — inner diameter of the outer layer 30)/2.

In some examples of the present invention, a first elastic buffer layer 40 is associated with each of the inner layer 10 and the core layer 20, and a second elastic buffer layer 50 is associated with each of the outer layer 30 and the core layer 20. Therefore, the first elastic buffer layer 40 and each of the inner layer 10 and the core layer 20 can be more firmly combined together, and the second elastic buffer layer 50 and each of the outer layer 30 and the core layer 20 can be more firmly combined together, so that when the inner layer 10 inwardly stretches the first elastic buffer layer 40 and the core layer 20 outwardly stretches the first elastic buffer layer 40, the first elastic buffer layer 40 is further prevented from being separated from the inner layer 10 and the core layer 20, and when the outer layer 30 outwardly stretches the second elastic buffer layer 50 and the core layer 20 inwardly stretches the second elastic buffer layer 50, the second elastic buffer layer 50 is further prevented from being separated from the outer layer 30 and the core layer 20.

In one embodiment of the present invention, a first adhesive layer is disposed between the inner layer 10 and the first elastic buffer layer 40, and a second adhesive layer is disposed between the outer layer 30 and the second elastic buffer layer 50. From this can make inlayer 10 and first elastic buffer layer 40 combine together more firmly, outer 30 and second elastic buffer layer 50 combine together more firmly, thereby inlayer 10 can inwards stretch first elastic buffer layer 40 better when being cold, outer 30 can outwards stretch second elastic buffer layer 50 better, so that further avoid inlayer 10 to break away from first elastic buffer layer 40, outer 30 breaks away from second elastic buffer layer 50, and then further avoid inlayer 10 to break away from sandwich layer 20, outer 30 breaks away from sandwich layer 20.

Preferably, a third bonding layer is disposed between the core layer 20 and the first elastic buffer layer 40, and a fourth bonding layer is disposed between the core layer 20 and the second elastic buffer layer 50. Thereby, the core layer 20 can be more firmly combined with the first elastic buffer layer 40 and the second elastic buffer layer 50, so that the core layer 20 can better stretch the first elastic buffer layer 40 outwards and stretch the second elastic buffer layer 50 inwards when being cooled, so that the core layer 20 is further prevented from being separated from the first elastic buffer layer 40 and the second elastic buffer layer 50, and the core layer 20 is further prevented from being separated from the inner layer 10 and the outer layer 30.

In another embodiment of the present invention, a first groove is formed on the outer peripheral surface of the inner layer 10, a first portion of the first elastic buffer layer 40 is fitted in the first groove, a second groove is formed on the inner peripheral surface of the core layer 20, and a second portion of the first elastic buffer layer 40 is fitted in the second groove. The inner circumferential surface of the outer layer 30 is provided with a third groove in which a first portion of the second elastic buffer layer 50 is fitted, the outer circumferential surface of the core layer 20 is provided with a fourth groove in which a second portion of the second elastic buffer layer 50 is fitted.

By fitting a first portion of the first elastic buffer layer 40 in the first groove and a second portion of the first elastic buffer layer 40 in the second groove, when the composite pipe 1 is cooled, the inner layer 10 drives the first elastic buffer layer 40 to move inward, and the core layer 20 drives the first elastic buffer layer 40 to move outward, so as to prevent the inner layer 10 and the core layer 20 from separating from the first elastic buffer layer 40.

By fitting the first part of the second elastic buffer layer 50 in the third groove and fitting the second part of the second elastic buffer layer 50 in the fourth groove, when the composite pipe 1 is cooled, the outer layer 30 drives the second elastic buffer layer 50 to move outwards, and the core layer 20 drives the second elastic buffer layer 50 to move inwards, so as to prevent the outer layer 30 and the core layer 20 from separating from the second elastic buffer layer 50.

Preferably, the cross-sectional area of the first groove increases in the outside-in direction, the cross-sectional area of the second groove increases in the inside-out direction, the cross-sectional area of the third groove increases in the inside-out direction, and the cross-sectional area of the fourth groove increases in the outside-in direction. Whereby the first elastic buffer layer 40 and each of the inner layer 10 and the core layer 20 are more firmly bonded together and the second elastic buffer layer 50 and each of the outer layer 30 and the core layer 20 are more firmly bonded together, thereby further preventing the first elastic buffer layer 40 from being separated from the inner layer 10 and the core layer 20 when the inner layer 10 inwardly stretches the first elastic buffer layer 40 and the core layer 20 outwardly stretches the first elastic buffer layer 40; second elastic buffer layer 50 is further prevented from separating from outer layer 30 and core layer 20 when outer layer 30 stretches second elastic buffer layer 50 outward and core layer 20 stretches second elastic buffer layer 50 inward.

More preferably, the cross-sectional area of the first groove gradually increases in an outside-in direction, the cross-sectional area of the second groove gradually increases in an inside-out direction, the cross-sectional area of the third groove gradually increases in an inside-out direction, and the cross-sectional area of the fourth groove gradually increases in an outside-in direction. Whereby the first elastic buffer layer 40 and each of the inner layer 10 and the core layer 20 are more firmly bonded together and the second elastic buffer layer 50 and each of the outer layer 30 and the core layer 20 are more firmly bonded together, thereby further preventing the first elastic buffer layer 40 from being separated from the inner layer 10 and the core layer 20 when the inner layer 10 inwardly stretches the first elastic buffer layer 40 and the core layer 20 outwardly stretches the first elastic buffer layer 40; second elastic buffer layer 50 is further prevented from separating from outer layer 30 and core layer 20 when outer layer 30 stretches second elastic buffer layer 50 outward and core layer 20 stretches second elastic buffer layer 50 inward. Wherein the inward and outward directions are indicated by arrows a in fig. 1.

Further, the first elastic buffer layer 40 may be in contact with only each of the inner layer 10 and the core layer 20, and the second elastic buffer layer 50 may be in contact with only each of the outer layer 30 and the core layer 20.

Specifically, the first elastic buffer layer 40 may be normally in a compressed state, and the second elastic buffer layer 50 may be normally in a compressed state. The first elastic buffer layer 40 is normally in a compressed state: when the composite pipe 1 is not cooled and heated, the first elastic buffer layer 40 is in a compressed state; the second elastic buffer layer 50 is normally in a compressed state: when composite pipe 1 is not subjected to heat and cold, second resilient buffer layer 50 is in a compressed state.

When composite pipe 1 is heated, expanded inner layer 10 and core layer 20 may compress first elastic buffer layer 40, and expanded outer layer 30 and core layer 20 may compress second elastic buffer layer 50. When the composite pipe 1 is cooled, the inner layer 10 contracts inward, the outer layer 30 contracts outward, and the core layer 20 contracts inward and outward, and since the first and second elastic buffer layers 40 and 50 are in a compressed state, the first elastic buffer layer 40 may rebound to be always in contact with the inner layer 10 and the core layer 20, and the second elastic buffer layer 50 may rebound to be always in contact with the outer layer 30 and the core layer 20. Whereby the inner layer 10 and the outer layer 30 can be prevented from being separated from the core layer 20.

When the inner layer 10 reaches a maximum amount of contraction, the first elastic buffer layer 40 may remain in compression or just in the natural state; second elastic buffer layer 50 may remain compressed or just in its natural state when outer layer 30 reaches a maximum amount of contraction.

In the description of the present invention, it is to be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential", and the like, indicate the orientation or positional relationship indicated based on the drawings, and are only for convenience of description and simplicity of description, and do not indicate or imply that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore, should not be construed as limiting the present invention.

Furthermore, the terms "first", "second" and "first" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one such feature. In the description of the present invention, "a plurality" means at least two, e.g., two, three, etc., unless specifically limited otherwise.

In the present invention, unless otherwise expressly stated or limited, the terms "mounted," "connected," and "fixed" are to be construed broadly and may, for example, be fixedly connected, detachably connected, or integrally formed; may be mechanically coupled, may be electrically coupled or may be in communication with each other; they may be directly connected or indirectly connected through intervening media, or they may be connected internally or in any other suitable relationship, unless expressly stated otherwise. The specific meaning of the above terms in the present invention can be understood according to specific situations by those skilled in the art.

In the present application, unless expressly stated or limited otherwise, the first feature may be directly on or directly under the second feature or indirectly via intermediate members. Also, a first feature "on," "over," and "above" a second feature may be directly or diagonally above the second feature, or may simply indicate that the first feature is at a higher level than the second feature. A first feature being "under," "below," and "beneath" a second feature may be directly under or obliquely under the first feature, or may simply mean that the first feature is at a lesser elevation than the second feature.

In the description herein, references to the description of the term "one embodiment," "some embodiments," "an example," "a specific example," or "some examples," etc., mean that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the invention. In this specification, the schematic representations of the terms used above are not necessarily intended to refer to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples. Furthermore, various embodiments or examples and features of different embodiments or examples described in this specification can be combined and combined by one skilled in the art without contradiction.

Although embodiments of the present invention have been shown and described, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention, and that variations, modifications, substitutions and alterations can be made to the above embodiments by those of ordinary skill in the art without departing from the scope of the present invention.

Claims

1. A composite conduit (1), characterized in that it comprises:

an inner layer (10), the inner layer (10) being made of a first material;

a core layer (20), said core layer (20) being sleeved on said inner layer (10), said core layer (20) being made of a second material; and

an outer layer (30), the outer layer (30) being sleeved on the core layer (20), the outer layer (30) being made of a third material, the coefficient of expansion of each of the first and third materials being greater than or less than the coefficient of expansion of the second material, wherein a first elastic buffer layer (40) is provided between the inner layer (10) and the core layer (20) and/or a second elastic buffer layer (50) is provided between the outer layer (30) and the core layer (20).

2. Composite conduit (1) according to claim 1,

said first elastic buffer layer (40) being associated with each of said inner layer (10) and said core layer (20); and/or

The second elastic buffer layer (50) is associated with each of the outer layer (30) and the core layer (20).

3. Composite conduit (1) according to claim 2,

a first bonding layer is arranged between the inner layer (10) and the first elastic buffer layer (40); and/or

And a second bonding layer is arranged between the outer layer (30) and the second elastic buffer layer (50).

4. Composite conduit (1) according to claim 3,

a third bonding layer is arranged between the core layer (20) and the first elastic buffer layer (40); and/or

And a fourth bonding layer is arranged between the core layer (20) and the second elastic buffer layer (50).

5. Composite conduit (1) according to claim 2,

a first groove is formed in the outer peripheral surface of the inner layer (10), a first part of the first elastic buffer layer (40) is matched in the first groove, a second groove is formed in the inner peripheral surface of the core layer (20), and a second part of the first elastic buffer layer (40) is matched in the second groove; and/or

The inner circumferential surface of the outer layer (30) is provided with a third groove, the first part of the second elastic buffer layer (50) is matched in the third groove, the outer circumferential surface of the core layer (20) is provided with a fourth groove, and the second part of the second elastic buffer layer (50) is matched in the fourth groove.

6. Composite conduit (1) according to claim 5,

the cross sectional area of the first groove is increased along the direction from outside to inside, and the cross sectional area of the second groove is increased along the direction from inside to outside; and/or

The cross-sectional area of the third groove increases along the direction from inside to outside, and the cross-sectional area of the fourth groove increases along the direction from outside to inside.

7. Composite conduit (1) according to claim 6,

the cross sectional area of the first groove is gradually increased along the direction from outside to inside, and the cross sectional area of the second groove is gradually increased along the direction from inside to outside; and/or

The cross-sectional area of the third groove gradually increases along the direction from inside to outside, and the cross-sectional area of the fourth groove gradually increases along the direction from outside to inside.

8. Composite pipe (1) according to claim 1, wherein said first elastic damping layer (40) is normally in compression and said second elastic damping layer (50) is normally in compression.

9. A composite pipe (1) according to any of claims 1-8, wherein the inner layer (10) is made of a thermoplastic resin, the outer layer (30) is made of a thermoplastic resin, the core layer (20) is made of a fibre reinforced thermoplastic composite, the first elastic buffer layer (40) is made of at least one of a polyolefin hot melt glue and a multipolymerized polyolefin and/or the second elastic buffer layer (50) is made of at least one of a polyolefin hot melt glue and a multipolymerized polyolefin.

10. Composite pipe (1) according to any of claims 1-8, wherein the thickness of the core layer (20) is 0.5-50 mm, the thickness of the first elastic buffer layer (40) is 0.05-5 mm and/or the thickness of the second elastic buffer layer (50) is 0.05-5 mm.