WO2007090209A1

WO2007090209A1 - Composite pipe containing fibre-reinforced concrete

Info

Publication number: WO2007090209A1
Application number: PCT/AT2006/000046
Authority: WO
Inventors: Pius LÄSSER
Original assignee: Ilf Beratende Ingenieure Zt Gesellschaft Mbh
Priority date: 2006-02-07
Filing date: 2006-02-07
Publication date: 2007-08-16

Abstract

Composite pipe, in particular for the transport of fluids under high pressure, in particular for laying in the earth, comprising at least one inner pipe and at least one concrete outer layer surrounding the pipe, wherein the outer layer contains fibre-reinforced, preferably plastic-fibre-reinforced, concrete, wherein an intermediate layer which contains an elastomer is arranged between the inner pipe (2) and the outer layer (4).

Description

FIBER-REINFORCED CONCRETE CONNECTING TUBE

The present invention relates to a composite pipe, in particular for the transport of fluids at high pressure, in particular for laying in the ground, with at least one inner pipe and at least one outer layer of concrete surrounding the pipe.

Furthermore, the invention relates to an arrangement with at least two such composite pipes.

Such media-carrying composite pipes are used for example as pipelines for fluids, wherein the liquids or gases can be transported at high pressure in the line. According to the prior art, it is known that such composite pipes have an internal steel cylinder, which is protected by a cement or plastic facing against erosion inwards. The steel cylinders are not connected. The main structural element is formed by limp or prestressed steel reinforced concrete body. As corrosion protection, the prestressing steels are connected with each other from pipe to pipe joint. A disadvantage of this construction is that in concrete-aggressive environment, caused by cracking, corroded by subsidence or deformation of the steel and thus the usability and stability of the pipe is no longer given. With different settlements of the individual pipe sections, leaks occur at the coupling points, which further increase the corrosion of the supporting reinforcement in addition to the loss of water. The electrical corrosion protection is not guaranteed in the long run. The leaks occurring at the coupling points can wash out the surrounding soil or the pipe bed in which the composite pipes are laid. In addition, such leaks can contaminate groundwater and pollute waterways.

Object of the subject invention is therefore to propose a composite pipe of the type mentioned, which ensures an increased stability while avoiding the above disadvantages.

This is achieved according to a first aspect of the invention in an advantageous embodiment, characterized in that the outer layer has fiber-reinforced, preferably plastic fiber-reinforced concrete. The fiber-reinforced concrete provided according to this aspect of the invention preferably serves as the main supporting element of the composite pipe. Even by chipping or cracking, no risk of corrosion, which would compromise the overall strength of the fiber-reinforced concrete, arise. The corrosion of the main support elements and thus a weakening of the overall construction of the composite pipe is thereby permanently effectively avoided. Basically, all known from the prior art composite materials made of concrete or cement and tensile fibers can be used as fiber-reinforced concrete. Preferably, the fibers are present at least in a certain range as spatially finely divided individual fibers. Particularly favorable is the use of, preferably 100%, plastic fibers such as polypropylene fibers, as these guaranteed not corrode and on the other hand, however, have a correspondingly high tensile strength. The fibers can be oriented in preferred directions or distributed without preferential direction in the concrete. Alternatively or additionally, instead of the finely divided fibers and fiber mats, preferably made of plastic fibers, glass or carbon fibers or the like may be used. These can be formed as a flat fabric and / or reticulated.

By appropriate addition of fiber, the ductility properties can be improved and, as a result of the bending tensile strength present at relatively high strains, a reduction in the cross-sectional thickness as well as improved serviceability and carrying capacity can be achieved.

The durability of the fibers in combination with the preferably alkaline cement stone is of particular importance for the durability of components. The composition of the concrete, in particular the largest grain and the grading curve of the aggregates, the type of fiber used, the fiber geometry and the fiber content should be coordinated. In comparison to reinforced concrete, a higher level of flour meal and a larger amount of binder are generally required. For better processability, hydraulically active additives can be used. Common starting materials and mixing ratios for fiber concrete per se are, for example, the guideline fiber concrete; March 2002 issue of the Austrian Association for Concrete and Construction Technology, Karlsgasse 5, 1040 Vienna. The term outer layer initially means only that the inner tube is covered by this layer. It does not necessarily mean that the outer layer is the outermost layer of the composite pipe. In addition, between the outer layer and the inner tube also more intermediate layers may be present. The fiber reinforcement of the concrete may extend over parts but also over the entire outer layer.

In accordance with a further aspect of the invention, in order to achieve the abovementioned object, at least one intermediate layer comprising an elastomer is arranged between the inner tube and the outer layer.

As a result, on the one hand, the inner tube additionally prevents the ingress of water, and thus, in the case of the preferably used inner metal or steel pipes, their corrosion. An important effect of the elastomer-containing intermediate layer is, moreover, to reduce or avoid the tension forces or tensile stresses emanating from the inner tube on the outer concrete casing. These stresses, which are caused for example by the internal pressure of the transported fluid or by the placement of the laid pipeline, can thus be compensated advantageously by the proposed intermediate layer, so that the lowest possible tensile stresses are transmitted to the outer layer or the concrete casing. The compressive forces are transmitted evenly and punctual peak loads are evenly distributed by deformation of the intermediate layer.

To ensure durability, the material properties of the interlayer should have two basic mechanical properties: (a) reversibility of the deformations and (b) adequate bedding of the steel pipe to prevent bulging of the pipe.

As a preferred material is polyurethane. The layer thickness is to be adapted to the material properties of the polyurethane used and is for example in the order of 5 to 25 mm, preferably from 5 to 10 mm. Common material data can be found, for example, in the standards DIN 53479, DIN 53519, DIN 53504 and DIN 53517 or ISO 815. In a preferred embodiment of the invention, it may be provided that the intermediate layer extends over at least a major part of the length of the inner tube. Thus, the inner tube is substantially completely enveloped by the intermediate layer. However, the two end portions of the inner tube can also be exempted from the intermediate layer at the factory to cause no thermal destruction of the intermediate layer at a performed on the building site welding two pipe parts. After the end-side joining of the individual inner tubes, the uncoated transition regions can preferably be covered with prefabricated, elastic structural parts and connected in a fluid-tight manner to the intermediate layers already present.

According to an advantageous embodiment of the invention, it is provided that the intermediate layer rests directly on the inner tube and / or directly on the concrete outer layer. But it can also be provided more intermediate layers.

With regard to the nature of the intermediate layer, it is advantageous if it has reversible material properties. Thus, the intermediate layer is exposed by the existing stresses or forces no lasting changes, so that a related change in shape is reversible again. According to an exemplary embodiment of the invention may also be provided when the intermediate layer is formed such that a radial extent of the inner tube, preferably in the order of about 5 mm, is compensated. In this context, it may also be favorable if the thickness of the intermediate layer is greater than 1 cm, preferably greater than 2.5 cm. Appropriately, it can also be the case that the compressive modulus of elasticity, for example measured according to DIN 53517 or ISO 815, of the intermediate layer is between 0.6 MN / m ² to 600 MN / m ² . It may likewise be advantageous if the transverse strain number - experimental boundary conditions, for example according to DIN 53504 - of the intermediate layer is less than 0.4, preferably less than 0.1. A further advantageous embodiment of the invention results from the fact that the reversibility - for example, measured according to DIN 53517 or ISO 815 at ambient temperature according to point 6.2 of this standard - the intermediate layer is preferably greater than 98%. This information about the intermediate layer should be understood as a rough guide and therefore should not imply a restrictive character, since the nature of the interlayer should be assessed and selected according to the application.

According to a further embodiment of the invention it can be provided that the intermediate layer, preferably completely, is formed on the basis of polyurethane. These dimensionally stable, but elastically deformable plastics can be used advantageously here, since these deform under tensile and compressive load, but can subsequently find their way back to their original shape. It may also be expedient if the intermediate layer can be foamed onto the tube. In this context, soft foam or integral foam components can be used. An advantage of the foamed material lies in the property of compensating for resulting pressures due to different coefficients of expansion in the matrix.

Alternatively or additionally, it may also be advantageous if the intermediate layer at least partially comprises polyurethane gel. This is a solid, but very soft set material, which, taking into account the principal mechanical requirements defined expansion joints needed to dodge.

The choice of the intermediate layer, however, depends on the expected factors, such as moisture ranges of the elastomeric intermediate layer, expected temperature ranges, expected chemical environments, etc. The useful life of the proposed composite pipes can be set at least 50 years.

Also, in connection with the intermediate layer, good adhesion properties on steel and concrete are of relevance. An important factor is the temperature resistance during the construction phase, since the thermal impact requires by the welding of the individual pipe sections to be provided connections of a defined distance of the intermediate layer of the respective pipe ends. The intermediate layer is therefore conveniently located at the factory with a defined distance to the welds. The strength of the elastomeric intermediate layer must be adapted to the selected material properties of the sandwich construction and thus to the boundary conditions. The main influencing factors are the pipe diameter of the inner steel pipe, the steel grade and the required internal pressure due to the liquid.

In one embodiment of the invention can be provided that the inner tube is preferably circular in cross-section. Likewise, other cross-sectional areas of the inner tubes are possible in an alternative manner. By way of example, the dimension can be made such that the inner tube has a diameter greater than 0.5 m, preferably greater than 3.5 m. It may also be expedient that the thickness of the wall of the inner tube is greater than 10 mm, preferably greater than 20 mm.

To complete the outer concrete coating, a proven spray method of fiber-reinforced shotcrete components is used. This method is already successfully used in tunneling. Alternatively, the concrete casing can also be applied manually in appropriate consistency.

According to a preferred embodiment of the invention it can be provided that the inner tube has on its inner side an inner layer, preferably a mortar layer or a plastic layer. By this measure, the inner tube is protected against erosion inwards. The inner mortar lining can be applied by means of a spun concrete method and the weld seam area between two adjacent pipe parts in a manual manner. From the point of view of corrosion protection, it should be added that an inner cement mortar lining has a passivating effect on the steel, is "self-healing" and thus active cathodic protection is not absolutely necessary within the pipe, but it is also within the scope of the invention to have an inner lining with plastic Thus, the configuration may be such that at least one layer is disposed on both the inside and on the outside of the inner tube, which at least partially comprises an elastomer. The arrangement according to the invention is characterized by at least two composite pipes of the type in question. Conveniently, it is provided that the composite pipes are connected to one another at their end faces, preferably welded, are. As a result, leaks are avoided even with different setting of the pipe sections due to the elasticity of the connected inner tubes. In the case of metallic pipes, cathodic corrosion protection can additionally be ensured throughout. In addition, the internal pipes can absorb longitudinal forces by the welding or connection, whereby elaborate fixed points in manifolds, changes in diameter and branches of the pipes can be avoided. It may be expedient if the transition region between two connected or welded composite pipes is covered by preferably prefabricated elastic structural moldings. In this way, the missing portion of the elastomeric intermediate layer after the welding of the steel tubes by means of the above-mentioned structural moldings is encased. As material, a bulky elastomer can be used. Conveniently, it can be provided that the properties of the structural moldings and the properties of the elastomeric intermediate layer, which extends over the majority of the length of the inner tube, are substantially equivalent.

A further embodiment of the invention provides that against corrosion of the composite pipe, a preferably active, cathodic corrosion protection is provided. Like all metallic pipelines, the composite pipe according to the invention can be protected against external corrosion by active cathodic corrosion protection (PPS). The protection current is generated here by galvanic anodes or by technical DC power sources (external current) outside the pipeline. The state of the art in large piping systems is the cathodic protection with external current, since the power output is controllable, "unlimited" and the effectiveness of the protection system is verifiable.The number and size of the protection systems are according to the Schutzstrombedärf, which depends on piping type, pipe diameter and pipe length, The protection systems consist of an anode field, a rectifier and the connecting line to the pipeline.Usually, the protection systems are set up at the start and end points, in the area of the slide valve station etc. Piping is connected to the pipeline at regular intervals along the pipeline in order to Check the effectiveness of the protective measures or the compliance with the protection criteria. Regular measurements can be used to detect, localize and assess damage to the insulation at an early stage.

Further details and advantages of the present invention will be explained in more detail below with reference to the description of the figures with reference to the drawings. It shows or shows:

Fig. 1: a schematic front view of a composite pipe according to the invention, Fig. 2: the partially broken composite pipe in a perspective

Presentation,

3 shows an arrangement with two frontally welded composite pipes in a partially broken perspective view.

Fig. 1 shows schematically a front view of a composite pipe 1. This has an internal preferably rigid metallic tube 2, on the inside of which an inner layer 5, preferably an applied mortar layer or a plastic layer, is located. On the outside of the inner tube 2, according to the second aspect of the present invention, at least one intermediate layer 3 comprising an elastomer is disposed. This elastomer layer 3 is used to reduce or compensate for the tensile stresses resulting, for example, from the internal pressure of the transported fluid. These expansions acting in particular in the radial direction of the inner tube 1 are compensated by the intermediate layer 3, so that the lowest possible tensile stresses are transmitted to the outer layer 4. In the embodiment shown, the elastomeric intermediate layer 3 is on the one hand directly to the inner tube 2 and on the other hand directly to the concrete casing 4 at. The outer layer 4 comprises fiber-reinforced concrete according to the first aspect of the invention. This serves as the main support element and does not pose any risk of corrosion.

2 shows a partially broken-away perspective view of the composite pipe 1 from FIG. 1. The composite pipe 1 produced in a sandwich construction with inner layer 5 and steel cylinder 2 can be seen, an intermediate layer 3 between the steel cylinder 2 and the outer concrete casing 4 is arranged, which is formed on the basis of an elastomer, preferably based on polyurethane.

Fig. 3 shows a perspective view of an arrangement with two composite pipes 1 and 1 ', the front side laughing at their U mängsf are welded together. Since very high temperatures occur during the welding process, the end regions of the two steel cylinders 2 and 2 'are initially uncoated. After the two steel cylinders 2 and 2 'have been welded together, the uncoated regions between the two elastomer layers 3 and 3' are encased by prefabricated elastic structural molded parts, preferably fluid-tightly connected to the already existing elastomer layers 3 and 3 '. After the application of a full-coverage intermediate layer 3, the concrete casing 4 is applied by means of shotcrete, wherein for reinforcing the concrete casing 4 fibers, preferably plastic fibers, are provided in the circumferential and / or longitudinal direction. An advantage of the construction shown in FIG. 3 lies in the fact that tensile and compressive stresses occurring due to the elastomeric intermediate layer 3 and 3 'can be compensated for on the outer concrete casing 4. In addition, this construction is also suitable for active cathodic corrosion protection. Underground pipelines according to the prior art are at risk of corrosion if the reinforcing steels provided in the concrete outer layer come into contact with the surrounding soil. The proposed, robust sheathing with fiber reinforced concrete avoids this problem. In addition, however, the corrosion risk can still be effectively counteracted by means of cathodic corrosion protection. Since such measures are known to the person skilled in the art, detailed explanations are omitted in this regard. The cathodic

Corrosion protection measures may therefore include all known in the art solutions.

An exemplary dimensioning of a composite pipe according to the invention can be carried out so that for a steel cylinder with a diameter of 3.5 m and an internal pressure of 50 bar according to international standards for steel construction - for example, according to the American National Standards Institute (ANSI) - a steel thickness of 22 mm is prescribed. The radial extent of the steel tube can be up to 4 mm in this case. This radial expansion of the steel tube is through To compensate for a suitable elastomeric intermediate layer in order to transmit the lowest possible tensile stresses on the outer main support element - the fiber-reinforced concrete shell 4 -. The necessary for compensation layer thickness of the intermediate layer 3 depends primarily on the choice of material. On the assumption of the abovementioned example dimensioning of a steel cylinder 2, a layer thickness of the intermediate layer 3 of 1.5 to 3 cm can be assumed.

The present invention is not limited to the embodiment shown, but includes all variants and technical equivalents, which may fall within the scope of the following claims.

Of course, two or more described intermediate layers, which at least partially comprise elastomers, or fiber-reinforced concrete layers in

Sandwich construction to be installed. If desired, the elastomeric layers can also be arranged with the addition of plasticizers.

Composite pipes 1 according to the invention are, for example, for drinking water pipelines, in

Sewage systems or in natural gas pipelines advantageously used.

Claims

claims:

1. Composite pipe, in particular for the transport of fluids at high pressure, in particular for laying in the ground, with at least one inside

Pipe and at least one outer layer surrounding the pipe of concrete, characterized in that the outer layer (4) has fiber-reinforced, preferably plastic fiber-reinforced concrete.

2. A composite pipe according to claim 1, characterized in that the inner tube (2) is designed as a metal tube, preferably as a steel tube.

3. Composite pipe according to one of claims 1 or 2, characterized in that the inner tube (2) is preferably circular in cross-section.

4. The composite pipe according to one of claims 1 to 3, characterized in that the inner tube (2) has a diameter greater than 0.5 m, preferably greater than 3.5 m.

5. The composite pipe according to one of claims 1 to 4, characterized in that the inner tube (2) is rigid.

6. Composite pipe according to one of claims 1 to 5, characterized in that the thickness of the wall of the inner tube (2) is greater than 10 mm, preferably greater than 20 mm.

7. The composite pipe according to one of claims 1 to 6, characterized in that the inner tube (2) on its inner side an inner layer (5), preferably a mortar layer or a plastic layer.

8. A composite pipe, in particular for the transport of fluids at high pressure, in particular for laying in the ground, with at least one inner pipe and at least one outer layer surrounding the pipe concrete, in particular according to one of claims 1 to 7, characterized in that between the inner tube (2) and the outer layer (4) at least one intermediate layer (3) is arranged, which has an elastomer.

9. The composite pipe according to claim 8, characterized in that the

Intermediate layer (3) extends over at least a majority of the length of the inner tube (2).

10. A composite pipe according to claim 8 or 9, characterized in that the intermediate layer (3) rests with its inner side directly on the outside of the inner tube (2).

11. A composite pipe according to one of claims 8 to 10, characterized in that the intermediate layer (3) rests with its outer side directly on the inside of the outer layer (4).

12. A composite pipe according to any one of claims 8 to 11, characterized in that the intermediate layer (3) surrounds the inner tube (2) substantially completely.

13. A composite pipe according to any one of claims 8 to 12, characterized in that the intermediate layer (3) has reversible material properties.

14. A composite pipe according to any one of claims 8 to 13, characterized in that the intermediate layer (3) is formed such that a radial

Extension of the inner tube (2), preferably in the order of about 5 mm, is compensated.

15. A composite pipe according to any one of claims 8 to 14, characterized in that the thickness of the intermediate layer (3) is greater than 0.5 cm, preferably greater than 2.5 cm.

16. A composite pipe according to any one of claims 8 to 15, characterized in that the compressive modulus of elasticity of the intermediate layer (3) is between 0.6 MN / m ² to 600 MN / m ² .

17. A composite pipe according to any one of claims 8 to 16, characterized in that the transverse expansion coefficient of the intermediate layer (3) is less than 0.4, preferably less than 0.1, is.

18. A composite pipe according to any one of claims 8 to 17, characterized in that the reversibility of the intermediate layer (3) is preferably greater than 98%.

19. A composite pipe according to any one of claims 8 to 18, characterized in that the intermediate layer (3), preferably completely, is formed on the basis of polyurethane.

20. The composite pipe according to one of claims 8 to 19, characterized in that the intermediate layer (3) can be foamed onto the pipe.

21. A composite pipe according to any one of claims 8 to 20, characterized in that the intermediate layer (3) comprises polyurethane gel.

22. A composite pipe according to any one of claims 8 to 21, characterized in that the inner tube (2) is designed as a metal tube, preferably as a steel tube.

23. Arrangement with at least two composite pipes according to one of claims 1 to 22.

24. Arrangement according to claim 23, characterized in that the inner tubes (2) connected to one another at their end faces, preferably welded, are.

25. The arrangement according to claim 23 or 24, characterized in that the transition region between two connected composite pipes (1, 1 ') is covered by, preferably prefabricated, elastic structural moldings.

26. Arrangement according to one of claims 23 to 25, characterized in that against corrosion of the composite pipe (1), a preferably active, cathodic corrosion protection is provided.