PIPE STRUCTURE AND METHOD FOR PRODUCING A PIPE STRUCTURE OF THIS TYPE

Abstract

The present disclosure concerns a pipe structure for high-pressure applications. To provide a pipe structure which overcomes at least one of the disadvantages of the pipes known from the state of the art, it is proposed according to the disclosure that the pipe structure has an inner pipe comprising a metal, wherein the inner pipe has an inner surface and an outer surface, at least one strand which surrounds the outer surface of the inner pipe and has a plurality of yarns, wherein at least one of the yarns has carbon fibres, and a protective pipe surrounding the strand and the inner pipe.

Claims

1. A pipe structure which has: an inner pipe comprising a metal, wherein the inner pipe has an inner surface and an outer surface; at least one strand which surrounds the outer surface of the inner pipe and has a plurality of yarns, wherein at least one of the yarns has carbon fibres; and a protective pipe surrounding the strand and the inner pipe.

2. A pipe structure according to claim 1, wherein the at least one strand is selected from a woven fabric, a mesh fabric, a knitted fabric and a multi-axial fabric or any combination thereof.

3. A pipe structure according to claim 1, wherein the at least one strand is of a tubular configuration.

4. A pipe structure according to claim 1, wherein the at least one strand has a proportion of at least 50% carbon fibres.

5. A pipe structure according to claim 1, wherein the inner pipe is a high-pressure pipe with an inside diameter, an outside diameter and a wall thickness, wherein the wall thickness is equal to or greater than the inside diameter.

6. A pipe structure according to claim 1, wherein the inner pipe is a seamless pipe.

7. A pipe structure according to claim 1, wherein the inner pipe is a cold-formed pipe.

8. A pipe structure according to claim 1, wherein a material of the inner pipe is selected from a carbon steel, a low-alloy steel and a high-alloy steel.

9. A pipe structure according to claim 1, wherein the inner pipe is of a surface quality such that cracks on the inner surface do not exceed a depth of 50 μm.

10. A pipe structure according to claim 1, wherein the protective pipe comprises a metal.

11. A pipe structure according to claim 1, wherein at least the protective pipe and the at least one strand are connected together in force-locking relationship or the at least one strand and the inner pipe are connected together in force-locking relationship.

12. Use of a pipe structure according to claim 1 for guiding a fluid subjected to a pressure of 15,000 bars or more.

13. A method of producing a pipe structure, comprising the steps: providing an inner pipe of a metal, wherein the inner pipe has an inner surface and an outer surface, applying at least one strand with a plurality of yarns to the outer surface of the inner pipe, wherein at least one of the yarns has carbon fibres, and introducing the strand with the inner pipe into a protective pipe.

14. A method according to claim 13, wherein the application of the at least one strand to the outer surface of the inner pipe includes weaving, meshing or knitting the at least one strand around the outer surface of the inner pipe.

15. A method according to claim 13, wherein the provision of the inner pipe includes cold forming of a seamless bloom to give the inner pipe.

Description

BRIEF DESCRIPTION OF THE FIGURES

[0064] Further advantages, features and possible applications of the present disclosure will be apparent from the description hereinafter of an embodiment and the related Figures. The description hereinafter of implementations of embodiments of the present disclosure will be better understood when they are considered in conjunction with the accompanying drawings. The illustrated implementations are not limited to the configurations described in detail. In the Figures similar elements are denoted by identical references.

[0065] FIG. 1 shows a diagrammatic cross-sectional view of an implementation of a pipe structure according to an embodiment of the present disclosure, and

[0066] FIG. 2 shows a flow chart of an implementation of a method according to the present disclosure of producing a pipe structure in an implementation of the present disclosure.

DETAILED DESCRIPTION

[0067] FIG. 1 is a diagrammatic cross-sectional view of an implementation of the pipe structure according to an embodiment of the present disclosure. In this arrangement the pipe structure has an inner pipe 2 with an inner surface 3 and an outer surface 4. The outer surface 4 of the inner pipe 2 is surrounded in this case by a strand 5. The strand 5 is in turn surrounded by a protective pipe 6.

[0068] The inner pipe 2 is a seamless, work-hardened pipe comprising an austenitic stainless steel identified as “21-6-9”. The inner pipe 2 was produced by cold drawing and by virtue of the work hardening effect produced thereby has a tensile strength of 1100 N. In addition the inner pipe 2 is of an inside diameter D1 and an outside diameter D2 as well as a wall thickness w. The wall thickness w of the inner pipe 2 is in this case larger than the inside diameter D1 of the inner pipe 2. This is therefore a high-pressure pipe. Due to cold drawing of the inner pipe 2 it has a high surface quality so that cracks present on the inner surface 3 do not exceed a depth of 10 μm.

[0069] The strand 5 comprises a plurality of yarns which in turn are produced completely from carbon fibres. In the illustrated embodiment the strand 5 is a tubular braid mesh which surrounds the inner pipe 2 in the peripheral direction like a sock.

[0070] The protective pipe 6 comprises aluminium and has a weld seam 7 extending in the longitudinal direction over the entire pipe structure 1. The protective pipe 6, the strand 5 and the inner pipe 2 are in this case connected together in force-locking relationship over the entire longitudinal direction of the pipe structure 1.

[0071] FIG. 2 shows a flow chart illustrating implementation of the method of producing the pipe structure 1 shown in FIG. 1. In a first step 100 the inner pipe 2 is provided, by a seamless bloom comprising the austenitic stainless steel “21-6-9” being cold-formed to provide the inner pipe 2.

[0072] In that case cold forming is effected by cold drawing of the seamless bloom through a drawing die. The drawing die works the outer surface of the inner pipe and thus determines the outside diameter D2 of the inner pipe 2. In addition a drawing core is used to work the inner surface 3 of the inner pipe and thus to establish the inside diameter D1 of the inner pipe 2. The surface quality of the inner pipe 2 at least on the inner surface 3 is enhanced by burnishing by the cold drawing through the drawing die and the over the drawing core.

[0073] In a step 101 the strand 5 is applied to the outer surface 4 of the inner pipe 2 by weaving around the outer surface 4 of the inner pipe 2 with a plurality of yarns which completely consist of carbon fibres. The weaving operation produces a positively locking connection between the inner pipe 2 and the strand 5 so that the strand 5 can no longer move in the radial direction with respect to the inner pipe 2. In addition the weaving operation provides that the strand 5 and the inner pipe 2 are connected together in force-locking relationship over the entire extent of the strand 5 in the longitudinal direction of the pipe structure 1. By virtue of the frictional forces which therefore act the strand 5 can no longer move in the axial direction with respect to the inner pipe 2.

[0074] In a step 102 the strand 5 is introduced into the protective pipe 6 together with the inner pipe 2. For that purpose the protective pipe 6 is drawn on to the strand 5 and the inner pipe 2 so that in addition a close positively locking relationship is produced between the strand 5, the inner pipe 2 and the protective pipe 6 in the radial direction.

[0075] The pipe structure 1 shown in FIG. 1, obtained with the method of FIG. 2, is high-pressure resistant and is suitable for carrying fluids which are subjected to a pressure of 15,000 bars or more.

[0076] For the purposes of the original disclosure it is pointed out that all features as can be seen by a man skilled in the art from the present description, the drawings and the claims, even if they are described in specific terms only in connection with certain other features, can be combined both individually and also in any combinations with others of the features or groups of features disclosed here insofar as that has not been expressly excluded or technical aspects make such combinations impossible or meaningless. A comprehensive explicit representation of all conceivable combinations of features is dispensed with here only for the sake of brevity and readability of the description.

[0077] While the disclosure has been illustrated and described in detail in the drawings and the preceding description that illustration and description is only by way of example and is not deemed to be a limitation on the scope of protection as defined by the claims. The disclosure is not limited to the disclosed embodiments.

[0078] Modifications in the disclosed embodiments are apparent to the man skilled in the art from the drawings, the description and the accompanying claims. In the claims the word ‘have’ does not exclude other elements or steps and the indefinite article ‘a’ does not exclude a plurality. The mere fact that certain features are claimed in different claims does not exclude the combination thereof. References in the claims are not deemed to be a limitation on the scope of protection.

REFERENCE NUMERALS

[0079] 1 pipe structure [0080] 2 inner pipe [0081] 3 inner surface [0082] 4 outer surface [0083] 5 strand [0084] 6 protective pipe [0085] 7 weld seam [0086] D1 inside diameter [0087] D2 outside diameter [0088] w wall thickness [0089] 100 providing the inner pipe [0090] 101 applying the strand to the inner pipe [0091] 102 introducing the inner pipe with the strand into the protective pipe