COMPOSITE PIPE COMPRISED OF A CARRIER PIPE AND AT LEAST ONE PROTECTIVE PIPE, AND METHOD FOR THE PRODUCTION THEREOF

Abstract

A composite pipe includes a carrier pipe and at least one protective pipe. The carrier pipe is produced from a non-corrosion resistant steel, which has at least a partially austenitic structure, with the following chemical composition (in wt. %): C: 0.005 to 1.4; Mn: 5 to 35; the remainder being iron including unavoidable elements accompanying steel, with the optional alloying of the following elements (in wt. %): Ni: 0 to 6; Cr: 0 to 9; Al: 0 to 15; Si: 0 to 8; Mo: 0 to 3; Cu: 0 to 4; V: 0 to 2; Nb: 0 to 2; Ti: 0 to 2; Sb: 0 to 0.5; B: 0 to 0.5; Co: 0 to 5; W: 0 to 3; Zr: 0 to 4; Ca: 0 to 0.1; P: to 0.6; S: 0 to 0.2; N: 0.002 to 0.3. In a method for producing a composite pipe of this type, the carrier pipe and the at least one protective pipe are mechanically or metallurgically connected to one another.

Claims

1.-30. (canceled)

31. A composite pipe, comprising: a carrier pipe; and at least one protective pipe, said carrier pipe being produced from a non-corrosion-resistant steel which comprises at least one part-austenitic microstructure, having the following chemical composition (in wt. %): C: 0.005 to 1.4 Mn: 5 to 35 with the remainder being iron including unavoidable, steel-associated elements, with optional addition by alloying of the following elements (in wt. %): Ni: 0 to 6 Cr: 0 to 9 Al: 0 to 15 Si: 0 to 8 Mo: 0 to 3 Cu: 0 to 4 V: 0 to 2 Nb: 0 to 2 Ti: 0 to 2 Sb: 0 to 0.5 B: 0 to 0.5 Co: 0 to 5 W: 0 to 3 Zr: 0 to 4 Ca: 0 to 0.1 P: 0 to 0.6 S: 0 to 0.2 N: 0.002 to 0.3.

32. The composite pipe of claim 31, wherein the steel of the carrier pipe contains (in wt. %): Ni: 1 to 4.

33. The composite pipe of claim 31, wherein the steel of the carrier pipe contains (in wt. %): Cr: 0.5 to 5.

34. The composite pipe of claim 31, wherein the steel of the carrier pipe contains (in wt. %): Al: 0.5 to 11.

35. The composite pipe of claim 31, wherein the steel of the carrier pipe contains (in wt. %): Si: 0.3 to 5.

36. The composite pipe of claim 31, wherein the steel of the carrier pipe contains (in wt. %): Mo: 0.01 to 1.8.

37. The composite pipe of claim 31, wherein the steel of the carrier pipe contains (in wt. %): Cu: 0.005 to 3.

38. The composite pipe of claim 31, wherein the steel of the carrier pipe contains (in wt. %): V: 0.004 to 1.

39. The composite pipe of claim 31, wherein the steel of the carrier pipe contains (in wt. %): Nb: 0.004 to 1.

40. The composite pipe of claim 31, wherein the steel of the carrier pipe contains (in wt. %): Ti: 0.005 to 1.2.

41. The composite pipe of claim 31, wherein that the steel of the carrier pipe contains (in wt. %): Sb: 0.003 to 0.2.

42. The composite pipe of claim 31, wherein the steel contains (in wt. %): B: 0. 0003 to 0.1.

43. The composite pipe of claim 31, wherein the steel of the carrier pipe contains (in wt. %): Co: 0.01 to 3.

44. The composite pipe of claim 31, wherein the steel of the carrier pipe contains (in wt. %): W: 0.1 to 2.

45. The composite pipe of claim 31, wherein the steel of the carrier pipe contains (in wt. %): Zr: 0.005 to 2.

46. The composite pipe of claim 31, wherein the steel of the carrier pipe contains (in wt. %): P: 0.0005 to 0.1.

47. The composite pipe of claim 31, wherein the steel of the carrier pipe contains (in wt. %): N: 0.004 to 0.2.

48. The composite pipe of claim 31, wherein the steel of the carrier pipe contains (in wt. %): C: 0.005 to 0.9, preferably 0.01 to <0.3 Mn: more than 4.0 to 12, preferably 4 to 8 with the remainder being iron including unavoidable steel-associated elements, with optional addition by alloying of one or more of the following elements (in wt. %): Al: 0 to 10, preferably 0.03 to 0.8 Si: 0 to 6, preferably 0.02 to 0.8 Cr: 0 to 6, preferably 0.05 to 4 Nb: 0 to 1.5, preferably 0.003 to 0.1 V: 0 to 1.5, preferably 0.006 to 0.1 Ti: 0 to 1.5, preferably 0.002 to 0.5 Mo: 0 to 3, preferably 0.01 to 0.8 Cu: 0 to 3, preferably 0.05 to 2 Sn: 0 to 0.5 W: 0 to 5, preferably 0.03 to 2 Co: 0 to 8, preferably 0.003 to 3 Zr: 0 to 1, preferably 0.03 to 0.5 B: 0 to 0.15, preferably 0.002 to 0.02 P: max. 0.1, in particular <0.04 S: max. 0.1, in particular <0.02 N: max. 0.1, in particular <0.05 Ca: to 0.1.

49. The composite pipe of claim 31, wherein the carrier pipe has a tensile strength of at least 800 MPa and an elongation at fracture of at least 15%.

50. The composite pipe of claim 31, wherein the carrier pipe is produced from a steel which has a TRIP and/or TWIP effect under the effect of mechanical stresses.

51. The composite pipe of claim 31, wherein the carrier pipe is produced from a steel which has a microstructure with an austenite content of 5 to 100%.

52. The composite pipe of claim 31, wherein the at least one protective pipe is produced from a corrosion-resistant or corrosion-passive steel.

53. The composite pipe of claim 31, wherein the at least one protective pipe has at least a part-austenitic microstructure and has, a TRIP and/or TWIP effect under the effect of mechanical stresses.

54. The composite pipe of claim 31, wherein the at least one protective pipe has a full-austenitic microstructure.

55. The composite pipe of claim 31, wherein the protective pipe is produced from a corrosion-resistant or corrosion-passive steel having the following chemical composition (in wt. %): C: 0.005 to 0.8 Cr: 7 to 30 with the remainder being iron including unavoidable, steel-associated elements, with optional addition by alloying of the following elements (in wt. %): Ni: 0 to 15 Mn: 0 to 25 Al: 0 to 15 Si: 0 to 8 Mo: 0.01 to 3 Cu: 0.005 to 4 V: 0 to 2 Nb: 0 to 2 Ti: 0 to 2 Sb: 0 to 0.5 B: 0 to 0.5 Co: 0 to 5 W: 0 to 3 Zr: 0 to 4 Ca: 0 to 0.1 P: 0 to 0.6 S: 0 to 0.2 N: 0.002 to 0.3.

56. The composite pipe of claim 31, wherein the protective pipe is produced from a corrosion-resistant or corrosion-passive steel having the following chemical composition (in wt. %): Cr: 7 to 20 Mn: 2 to 9 Ni: up to 9 C: 0.005 to 0.4 N: 0.002 to 0.3 with the remainder being iron including unavoidable, steel-associated elements, with optional addition by alloying of the following elements (in wt. %): Al: 0 to 3 Si: 0 to 2 Mo: 0.01 to 3 Cu: 0.005 to 4 V: 0 to 2 Nb: 0 to 2 Ti: 0 to 2 Sb: 0 to 0.5 B: 0 to 0.5 Co: 0 to 5 W: 0 to 3 Zr: 0 to 2 Ca: 0 to 0.1 P: 0 to 0.6 S: 0 to 0.2.

57. The composite pipe of claim 31, wherein the protective pipe is produced from a corrosion-resistant or corrosion-passive steel having the following chemical composition (in wt. %): Mn: 5 to 30% C: 0.01 to 0.8% Al: 4 to 10% Cr: 2 to 10% Si: 0 to 3.5% with the remainder being iron including unavoidable, steel-associated elements, with optional addition by alloying of the following elements (in wt. %): Co: 0 to 5 W: 0 to 3 Ca: 0 to 0.1 P: 0 to 0.6 S: 0 to 0.2 Cu: 0.005 to 4 Sb: 0 to 0.5 and optionally in each case up to 1 wt. % of one or more elements from the group of the following elements: Zr, Ti, V, Nb, B, Mo, Ni, N, rare earths.

58. The composite pipe of claim 31, wherein the protective pipe is produced from a corrosion-resistant or corrosion-passive nickel-based alloy.

59. A method for producing a composite pipe comprised of a carrier pipe and at least one protective pipe, said carrier pipe being produced from a non-corrosion-resistant steel which comprises at least one part-austenitic microstructure, having the following chemical composition (in wt. %): C: 0.005 to 1.4 Mn: 5 to 35 with the remainder being iron including unavoidable, steel-associated elements, with optional addition by alloying of the following elements (in wt. %): Ni: 0 to 6 Cr: 0 to 9 Al: 0 to 15 Si: 0 to 8 Mo: 0 to 3 Cu: 0 to 4 V: 0 to 2 Nb: 0 to 2 Ti: 0 to 2 Sb: 0 to 0.5 B: 0 to 0.5 Co: 0 to 5 W: 0 to 3 Zr: 0 to 4 Ca: 0 to 0.1 P: 0 to 0.6 S: 0 to 0.2 N: 0.002 to 0.3, said method comprising mechanically or metallurgically connecting the carrier pipe and the at least one protective pipe to one another.

60. The method of claim 59, wherein the carrier pipe is formed in the composite with the at least one protective pipe by internal high-pressure forming.

Description

[0051] A composite pipe 1 in accordance with the invention will be explained in greater detail hereinafter with reference to a drawing. In the Figures:

[0052] FIG. 1a is a cross-sectional view of a first embodiment of a composite pipe 1,

[0053] FIG. 1b is a cross-sectional view of a second embodiment of a composite pipe 1, and

[0054] FIG. 1c is a cross-sectional view of a third embodiment of a composite pipe 1.

[0055] A composite pipe 1 produced in accordance with the invention includes, according to FIGS. 1a to 1c, of a carrier pipe 2 and at least one protective pipe 3 mechanically connected thereto. The protective pipe 3 can be on the inside (see FIG. 1a) or outside (see FIG. 1b). A combination with a protective pipe 3 inside and outside (see FIG. 1c) is also possible. The carrier pipe 2 is made, as described above, a higher manganese-content, non-corrosion-resistant steel; the protective pipe 3 is made of a corrosion-resistant or corrosion-passive steel. The inner and outer protective pipe 3 can also be made of different materials. In the composite pipe 1 of FIG. 1a a corrosive medium can be transported inside the protective pipe 3 of the composite pipe 1. In relation to this, the protective pipe 3 is advantageously formed in such a way that its thickness results only from the requirement of being corrosion-resistant. The carrier pipe 2 can be formed by the use of a higher manganese-content steel with a clearly reduced wall thickness and also ensures a high level of pressure and bending resistance compared to a conventional carrier pipe 2 made of carbon steel. In addition, by increasing the wall thicknesses of the high manganese-content carrier pipes 2 clearly higher levels of pressure resistance can also be achieved compared with carbon steel-based carrier pipes 2. Using the composite pipe 1 of FIG. 1b non-aggressive or non-corrosive media can be conveyed within an aggressive or corrosive external: environment.

[0056] Instead of a second protective pipe 3 on the outside or inside, the composite pipe 1 formed from the carrier pipe 2 and protective pipe 3 can also be provided with an active and/or passive anti-corrosion layer, e.g. in the form of a metallic coating (e.g. zinc, zinc alloy, nickel or chromium layer) or an alternative organic or inorganic coating or lacquer. The connection of individual pipe ends of the composite pipes 1 to one another can be effected by different means or methods such as e.g. welding, laser welding, resistance welding, gluing, clinching, flanges or screw sockets.

[0057] The carrier pipe 2 is metallurgically or mechanically connected to the protective pipe or pipes 3 in a known manner. Metallurgical connecting methods include e.g. co-extrusion, roll plating, hot isostatic pressing, explosive plating or weld plating. As a method for mechanical connection, e.g. in relation to an embodiment with an inner protective pipe 3, hydraulic widening of the protective pipe 3, with or without simultaneous heating of the carrier pipe 2, widening of the protective pipe 3 with a drawing plug, or reducing the carrier pipe 2 by means of a drawing ring are to be considered. Prior to the mechanical connection the carrier pipe 2 and the protective pipe 3 or the protective pipes 3 are pushed one inside the other. In relation to this, the inner protective pipe 3 has a slightly smaller outer diameter than the inner diameter of the carrier pipe 2 or the outer protective pipe 3 has a slightly larger inner diameter than the outer diameter of the carrier pipe 2. In relation to this, the protective pipe 3 and the carrier pipe 2 can be seamless, welded on a longitudinal seam or welded on a spiral seam.

[0058] The invention is described above in relation to composite pipes 1 with a round cross-section. It is obvious that this invention also applies to the case of composite pipes 1 with any cross-section (e.g. rectangular, elliptical or having a cross-section that changes over the pipe length) and pipes for internal high-pressure forming (IHPF).

[0059] The pipe produced in accordance with the invention can be used in areas with corrosive and/or abrasive environmental conditions or to convey and transport corrosive and/or abrasive media. It can be used in particular in the following areas: plant construction (e.g. chemical or pharmaceutical plants), food technology, boiler construction (e.g. pressure vessels and heat storage boilers), conveying technology (e.g. oil and gas supply, conveying of other media), pipeline construction (e.g. oil and gas pipelines), lower temperature application (e.g. gas liquefaction, liquid gas transport, as casing material for (high-temperature) supraconductors, cryotechnology), vehicle construction (e.g. utility vehicles, yellow goods), IHPF applications (e.g. automobile construction, plant construction).

LIST OF REFERENCE SIGNS

[0060] 1 composite pipe [0061] 2 carrier pipe [0062] 3 protective pipe