AU2016272240B2

AU2016272240B2 - Method and device for producing bimetallic pipes

Info

Publication number: AU2016272240B2
Application number: AU2016272240A
Authority: AU
Inventors: Hans-Jürgen KOCKS; Jörn WINKELS
Original assignee: Salzgitter Mannesmann Line Pipe GmbH
Current assignee: Salzgitter Mannesmann Line Pipe GmbH
Priority date: 2015-05-29
Filing date: 2016-05-17
Publication date: 2021-06-10
Anticipated expiration: 2036-05-17
Also published as: BR112017024101B1; EP3302847B1; WO2016192709A1; EP3302847A1; EA201792464A1; AU2016272240A1; BR112017024101A2; EA031790B1; DE102015108500A1

Abstract

The invention relates to a method for producing bimetallic pipes, consisting of a thin-walled inner pipe made of a high-alloyed or alloyed steel, and an outer pipe made of a non-alloyed or unalloyed steel, which, after being inserted one into the other, are form-fittingly interconnected by expansion under internal pressure, as well as to a device for carrying out said method, comprising sealing heads (3) that can be placed against the pipes (1; 2) to be expanded, for the purpose of supplying the pressure medium. The device is characterised in that a retainer (5) comprising a radially inward-projecting projection (7) is provided on said sealing head (3) for the purpose of securing the inner pipe (1, 1') being expanded, and this can be brought to engage with a peripheral groove (6) on the inner pipe (1; 1').

Description

METHOD AND DEVICE FOR PRODUCING BIMETALLIC PIPES

The invention relates to a method for producing bimetallic pipes consisting of a thin walled inner pipe made of a high-alloyed or alloyed steel, and an outer pipe made of a non alloyed or unalloyed steel, which, after being inserted one into the other, are form-fittingly interconnected, and to a device for carrying out the method. Bimetallic pipes are usually characterized in that a pipe assuming a static function, made of an unalloyed or low-alloyed steel, is provided with an inner layer made of alloyed steel. For the production of bimetallic pipes, "cladded pipes" must be distinguished from "lined pipes." In the case of the "cladded pipes," a metallurgic bond exists between the unalloyed or low-alloyed steel and the layer made of alloyed or high-alloyed steel. A typical production method here is plasma deposition welding. In the case of the "lined pipe," in the simplest case, a thin-walled pipe made of a high alloyed or alloyed steel is inserted into the pipe made of low-alloyed or unalloyed steel. A form fitting bond forms here due to the targeted expansion of the stainless steel pipe by internal pressure. For this purpose, the pipe is closed at the ends with sealing heads and filled with water. By increasing the internal pressure and simultaneous feeding with water, the pipe expands. In this expansion process, the pipe made of alloyed or high-alloyed steel tends to contract. The material for the expansion originates partially from the periphery and partially from the pipe length. Therefore, such processes require either the welding of the two pipes or, on the other hand, the tracking of the sealing unit, wherein the pipes in terms of production length have to be adjusted to this process. An example for a production method in which the expansion and connection occur by internal hydraulic pressure is disclosed in DE 10 2010 044 463 Al. Here, it is essential that the pressure and the diameter of the two pipes are adjusted to one another in such a manner that both plastically expanding deformation of the inner pipe and also elastically expanding deformation of the outer pipe occur at the same time. Due to the elastic resilience of the outer pipe, a frictional locking shrink connection forms. For the pressure application, the pipe ends have to be sealingly closed, wherein, as a rule, the ends are welded to one another beforehand for the securing of the pipes which have been inserted one into the other. In some forms the present disclosure may simplify the production of bimetallic pipes. 1 17689742_1 (GHMatters) P107239.AU

According to the invention, this may be achieved by a method for producing bimetallic pipes consisting of a thin-walled inner pipe made of high-alloyed or alloyed steel and an outer pipe made of a non-alloyed or unalloyed steel, which, after being inserted one into the other, are form-fittingly interconnected by expansion under internal pressure, in that, after the insertion into the outer pipe but before the expansion, the inner pipe which has a greater length than the outer pipe, close to its two pipe ends protruding beyond the length of the outer pipe, is provided with a radially inward pointing peripheral groove, with which a retainer can be made to engage, retainer which secures the axial position of the inner pipe with respect to the outer pipe during the expansion. The key idea consists in making a groove in the stainless steel pipe at the pipe ends before the expansion. On the one hand, this groove prevents the pipe from expanding under an internal pressure in the sealing head and thus becoming difficult to pull out. On the other hand, the groove provides the possibility of securing the stainless steel pipe to the sealing unit in such a manner that the material for the expansion is provided entirely from the pipe periphery. Thus, with unchanging pipe length, only a decrease in the wall thickness of the inner pipe to be expanded occurs. The invention further relates to a device for carrying out the method, as described below and indicated in Claims 2 to 5. As mentioned at the start, for the hydraulic expansion, pressure heads are arranged at the two ends of the pipes to be expanded, through which the pressure medium is supplied to the inner pipe. For this purpose, sealing units known from the sector of hydraulic test pressurization equipment for pipes are used. Here, the sealing with respect to the inner pipe occurs by means of seals provided in the sealing head, in contact with the inner pipe. According to the invention, on the sealing head, a retainer for securing the inner pipe is arranged, in particular, preferably detachably. In this way, in a corresponding design of the sealing head, this retainer can also be attached later. This retainer has a radially inward pointing projection corresponding to the shape of the peripheral groove, which can be made to engage with the peripheral groove. In this way, the inner pipe can be axially secured with respect to the outer pipe when the inner pipe is clamped in the pressure heads and a pressure is applied for the expansion.

2 17689742_1 (GHMatters) P107239.AU

By means of the pressure, the inner pipe expands between the two securing locations, wherein the material flow originates from the wall, while the length remains unchanged. A tracking of the sealing heads is thus no longer necessary. An alternative application possibility of this groove is offered by the securing of a horizontally shiftable retainer, the position of which can be acquired by a proximity sensor. In this way, the sealing unit can optionally follow a change in length, if, in deviation from the above-described targeting, material flow is allowed not only from the pipe wall but also by shortening of the pipe length. Since the diameter of the inner pipe does not change due to the supporting action of the groove in the sealing head, the inner pipe can be removed easily from the sealing head after the completion of the expansion process. The method and the design of the invention can be obtained easily from the diagrammatic representation in the drawing. In detail, the inner pipe in the initial state is here marked with 1, in the expanded state it is marked with ', and the outer pipe is marked with 2. Of the sealing heads arranged on the two sides, only the sealing head arranged on one side is indicated and marked with 3. The seal in contact with the inner pipe bears the reference numeral 4. On the sealing head, the detachable retainer 5 is indicated, which comprises a radially inward pointing peripheral projection 7 corresponding to the peripheral groove 6. This retainer 5 is moreover shiftable on the sealing head both vertically and - in an alternative design - also horizontally relative to said sealing head. The shifting possibility indicated with the vertical double arrow allows easy pulling out of the bimetallic pipe from the sealing head after the expansion. Due to the optional additional horizontal shifting possibility, which is also indicated by a double arrow, the retainer 5 can be adjusted horizontally, when the pipe becomes shorter during the expansion. For this purpose, the sealing head of the retainer, which continues to move with the shortening of the pipe, is tracked by means of the proximity sensor 8 in order to continue to ensure the sealing function. The method according to the invention and the device for carrying out the method are, for example, particularly suitable for outer pipes having diameters from 100 to 600 mm and wall

3 17689742_1 (GHMatters) P107239.AU thicknesses from 2.9 to 25 mm and inner pipes with diameters of 70 to 570 mm and a wall thickness from 3.0 to 5.0 mm.

It is to be understood that, if any prior art publication is referred to herein, such reference does not constitute an admission that the publication forms a part of the common general knowledge in the art, in Australia or any other country.

In the claims which follow and in the preceding description of the invention, except where the context requires otherwise due to express language or necessary implication, the word "comprise" or variations such as "comprises" or "comprising" is used in an inclusive sense, i.e. to specify the presence of the stated features but not to preclude the presence or addition of further features in various embodiments of the invention.

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Claims

1. A method for producing bimetallic pipes consisting of a thin-walled inner pipe made of a high-alloyed or alloyed steel, and an outer pipe made of a non-alloyed or unalloyed steel, which, after being inserted one into the other, are form-fittingly interconnected by expansion under internal pressure, wherein after the insertion into the outer pipe but before the expansion, the inner pipe which has a greater length than the outer pipe, close to its two pipe ends protruding beyond the length of the outer pipe, is provided with a radially inward pointing peripheral groove, with which a retainer can be made to engage, retainer which secures the axial position of the inner pipe with respect to the outer pipe during the expansion.

2. A device for carrying out the method according to Claim 1, with sealing heads which can be placed against the pipes to be expanded, for the purpose of supplying the pressure medium, wherein a retainer comprising a radially inward pointing projection may be provided on the sealing head for the purpose of securing the inner pipe to be expanded, and said projection can be made to engage with a peripheral groove on the inner pipe.

3. The device according to Claim 2, wherein the retainer is arranged on the sealing head so as to be vertically shiftable relative to the sealing head.

4. The device according to any one of the preceding claims, wherein the retainer is arranged on the sealing head so as to be horizontally shiftable relative to the sealing head.

5. The device according to Claim 4, wherein, on the sealing head, a proximity sensor for the acquisition of the horizontal position of the retainer is arranged.

6. The device according to Claims 2 to 5, wherein the retainer is fastened detachably to the sealing head.

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