JPH07214345A - Production of high strength corrosion resistant branch tube - Google Patents

Abstract

PURPOSE:To provide a means to solve any problem in hot ball drawing method and cut out method used for obtaining the desired shape branch tube in producing a high strength corrosion resistant branch tube in which the outer layer part made of high strength material and inner layer part made of corrosion resistant material are integrated. CONSTITUTION:After an outer layer part 1 is formed to branch tube shape independently from an inner layer part 2, a first cylindrical body 5A is fitted inside the part to be a straight tube 4 of the outer layer part 1, further, a core 6, the outside of which is fitted with a second cylindrical body 5B, is plugged in the opening part of to be a branched part 3 of the outer layer part 1, the internal space on the part to be a branched part 3 is evacuated and sealed. Further, the assembly is subjected to hot static pressure compression treatment, while the first cylindrical body 5A is adhered/deformed on each inner surface of the outer layer part 1 and core 6, after both layer parts 1, 2 and both cylindrical parts 5a, 5B are integrated respectively, the whole core 6 and the part of the first cylindrical part 5A adhered on the inner surface of the core 6 are removed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a high-strength corrosion-resistant branch pipe used for petroleum pipes, etc., and more specifically, it intersects with a straight pipe portion at an intermediate portion in the longitudinal direction of the straight pipe portion. When manufacturing a branch pipe in which a branch portion that branches in a direction is connected, the outer layer portion of the branch pipe is made of a high-strength material, and the inner layer portion is made of a corrosion-resistant material, and both of these layer portions are formed. The present invention relates to a method for manufacturing a high-strength corrosion-resistant branch pipe by integrating them.

[0002]

2. Description of the Related Art High-strength corrosion-resistant branch pipes used for applications such as branch joints in petroleum pipes from subsea oil fields to offshore bases are structural carbon steel, stainless steel, or high-strength materials such as cast steel. Inconel6 with the outer layer composed of
An inner layer portion made of a corrosion-resistant material such as 25 or Incoloy 825 is integrated into a branch pipe shape. In order to manufacture such a high-strength corrosion-resistant branch pipe, conventionally, a two-layer pipe (for example, a two-layer pipe) in which an outer layer portion made of the high-strength material and an inner layer portion made of the corrosion-resistant material are integrally molded in a straight pipe state (A straight tube that has been centrifugally cast into a state), an opening is provided by machining in the portion where the branch is to be formed, and then the two-layer tube is heated to an appropriate hot working temperature while the two-layer tube is formed. By subjecting the pipe to a process in which a semi-spherical jig with a rod is moved from the inside of the pipe to the outside of the pipe through the opening so as to squeeze the opening of the pipe (hereinafter, referred to as hot-ball-punching method), The method of forming a branch part and completing the said branch pipe was implemented.

[0003]

However, according to the above-mentioned conventional method, since the double-layer pipe is processed so that the opening portion of the pipe is locally squeezed, the double-layer pipe is made of the corrosion-resistant material. A problem that wrinkles occur such that the inner layer part bulges outward at the opening part, and the shape of the finally obtained branch pipe (particularly, the cross-sectional shape of the branch part) cannot be made into a desired shape. was there. Therefore, in order to obtain the branch pipe having a desired shape, a method of shaving a material entirely made of the corrosion resistant material into a branch pipe shape by machining (hereinafter referred to as a shaving method) has been conventionally used. However, in the case of this shaving method, the processing cost becomes very high, and it becomes necessary to adopt a thick branch pipe in order to obtain a predetermined strength, and it is difficult to realize a thin and lightweight product. There was a problem. The present invention has been made by paying attention to such an actual situation, and there are problems in the conventional hot ball punching method and problems in the carving method adopted when a branch pipe having a desired shape is desired. , All of them are intended to provide means that can be solved at once.

[0004]

The characteristic construction of the method for producing a high-strength corrosion-resistant branch pipe according to the present invention (hereinafter referred to as the method of the present invention) is that the straight pipe portion intersects with the straight pipe portion at the longitudinal middle portion. When manufacturing a branch pipe in which a branch portion that branches in the direction of is formed, the outer layer portion of the branch pipe is made of a high-strength material, and the inner layer portion is made of a corrosion-resistant material, and both of these layer portions are formed. A method of manufacturing a high-strength corrosion-resistant branch pipe by integrating the outer layer portion, after being formed into a branch pipe shape independently of the inner layer portion, in the outer pipe portion corresponding to the straight pipe portion. A first tubular body for forming the inner layer portion is fitted inside, and an opening side portion of the outer layer portion corresponding to the branch portion,
While maintaining the state in which the inner space of the portion corresponding to the branch portion is degassed and sealed, while the core to which the second tubular body for forming the inner layer portion is fitted is attached in a plug shape, The combined body is subjected to hot hydrostatic compression treatment to closely deform the first cylindrical body to the inner surfaces of the outer layer section and the core, while integrating the two layer sections and the two cylindrical bodies. After that, the entire core and the portion of the first tubular body that is in close contact with the inner surface of the core are removed.

[0005]

According to such a method of the present invention, the first tubular body for forming the inner layer portion is fitted in the portion corresponding to the straight pipe portion in the outer layer portion which is formed in the branch pipe shape independently of the inner layer portion. And, at the opening side portion of the portion corresponding to the branch portion in the outer layer portion, a core in which a second tubular body for forming the inner layer portion is fitted is attached in a plug-like shape, and the inner space is sealed. Since the hot isostatic pressing process is performed while maintaining the above, the local ironing process such as the conventional hot punching method is not applied to the first tubular body. Instead, the isotropic pressing process is applied to each inner surface of the outer layer portion and the core based on the hot isostatic pressing process. Therefore, while the first cylindrical body is effectively deformed in close contact with the inner surfaces of the outer layer portion and the core, the both layer portions and the both cylindrical bodies are effectively integrated with each other. As a result, a problem that occurs in the case of using the conventional hot ball punching method, that is, wrinkles that the inner layer part partially bulges outward, and a high-strength corrosion-resistant branch pipe having a desired shape cannot be obtained. That problem will be solved. In addition, as described above, the first tubular body is effectively contact-deformed with the inner surfaces of the outer layer portion and the core to effectively integrate the both layer portions and the both tubular bodies. After that, the entire core and the portion where the first tubular body is in close contact with the inner surface of the core are removed by, for example, machining or the like to easily manufacture the high-strength corrosion-resistant branch pipe in the final shape. Will be done. Also, by the hot isostatic pressing process described above,
Since the contact deformation of the first tubular body to the outer layer portion is effectively performed, and the second tubular body is effectively joined to the outer layer portion, the both layer portions and the both A substantially finished product of a high-strength corrosion-resistant branch pipe in which tubular bodies are effectively integrated can be easily obtained. Therefore, it is possible to reduce the processing cost as compared with the carving method of carving a material entirely made of a corrosion resistant material, and the thin and lightweight product is realized by the existence of the outer layer part made of a high strength material. Become so.

[0006]

As described above, according to the method of the present invention, there are problems in the conventional hot ball punching method and the problems in the shaving method adopted when a branch pipe having a desired shape is desired.
All of them are resolved all at once, and the object of the present invention is achieved. Further, according to the method of the present invention, since the second tubular body for forming the inner layer portion is preliminarily attached to the opening side portion of the portion corresponding to the branch portion, the first tubular body based on the hot isostatic pressing treatment is performed. It becomes unnecessary to cause the contact deformation of the tubular body over the entire branching direction of the portion corresponding to the branching portion.
Therefore, when the contact deformation is caused, the amount of extensional deformation of the first tubular body can be made relatively small. As a result, there is an advantage that the room for selecting the material of the inner layer portion can be expanded to a material having a small deformability.

When a release material layer is previously formed on the outer peripheral surface of the core, the first cylinder is formed on the entire core and the inner surface of the core after hot isostatic pressing. When removing the part where the sheet adheres, the mold releasing action of the release material layer is used to first manually remove only the core, and then the remaining part where it is removed is machined. You can remove it with. Therefore, as compared with the case where the entire core and the portion where the first tubular body is in close contact with the inner surface of the core are all removed by machining, the removal work becomes very easy.

[0008]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows the procedure of one embodiment of the method of the present invention.

In the figure, 1 is a structural carbon steel (for example, JI
S standard: S45C or various standard steels close thereto or stainless steel (for example, JIS standard: SUS304, S)
US316 or various standard steel materials close to them, or an outer layer portion composed of a high-strength material such as cast steel, and 2 is an appropriate corrosion resistant material (for example, Inconel625
Or an anticorrosion alloy such as Incoloy 825).

To explain the procedure of the method of the present invention, first, the outer layer portion 1 is replaced with the inner layer portion 2 (see FIGS. 1D and 1E).
Independently of, is formed into a branch pipe shape (wall thickness: 23 mm) (see FIG. 1 (a)). The shaping into the branch pipe shape is completed, for example, as follows. That is, a centrifugal casting pipe made of the high-strength material is adopted as a raw pipe, and an opening is formed in the portion where the branch portion 3 is to be formed by machining, and then the raw pipe is appropriately cut. While heating to the hot working temperature, a process of moving a semi-spherical jig with a rod from the inside of the pipe to the outside of the pipe so as to squeeze the opening of the pipe (that is, the above-mentioned By performing a hot ball punching method, the branch portion 3 is formed and the molding into the branch pipe shape is completed. In addition, molding into this branch pipe shape is
It is also possible to use other means other than the above-mentioned method (for example, bulge molding or casting method).

In this way, after the outer layer portion 1 is independently formed into a branch pipe shape, the inner layer portion 2 (see FIG. )reference)
The first cylindrical body 5A (thickness: 3 mm) for forming the main part of the inner layer portion 2 is inserted into the inner layer portion 2 (see FIG. ), (E))
The core 6 to which the second tubular body 5B (thickness: 3 mm) for forming the branch portion is fitted is attached in a plug-like shape (see FIG. 1B).
The first cylindrical body 5A is formed by rolling a plate-shaped material made of the corrosion-resistant material into a cylindrical shape, and then forming the butted portion by TI.
It can be easily obtained by G welding to complete the cylindrical body, but it can also be easily obtained by a centrifugal casting method. Further, as the material of the core 6, a material having good weldability (for example, JIS standard: S25C or various standard steel materials close thereto) is selected. Further, before the second cylindrical body 5B is fitted onto the core 6, a mold release material layer 9 made of an Al ₂ O ₃ sprayed layer or the like is formed on the outer peripheral surface of the core 6 in advance. deep. The reason why the mold release material layer 9 is formed is that after the hot isostatic pressing treatment described later is finished, the mold release effect is effectively generated in the mold release material layer 9 so that the core 6 can be easily worked by hand. This is because it can be removed.

After mounting the core 6, the internal space of the portion corresponding to the branch 3 is degassed and maintained in a sealed state (see FIG. 1C). Specifically, the maintenance of the sealed state is performed as follows. That is, all of the joint exposed portion 7 between the outer layer portion 1 and the first tubular body 5A and the joint exposed portion 8 between the outer layer portion 1 and the core 6 with the second tubular body 5B are TIG. Welding is performed by a welding method or an electron beam welding method in a sealable state, but at least the seam exposed portion 7 or 8 to be welded at the end is welded by the electron beam welding method in order to deaerate the internal space. It should be noted that all exposed seams 7, 8 may be electron beam welded.

Then, a combination of the outer layer 1, the first tubular body 5A and the second tubular body 5B for forming the inner layer 2 and the core 6 is used as a hot isostatic pressing apparatus. And the appropriate conditions for the combination (eg temperature: 1
The first tubular body 5A is obtained by performing a hot isostatic pressing treatment at 100 to 1200 ° C. and a pressure of around 1000 atm.
While closely deforming the inner surface of the outer layer portion 1 and the inner surface of the core 6, the both layer portions 1, 2 and the both tubular bodies 5 are
A and 5B are integrated with each other (see FIG. 1D).

After that, the entire core 6 and the core 6
And the portion of the first tubular body 5A that is in close contact with the inner surface of the. More specifically, by utilizing the releasing action of the release material layer 9, first, only the core 6 is manually removed (see FIG. 1).
(See (e)), the remaining portion 10 from which it has been removed is removed by machining to obtain a desired high-strength corrosion-resistant branch pipe.

Next, another embodiment will be described. In the above-described embodiment, in order to maintain the degassed and sealed state of the internal space of the branching portion, in addition to the TIG welding method, an electron beam welding method in which welding is performed in a vacuum atmosphere is used. However, if it is not possible to use the electron beam welding method due to various circumstances, after welding all exposed joints by the TIG welding method, the It is also possible to adopt a means of degassing the internal space in vacuum and then pinching the degassing tube.

In the above-mentioned embodiment, the method of the present invention is applied to the method of manufacturing a branch pipe having one branch portion, but the method of the present invention is also applied to the method of manufacturing a branch pipe having a plurality of branch portions. Can be applied.

Needless to say, the material of the outer layer portion and the material of the inner layer portion are not limited to those of the above-mentioned embodiment.

When all of the work of removing the whole of the core and the portion of the first tubular body which is in close contact with the inner surface of the core is carried out by machining, the outer peripheral surface of the core is separated. It is not necessary to form the mold material layer in advance.

It should be noted that reference numerals are given in the claims for convenience of comparison with the drawings, but the present invention is not limited to the configurations of the accompanying drawings by the entry.

[Brief description of drawings]

FIG. 1 is an explanatory diagram showing the procedure of the method of the present invention.

[Explanation of symbols]

 1 Outer layer part 2 Inner layer part 3 Branch part 4 Straight pipe part 5A 1st cylindrical body 5B 2nd cylindrical body 6 Core 9 Release material layer

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Hiroshi Makino 1-47 Shikazu East, Naniwa-ku, Osaka-shi, Osaka Kubota Co., Ltd. (72) Inventor Hiroaki Okano Tokichi Shikazu, Naniwa-ku, Osaka 2-47, Kubota Co., Ltd.

Claims (2)

[Claims] 1. When manufacturing a branch pipe in which a branch portion (3) for branching in a direction intersecting with the straight pipe portion (4) is continuously provided at an intermediate portion in the longitudinal direction of the straight pipe portion (4), the branch is produced. The outer layer portion (1) of the pipe is made of a high-strength material, and the inner layer portion (2) is made of a corrosion resistant material, and both of these layer portions (1), (2)
Is a method for manufacturing a high-strength corrosion-resistant branch pipe by molding the outer layer portion (1) into a branch pipe shape independently of the inner layer portion (2), and then forming the outer layer portion (2). ), The first tubular body (5A) for forming the inner layer portion (2) is fitted into the portion corresponding to the straight pipe portion (4), and the branch portion (3) in the outer layer portion (1). Corresponding to the branch part (3) while mounting a core (6) fitted with the second tubular body (5B) for forming the inner layer part (2) on the opening side part of the corresponding part in a plug-like manner. After degassing the internal space of the part and maintaining the sealed state, hot isostatic pressing treatment is applied to the combined body,
While closely deforming the first cylindrical body (5A) to the inner surfaces of the outer layer portion (1) and the core (6), the both layer portions (1) and (2) and the both cylindrical bodies. (5A) and (5B) are integrated with each other, and then the entire first core (6) and the first tubular body (5A) closely attached to the inner surface of the first core (6).
And a method for manufacturing a high-strength corrosion-resistant branch pipe. 2. The method for producing a high-strength corrosion-resistant branch pipe according to claim 1, wherein a mold release material layer (9) is previously formed on the outer peripheral surface of the core (6).