JPH11290939A - Manufacture of long double metallic tube - Google Patents

Abstract

PROBLEM TO BE SOLVED: To manufacture at low cost a long double metallic tube without limitation in the manufacturable length, free from quality instability such as lowering of corrosion resistance and generation of cracks, regardless of the wall thickness and the size of the diameter. SOLUTION: A long double metallic tube 50 is manufactured by inserting, into an outer metallic tube 10 having one or more joined or bonded parts (e.g. weld zone 16N), an inner metallic tube 30 having an outside diameter smaller than the bore of the outer tube 10 and also one or more joined parts (e.g. weld zone 33N), and by expanding the inner tube 30 so inserted.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a long double metal pipe, and more particularly, to a long pipe suitable for use in a chemical industry, a petroleum industry, etc., for a plant pipe, a line pipe, an oil well pipe, and the like. The present invention relates to a method for manufacturing a double metal tube.

[0002]

2. Description of the Related Art Conventionally, corrosive fluids have been transported over long distances using pipes in the fields of the chemical industry and the petrochemical industry. Piping used in such applications needs to have high corrosion resistance to corrosive fluids. As a means for improving the corrosion resistance of pipes, there are known a method of manufacturing pipes using a material having high corrosion resistance as it is and a method of using a double metal pipe.

[0003] A method of fabricating piping using a material having high corrosion resistance as it is is ideal in that high corrosion resistance and reliability can be obtained. However, materials having high corrosion resistance are generally expensive, such as Ni and Cr. There is a disadvantage that the cost is increased because the alloy element is contained in a large amount. Therefore, in the fields of chemical industry, petrochemical industry, etc., in order to reduce costs, double metal pipes, which are made of expensive corrosion-resistant material only inside the pipe where corrosion resistance is required and made of inexpensive structural material on the outside, are used. It is frequently used as edible piping.

[0004] A seamless pipe is generally used as a double metal pipe requiring high corrosion resistance, but the length of a seamless pipe industrially produced is usually 20 to 30.
m. Therefore, especially in the case of oil country tubular goods and pipelines where the length of pipes is several thousand meters to several tens of kilometers,
It is indispensable to join a double metal pipe of several tens of meters in length previously produced in a factory on site.

[0005] In addition, since the outer and inner materials of the double metal tube are different, a special technique is required for joining. For example, when welding a double metal pipe using a girth welding method as the joining method and using a corrosion-resistant material such as stainless steel on the inside and a structural material such as inexpensive carbon steel on the outside, use the inner corrosion-resistant material first. After that, the outer structural material is welded by changing the welding conditions.

[0006]

However, when welding a double metal pipe by the circumferential welding method, when welding the inner corrosion-resistant material and then welding the outer structural material,
The weld of the corrosion resistant material may remelt and the corrosion resistant material may be diluted with the structural material. Therefore, there is a problem that the corrosion resistance of the welded portion is reduced, and the welded portion is hardened and cracks are easily generated.

[0007] In order to solve this problem, for example, Japanese Patent Application Laid-Open No. 58-167094 discloses an inner layer, an intermediate layer, and a base material containing the same alloy element as the base material from the base material to the base material. A joint welding method in which an outer layer containing the same kind of alloy element as described above is sequentially formed is disclosed.

[0008] However, Japanese Patent Application Laid-Open No. 58-167094
In the method disclosed in Japanese Patent Laid-Open Publication No. H11-157, the welding material and welding conditions must be sequentially changed in the order of the inner layer, the intermediate layer, and the outer layer, and the welding operation is complicated. In addition, the quality of a welded joint is generally affected by the skill of a welding worker, so that there is a problem that the more complicated the welding work, the more unstable the quality.
Furthermore, in order to prevent the occurrence of welding defects, it is necessary to suppress the welding speed, and there is a problem that the joining efficiency is extremely poor.

On the other hand, Japanese Patent Publication No. Hei 8-13428 discloses an inner clad steel pipe in which an insert material having a predetermined composition is inserted into the end face of the clad steel pipe and the inner pipe is made of a corrosion-resistant material. A method is disclosed in which induction heating is performed using a high frequency of 100 to 400 kHz, and in the case of an outer clad steel pipe using a corrosion-resistant material for the outer tube, induction heating is performed at a high frequency of 10 kHz or less.

According to the method disclosed in Japanese Patent Publication No. Hei 8-13428, since the joining of the double metal pipes is performed by using the diffusion joining method, the joining operation is simplified as compared with the welding method, and the work efficiency is improved. There is an advantage that is high. However,
According to the method disclosed in the publication, when joining the inner clad steel pipe, 100 to 100%
It is necessary to perform induction heating using a high frequency of 400 kHz. Therefore, the skin effect becomes remarkable, and there is a problem that it cannot be applied to the joining of a thick double metal pipe.

Such a problem can be solved if a double metal pipe having a required length can be manufactured. However, the length of a seamless pipe that can be manufactured is currently limited to about 100 m. It is technically difficult to manufacture a long double tube having the same. Furthermore, in addition to being long, it is technically difficult to manufacture a small-diameter double metal tube or a large-diameter double metal tube. However, the conventional method has a limited range of application.

The problem to be solved by the present invention is that there is no limitation on the length that can be manufactured, the quality does not become unstable such as a decrease in corrosion resistance or cracks, and the length of the thick wall is long. It is an object of the present invention to provide a method for manufacturing a long double metal tube which can be manufactured at low cost even if it is a long double metal tube, a small-diameter long double metal tube, or a large-diameter long double metal tube.

[0013]

In order to solve the above-mentioned problems, a method of manufacturing a long double metal tube according to the present invention is to provide a method for manufacturing a long double metal tube inside an outer metal tube joint having one or more joints or joints. Inserting an inner metal pipe joint having an outer diameter smaller than the inner diameter of the outer metal pipe joint and having one or more joints, and expanding the inserted inner metal pipe joint. Accordingly, the gist of the present invention is to manufacture a double metal tube.

Here, the outer metal pipe joint is obtained by joining or fastening a metal pipe having a predetermined length at the pipe end face, and has a joint having one or more joints or fasteners. It is necessary to be. The joining method or the fastening method is not particularly limited, and may be, for example, a mechanical fastening method such as a flange joint or a threaded joint, a welding method, a friction welding method, or a metallurgical joining method such as a diffusion welding method. Good. Further, each metal pipe constituting the outer metal pipe joint may be an electric resistance welded pipe or a seamless pipe.

[0015] The inner metal pipe joint is obtained by joining a metal pipe having a predetermined length at the pipe end face, similarly to the outer metal pipe joint, and has a joint having one or more joints. It is necessary to be. Since the inner metal pipe joint is required to be airtight, the joining method is limited to metallurgical joining methods such as welding, friction welding, and diffusion joining. In addition, each metal tube constituting the inner metal tube joined body,
Although an ERW pipe may be used, a seamless pipe is preferable from the viewpoint of corrosion resistance and uniformity of the pipe expansion.

It is preferable that at least the inner metal pipe joint of the outer metal pipe joint and the inner metal pipe joint is joined by a liquid phase diffusion bonding method. The liquid-phase diffusion bonding method can suppress the occurrence of burrs at the joints and the deformation of the joints as compared with other metallurgical joining methods, and has a high joining efficiency. It is suitable for oil country tubular goods, line pipes, etc., ranging from m to several tens km. Further, if both the outer and inner metal tubes are joined by the liquid phase diffusion joining method, the operation of removing burrs becomes unnecessary depending on the joining conditions, so that the manufacturing process of the double metal tube can be simplified.

Further, the inner metal pipe joint must have an outer diameter smaller than the inner diameter of the outer metal pipe joint. The difference between the inner diameter of the outer metal pipe and the outer diameter of the inner metal pipe may be appropriately selected according to the workability of the joint pipe inserted inside.

The method of expanding the inner metal pipe joined body is not particularly limited. For example, a method of expanding the pipe using a mandrel or a plug, a method of expanding the pipe by hydraulic pressure,
A method of inserting a plunger and expanding the tube is used. In particular, the method of expanding a pipe using hydraulic pressure and the method of expanding a pipe by inserting a plunger have an advantage that there is substantially no limitation on the length and diameter that can be manufactured.

According to the method of manufacturing a long double metal pipe according to the present invention having the above-described structure, first, a predetermined length of the outer metal pipe joined to the pre-joined outer metal pipe having a predetermined length. Is inserted. Next, the inner metal pipe joined body is expanded, and the inner metal pipe joined body is brought into close contact with the outer metal pipe joined body to produce a long double metal pipe. Therefore, the length of the double metal pipe that can be manufactured is not substantially limited, and depending on the joining method and the expanding method, it is also possible to manufacture a long double pipe with a small diameter or a long double pipe with a large diameter. Becomes

Further, since the joining operation of the outer metal pipe joint and the inner metal pipe joint is performed individually,
Optimal joining conditions can be selected according to the material. Therefore, unlike the conventional method of joining double metal tubes to form a long double metal tube, a thick long double metal tube can also be easily manufactured, and furthermore, the corrosion resistance of the joint caused by remelting of the weld metal. And the occurrence of cracks due to hardening caused by heat history during welding can also be suppressed.

[0021]

Embodiments of the present invention will be described below in detail with reference to the drawings. The method for manufacturing a long double metal pipe according to the present invention includes a joining step, an inner pipe inserting step, and a pipe expanding step.

The joining step further includes a step of joining the outer metal pipe to obtain a joint of the outer metal pipe and a step of joining the inner metal pipe to obtain a joined article of the inner metal pipe. It is characterized in that the pipes are joined individually. As the joining method of the outer metal tube and the inner metal tube used for manufacturing the long double metal tube according to the present invention, specifically, a welding method, a friction welding method, a metallurgical joining method such as a diffusion joining method, and the like can be mentioned. Can be

FIG. 1A shows an example in which an outer metal pipe joined body 10 is manufactured by a welding method. The welding method is based on the groove 1 formed on the pipe end face of each outer metal pipe 12 _N , 12 _{N + 1} ,.
4 _N , 14 _{N + 1} ,... Are welded from outside to form a welded portion 16 _N to form each outer metal pipe 12.
_{N, 12 N + 1,} joining ..., a method for obtaining an outer metal tube assemblies 10. In the welding method, as shown by the dotted line in FIG. 1A, the outer peripheral surface and the inner peripheral surface of the welded portions 16 _N ,. Therefore, after welding, it is necessary to process at least the inner peripheral surface of the welded portions 16 _N ,.

The welding method is not particularly limited, and may be covered arc welding, submerged arc welding, MI welding, or the like.
Various welding methods can be used, such as a welding type arc welding such as G welding and carbon dioxide gas arc welding, a non-welding type arc welding such as TIG welding, plasma welding, electron beam welding, and laser welding.

FIG. 1B shows an example in which an outer metal pipe joined body 10 is manufactured by a friction welding method. In the friction welding method, the pipe end faces 18 _N , 18 of the outer metal pipes 12 _N , 12 _{N + 1} ,.
_{N + 1,} formed to have a right angle ... with respect to the tube axis, the outer metal tube _{12 N, 12} N _{+ 1,} the pipe end face an ... ₁₈ N, 18
_{N + 1} ,..., Are relatively rotated under pressure, and are joined by generated frictional heat.

In the friction welding method, as shown by a dotted line in FIG. 1B, burrs are generated on the outer peripheral surface and the inner peripheral surface in the vicinity of the press contact portions 20 _N ,. It is necessary to remove burrs on the inner peripheral surface of 20 _N ,.
Various methods such as a method in which one is fixed and the other is rotated, a method in which they are rotated in opposite directions, and a method in which they are vibrated up and down can be used as the pressure contact method.

FIG. 1 (c) shows a diffusion bonding method.
This is an example in which the outer metal pipe joined body 10 is manufactured. Diffusion bonding method
Is the outer metal tube 12_N, 12_{N + 1}, ... pipe end face 1
8_N, 18_{N + 1}So that they are perpendicular to the tube axis
Forming the outer metal tube 12_N, 12 _{N + 1}, ... to the pipe end face 1
8_N, 18_{N + 1}, ..., and the outer metal tube 12_N,
12_{N + 1}Heats to a temperature below the melting point of
This is a method of joining
Solid phase diffusion bonding method and liquid phase diffusion bonding using insert material
There is a match.

In particular, the liquid phase diffusion bonding method can provide a highly airtight bonded body having the same strength and corrosion resistance as the base material, and can perform bonding in a shorter time than the solid phase diffusion bonding method. There is the advantage that it can be done. If the thickness, shape, etc. of the insert material are optimized, it is possible to obtain a joined body having no burrs at the joining portions 20 _N ,... Unlike the welding method, and the time required for the joining operation is short. There are advantages.

As described above, the outer metal tubes 12 _N , 12 _{N + 1} ,.
Although the method for joining the outer metal pipes to form the outer metal pipe joined body 10 has been described, the method for joining the inner metal pipes to form the inner metal pipe joined body is not shown, but the outer metal pipes 12 _N and 12 _N are not shown.
_It is performed in exactly the same way as the bonding of _{N + 1} ,. However, when burrs are generated, it is necessary to remove at least the surface of the joint portion of the inner metal pipe joined body that is in contact with the outer metal pipe joined body 10, that is, the burr on the outer peripheral surface side.

In general, the double metal pipe is often provided with corrosion resistance and airtightness by the inner metal pipe, and the outer metal pipe merely supports the inner metal pipe. Therefore,
In such a long double metal pipe, the method of joining the outer metal pipe joined body 10 is not limited to a metallurgical joining method such as a welding method, but may be a mechanical fastening method.

For example, as shown in FIG. 2A, each of the outer metal tubes 12 _N , 12
_{N + 1,} the flange _{22 N, 22} N _{+ 1} to ... ends of welded ..., the flange _{22 N, 22} N _{+ 1,} ... may be used a flange joint that is bolted against a. Further, as shown in FIG. 2 (b), one end of the outer metal tube 12 _N constituting the outer metal tube assemblies 10 to form the male screw 24 _N, internal thread at one end of the outer metal tube 12 N _{+ 1} 2
_{4N + 1} may be used, and a threaded joint in which these are screwed and fastened may be used.

The method of joining the outer metal tube and the inner metal tube may be appropriately selected according to the use of the long double metal tube. Liquid phase diffusion bonding is preferred. If the inner metal pipe is joined by the liquid phase diffusion joining method, as described above,
An inner metal pipe joint with excellent corrosion resistance and airtightness can be easily obtained, and burrs are less likely to occur.If this is used for long double metal pipes, high quality long double metal pipes can be manufactured at low cost. This is because it can be manufactured.

If both the outer metal tube and the inner metal tube are joined by the liquid phase diffusion joining method, the joining efficiency is high, and the shape and the like of the insert material are optimized to eliminate burrs. Since the joined body can be easily obtained, there is an advantage that even a long double metal tube having a small diameter, which is difficult to remove burrs, can be easily manufactured.

As described above, in the present invention, since the outer metal tube and the inner metal tube are individually joined, even if the materials of the inner metal tube and the outer metal tube are different, each material is different. Optimal joining conditions can be arbitrarily selected. Therefore, for example, even if the outer metal pipe is a thick-walled pipe, a sound outer metal pipe joint can be obtained without melting the inner metal pipe. Further, when joining the outer metal pipe after joining the inner metal pipe, it is unlikely that the joining portion of the joined inner metal pipe is re-melted. For this reason, it becomes possible to suppress the deterioration of the corrosion resistance of the inner metal pipe joined body and the occurrence of cracks due to hardening, which have been problems in the conventional method of joining the double metal pipes.

Next, the inner tube inserting step will be described. The inner pipe insertion step is a step of inserting the inner metal pipe joint into the outer metal pipe joint. The insertion procedure is not particularly limited, and after the outer metal pipe joint and the inner metal pipe joint are individually joined, the completed inner metal pipe joint may be inserted into the completed outer metal pipe joint. Good.

When the length of a double metal pipe such as an oil well pipe or a line pipe exceeds several thousand meters, the completed inner metal pipe joint is inserted into the completed outer metal pipe joint.
It is not practical in practice. In such a case, the joining of the inner metal tube and the joining of the outer metal tube may be performed alternately with the inner metal tube inserted into the outer metal tube. With this configuration, the outer metal pipe joint and the inner metal pipe joint are alternately added, so that even a double metal pipe exceeding several thousand meters can be manufactured.

Next, the pipe expanding step will be described. FIG.
(A) is an example of expansion using a mandrel (hereinafter, referred to as “mandrel method”), and includes outer metal tubes 12 _N and 12 _{N.
N + 1,} ... welds 16 _N, ... in the outer metal tube assembly 10 which is joined through the inner metal tube ₃₂ N, 3
_{2N + 1} ,... Insert the inner metal pipe joined body 30 joined via the welded portions _33N ,..., Insert the mandrel 34 from one end of the inner metal pipe joined body 30, and move the mandrel 34 toward the other end. By pressing the inner metal pipe joint 30
Is a method of expanding the pipe. In the expansion by the mandrel method,
The length of the shaft 34a of the mandrel 34 limits the length that can be manufactured.

FIG. 3 (b) shows a tube expansion using a plug (hereinafter, referred to as a plug expansion).
This is an example of the “plug method”, in which the plug 36 is inserted from one end of the inner metal pipe joint 30 inserted into the outer metal pipe joint 10 and the plug 36 is pulled out to the other end. This is a method of expanding the body 30. In the tube expansion by the plug method, the length of the shaft 36a of the plug 36 is the limit of the length that can be manufactured.

FIG. 3 (c) shows a tube expansion by hydraulic pressure (hereinafter referred to as "tube expansion").
"Hydraulic method"), the outer metal pipe joined body 1
One end of the inner metal pipe joined body 30 inserted into the inner metal pipe joined body 30 is sealed, and a liquid 38 such as water is injected into the inner metal pipe joined body 30 from the other end by using a pressurizing means such as a hydraulic pump (not shown). This is a method of press-fitting and expanding the inner metal pipe joined body 30 by hydraulic pressure.

The hydraulic method is not limited except that it is necessary to have a piping structure capable of releasing the sealing at one end after the end of the pipe expansion step, and there is no limit to the length that can be manufactured. Therefore, it is suitable as a method for manufacturing a long double metal pipe used for a pipeline or the like in which both ends of the pipe are on the ground surface and the length of the pipe is several tens km. Further, since it is not necessary to use a tube expander such as a mandrel, there is an advantage that a large diameter double metal tube can be manufactured.

FIG. 3 (d) shows a pipe expansion using a plunger (hereinafter, referred to as “plunger method”), and the plunger 40 is inserted from one end of the inner metal pipe joint 30 inserted into the outer metal pipe joint 10. And pressurizing a liquid 38 such as water into the inside of the inner metal pipe joint 30 using a pressurizing means such as a hydraulic pump (not shown) to apply a liquid pressure to the end face 40 a of the plunger 40. , The plunger 40 is pushed toward the other end, and the inner metal pipe joined body 30 is expanded by the plunger 40.

In the plunger method, since the plunger 40 is pushed in using hydraulic pressure, there is an advantage that the length of the double metal tube that can be manufactured is not limited. Also, the inner metal tube 3
The plunger 40 inserted from one end of 0 and pushed into the other end is pushed out of the other end by the hydraulic pressure. Therefore, unlike the hydraulic method, it is not necessary to seal the other end or release the seal, so that the production of a long double metal pipe used for oil country tubular goods or the like whose other end is buried deep underground. It is particularly suitable as a method.

Here, since the inner metal pipe joined body 30 needs to be inserted into the outer metal pipe joined body 10, it is naturally necessary to have an outer diameter smaller than the inner diameter of the outer metal pipe joined body 10. The outer diameter of the inner metal pipe joint 30 is determined in consideration of the material of the inner metal pipe joint 30 by the expansion ratio (= (outer diameter after expansion−outer diameter before expansion) / outer diameter before expansion × 100 (%). ))
Must be selected so as to be equal to or less than a predetermined value.

If the expansion ratio is too large, many microcracks may occur along the longitudinal direction of the inner metal joined body 30 after the inner metal joined body 30 is expanded. The micro cracks increase the surface area of the inner peripheral surface of the inner metal pipe joint 30 and cause a reduction in corrosion resistance.
For example, when SUS329J1, which is a kind of duplex stainless steel, is used as the inner metal pipe joint 30, the expansion ratio needs to be 30% or less.

Next, how the double metal tube is manufactured by the manufacturing method according to the present invention will be described with reference to FIG. FIG. 4A shows an inner pipe insertion step in which the joined inner metal pipe joint 30 is inserted into the outer metal pipe joint 10 joined by a joining step (not shown).

[0046] In the example shown in FIG. 4, as the outer metal tube assembly 10, used as outer metal tube _{12 N, 12} N _{+ 1,} where ... is joined via a weld 16 _N, inner metal pipe bonded body Similarly, the inner metal tubes 32 _N , 32
_{N + 1,} ... are used as joined via a weld 33 _N. In this case, the outer metal pipe joined body 10 and the inner metal pipe joined body 30 perform the work of removing burrs on both the outer peripheral surface and the inner peripheral surface.

FIG. 4 (b) shows a pipe expansion step, in which the inner metal pipe joint 30 inserted into the outer metal pipe joint 10 in the inner pipe insertion step is expanded at a stroke. Then, the outer diameter of the inner metal pipe joint 30 is enlarged by plastic deformation, and the inner peripheral surface of the outer metal pipe joint 10 and the outer peripheral surface of the inner metal pipe joint 20 are completely adhered to each other. A long double metal tube 50 as shown in c) is obtained.

(Example 1) As an outer metal tube, an outer diameter of 21 was used.
A carbon steel pipe for high pressure piping STS480 (JIS G3455) having a diameter of 6.3 mm, an inner diameter of 190.9 mm, and a length of 5 m was used. As an inner metal pipe, an outer diameter of 165.2 mm and an inner diameter of 15 mm were used.
9.6mm, 5m long duplex stainless steel pipe SUS32
9J1 (JIS G3459) was used. In this case, the expansion ratio is 15.6%.

The 10 outer metal pipes were welded by a TIG welding method to produce a 50 m long outer metal pipe joint. Also, eleven inner metal pipes were welded by a TIG welding method to produce a 55 m long inner metal pipe joined body. Then, after removing the burrs, the obtained inner metal pipe joined body is inserted into the outer metal pipe joined body, and the inner metal pipe joined body is expanded by using a plug method, thereby forming a long double metal pipe having a length of 50 m. Manufactured.

(Example 2) The procedure was carried out except that the joining method of the outer metal pipe was a flange joint, the joining method of the inner metal pipe was a liquid phase diffusion joining method, and the joined body of the inner metal pipe was expanded using a hydraulic method. According to the same procedure as in Example 1, a long double metal tube having a length of 50 m was manufactured.

For the liquid phase diffusion bonding of the inner metal tube, the insert material has a composition equivalent to JIS Z3265 BNi-5, a thickness of 40 μm, and an outer diameter and an inner diameter of 98 mm, respectively, of the outer diameter of the inner metal tube. % And a ring-shaped Ni-based alloy foil having an inner diameter of 100%. In addition, the joining surface roughness Rmax of the inner metal pipe is set to 25 μm or less, and the joining temperature is set to 1
At 300 ° C., the holding time was 60 seconds, the pressure was 4 MPa, and the bonding atmosphere was Ar. Further, since no burrs were generated at the joint portion, the operation of removing the burrs was not performed.

Example 3 The same procedure as in Example 1 was carried out except that the joining method of the outer metal tube and the inner metal tube was both a liquid phase diffusion bonding method and the inner metal tube joined body was expanded using a plunger method. A long double metal tube having a length of 50 m was manufactured by the procedure.

The liquid phase diffusion bonding of the outer metal tube has a composition equivalent to JIS Z3265 BNi-1 as an insert material, a thickness of 30 μm, and an outer diameter and an inner diameter of 98% of the outer diameter of the outer metal tube. A ring-shaped Ni-based alloy foil having an inner diameter of 99% was used. In addition, the joining surface roughness Rmax of the inner metal pipe is set to 50 μm or less, and the joining temperature is set to 130 μm.
At 0 ° C., the holding time was 60 seconds, the pressure was 4 MPa, and the bonding atmosphere was Ar. The liquid phase diffusion bonding of the inner metal tube is
Performed under the same conditions as in Example 2. Further, since neither the inner metal pipe joint nor the outer metal pipe joint produced burrs, the burrs were not removed.

Comparative Example 1 A duplex stainless steel pipe SUS329J1 (JIS G345) having an outer diameter of 216.3 mm, an inner diameter of 190.9 mm, and a length of 5 m without using an inner metal tube.
9) was welded using a TIG welding method to produce a long metal pipe having a length of 50 m.

(Comparative Example 2) Outer diameter 216.3 mm, inner diameter 1
90.9mm carbon steel pipe STS480 for high pressure piping (JI
SG3455) has a duplex stainless steel pipe SUS329J1 with an outer diameter of 165.2 mm and an inner diameter of 159.6 mm on the inner surface.
A 5 m long clad steel pipe clad with (JIS G3449) was welded by a TIG welding method to produce a long double metal pipe having a length of 50 m.

Table 1 shows the results obtained by examining the material costs, joining efficiencies, and corrosion test results of the steel pipes obtained in Examples 1 to 3 and Comparative Examples 1 and 2. The corrosion test was performed after pipe expansion (or T
Length 1 with joint at center from steel pipe after IG welding)
Cut out a strip test piece of 00 mm and width of 12.5 mm,
10% FeCl + N / 20HC kept at 50 ° C.
1 for 24 hours. The corrosion resistance was represented by the corrosion loss per unit area and unit time.

[0057]

[Table 1]

In the first to third embodiments, an outer metal pipe made of a carbon steel pipe for high-pressure piping and an inner metal pipe made of a duplex stainless steel pipe were prepared, joined individually, and then expanded at once to form a double metal pipe. Since it was a tube, the material cost was the lowest. On the other hand, in Comparative Example 1, the material cost was the highest because the duplex tube was used as it was to form the long tube using the duplex stainless steel containing a large amount of Cr. In Comparative Example 2 using a clad steel pipe, the material and thickness of the outer and inner sides are the same as in Examples 1 to 3, but since the joining step is included during the production of the clad steel pipe, the thickness is smaller than that of Examples 1 to 3. As a result, the material costs became higher.

The bonding efficiency was highest in Example 3 in which both the outer metal tube and the inner metal tube were bonded by the liquid phase diffusion bonding method. This is because the work time required for liquid phase diffusion bonding is less than half that of the welding method, and by optimizing the shape of the insert material, etc., a joined body without burrs can be obtained. This is because it becomes unnecessary.

Then, the inner metal pipe was joined by a liquid phase diffusion bonding method, and the outer metal pipe was flange-jointed. In Example 2, the joining efficiency was high.
The efficiency of Example 1 and Comparative Example 1 joined using the G welding method was lower than that of Example 2. Furthermore, in Comparative Example 2 in which the clad steel pipe was TIG-welded, the welding efficiency had to be changed between the inside and the outside, so that the joining efficiency was the lowest.

No pitting corrosion was observed on the inner peripheral surface of the long double metal pipes obtained in Examples 1 to 3, and the corrosion weight loss was determined by comparing the duplex stainless steel pipe SUS329J1 with TIG welding as it was. It was equivalent to Example 1, and no decrease in corrosion resistance due to expansion was observed. On the other hand, in Comparative Example 2 in which the clad steel pipe was TIG-welded, no pitting was observed, but the corrosion resistance of the welded portion was reduced, so that the weight loss due to corrosion was slightly increased.

From the above results, it was found that Examples 2 and 3 in which the inner metal pipe was joined by the liquid phase diffusion bonding method were the most excellent, and then both the inner metal pipe and the outer metal pipe were TIG-welded. Example 1 was found to be excellent.

(Embodiment 4) An outer metal tube having an outer diameter of 16
A stainless steel pipe SUS316TP (JIS G3449) having a diameter of 5.2 mm, an inner diameter of 143.2 mm and a length of 5 m was used, and as an inner metal pipe, an outer diameter of 114.3 mm and an inner diameter of 1 mm were used.
10.1mm, 5m long titanium pipe for piping TTP270
WC (JIS H4630) was used. In this case, the expansion ratio is 25.3%.

The outer metal pipes were welded by a TIG welding method to produce a 50 m-long outer metal pipe joint. Also, eleven inner metal pipes were welded by a TIG welding method to produce a 55 m long inner metal pipe joined body. Next, after removing the burrs, the obtained inner metal pipe joined body was inserted into the outer metal pipe joined body, and the inner metal pipe joined body was expanded using a plunger method, and the long metal pipe joined body was 50 m long. Heavy metal tubes were manufactured.

Example 5 The procedure was the same as that of the first embodiment except that the joining method of the outer metal pipe was a flange joint, the joining method of the inner metal pipe was a liquid phase diffusion joining method, and the inner metal pipe joined body was expanded using a hydraulic method. According to the same procedure as in Example 1, a long double metal tube having a length of 50 m was manufactured.

For the liquid phase diffusion bonding of the inner metal tube, a ring-shaped Ti having a thickness of 30 μm, an outer diameter and an inner diameter of 99% of the outer diameter and an inner diameter of 100% of the inner metal tube, respectively, is used as an insert material. -Zr-Cu-Ni alloy foil was used.
The bonding surface roughness Rmax of the inner metal tube was 25 μm or less, the bonding temperature was 900 ° C., the holding time was 180 seconds, the pressure was 3 MPa, and the bonding atmosphere was He. In addition, since no burrs were generated at the joints, the burrs were not removed.

(Example 6) The same procedure as in Example 1 was adopted except that the joining method of the outer metal tube and the inner metal tube was both liquid phase diffusion bonding, and the inner metal tube joined body was expanded using a plug method. Produced a long double metal tube having a length of 50 m.

For the liquid phase diffusion bonding of the outer metal tube, the insert material has a composition equivalent to JIS Z3265 BNi-2, a thickness of 25 μm, and an outer diameter and an inner diameter each being 100 mm of the outer diameter of the outer metal tube. % And 99.5% of the inner diameter of a ring-shaped Ni-based alloy foil. Further, the joining surface roughness Rmax of the outer metal tube is set to 50 μm or less, the joining temperature is 1290 ° C., the holding time is 60 seconds, and the pressing force is 3.5MP.
a, the bonding atmosphere was Ar. The liquid-phase diffusion bonding of the inner metal tube was performed under the same conditions as in Example 5. Also,
Neither of the outer metal pipe joints nor the inner metal pipe joints had burrs generated, and thus no burrs were removed.

(Comparative Example 3) A titanium pipe for pipe TTP270WC (JIS H4630) having an outer diameter of 165.2 mm, an inner diameter of 143.2 mm, and a length of 5 m was welded by TIG welding without using an inner metal pipe. Due to the length 50m
Was manufactured.

(Comparative Example 4) Outer diameter 165.2 mm, inner diameter 1
43.2mm stainless steel pipe for pipe SUS316TP
An outer diameter of 114.3m on the inner surface of (JIS G3449)
m, titanium pipe for piping with inner diameter 110.1mm TTP270
5m length with WC (JIS H4630) clad
Welded clad steel pipe by TIG welding method, length 50
m long double metal tube was manufactured.

Table 2 shows the results of examining the material cost, joining efficiency, and corrosion test results of the steel pipes obtained in Examples 4 to 6 and Comparative Examples 3 to 4. The corrosion test was performed after pipe expansion (or T
Length 1 with joint at center from steel pipe after IG welding)
Cut out a strip test piece of 00 mm and width of 12.5 mm,
This was performed by immersing in a 5% HCl solution at 25 ° C. for 720 hours. The corrosion resistance was represented by the corrosion depth per unit time.

[0072]

[Table 2]

In Examples 4 to 6, an outer metal pipe made of a stainless steel pipe for a pipe and an inner metal pipe made of a titanium pipe for a pipe were prepared, joined individually, and then expanded at a stretch to form a double metal pipe. As a result, material costs were the lowest. On the other hand, in Comparative Example 3, the material cost was the highest because a long pipe was used by directly using a titanium pipe for piping containing a large amount of Ti. In Comparative Example 4 using a clad steel pipe, the material and thickness of the outer and inner sides are the same as those of Examples 4 to 6.
However, the material cost was higher than in Examples 4 to 6 because the joining step was performed during the production of the clad steel pipe.

The joining efficiency was highest in Example 6 in which both the outer metal tube and the inner metal tube were joined by the liquid phase diffusion joining method. Next, the efficiency of Example 5 in which the inner metal pipe was joined by a liquid phase diffusion bonding method and the outer metal pipe was a flange joint was high, and Example 4 and Comparative Example 3 using the TIG welding method were higher than Example 5. Efficiency also decreased. Furthermore, in Comparative Example 4 in which the clad steel pipe was TIG-welded, the welding efficiency had to be changed between the inside and the outside, so that the joining efficiency was lowest.

Further, the corrosion depth of the inner peripheral surface of the long double metal pipe obtained in Examples 4 to 6 was determined by using the titanium pipe TTP2 for piping.
This was equivalent to Comparative Example 3 in which 70WC was subjected to TIG welding as it was, and no reduction in corrosion resistance due to pipe expansion was observed.
On the other hand, in Comparative Example 4 in which the clad steel pipe was TIG-welded, the corrosion depth of the welded portion was slightly increased, so that the corrosion depth was slightly increased.

From the above results, it can be seen that Example 4 or 5 in which the inner metal pipe was joined by the liquid phase diffusion bonding method was the best, and then both the inner metal pipe and the outer metal pipe were subjected to TIG welding. Example 1 was found to be excellent.

Although the embodiments of the present invention have been described in detail above, the present invention is not limited to the above embodiments, and various modifications can be made without departing from the gist of the present invention. It is.

For example, when only the corrosion resistance is required for the long double metal pipe 50 and high strength is not required, the inner metal pipe joint 30 and the outer metal pipe joint 10 are subjected to the expanding process.
It may be used as it is in a state where it is adhered. However, when high strength is required for the long double metal pipe 50, the inner metal pipe joined body 30 and the outer metal pipe joined body 10 may be joined after the expansion in the expanding step.

Specifically, after expanding the inner metal pipe joint 30, it is heated using an induction coil, and the outer peripheral surface of the inner metal pipe joint 30 and the inner peripheral surface of the outer metal pipe joint are solid-phased. The bonding may be performed by a diffusion bonding method. Alternatively, after a tape-shaped insert material is spirally wound around the outer peripheral surface of the inner metal pipe joint 30 and inserted into the outer metal pipe joint 10 to expand the inner metal pipe joint 30, an induction coil is used. Then, the inner metal pipe joint 30 and the outer metal pipe joint 10 may be subjected to liquid phase diffusion bonding by heating.

When the inner metal pipe is made of a thin or soft metal, instead of applying hydraulic pressure to the inner metal pipe joint 30 using a hydraulic pump or the like in a hydraulic method or a plunger method, a compressor or the like is used. May be pressurized by using a gas such as air by using the pressurizing means, and the same effect as in the above embodiment can be obtained.

[0081]

According to the method of manufacturing a long double metal pipe according to the present invention, an inner metal pipe joint having one or more joints inside an outer metal pipe joint having one or more joints. Since a long double metal tube is manufactured by inserting a body and expanding the inner metal tube joint, there is no limit on the length that can be manufactured, depending on the expansion method, and a length of several thousand meters or more. There is an effect that a long double metal tube having the following can be manufactured.

Further, since the outer metal pipe and the inner metal pipe are individually joined, the inner metal pipe has to be re-attached at the time of welding, which has been a problem in the conventional method of joining a double metal pipe manufactured in advance. There is an effect that deterioration of corrosion resistance of the welded portion due to melting and generation of cracks due to hardening can be suppressed. In addition, since the joining conditions can be individually optimized, even if either the inner metal tube or the outer metal tube is thick, a healthy long double metal tube can be manufactured.

If the hydraulic method or the plunger method is used as the pipe expansion method, there is no limitation on the length that can be manufactured.
Further, in the hydraulic method, there is an effect that the production of a large-diameter long double metal tube becomes easy. Also, if at least the liquid-phase diffusion bonding method is used to join the inner metal pipes, a long double metal pipe having excellent corrosion resistance and airtightness can be manufactured at a low cost. If the joining is performed by the diffusion joining method, the operation of removing burrs can be made unnecessary, so that a long double metal tube with a small diameter can be manufactured.

As described above, the method for manufacturing a long double metal tube according to the present invention is a method capable of inexpensively and efficiently manufacturing a long double metal tube having excellent quality. Therefore, for example, when this is applied to oil country tubular goods, line pipes, etc., unlike the conventional method of welding a double metal pipe manufactured in a factory in advance at the site, the inner metal pipe and the outer metal pipe are applied at the site. Since the pipes can be individually joined and the pipe expansion work can be performed on site, the time required for the excavation work and the pipe laying work can be greatly reduced, and this is an invention having an extremely large industrial effect.

[Brief description of the drawings]

FIG. 1 is a partial cross-sectional view of an outer metal pipe joined body joined by a metallurgical joining method as one embodiment of the present invention.

FIG. 2 is a partial cross-sectional view and a cross-sectional view taken along the line AA ′ of the outer metal pipe joined body similarly joined by a mechanical fastening method.

FIG. 3 is a view for explaining a method of expanding the inner metal pipe joined body.

FIG. 4 is also a view showing a manufacturing process of a long double metal tube of the present invention, wherein the left figure is a partial cross-sectional view, and the right figure is AA ′ thereof.
It is a line sectional view.

[Explanation of symbols]

Reference Signs List 10 outer metal pipe joint 16 _N welded part 30 inner metal pipe joint 33 _N welded part 50 long double metal pipe

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Shigeyuki Inagaki 3-9-111, Tenpakucho, Minami-ku, Nagoya-shi, Aichi 205 Datong Special Steel Tenpakuso 205

Claims (2)

[Claims] 1. An outer metal pipe joint having one or more joints or fastening parts, an inner diameter of which is smaller than an inner diameter of the outer metal pipe joint, and one or more joints. A method for manufacturing a long double metal pipe, comprising: inserting a bonded inner metal pipe having: and expanding the inserted bonded inner metal pipe to manufacture a double metal pipe. 2. An elongated metal pipe, wherein at least the inner metal pipe joint of the outer metal pipe joint and the inner metal pipe joint is joined using a liquid phase diffusion bonding method. Manufacturing method of heavy metal tube.