JPH0455074A - Production of clad pipe - Google Patents

Abstract

PURPOSE:To allow the easy execution of the operation to assemble blank materials by using the assembled blank material formed by packing fine powder which does not melt at the time of heating and working into the spacing at the rear end of rolling and filling an inert gas into the spacing. CONSTITUTION:The assembled blank material formed by fitting an inside pipe material 20 into an outside pipe material 10 is hot worked to produce the clad pipe. The spacing between the inside and outside pipes 20 and 10 is so formed as to be slight in the prescribed region at the rear end of the rolling and to be slightly larger from the front end of rolling to the rear end of rolling than the spacing in the prescribed region at the rear end of rolling at the time of heating and working. The superposed part of the inside and outside pipe materials 20, 10 at the front end face of rolling is subjected to circumferential hermetic welding 40. The fine powder 50 which does not melt at the time of heating and working is packed into the spacing at the rear end of rolling and the inert gas is packed in the spacing. The joint strength of the inside and outside pipe materials is improved in this way.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention is a method of hot processing an assembled material made by fitting a hollow or solid inner tube into a hollow outer tube to form a clad pipe. The present invention relates to a method for manufacturing a clad pipe.

[Conventional technology]

In recent years, the environments of oil country tubular goods, line pipes, and chemical industry piping often contain large amounts of corrosive gases and substances such as H, S, Co, and caps. For this reason, it is advantageous to use seamless clad pipes. In particular, it is economical to use clad pipes in which the inner surface of carbon steel pipes, low-alloy steel pipes, etc. is lined with corrosion-resistant materials such as stainless steel or high-alloy materials such as nickel. It is also advantageous from the viewpoint of efficiency and effective use of resources.

In clad pipes used for oil country tubular goods and line pipes, it is particularly desirable that the base material pipe and the live pipe be metallurgically bonded. A method for industrially manufacturing such a rad tube is to insert an inner tube material (pipe tube) into an outer tube material (base material tube), and to seal the gap between the inner and outer tube materials, TIG welding the ends of both tubes, etc. The air in the sealed gap is replaced with an inert gas, or removed by vacuum deaeration, etc. to prevent oxidation and corrosion of the joint surfaces of the inner and outer tube materials, while hot rolling (e.g. plug mill, mandrel mill) etc.) is usually adopted.

In this method of manufacturing raft pipes, the degree of air discharge from the gaps in the assembled material before hot rolling, in which the inner pipe material is fitted to the outer pipe material, has a large effect on the joint strength of the clad pipe after hot rolling. effect. Therefore, in the production of assembly materials, a press-fitting technique is used to forcibly fit an inner tube material having an outer diameter larger than the inner diameter of the outer tube material, as disclosed in Japanese Patent Application Laid-Open No. 19958/1983. It is widely used. Furthermore, JP-A-61-199504 discloses a technique that eliminates the need for seal welding at both ends by melt-sealing the outer tube material and the inner tube material at both ends with a glass material after this press-fitting. ing.

[Problems to be Solved by the Invention] However, in any of the techniques, the outer diameter of the inner tube material (usually a composite material) is greater than the inner diameter of the outer tube material (usually the base material), and cold press-fitting or Because it is assembled by heating the outer tube and press-fitting it,
In addition to requiring special equipment such as a press-fitting device for assembly, it takes a lot of man-hours and inevitably increases costs.In addition, the thickness of the composite material is usually thinner than the thickness of the base material and is thicker than necessary. Although it is not necessary, if you try to improve work efficiency by preventing buckling during press-fitting (which becomes more noticeable with long pieces), you will have to make it thicker than necessary, which is a waste of material and , this also leads to an increase in cost.Of course, even if the above two problems can be solved to some extent by adopting outer tube heating press-fitting, the surface of the outer tube will be oxidized during this heating, resulting in a decrease in bondability. This becomes a new problem.

Furthermore, in addition to the above problems, the latter glass melt sealing technology also poses the following problems.

Glass installed in a cold state before heating may not peel or fall off if handled carefully during tests in a laboratory, etc., but in actual production, where mass production is the responsibility. Materials are transported in factories using conveyors that generate large vibrations, so they easily peel off partially or completely when they are picked, and are of no use when heated, making them difficult to use industrially. This is virtually impossible. Further, even if it were possible to melt and seal without peeling or falling off, the gas generated from within the steel would not be exhausted, so it would not be possible to prevent the formation of parts with low bonding strength.

The present invention has been made in view of the above circumstances, and allows assembly materials to be easily produced without press-fitting, and moreover, completely replaces air with inert gas by completely discharging air from the gap between the inner and outer tube materials, and during heating processing. The object of the present invention is to provide a method for manufacturing a clad pipe that achieves as much gas as possible from steel and obtains high metallurgical bonding strength.

[Means for Solving the Problems] The method for manufacturing a clad pipe of the present invention includes a hollow outer pipe material that includes
In a method of manufacturing a clad pipe by hot processing an assembled material formed by fitting hollow or solid inner tube materials, the gap between the inner and outer tube materials during heat processing is within a predetermined area at the rolling rear end of the assembled material. The gap from the rolling tip to the rolling rear end is slightly larger than the gap in the predetermined length region of the rolling rear end, and the overlapping part of the inner and outer tube materials on the rolling tip surface is welded with a circumferential airtight seal, and the rolling rear end is The assembly material is characterized in that the gap between the parts is filled with fine powder that does not melt during heat processing, and the gap is filled with an inert gas.

Another method of manufacturing a clad pipe according to the present invention is a method of manufacturing a clad pipe by hot working an assembled material formed by fitting a hollow or solid inner pipe material into a hollow outer pipe material, the method comprising: As a raw material, the gap between the inner and outer tube materials is virtually zero before and after heating in the predetermined long gate area at the rolling rear end, and is tightly sealed, and from the rolling tip to the rolling rear end, there is zero or a slight gap during heat processing, and the rolling tip surface The overlapping parts of the inner and outer tube materials are welded in a circumferential airtight seal, and a metal rod that melts at a temperature slightly lower than the heating temperature is attached to at least one circumferential point of the tightly sealed rolling rear end of the overlapping part of the inner and outer tube materials. The present invention is characterized by using an assembly material which is filled through the space in the direction and filled with an inert gas in the space.

[For production]

FIG. 1 is a cross-sectional view of a typical assembled material used in the method of manufacturing a clad pipe of the present invention.

When assembling the assembly materials, first, the inner tube material 20 is fitted into the outer tube material 10 in an oxygen-free atmosphere such as argon or nitrogen.

The outer tube material IO has the same diameter over its entire length on both the inner peripheral surface and the outer peripheral surface. The inner circumferential surface of the inner tube material 20 fitted into the outer tube material 1O has the same diameter over its entire length, while the outer circumferential surface has a diameter slightly larger at the end on the rolling rear end side than at other parts. It is said to have a large diameter. A groove 22 is provided on the outer peripheral surface of the large diameter portion 21 of the inner tube 20 over the entire circumference, and a groove 12 is also provided on the inner peripheral surface of the end of the outer tube 10 facing the groove 22 over the entire circumference. It is provided. And, in communication with the groove 12, at the end of the rolled rear end of the outer tube material IO,
A through hole 11 is provided perpendicular to the tube axis to be closed with a plug 30.

The outer tube material IO and the inner tube material 20 are fitted with a gap.

The clearance is 0.05 to 0.05 at the end of the rolling rear end where the large diameter portion 21 is formed, even during heating for rolling.
It is better to ensure a clearance of 2 m. If the clearance at the end of the rolling rear end during heating is less than 0.05 mm, the inner and outer pipes will locally contact each other, making it difficult to discharge gas, and
．． If the clearance exceeds 2, it becomes difficult to retain sealing powder filled with LIi Keyaki, which will be described later, in this clearance portion. The clearance in other parts is larger than this to ensure gas flow, but it is desirable that the clearance does not exceed f:1 during heating. Clearance during heating in other parts is 1
If it exceeds m, it becomes difficult to metallurgically join the inner and outer tubes.

The inner circumferential surface roughness of the outer tube material 1O and the outer circumferential surface roughness of the inner tube material 2o require a puff finish level to improve their adhesion when the inner and outer tube materials are press-fitted. In the case of the tube material 20, since both are fitted with a gap, a finish of about 25S, which is rougher than a puff finish, is acceptable.

When the inner tube material 20 is fitted into the outer tube material 10, TIC is applied between the outer tube material 10 and the inner tube material 20 at the end surface on the rolling tip side.
, by seal welding 40 such as welding. Further, after filling the sealing powder 50 through the through hole 11 into the space surrounded by the grooves 12 and 22 at the end on the rolling rear end side, the through hole 11 is closed with a plug 30. This results in
An oxygen-free atmosphere gas such as argon or nitrogen is sealed between the inner and outer tube materials.

The sealing powder 50 is a heat-resistant powder such as glass powder or alumina powder that does not melt even when heated for rolling.
In the space surrounded by 2 and 22, if there is no pressure difference between the inner and outer tubes and the outside, the space between the inner and outer tubes is sealed from the outside, and if the pressure between the inner and outer tubes is higher than the outside. The tube is filled so that the oxygen-free atmospheric gas interposed between the inner and outer tubes is exhausted to the outside. From this point of view, the particle size of the sealing powder 50 is preferably 50 to 400 mesh when using the same particle size, and 50 to 400 mesh when using a mixture of different particle sizes. granular powder and about half of this coarse powder, 100 to 8
It is preferable to use a mixture of 0.00 menonyu fine grain powder at a ratio of 1=1, and the packing density and specific gravity are 1.5" and 2.0.
It is desirable to set it to about g/cj.

The completed assembly material is heated to a predetermined temperature and then passed through a hot rolling mill from the rolling tip side.

Concave grooves 12 and 22 for filling sealing powder 50
The dimensions are 5 to 20 cm from the rolling rear end surface, and the width is 2 to 20 cm.
It is desirable to form the through hole 11 to have a diameter of about 2 to 51 cm, and a depth of about 1 to 5 cm.

Although it is not necessary to provide this groove, the outer tube material l
It is preferable to provide this groove in order to prevent as much as possible the powder from entering between the inner and outer tube materials when filling the powder from the through hole 11 formed in the hole 11. It can also be provided on one side.

According to the method of manufacturing a clad pipe of the present invention, the outer tube material 10 and the inner tube material 20 are fitted with a gap, so that the fitting operation is extremely simple compared to press-fitting.

During heating, the oxygen-free atmospheric gas in the tube gap increases the internal pressure in the gap due to thermal expansion, and the gas generated from within the steel further increases the internal pressure. This high-pressure gas passes through the gap between the sealing powder 50 filled in the end of the rolled rear end of the assembled material and is discharged outside the tube until the pressure inside and outside the tube is the same, reducing the gas concentration in the tube gap. do.

In addition, during joint rolling, rolling is performed from the rolling tip side of the assembled material, so gas in the gap is pushed out to the rolling rear end side and is discharged to the outside through the sealing powder 50 filled at the rolling rear end. As a result, close to ideal bonding can be achieved without vacuum degassing.

For assembled materials that are also seal welded at the rolling rear end, even if vacuum deaerated, the gas generated in the steel will be wrinkled toward the rolling rear end as the joint rolling progresses, and the rolling rear end will be wrinkled. High pressure will occur in the vicinity, which will have a negative effect on the bond.

Note that JP-A-61-199504 states that air intrusion occurs because the outer tube material expands first during heating and the gap expands, but this is only when the gap is evacuated.
If an oxygen-free atmosphere gas is sealed in the gap,
The expansion ratio of the oxygen-free atmospheric gas in the gap and the solid outer tube material at the same temperature is about 400:1, and the amount of pressure increase in the gap is much larger than the amount of decrease in the pressure inside the gap due to the gap expansion. , it is impossible for air to enter the gap from the outside.

FIG. 2 is a sectional view of an assembly material used in another method of manufacturing a clad pipe according to the present invention.

This assembly material differs from the assembly material shown in FIG. 1 in the clearance between the inner and outer tube members and in the form of a seal at the end of the rolling rear end.

In other words, the clearance between the outer tube material IO and the inner tube material 20 is set so that the clearance between the outer tube material 1O and the inner tube material 20 is set over the entire length during rolling heating, in order to allow gas passage in the tube axis direction during rolling, before the end of the rolling rear end is processed. A value of 0■Zhao, l■ or less is ensured.

When the inner tube material 20 is fitted into the outer tube material 10, a rod-shaped temperature fuse 60 is placed at one or more locations in the circumferential direction between the inner and outer tube materials at the end of the rolling rear end, and the space is tightly sealed. In order to do so, the diameter of the end of the inner tube 20 is expanded to be equal to or larger than the inner diameter of the outer tube 10. Even after the diameter expansion, one end of the temperature fuse 6.0 is exposed to the outside, and the other end extends toward the inner side from the diameter expansion processing part and reaches the gap between the inner and outer tube members.

The temperature 60 is 30 to 50°C higher than the rolling heating temperature.
It is a metal bar made of, for example, amorphous Ni-based alloy, which has a low melting point, and an appropriate one is selected and used according to the rolling heating temperature. ℃
, JIS BNi=5 standard product has a melting point of 1150°C.

The cross-sectional shape of the temperature fuse 60 may be either circular or square, but it is desirable that the cross-sectional area is approximately 0.5 to 3-1/n (where n is the number of temperature fuses 60 arranged in the circumferential direction).

It is desirable that the length in the tube axis direction of the close sealing portion at the end of the rolling rear end example is approximately 0.1 to 0.5 times the joining interface diameter.

Other assembly specifications, such as performing assembly in an oxygen-free atmosphere such as argon or nitrogen, or welding the outer tube material 10 and the inner tube material 20 for a circumferential airtight seal at the end on the rolling tip side, are shown in Figure 1. The same is true for the assembly materials. Therefore, by tightly sealing the end portion on the rolling rear end side, oxygen-free atmospheric gas is sealed in the gap between the inner and outer tube members.

Note that tight sealing at the end after rolling can also be achieved by reducing the diameter of the end of the outer tube material IO, as shown in FIG.

Also in the case of another clad pipe manufacturing method of the present invention, the outer pipe material 10 and the inner pipe material 20 are fitted with a gap, so the fitting operation is easier than press-fitting.

After both ends are sealed, air infiltration and water intrusion into the space between the inner and outer tubes can be avoided, making it possible to withstand long-term storage and storage.

During heating, the oxygen-free atmospheric gas in the tube gap increases the internal pressure in the gap due to thermal expansion, and the gas generated from within the steel further increases the internal pressure. Therefore, the heating temperature is 6
When the melting point of 0 is reached, the temperature fuse 60 melts and is blown to the outside by the internal pressure in the gap. As a result, the high-pressure gas in the gap passes through the hole after the temperature fuse 60 has escaped, and is discharged outside the tube until the pressure inside and outside the tube is the same, thereby lowering the gas concentration in the tube gap.

Also, during joint rolling, the gas in the gap causes a temperature fuse 60.
The gas is discharged through the hole, and even if vacuum degassing is performed, a close to ideal bond can be achieved.

(Example) The present invention will be explained in detail below.

The assembly material shown in FIG. 1 was produced using the outer tube material (JIS 5TPA24) and the inner tube material (Inconel 825: trade name) shown in Table 1. The roughness of the opposing circumferential surface was 12S. The opposing circumferential surface of the end on the rolling rear end side over a length of 10 mm (
In the center of each of the 10 lengths, a concave groove with a depth of 1.5 lengths and a width of 3 lengths was formed. The space surrounded by each groove was filled with alumina of various particle sizes (A/!, O,) at various densities. Table 2 shows the alumina filling specifications.

The fabricated assembled material was hot-rolled using a two-way piercer under the conditions of soaking at 1200°C for 15 minutes, a stretching ratio of 2.01, and a diameter expansion ratio of 1.034, resulting in an outer diameter of 61.0 mm. Total wall thickness 5
．． It was finished as a product with 48 temples and a length of 603 kan. JIS 0060 was obtained by developing specimens with a width of 30 cm taken from both ends of the manufactured clad pipe and from the central part.
Table 2 shows the results of a shear test limited to 1.

For comparison, the same applies to the case where both ends of the assembled material were vacuum degassed and then welded for a circumferential airtight seal (conventional example), and the case where sealing powder was not filled in the clearance part of the rolling end example (comparative example). The test was conducted.

As is clear from Table 1 and Table 2, in the case of the example of the present invention, almost the same joint strength was obtained over the entire length, but in the case of the conventional example, gas aggregated on the rolling trailing end side. As a result, the joint strength is reduced on the rear end side.

In addition, in the comparative example, the inner and outer tubes peeled off during specimen preparation, making measurement impossible.

The inner tube material is the outer tube material shown in Table 3 (JIS 5TPA24
) and an inner tube material (Inconel 825: trade name) were used to fabricate the assembly material shown in FIG. 2.

The temperature fuse is JIS BN with a melting point of 1150°C.
i-5 equivalent product (MET made by Japan Amorphous Metals (1, LAS)
MBF-50) was made into a thin plate rod shape with a thickness of 0.5 cm and a length of 15 cm with varying widths, and was interposed at opposing positions 180 degrees apart in the circumferential direction of the tube. The close sole on the rolling rear end side was done in the sJI area from the pipe end to 12 holes using a plug with an outer diameter of 34 holes, and welded it so that 2 holes protruded to the innermost side of the close seal part. .

Soak the assembled material at 1190°C for 15 minutes and stretch the material! , 49. Hot rolling was carried out using a double piercer under the conditions of a pipe expansion ratio of 1.029, resulting in a product with an outer diameter of 61.74 m, a total wall thickness of 7.72 m, and a length of 447 m. Table 4 shows the results of the same shear test as above.

For reference, Ni-based alloy amorphous (manufactured by Japan Amorphous Metal ■ METC, LAS MB) with a melting point of 1165°C is used.
F-75) (Comparative Example ■), JIS with a melting point of 1125°C
Temperature fuses (each with a width of 1.5 mm and a cross-sectional area of 0.75 mm) made of amorphous Ni-based alloy equivalent to BNi-IA (METGLAS MBF-15 manufactured by Nippon Amorphous Metal ■) (comparative example ■). used.

As is clear from Table 4, in the case of the inventive example, almost the same bonding strength was obtained over the entire length, but if the melting point was too high or too low, the bonding strength was slightly greater at the center in the axial direction. However, the ends of both tubes were peeled off during specimen preparation, making it impossible to measure.

[Effects of the Invention] All of the clad pipe manufacturing methods of the present invention can lower the finish accuracy of opposing surfaces of inner and outer pipe materials compared to press-fitting, and can simplify assembly work. Moreover, vacuum degassing is not required, and the joint strength can be improved compared to the conventional double-end weld sealing method in which inert gas replacement is performed.

Therefore, the clad pipe can be manufactured at low cost and with good quality.

[Brief explanation of drawings]

1 to 3 are cross-sectional views illustrating the structure of the assembly material used in the method of manufacturing a clad pipe of the present invention. lO: outer tube material, 20: inner tube material, 50: sealing powder, 6
0: Temperature fuse. Applicant: Sumitomo Metal Industries, Ltd. (Q) (b) Figure

Claims (2)

[Claims] (1) In a method of manufacturing a clad pipe by hot processing an assembled material in which a hollow or solid inner tube material is fitted into a hollow outer tube material, the inner and outer tube materials during heat processing are used as the assembly material. The gap is small in the predetermined area of the rolling rear end, and is slightly larger from the rolling tip to the rolling rear end than the gap in the predetermined area of the rolling rear end. A clad pipe characterized by using an assembly material that is hermetically sealed and welded, the gap at the rolling rear end is filled with fine powder that does not melt during heating processing, and the gap is filled with inert gas. manufacturing method. (2) In a method of manufacturing a clad pipe by hot processing an assembly material formed by fitting a hollow or solid inner tube material into a hollow outer tube material, the gap between the inner and outer tube materials is The predetermined length region of the rolling rear end is tightly sealed with virtually no gap before and after heating, and from the rolling tip to the rolling rear end there is zero or a slight gap during heat processing, and the overlapping part of the inner and outer tube materials on the rolling end surface is circumferentially airtight. A metal rod that melts at a temperature slightly lower than the heating temperature is passed through and filled in the axial direction of the tube at at least one circumferential location of the overlapping portion of the inner and outer tube materials at the rolling rear end that is seal welded and tightly sealed, and A method for producing a clad pipe, characterized by using an assembly material filled with an inert gas.