JPS59159284A - Production of clad steel pipe by diffusion joining - Google Patents

Abstract

PURPOSE:To join safely and thoroughly both inside and outside pipes irrespectively of the diameter and length of the pipes by heating both pipes and welding both pipes by diffusion joining with an insert metallic layer interposed therebetween by the stress generated by the difference in thermal expansion between both pipes. CONSTITUTION:The outside circumferential surface of an inside pipe 1 and the inside circumferential surface of an outside pipe 2 are worked to provide a clearance between both pipes 1 and 2. An insert metallic layer 3 is adhered by spot welding to the defatted outside circumferential surface of the pipe 1 and the pipe 1 is fitted into the pipe 2. Both pipes 1, 2 are put in a vacuum chamber and the end faces 4, 5 of the pipes 1, 2 are welded by an electron beam to seal the gap between both pipes 1 and 2. The pipes 1, 2 are then put in a heating furnace and are thus heated. Since the pipe 2 has the smaller coefft. of thermal expansion, the gap between the pipes is eliminated by the difference in the thermal expansion. The pipes 1, 2 are welded to each other by diffusion joining with the layer 3 interposed therebetween, on account of the stress generated by said difference, by which the clad steel pipe is produced.

Description

【発明の詳細な説明】 本発明は拡散接合によるクラッド鋼管の製造法に関する
。DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing clad steel pipes by diffusion bonding.

石油精製プラント等の高温配管としては、耐食性の観点
からステンレス鋼パイプが用いられているが、このステ
ンレス鋼パイプは高価である上に熱膨張の面から問題で
ある。そこでかかる問題点を解消するものとして、ステ
ンレス鋼からなる内パイプと一般の鋼（たとえば炭素鋼
）からなる外パイプを互いに接合させて形成したクラッ
ド鋼製パイプが注目されている。クラッド鋼の製造法と
して、一般に爆発圧着法、熱間ロール押出法、溶接肉盛
法等がある。爆発圧着法では、パイプ径の小さいものに
利用できず、また安全のための設備費が大きくなる。熱
間ロール押出法によれば、大気中で行なうため接合不良
になりやすく、また真空中で行なうためには設備費が大
きくなる。溶接肉盛法ではパイプ径の小さいものでは溶
接トーチが入りにくいため、作業が困難である。Stainless steel pipes are used as high-temperature piping in oil refinery plants and the like from the viewpoint of corrosion resistance, but these stainless steel pipes are expensive and have problems in terms of thermal expansion. As a solution to this problem, a clad steel pipe, which is formed by joining an inner pipe made of stainless steel and an outer pipe made of ordinary steel (for example, carbon steel), is attracting attention. Generally, methods for manufacturing clad steel include explosive crimping, hot roll extrusion, and welding. The explosive crimping method cannot be used for pipes with small diameters, and the cost of equipment for safety increases. According to the hot roll extrusion method, since it is carried out in the atmosphere, poor bonding is likely to occur, and since it is carried out in a vacuum, the equipment cost increases. The welding overlay method is difficult to work with because it is difficult to insert a welding torch into pipes with small diameters.

本発明はかかる問題点を解消した拡散接合によるクラッ
ド鋼管や製造法を提供するものであって、その特徴とす
るところは、接合すべき内パイプの外周面または内パイ
プよりも熱膨張係数の小さい外パイプの内周面にインサ
ート金属層を形成し、内外両パイプを嵌合させ、内外両
パイプ間を真空状態にすると共に内外両パイプを加熱し
て内外両パイプの熱膨張差により発生する応力によりそ
の内外両パイプをインサート金属層を挾んで拡散接合さ
せることにあり、かかる方法によれば、爆発圧着法のよ
うに危険をともなわず、熱間ロール押出法のように接合
面が大気にふれて接合不良になることもなく、溶接肉盛
法のように小径パイプでは作業が困難になるということ
もない。内外両パイプを安全にしかも完全に接合するこ
とができ、小径パイプから大径パイプまでパイプ径に関
係なく、またパイプの長さに関係なく適用できるもので
ある。The present invention provides a clad steel pipe and manufacturing method using diffusion bonding that solves such problems, and is characterized by having a coefficient of thermal expansion smaller than that of the outer peripheral surface of the inner pipe to be joined or the inner pipe. An insert metal layer is formed on the inner peripheral surface of the outer pipe, the inner and outer pipes are fitted together, a vacuum is created between the inner and outer pipes, and both the inner and outer pipes are heated to reduce the stress generated by the difference in thermal expansion between the inner and outer pipes. The purpose of this method is to diffusion bond both the inner and outer pipes by sandwiching the insert metal layer.This method does not involve the dangers of explosive crimping, and does not involve the risk of exposing the joint surface to the atmosphere, unlike hot roll extrusion. There is no problem with joint defects, and there is no difficulty in working with small-diameter pipes, unlike with the welding overlay method. Both internal and external pipes can be safely and completely joined, and it can be applied regardless of the pipe diameter, from small to large diameter pipes, and regardless of the length of the pipe.

以下、本発明の第１の実施例を図に基づいて説明する。Hereinafter, a first embodiment of the present invention will be described based on the drawings.

まず第１図（ａ）に示すごとく外径４０ｍｍ、肉厚５ｍ
ｍのＳＵＳ３４７鋼管からなる内パイプ（１）と、内径
４０ｍｍ、肉厚５ｍｍの２１／４Ｃｒ−１Ｍｏ鋼管から
なる外パイプ（２）とを用意し、内パイプ（１）の外周
面と外パイプ（２）の内周面を加工して内外両パイプ（
１）（２）間に１００μｍのクリアランスが生じるよう
にする。次に同図（ｂ）に示すごとく内パイプ（１）の
脱脂した外周面に厚さが４０μｍのＮｉ箔からなるイン
サート金属層（３）をしわのできないようにスポット溶
接により張り付ける。First, as shown in Figure 1 (a), the outer diameter is 40 mm and the wall thickness is 5 m.
Prepare an inner pipe (1) made of SUS347 steel pipe with a diameter of 40 mm and an outer pipe (2) made of a 21/4Cr-1Mo steel pipe with an inner diameter of 40 mm and a wall thickness of 5 mm. 2) Machining the inner peripheral surface of both the inner and outer pipes (
A clearance of 100 μm should be created between 1) and (2). Next, as shown in FIG. 4(b), an insert metal layer (3) made of Ni foil having a thickness of 40 μm is attached to the degreased outer peripheral surface of the inner pipe (1) by spot welding to avoid wrinkles.

次に同図（ｃ）に示すごとく内周面を脱脂した外パイプ
（２）に対し内パイプ（１）を嵌入させ、同図（ｄ）の
ようにする。次にその内外両パイプ（１）（２）を真空
室内に入れて真空（１０＾−＾４〜１０＾−＾５Ｔｏｒ
ｒ）にし、電子ビームにより内外両パイプ（１）（２）
の端面（４）（５）を溶接して内外両パイプ（１）（２
）間の間隙（６）をシールする。次に内外両パイプ（１
）（２）を真空室から取出して加熱炉（大気雰囲気）に
入れ、９００℃で１時間加熱する。これによって内パイ
プ（１）に比べて外パイプ（２）の方が熱膨張係数が小
さいので、内外両パイプ（１）（２）の熱膨張差により
互いに圧接しあって間隙（６）がなくなり、これによっ
て発生する応力によりその内外両パイプ（１）（２）が
インサート金属層（３）を挾んで拡散接合しあい、クラ
ッド鋼管（７）が製造されるものである。第４図（Ａ）
は同図（Ｃ）のＡ部分の顕微鏡写真であって、電子ビー
ムによって内外両パイプ（１）（２）が完全に接合させ
られているのがわかる。したがって内外両パイプ（１）
（２）が剥離する現象が生じることはない。また第４図
（Ｂ）は同図（Ｃ）のＢ部分の顕微鏡写真であって、内
外両パイプ（１）（２）がインサート金属層（３）を挾
んで拡散接合させられているのがわかる。Next, the inner pipe (1) is fitted into the outer pipe (2) whose inner circumferential surface has been degreased as shown in FIG. Next, put both the inner and outer pipes (1) and (2) into a vacuum chamber and vacuum (10^-^4~10^-^5 Torr).
r), and both the inner and outer pipes (1) and (2) are exposed to the electron beam.
Weld the end faces (4) and (5) of the inner and outer pipes (1) and (2).
) to seal the gap (6) between them. Next, both the inner and outer pipes (1
) (2) is taken out from the vacuum chamber, placed in a heating furnace (atmospheric atmosphere), and heated at 900° C. for 1 hour. As a result, the outer pipe (2) has a smaller coefficient of thermal expansion than the inner pipe (1), so the difference in thermal expansion between the inner and outer pipes (1) and (2) presses them against each other, eliminating the gap (6). Due to the stress generated by this, both the inner and outer pipes (1) and (2) are diffusion bonded to each other with the insert metal layer (3) in between, thereby producing a clad steel pipe (7). Figure 4 (A)
is a microscopic photograph of part A in Figure (C), and it can be seen that both the inner and outer pipes (1) and (2) are completely joined by the electron beam. Therefore, both the inner and outer pipes (1)
(2) The phenomenon of peeling does not occur. Fig. 4 (B) is a microscopic photograph of part B in Fig. 4 (C), showing that both the inner and outer pipes (1) and (2) are diffusion bonded with the insert metal layer (3) in between. Recognize.

なお第２図では間隙（６）を誇張してあり、実際上、肉
眼ではほとんど見ることができないものである。Note that the gap (6) is exaggerated in FIG. 2 and is practically invisible to the naked eye.

また拡散接合のための加熱温度は融点×０．４〜０．８
が適当である。In addition, the heating temperature for diffusion bonding is melting point x 0.4 to 0.8
is appropriate.

本発明の第２の実施例を説明する。すなわち第１の実施
例におけるインサート金属層（３）としてＮｉ箔に代え
て内パイプ（１）の外周面に１０％のリンを含むＮｉメ
ッキ（無電解メッキ）を施し（メッキ厚さ１０μｍ）、
それ以外は第１の実施例と同じようにした。その結果、
内外両パイプ（１）（２）が完全接合されたクラッド鋼
管（７）を得ることができた。A second embodiment of the invention will be described. That is, instead of Ni foil as the insert metal layer (3) in the first embodiment, Ni plating (electroless plating) containing 10% phosphorus was applied to the outer peripheral surface of the inner pipe (1) (plating thickness 10 μm),
The rest was the same as the first example. the result,
It was possible to obtain a clad steel pipe (7) in which both the inner and outer pipes (1) and (2) were completely joined.

本発明の第３の実施例を説明する。すなわち内パイプ（
１）として外径８０ｍｍ、肉厚１０ｍｍのＳＵＳ３１６
鋼管を用い、外パイプ（２）として内径８０ｍｍ、肉厚
１０ｍｍの炭素鋼を用い、３０μｍのＮｉ箔からなるイ
ンサート金属層（３）を用いて、それ以外は第１の実施
例と同じようにした。その結果、内外両パイプ（１）（
２）が完全接合されたクラッド鋼管（７）を得ることが
できた。A third embodiment of the present invention will be described. In other words, the inner pipe (
1) SUS316 with an outer diameter of 80 mm and a wall thickness of 10 mm
A steel pipe was used, and the outer pipe (2) was made of carbon steel with an inner diameter of 80 mm and a wall thickness of 10 mm, and an insert metal layer (3) made of a 30 μm Ni foil was used, but the rest was the same as in the first example. did. As a result, both the inner and outer pipes (1) (
A clad steel pipe (7) in which 2) was completely joined could be obtained.

本発明の第４の実施例を説明する。すなわち第１図（ｄ
）に示すごとく内外両パイプ（１）（２）を嵌合させた
後、大気中でその両パイプ（１）（２）の一方の端面を
溶接してシール、両パイプ（１）（２）の他方の端面か
ら隙間（６）内に吸引パイプを挿入すると共にこの他方
の端面を溶接し、吸引パイプを真空ポンプに接続すると
共に該ポンプを作動させて間隙（６）内の空気を抜いて
真空にし、次に吸引パイプを押しつぶして間隙（６）内
の真空状態を保持し、以後は第１の実施例と同じように
して加熱する。その結果、内外両パイプ（１）（２）が
完全接合されたクラッド鋼管（７）を得ることができた
。このようにすると、大きな真空室が不用となり、コス
トダウンを図ることができる。A fourth embodiment of the present invention will be described. In other words, Figure 1 (d
) After fitting both the inner and outer pipes (1) and (2), weld one end face of both pipes (1) and (2) in the atmosphere to seal them, and then seal both pipes (1) and (2). Insert a suction pipe into the gap (6) from the other end surface, weld this other end surface, connect the suction pipe to a vacuum pump, and operate the pump to remove air from the gap (6). A vacuum is created, then the suction pipe is crushed to maintain the vacuum state in the gap (6), and thereafter heating is performed in the same manner as in the first embodiment. As a result, it was possible to obtain a clad steel pipe (7) in which both the inner and outer pipes (1) and (2) were completely joined. In this way, a large vacuum chamber is not required and costs can be reduced.

なお上記各実施例ではインサート金属層（３）を内パイ
プ（１）の外周面に施したが、外パイプ（２）の内周面
に施してもよい。In each of the above embodiments, the insert metal layer (3) is applied to the outer peripheral surface of the inner pipe (1), but it may also be applied to the inner peripheral surface of the outer pipe (2).

以上述べたごとく本発明の拡散接合によるクラッド鋼管
の製造法によれば、爆発圧着法のように危険をともなわ
ず、熱間ロール押出法のように接合面が大気にふれて接
合不良になることもなく、溶接肉盛法のように小径パイ
プでは作業が困難になるということもない。内外両パイ
プを安全にしかも完全に接合することができ、小径パイ
プから大径パイプまでパイプ径に関係なく、またパイプ
の長さに関係なく適用することができるものである。As described above, according to the method for manufacturing clad steel pipes by diffusion bonding of the present invention, there is no danger like the explosive crimping method, and there is no risk of joint failure due to exposure of the joint surface to the atmosphere like the hot roll extrusion method. There is no difficulty in working with small diameter pipes, unlike the welding overlay method. Both internal and external pipes can be safely and completely joined, and it can be applied regardless of the pipe diameter, from small diameter pipes to large diameter pipes, and regardless of the length of the pipe.

【図面の簡単な説明】[Brief explanation of the drawing]

図は本発明の第１の実施例を示し、第１図（ａ）〜（ｄ
）は内外両パイプの嵌合手順を示す斜視図、第２図は拡
散接合前の横断面図、第３図は拡散接合後の横断面図、
第４図（Ａ）は同図（Ｃ）のＡ部分の顕微鏡写真、第４
図（Ｂ）は同図（Ｃ）のＢ部分の顕微鏡写真である。 （１）・・・内パイプ、（２）・・・外パイプ、（３）
・・・インサート金属層、（４）（５）・・・端面、（
６）・・・間隙、（７）・・・クラッド鋼管The figure shows a first embodiment of the present invention, and FIGS. 1(a) to (d)
) is a perspective view showing the fitting procedure for both the inner and outer pipes, Figure 2 is a cross-sectional view before diffusion bonding, Figure 3 is a cross-sectional view after diffusion bonding,
Figure 4 (A) is a micrograph of part A in Figure 4 (C).
Figure (B) is a micrograph of part B in Figure (C). (1)...Inner pipe, (2)...Outer pipe, (3)
... Insert metal layer, (4) (5) ... End surface, (
6)... Gap, (7)... Clad steel pipe

Claims (1)

【特許請求の範囲】[Claims] １、接合すべき内パイプの外周面または内パイプよりも
熱膨張係数の小さい外パイプの内周面にインサート金属
層を形成し、内外両パイプを嵌合させ、内外両パイプ間
を真空状態にすると共に内外両パイプを加熱して内外両
パイプの熱膨張差により発生する応力によりその内外両
パイプをインサート金属層を挾んで拡散接合させること
を特徴とする拡散接合によるクラッド鋼管の製造法。1. Form an insert metal layer on the outer circumferential surface of the inner pipe to be joined or on the inner circumferential surface of the outer pipe whose coefficient of thermal expansion is smaller than that of the inner pipe, fit both the inner and outer pipes, and create a vacuum between the inner and outer pipes. At the same time, both the inner and outer pipes are heated and the inner and outer pipes are diffusion bonded by sandwiching an insert metal layer between the inner and outer pipes using stress generated due to the difference in thermal expansion between the inner and outer pipes.