JP2001252781A - Method of connection for clad steel - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a new connecting method for clad steel by which a connecting work of clad steel members, which usually requires a large amount of manpower and cost, is efficiently and economically performed. SOLUTION: An engaging plate 4 is engaged between clad layers 3 and 3 after forming gaps 6 and 6 by cutting off base material 2 and 2 at the end of each of clad layers 3 and 3, the butt ends of the engaging plate 4 are butted against each side of the end of the clad layers 3 and 3 and welded, in the butt welding of the clad steel members 1 and 1. Thus the clad layers 3 and 3 and the engaging plate 4 is excellently welded together so that the connection of the clad steel, which usually requires a large amount of manpower and cost, is efficiently and economically performed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for connecting clad steel having a clad layer made of a corrosion-resistant metal on the surface of a metal base material.

[0002]

2. Description of the Related Art Conventionally, clad steel used for a reactor pressure vessel or a closed vessel for spent nuclear fuel is made of a material such as stainless steel, inconel, nickel, titanium or the like on the surface of a base material made of carbon steel, low alloy steel, or the like. The cladding layers made of corrosion-resistant metal are superimposed and joined by hot rolling, overlay welding, etc., and the base metal exhibits the mechanical strength required for the structure and covers its surface. By protecting the base material with the clad layer, excellent corrosion resistance is exhibited.

[0003] The clad steel having such characteristics is not limited to the above-mentioned onshore structure, but also has recently attracted particular attention as an offshore structure, such as a megafloat (large offshore floating structure) and an offshore oil field base. It has been studied to apply it as a basic structure such as.

[0004] An offshore structure such as a megafloat is required to have excellent corrosion resistance particularly against seawater and the like. Therefore, a clad steel applied to such an offshore large structure is particularly required as a clad layer. Titanium clad steel using titanium having excellent corrosion resistance to seawater will be used.

[0005]

When a large-sized structure is formed from such clad steel,
After carrying a plurality of clad steels (units) that have been integrally molded in a predetermined size and shape in advance to the site or an assembly plant,
Here, it is common to connect sequentially by butt welding or the like, but as described above, since the clad steel is composed of two layers of the base material and the clad layer, the clad steel is compared with a single layer. Connection work is not easy.

That is, in order to butt-weld the clad steels, as shown in FIG. 6A, the clad layer 3 at the butt end of each of the clad steels 1 and 1 is removed by machining or the like to form a base on the surface. After the base material 2 is exposed, the base materials 2 and 2 are butted against each other and the butted ends are welded as shown in FIG.
The fitting plate 4 is fitted between the clad layers 3 and 3 so as to cover the (welded portion), and then a wider sealing plate is overlaid on the fitting plate 4 as shown in FIG.
The clad steels 1 and 1 must be connected to each other by fillet welding both sides to the clad layers 3 and 3 respectively.

[0007] In fillet welding, since the adjustment of the angle of the welding torch is complicated, many of them have to rely on manual work by skilled welders.

Accordingly, such connection (butt welding) between the clad steels 1 and 1 requires a large amount of labor, time and material as compared with a single-layer clad steel, and an automatic welding machine. There is a drawback that remote operation by such as is difficult.

Therefore, as shown in FIG. 6 (2), both sides of the fitting plate 4 are welded directly to the cladding layers 3 and 3 without using the sealing plate 5 in a state where the fitting plate 4 is fitted. However, since the base material 2 and the cladding layer 3 are different metals that are hardly compatible with each other as described above, when the portions are welded, the corrosion-resistant metal melts into the base material 2 side. , A brittle metal layer is formed, and there is a possibility that cracks may be generated from the metal layer as a starting point. In particular, in the case of the titanium clad steel as described above, such a problem occurs more remarkably because the familiarity between titanium and the base material 2 (carbon steel) is poor.

Therefore, the present invention has been devised in order to effectively solve such a problem, and an object of the present invention is to efficiently and economically connect clad steels which require a great deal of labor and cost. The present invention provides a novel method of connecting clad steel that can be performed.

[0011]

According to the present invention, a clad layer of clad steel to be butt-welded with each other is formed over a certain width from the butt end thereof. After removing the base materials by butt welding, the base materials near the ends of the respective cladding layers are scraped to form voids, and then a fitting plate is fitted between the cladding layers, and the butt ends of the fitting plates The parts are butt-welded to the end sides of the cladding layer, respectively.

By shaving the base material near the end of the cladding layer to form a gap in this manner, the butting portion between the cladding layer and the fitting plate can be butt-welded without contacting the base material. Part of the metal does not melt into the base material side, and a brittle metal layer is no longer formed in the vicinity, so that cracks and cracks can be reliably prevented from occurring. In addition, since the seal plate on the fitting plate is not required as in the conventional case, the labor and cost for preparing the seal plate can be reduced, and the fillet welding is not required.
Welding work is also easier.

Further, according to the present invention, more remarkable effects can be obtained when a titanium clad steel comprising a base material of carbon steel and a clad layer of titanium is used.

Further, if a laser welding method is used as a butt welding method between the cladding layer and the fitting plate, welding can be easily performed without applying a special seal or the like, and the penetration depth and the like can be controlled. Since it can be easily performed, a better and more efficient welding operation can be performed.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, a preferred embodiment of the present invention will be described with reference to the accompanying drawings.

FIG. 1 is a partially enlarged sectional view showing the vicinity of a connection (weld) between titanium clad steels 1 and 1 obtained by the method of the present invention. The materials 3, 3 are titanium cladding layers joined on the base materials 2, 2, and 4 is a titanium fitting plate fitted between the cladding layers 3, 3 and butt-welded. .

As a method for connecting the titanium clad steels 1 and 1 having such a structure, first, a part of the clad layers 3 and 3 is removed from the butt end thereof over a predetermined width as in the conventional case. Then, the base materials 2 and 2 are butt-welded to each other, and then, as shown in FIG. 2, the surface of the welded portion is flattened by machining so as to have the same height as the boundary between the base material 2 and the clad layer 3. At the same time, the base material near the ends of the clad layers 3 and 3 is scraped off along the length direction to form smooth R-shaped gaps 6 and 6, respectively. The ends are the base material 2,
It will be in a state of floating from 2. Next, as shown in the figure, the clad layer 3 is covered so as to cover the welded portion on the base material 2 side.
After a cladding layer 4 having a thickness substantially equal to that of the cladding layer 3 is fitted between the cladding layers 3 so that the cladding layers 3 and 3 are flush with each other, the cladding layer 3 and the cladding layers 3 and 3 are connected to each other. Butt ends are butt-welded to each other.

Here, the fitting plate 4 and the cladding layers 3, 3
Butt welding is performed by applying high heat such as arc, laser, gas combustion flame, etc. along the butt line,
And the titanium constituting the cladding layers 3 and 3 are forcibly melted and fused to each other. However, as described above, the gaps 6 and 6 are formed in the downward direction of the fused portion. The metal (titanium) melted during the welding is used as the base material 2
It does not mix with the metal (carbon steel) on the side. As a result, a good underflow can be ensured at the butted portion of the fitting plate 4 and the cladding layers 3 and 3, and a brittle metal layer which causes cracks and cracks is not generated in the vicinity thereof. Since the influence of heat on the base material 2 can be reduced, very high-quality welding can be performed.

Further, in the method of the present invention, since the conventional sealing plate 5 is not required, the labor and cost for preparing the sealing plate 5 can be all reduced, and the welding work can be reduced. Is more simplified and the economy is improved. In particular, when expensive titanium is used for the cladding layer 3 as in the present embodiment, the sealing plate 5 is also made of titanium, so that the cost reduction effect is particularly remarkable. In addition, since the welding method is not the fillet welding as in the related art, complicated adjustment of the angle of the welding torch and the like become unnecessary, and the welding operation is facilitated.

The method of butt welding the fitting plate 4 and the cladding layers 3 and 3 is not particularly limited, but when titanium is used as the material, an inert gas arc which is most suitable for welding titanium is used. Welding, laser beam welding, electron beam welding, etc. will be used. Above all, according to laser beam welding, a gas seal such as inert gas arc welding or a vacuum state such as an electron beam is unnecessary, and the clad layer 3 is generally a thin plate having a thickness of 2 to 3 mm. This is the most suitable welding method in the case of titanium clad steel because a large output laser is not required and the penetration depth and the like can be easily controlled. In addition, since automatic welding can be easily performed by remote control using this laser beam welding, excellent workability can be exhibited when welding large offshore structures such as the aforementioned mega-floats. Thus, it is possible to significantly shorten the construction period and reduce the cost.

Further, in the present embodiment, an example of titanium clad steel has been described. However, even in the case of clad steel made of other corrosion resistant metal such as stainless steel or nickel, the same operation and effect can be obtained. Of course.

Next, FIG. 3 to FIG. 5 show an embodiment of the present invention, and the same operation and effect as in the above embodiment can be exhibited by such an embodiment.

That is, first, in the embodiment shown in FIG. 3, one of the gaps 6 formed on the base material 2 is cut off so as to continue to the other gap 6 as it is, and the depth of the gap 6 is made up. The projection 4a is formed at the lower center of the fitting plate 4 as described above. In the present embodiment, the size of the gap 6 can be made larger than that in the above-described embodiment while maintaining the flush state with the cladding layers 3 and 3 fitting plate 4. The dissolution of the corrosive metal constituting the third material 3 and the base material 2 and the thermal effect can be further reduced, and the working of the void 6 itself can be easily performed.

FIG. 4 shows the fitting plate 4 and the cladding layers 3,
Notch 4 on the lower surface side of the butted end with 3
b, 4b are formed, and the size of the gap 6 can be made large similarly to the above, so that the penetration of the corrosive metal constituting the cladding layer 3 and the like and the base material 2 and the influence of heat are reduced. In addition to being able to further reduce, it is also possible to easily perform the work of processing the gap 6 itself. Moreover,
In the present embodiment, the butted width (thickness) between the fitting plate 4 and the clad layers 3 is reduced, so that the amount of heat required for welding and the welding time can be further reduced.

Further, FIG. 5 is located in the middle between the embodiment shown in FIG. 1 and the embodiment shown in FIG. 3, and this embodiment does not reach the embodiment shown in FIG. However, similarly, since the size of the gap 6 can be made large, the penetration into the base material 2 and the thermal effect can be further reduced, and the working of the gap 6 itself can be easily performed.

[0026]

In summary, according to the present invention, a gap is previously formed in the butt welding portion between the fitting plate and the cladding layer so that the two are butt-welded. High-quality welding can be easily performed without melting. In addition, since the sealing plate provided on the fitting plate is not required, the material cost can be reduced, and the welding time can be shortened by simplifying the welding operation. As a result, it is possible to exhibit excellent effects such as a more efficient and economical connection operation between clad steels conventionally requiring a great deal of labor and labor.

[Brief description of the drawings]

FIG. 1 is a partially enlarged cross-sectional view showing one embodiment of a clad steel connection obtained by a method of the present invention.

FIG. 2 is an explanatory diagram showing one embodiment of the method of the present invention.

FIG. 3 is an explanatory view showing another embodiment of the method of the present invention.

FIG. 4 is an explanatory view showing another embodiment of the method of the present invention.

FIG. 5 is an explanatory view showing another embodiment of the method of the present invention.

FIG. 6 is a process chart showing an example of a conventional clad connection method.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Clad steel 2 Base material 3 Cladding layer 4 Fitting plate 5 Seal plate 6 Void

Claims (3)

[Claims] 1. A cladding layer of clad steel to be butt-welded is removed from a butt end thereof over a predetermined width, and the base materials are butt-welded to each other. The material is scraped off to form a void, and then a fitting plate is fitted between the clad layers, and then the butt ends of the fitting plate are butt-welded to the end sides of the cladding layer, respectively. How to connect clad steel. 2. The method for connecting clad steel according to claim 1, wherein the clad steel is a titanium clad steel comprising a base material of carbon steel and a clad layer of titanium. 3. The method for connecting clad steel according to claim 1, wherein the butt welding of the clad layer and the fitting plate is performed by a laser welding method.