JPH0768711B2 - Offshore structure with excellent corrosion resistance - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial field of application) The present invention relates to a marine structure having excellent corrosion resistance, in particular, in the case of coating and joining a titanium clad steel plate to a seawater splash zone, the joining exposed end surface of the titanium clad steel is The present invention relates to an offshore structure having not a few columns.

(Prior Art) The pillars of offshore structures are usually prismatic structures or steel pipes, and the surface of them is subjected to anticorrosion treatment such as painting to prevent seawater corrosion. In the zone, surface corrosion protection alone cannot withstand the long-term seawater splash, and corrosion progresses. Therefore, the splash zone is wound and coated with titanium-clad steel having high corrosion resistance as described in Japanese Utility Model Laid-Open No. 62-44948.

Conventionally, the winding attachment of titanium clad steel plate to the pedestal is
This has been done by welding and fixing the ends of the titanium clad steel plate, but it is difficult to weld titanium and steel, and therefore various kinds of devices have been devised. For example, in Japanese Unexamined Patent Publication No. 2-52176, when butt-welding a titanium clad steel plate, a recess is formed on the steel side at the boundary between titanium and carbon steel, and an inert gas is sealed in the recess or backed. It is proposed to insert gold and separately weld the titanium and steel backside.

(Problems to be Solved by the Invention) In joining the above-mentioned conventional titanium clad steel plates,
There is a void in the joint end face, and if this is used for an offshore structure, especially a splash zone, sea water will invade through the void and cause a problem of corroding the welded portion, especially the welded portion of carbon steel.

The present invention solves the conventional problems in more easily welding and fixing a titanium clad steel plate to a pedestal that supports the marine structure. In order to improve the corrosion resistance of titanium clad steel plate as well as the corrosion resistance of the entire structure by reducing the exposed joint end surface part in consideration of the layout so as to arrange and bond and sealing the void formed in this end surface. And

(Means for Solving the Problems) The present invention has the following structures in order to achieve the above object. That is, (1) In the offshore structure where rectangular titanium clad steel plates are continuously joined vertically and horizontally around the structure above and below the water surface to be washed by waves, the top and bottom titanium When the clad steel plates are arranged and joined so that the longitudinal direction is horizontal, and when the base metals of the adjacent titanium clad steel plates are joined together, the missing part of the titanium laminated material formed in the joint is the same as the laminated material. An ocean with excellent corrosion resistance, characterized in that a titanium cover plate is jointly coated as if it bridges between the laminated materials, and the voids formed on the exposed exposed end faces of the uppermost and lowermost stages are hermetically sealed with a weld metal. It is a structure, and (2) the weld metal that hermetically covers the voids formed on the exposed joint end surface is a Ag-Cu-based metal TIG-welded, which has excellent corrosion resistance as described in the preceding paragraph. It is a structure. The base of the Ag—Cu based weld metal may be coated with a Co weld metal.

(Operation / Example) The present invention will be described in detail below.

FIG. 1 shows an embodiment in which the present invention is used for a pedestal of an offshore structure. As shown in the figure, the sea surface ΔTP of the pedestal 1 is shown.
A rectangular flat titanium clad steel plate 2 in which a mating material made of pure titanium and a base material made of carbon steel or alloy steel are joined to a so-called splash zone near the range of ΔTP +3 m to −2 m is vertically and horizontally connected. The surrounding corrosion-resistant coating S is installed. The surface of this anticorrosion coating S is coated with pure titanium, but as shown in FIG. 4, the welded joint W is exposed at the upper and lower end surfaces and is washed with seawater or its splash. The welded joint W has low marine corrosion resistance and is easily embrittled due to corrosion.

The present invention is configured such that rectangular planar titanium clad steel plates 2a and 2c are arranged side by side in the lengthwise direction and adjacent short piece sides are welded and joined together so that the welded portions exposed on the long side are reduced. With this structure, the brittle portions can be reduced as much as possible, and the corrosion resistance of the structure is improved.

Titanium clad steel plate 2a in the middle part of the corrosion resistant coating S
In FIG. 1, the long sides are arranged vertically, but the present invention is not limited to this and may be set horizontally like the upper and lower steel plates 2b and 2c. It may be.

The adjoining titanium clad steel plates 2a, 2b are joined together as shown in FIG. 2 (enlarged view of part A in FIG. 1).
The end of b is notched, and the base carbon steels 4a and 4b are butted and welded (TIG). At this time, the notch part of the mating material is the missing part 5
To form. As shown in FIG. 3, this missing portion 5 is a pad plate 6 made of the same titanium material as the titanium composite materials 3a and 3b.
Thus, the covering plate 6 is covered across the joining materials 3a and 3b, and the pad plate 6 is welded to the joining materials 3a and 3b by fillet welding 7. The missing part 5
A spacer (not shown) may be inserted to fill this.

FIG. 4 is an enlarged plan view of the exposed end surface of the welded portion in FIG. 1B, in which a void 8 is formed because it is difficult to weld titanium and steel. Since seawater penetrates through the exposed voids 8 to corrode the base metal welded portion, in the present invention, as shown in FIG. 5, TIG seal welding is performed using an Ag-Cu based welding material, and the weld metal 9 With void 8
To cover. During this seal welding, Co, Fe-
It is preferable to deposit a Co-based metal on the base material and then perform the Ag-based seal welding on the base metal. This makes it possible to prevent Fe, C, etc. from being mixed into the Ag-based molten metal from the base material and prevent embrittlement. The weld metal is not limited to the Ag-Cu system as long as it is a material capable of joining dissimilar materials of steel and titanium and having corrosion resistance. In the figure, 10 is a fillet weld between the pedestal 1 and the titanium clad steel plate 7.

(Effects of the Invention) As described above, the present invention arranges titanium clad steel plates on the upper and lower end surfaces so that the welded joints are reduced, and further, the adjacent titanium clad steel plates are joined by an extremely simple method,
It has a structure in which it is fixed to the pedestal by covering the surface with titanium composite material and similar material, and the structure of the joint end face is closed with a corrosion-resistant metal to block the intrusion of seawater, so the overall corrosion resistance is extremely excellent. It can be an offshore structure.

[Brief description of drawings]

FIG. 1 is a perspective view showing an example of the present invention, FIGS. 2 and 3 are enlarged explanatory views of part A in FIG. 1, and FIG. 2 is a base metal joining state of titanium clad steel plates, FIG. Shows a state in which the contact plates are joined, and FIGS. 4 and 5 are enlarged explanatory views of the part B in FIG. 1, FIG. 4 is a state of the joining end face of the titanium clad steel plate, and FIG. 5 is a seal coating. Shows the state. 1: Pillar, 2: Titanium clad steel plate 3: Titanium laminated plate, 4: Base metal 5: Missing part, 6: Laminated material 7: Fillet weld, 8: Void 9: Weld metal, 10: Fillet weld

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Seiichi Soeda 2-3-6 Otemachi, Chiyoda-ku, Tokyo Within Nippon Steel Corporation (72) Inventor Kazuo Sakai 2-6, Otemachi, Chiyoda-ku, Tokyo No. 3 within Nippon Steel Corporation

Claims (2)

[Claims] 1. In an offshore structure in which rectangular titanium clad steel plates are continuously joined vertically and horizontally around the structure above and below the water surface to be washed by waves, the uppermost and lowermost titanium clad steel plates are installed. Are arranged so that the longitudinal direction is horizontal and joined, and when joining base metals of adjacent titanium clad steel plates, the missing portion of the titanium joining material formed in the joining portion is replaced by a titanium pad of the same kind as the joining material. A marine structure with excellent corrosion resistance, characterized in that a plate is jointly coated as if it bridges between the laminated materials, and the voids formed at the uppermost and lowermost exposed joint end faces are hermetically sealed with a weld metal. . 2. A marine structure having excellent corrosion resistance according to claim 1, wherein the weld metal for hermetically covering the void formed on the exposed end face of the joint is TIG welded Ag-Cu based metal. .