JP2512652B2 - Offshore structure with excellent corrosion resistance - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a marine structure having excellent corrosion resistance, and particularly to a marine structure having a stanchion with few exposed end faces of the titanium clad steel when the titanium clad steel is coated and joined to a seawater splash zone. It is about things.

[0002]

2. Description of the Related Art Generally, a prismatic structure of a marine structure is a prismatic structure or a steel pipe, and its surface 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 or titanium alloy having high corrosion resistance as described in Japanese Utility Model Laid-Open No. 62-44948.

Conventionally, the winding or mounting of the titanium or titanium alloy plate on the pedestal has been carried out by welding and fixing the ends of the titanium or titanium alloy plate. However, welding of titanium and steel is not possible. It is difficult, and so various 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 filled in the recess or backed. It is proposed to insert gold and separately weld the titanium and steel backside.

[0004]

In the above-mentioned conventional joining of titanium clad steel plates, there is a void in the joining end face, and if this is used in an offshore structure, especially in a splash zone, seawater will penetrate through the void and weld. There arises a problem of corroding the welded portion of carbon steel, especially the welded portion. 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 the entire structure as well as the corrosion resistance of the titanium clad steel plate by reducing the exposed joint end surface portion in consideration of the arrangement so as to arrange and join and sealing the void formed in this end surface. .

[0005]

The present invention has the following structures in order to achieve the above object. That is, in a marine 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 top and bottom titanium clad steel plates are longitudinally aligned. Are placed so that they are horizontal, and when joining the base metals of adjacent titanium clad steel plates, the missing part of the titanium mating material formed at the joining part is matched with the titanium patch of the same kind as the mating material. Bonding is performed as if it is bridged between materials, and the voids formed on the exposed exposed end surfaces of the uppermost and lowermost layers are hermetically covered with a weld metal formed by plasma welding of an Ag-Cu-based metal. It is an excellent offshore structure.

In plasma welding, it is desirable to use an inert gas such as Ar or He as a shield gas and He gas as a center gas, but Ar gas may be used if necessary. Usually, H ₂ gas is used as the center gas, but when H ₂ gas is used, a brittle hydrogen compound is formed as a compound of Ti, so it is not preferable to mix H ₂ therein.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail below based on the embodiments shown in the drawings. FIG. 1 shows an embodiment in which the present invention is used in a pedestal of a marine structure.
A rectangular flat titanium clad steel plate 2 in which a joining material made of pure titanium and a base material made of carbon steel or alloy steel are joined to a so-called splash zone in the vicinity of ΔTP + 3 m to −2 m from the sea surface of ΔTP The corrosion-resistant coating S is connected and surrounded in the horizontal direction and the horizontal direction. The surface of the corrosion-resistant coating S is coated with pure titanium.
As shown in FIG. 3, the welded joint W is exposed on the upper and lower end surfaces and is washed with seawater or its splash. Since the welded joint W has low seawater corrosion resistance and is easily embrittled by corrosion, it is preferable that the number of end faces be small.

The present invention is a rectangular plane titanium clad steel plate 2
By arranging a and 2c side by side in the length direction and welding adjacent short piece sides to each other, 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.

The titanium clad steel plate 2a in the middle portion of the corrosion-resistant coating S is arranged so that the long sides are vertical in FIG. 1, but the invention is not limited to this, and it is similar to the upper and lower steel plates 2b and 2c. May be set horizontally, and other arrangements may be used.

For joining the titanium clad steel plates 2a and 2b adjacent to each other, as shown in FIG. 2 (enlarged view of portion A in FIG. 1), the end portions of the titanium composite materials 3a and 3b are notched, and the base carbon steel 4a is formed. , 4b are butted and welded (plasma). At this time, the notch of the mating material forms the missing portion 5. As shown in FIG. 3, the missing portion 5 is a caul plate 6 made of a titanium material of the same quality as the titanium mating materials 3a and 3b.
The covering plate 6 is welded to the mating members 3a and 3b by fillet welding 7, respectively. A spacer (not shown) may be inserted in the missing portion 5 to fill it.

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.
Seal welding is performed by plasma welding using a g-Cu based melting material,
The weld metal 9 covers the void 8.

The above-mentioned weld metal is Ag--Cu if it is a material capable of joining dissimilar materials of steel and titanium and has corrosion resistance.
Not limited to the system. In the figure, 10 is a fillet weld between the pillar 1 and the titanium clad steel plate 7.

[0013]

As described above, according to the present invention, the titanium clad steel plates are arranged on the upper and lower end faces so as to reduce the welded joints, and the adjoining titanium clad steel plates are joined by an extremely simple method. Also, the structure is covered with a similar material and fixed to the pedestal, and the structure of the joint end face is closed with a corrosion-resistant metal to block the intrusion of seawater, making it a marine structure with extremely excellent corrosion resistance overall. be able to.

[Brief description of drawings]

FIG. 1 is a perspective view showing an example of the present invention.

FIG. 2 is an enlarged explanatory view of a portion shown in FIG. 1A and is a diagram showing a base material joining state of a titanium clad steel plate.

FIG. 3 is an enlarged explanatory view of a portion shown in FIG. 1A, showing a state in which a backing plate is joined.

FIG. 4 is an enlarged explanatory view of a portion shown in FIG. 1B, showing a state of a joint end surface of a titanium clad steel plate.

FIG. 5 is an enlarged explanatory view of a portion of FIG. 1B, showing a state in which a seal is covered.

[Explanation of symbols]

 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 welded part

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Kazuo Sakai 2-6-3 Otemachi, Chiyoda-ku, Tokyo Inside Nippon Steel Corp. (56) References JP-A-4-182522 (JP, A) Special Features Kaihei 2-52176 (JP, A)

Claims (1)

(57) [Claims] 1. In an offshore structure in which rectangular titanium clad steel plates are continuously joined vertically and horizontally around a structure above and below the water surface to be washed by waves, the top and bottom 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. It is characterized in that the plate is jointly coated as if it is bridged between the laminated materials, and the voids formed on the exposed joint end faces of the uppermost stage and the lowermost stage are hermetically coated with a weld metal formed by plasma welding of an Ag—Cu-based metal. Marine structure with excellent corrosion resistance.