JPS5942131B2 - Corrosion prevention method for bottom-mounted marine structures - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for preventing corrosion of bottom-mounted marine structures, and more particularly to a method for preventing corrosion of bottom-mounted marine structures, such as bottom-mounted plant barges, etc., which are used in shallow waters near the coastline. Concerning corrosion protection methods for marine structures.

When using a bottom-mounted marine structure as described above installed on the seabed, it is necessary to prevent corrosion of the structure by seawater.

In the case of floating offshore structures such as ships or floating plant barges, a corrosion-preventing anode (galvanic anode) made of a metal with a greater tendency to ionize than the structure is attached to the outer surface of the structure to be submerged in the sea. , Electrolytic protection (cathodic protection) called galvanic anode method, which connects electrically to structures to form batteries, is widely applied.

This type of cathodic protection can also be applied to bottom-mounted offshore structures, but this requires the installation of anticorrosion anodes on the bottom and side external surfaces of the structure, and such structures are If the structure is placed on a foundation, there is a risk that the bottom plate of the structure will be damaged by the anti-corrosion anode when it lands on the bottom.

This invention was made in view of the above circumstances, and
An object of the present invention is to provide a method for preventing corrosion of a bottom-mounted marine structure by which the structure can be protected from corrosion using a corrosion-preventing anode, and in which the structure is not likely to be damaged by the corrosion-protective anode.

The corrosion prevention method for bottom-mounted marine structures according to the present invention is such that when installing a bottom-mounted marine structure for use in shallow waters near the ocean line, the structure is mounted on a foundation provided on the seabed. Before or after the structure reaches the bottom, a corrosion-protective anode to which one end of the electric wire is connected is installed in the foundation, and the other end of the electric wire is connected to the structure that has bottomed out on the foundation.

The anti-corrosion electrode may be buried within the foundation, or may be provided in a groove-like recess on the top surface of the foundation and installed within this recess.
Furthermore, it may be provided within the foundation by other means.

The present invention will be described below with reference to drawings showing embodiments.

1 and 2 show an embodiment of the present invention, in which a bottom-mounted plant barge (bottom-mounted marine structure) 2 is installed on a crushed stone foundation 1 provided on the seabed, and is located above the sea surface. A plant is installed on the upper surface of the barge 2.

On the barge 2, there is a
A plurality of anticorrosion anodes 4 are attached at appropriate intervals in the longitudinal direction.

These anodes 4 are made of a metal that has a higher ionization tendency than the steel plate constituting the barge 2, such as a zinc alloy or an aluminum alloy, and are directly electrically connected to the barge 2 to form a battery.

These anodes 4 may be attached to the barge 2 at any stage until the barge 2 is bottomed on the foundation 1, but they should be attached to the barge 2 on the platform when the barge 2 is constructed. I can do it.

In the crushed stone foundation 1, a plurality of anticorrosion anodes 5 similar to those described above are buried at appropriate intervals in the longitudinal direction of the foundation 1 at the center in the width direction.

One end of an electric wire 6 is connected to each anode 5 in the foundation 1, and the other end of each electric wire 6 is connected to the barge 2 via terminals provided on the front and rear end surfaces of the combined wire 2.

Thereby, the anode 5 and the barge 2 are directly electrically connected, and a battery is constituted by them.

In order to install the barge 2 with the anti-corrosion anode 4 attached only to the outer surface of the side plate 3 on the crushed stone foundation 1 as described above, first, when installing the foundation 1, the anti-corrosion anode 5 to which one end of the electric wire 6 is connected is buried in the foundation 1, and the other end of each electric wire 6 is exposed outside the foundation 1.

Next, the barge 2 is towed above the foundation 1 while floating on the sea surface, and ballast is poured into the barge 2 to sink it and land on the foundation 1.

Once the barge 2 has landed on the bottom, connect the tips of the electric wires 6 that have been placed outside the foundation 1 to the terminals provided on both the front and rear end surfaces of the barge 20, thereby connecting the anode 5 and the barge 2 with electricity. to form a battery.

The installation of the barge 2 is thus completed, and since the anti-corrosion anode is not attached to the bottom plate 1 of the barge 2, there is no fear that the bottom plate 1 will be compressed and damaged when the barge 20 lands on the bottom.

The arrangement of the anodes 4 and 5 on the barge side plate 3 and within the foundation 1 is arbitrary and can be changed as appropriate.

3 and 4 show other embodiments of the invention.

3 and 4 that are the same as those shown in FIGS. 1 and 2 are designated by the same reference numerals.

A groove-like recess 8 is formed on the upper surface of the crushed stone foundation 1 at the center in the width direction.

This recess 8 is formed in a groove provided on the upper surface of the foundation 1 with a cross section of approximately U.
It is formed by embedding a long and narrow frame 9 in the shape of a letter, and is installed in advance before the barge 2 is placed on the foundation 1.

Although the frame 9 is for preventing the crushed stone from collapsing, it is not necessarily necessary.

Inside the groove-like recess 8, a plurality of anti-corrosion anodes 5 to which the negative ends of the electric wires 6 are connected are installed at appropriate intervals in the longitudinal direction of the recess 8, and the other end of each electric wire 6 is connected to the recess 8. It comes out of the foundation 1 from both ends and is connected to both the front and rear end surfaces of the barge 20 as described above.

In order to install this barge 2 on the crushed stone foundation 1, the groove-shaped recess 8
The anti-corrosion anode 5 is installed at a predetermined position inside the foundation 1, and the tip of each electric wire 6 is placed outside the foundation 1. After the barge 2 is bottomed on the foundation 1 in the same manner as described above, each electric wire is Connect the tips of 6 to both the front and rear end surfaces of the barge 20.

In addition, depending on the case, or after the barge 2 is bottomed on the foundation 1, the anticorrosion anode 5 may be installed in the groove-shaped recess 8 by appropriate means.

When performing cathodic protection as described above, the anticorrosion anodes 4 and 5 gradually dissolve over time.

Corrosion-preventing anode +'4 Generally, it is designed to have a sufficiently long life, but in the case of the embodiments shown in FIGS. It can be replaced with .

To replace the anode 5, remove the electric wire 6 from the barge 2, take out the melted anode 5 from the recess 8, install a new anode 5 in the recess 8, and connect the electric wire 6 to the barge 2. Bye.

At this time, the barge 2 may be floated and the anode 5 may be taken in and taken out from above the recess 8, or the anode 5 may be taken in and taken out from both sides of the recess 8 while the barge 2 is on the bottom. can.

The arrangement of the groove-shaped recess 8 and the anode 5 within the recess 8 is arbitrary and can be changed as appropriate.

As described above, according to the method of the present invention, bottom-mounted marine structures can be protected from corrosion by the anticorrosion anode provided in the foundation, and there is no need to attach the anticorrosion anode to the outer surface of the bottom of the structure. Therefore, there is no risk of damage to the bottom plate of the structure even if the structure is placed on the bottom of the seabed as is.

[Brief explanation of drawings]

FIG. 1 and FIG. 2 show one embodiment of the present invention.
The figure is a front view showing a bottom-mounted marine structure installed on a crushed stone foundation by the method of the present invention, Figure 2 is a sectional view taken along line ■-■ in Figure 1, and Figures 3 and 4 are according to the present invention. FIG. 3 is a front view similar to FIG. 1, and FIG. 4 is a sectional view taken along the line IV--IV in FIG. 3. 1... Crushed stone foundation, 2... Bottom-mounted plant barge (bottom-mounted marine structure), 5... Anti-corrosion anode, 6... Electric wire, 8...Groove-shaped recess.

Claims (1)

[Claims] 1. When installing a bottom-mounted marine structure 2 that is used by landing on the bottom of a shallow sea near the coastline, the structure 2 is placed on the bottom of a foundation 1 provided on the seabed, and the structure 20 Before or after landing on the bottom, a corrosion-protective anode 5 to which one end of an electric wire 6 is connected is installed in the foundation 1, and the other end of the electric wire 6 is connected to a structure 2 that has landed on the foundation 1. How to prevent corrosion of objects. 2. The method for preventing corrosion of a bottom-mounted marine structure according to claim 1, wherein the anti-corrosion electrode 5 is buried in the foundation 1. 3. The method for preventing corrosion of a bottom-mounted marine structure according to claim 1, wherein a groove-like recess 8 is provided on the upper surface of the foundation 1, and a corrosion-preventing anode 5 is installed in the recess 8.