JPS5942130B2 - Installation method for bottom-mounted offshore structures - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for installing a bottom-mounted marine structure, and more particularly, to a method for installing a bottom-mounted marine structure, such as a bottom-mounted plant barge, etc. Relates to methods for installing offshore structures on the seabed.

When a bottom-mounted marine structure such as the one described above is used by being 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 the galvanic anode method, which constructs a battery by directly electrically connecting it to a structure, is widely applied.

Such cathodic protection can also be applied to bottom-mounted offshore structures, but this requires the installation of anti-corrosion anodes on the outside surfaces of the bottom and sides of the structure; If the structure is placed on a foundation on the seabed, the bottom plate of the structure may be damaged by the anti-corrosion anode when it hits the bottom.

This invention has been made in view of the above-mentioned circumstances, and it is possible to protect the structure from corrosion by attaching an anticorrosive anode to the outer surface of the bottom of a bottom-mounted marine structure. An object of the present invention is to provide a method for installing a bottom-mounted marine structure that allows a structure equipped with an anti-corrosion anode to be placed on a foundation on the seabed so that the bottom plate of the structure is not damaged by the anti-corrosion anode. shall be.

The method for installing a bottom-mounted marine structure according to the present invention is, when installing a bottom-mounted marine structure for use by landing on the bottom in shallow waters near the ocean line, a corrosion-preventing anode is attached to the outer surface of the bottom of the structure. , A groove-like recess corresponding to the anti-corrosion anode is provided in advance on the top surface of the foundation installed on the seabed, and the structure is placed on the foundation so that the anti-corrosion anode at the bottom of the structure is located within the groove-like recess. It is something.

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

The drawing shows a bottom-mounted plant barge (bottom-mounted offshore structure) 2 installed on a crushed stone foundation 1 on the seabed, and a plant is provided on the top surface of the barge 2 located above the sea surface.

On the barge 2, a plurality of anti-corrosion anodes 5 and 6 are installed at appropriate intervals in the longitudinal direction of the barge 2, at the center of the width direction of the outer surface of the bottom plate 3 and on the part of the outer surface of the side plate 4 that is submerged in the sea. ing.

These anodes 5 and 6 are made of a metal that has a greater 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 5゜6 may be attached to the barge 2 at any stage before the barge 2 bottoms on the foundation 1.
It can be attached to the barge 2 on the platform during construction.

A groove-shaped recess 1 corresponding to the anticorrosion electrode 5 of the barge bottom plate 3 is formed on the upper surface of the crushed stone foundation 1.

This recess 7 has a cross section of approximately U in the groove provided on the upper surface of the foundation 1.
It is formed by embedding a long and narrow frame 8 in the shape of a letter, and is provided in advance before the barge 2 is placed on the foundation 1.

Although the frame 8 is for preventing the crushed stone from collapsing, it is not necessarily necessary.

In order to install the barge 2 with the anti-corrosion anodes 5 and 6 attached to the outer surface of the bottom plate 3 and the side plate 4 as described above on the crushed stone foundation 1 with the groove-shaped recess 7 provided on the upper surface, the barge 2 is installed as follows. While floating on the sea surface, it will be towed above Foundation 1, and ballast will be poured into it to sink it.

Then, the barge 2 is placed on the foundation 1 so that the anticorrosion anode 5 of the barge bottom plate 3 is located within the groove-like recess 1.

The installation of the barge 2 is now complete, and even after the barge 2 has landed on the bottom, the anti-corrosion anodes 5 on the bottom plate 3 of the barge remain in the groove-shaped recess 1. There is no risk of damage due to pressure.

The anti-corrosion anode 5.6 on the bottom plate 3 and side plate 4 of the barge 2 can be arranged arbitrarily, and the groove-shaped recess 7 on the upper surface of the foundation 1 is located on the bottom plate 3 of the barge 2.
An appropriate film may be used depending on the anticorrosion anode 5.

As described above, according to the method of the present invention, it is possible to protect the structure from corrosion by attaching an anticorrosion anode to the outer surface of the bottom of the bottom-mounted marine structure, and when the structure bottoms on the foundation. Since this anti-corrosion anode is located within the groove-shaped recess provided on the upper surface of the foundation, there is no risk that the bottom plate of the structure will be damaged by the anti-corrosion anode.

[Brief explanation of the drawing]

The drawings show an embodiment of the present invention, and Fig. 1 is a front view showing a bottom-mounted marine structure installed on a crushed stone foundation by the method of the invention, and Fig. 2 is a cross section taken along the line n-■ in the drawing. It is a diagram. 1... Crushed stone foundation, 2... Bottom-mounted plant barge (bottom-mounted marine structure), 5... Anti-corrosion anode, I... groove-like recess.

Claims (1)

[Claims] 1. When installing a bottom-mounted marine structure 2 to be used by landing on the bottom of a shallow sea near the coastline, an anti-corrosion anode 5 is attached to the outer surface of the bottom of the structure 2, and an anti-corrosion anode 5 is attached to the top surface of the foundation 1 installed on the seabed. A groove-shaped recess 7 corresponding to the anode 5 is provided in advance, and the structure 2 is placed on the foundation 1 so that the anti-corrosion anode 5 at the bottom of the structure 2 is located in the groove-shaped recess 7. How to install offshore structures.