JP2809351B2 - Antifouling and anticorrosion methods for hull skin in contact with seawater - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to an antifouling and anticorrosion method for a hull outer panel in contact with seawater.

[Conventional technology]

As antifouling and anticorrosion means for a hull outer panel that comes in contact with seawater, it is conventionally known to apply an antifouling paint to a water-contacting portion of the hull outer panel and attach a sacrificial anode such as zinc.

However, such means have the following disadvantages.

(1) Since the dissolution rate of the antifouling component of the antifouling paint cannot be adjusted, it is not possible to freely respond to seasons, ocean currents, changes in water quality, and the like.

(2) Since the content of toxic substances in the antifouling paint is limited, repainting work is required about every two years.

(3) A structure that cannot be exposed to the atmosphere due to its structure cannot be repainted.

(4) Since the corrosion prevention effective range of one sacrificial anode is limited, a large number of sacrificial anodes must be provided to protect a large area.

In view of this, the present applicant has proposed a device as shown in FIG. 5, FIG. 6, and FIG. 7 in a partial cross-sectional view using Japanese Patent Application No. 61-248897 "An antifouling device for structures in contact with seawater". .

That is, in FIG. 5, reference numeral 01 denotes a hull outer plate having a steel structure in contact with seawater 02, 03 denotes an insulating layer made of a resin-based reinforced plastic or the like that covers the outer surface of the outer plate 01, and 04 denotes an insulating layer that covers the outer surface. An electrically conductive film made of carbon, magnetite, a noble metal, or the like and an organic binder, which is connected to a (+) pole, which is one terminal of a DC power supply 06, through a conductive piece 011 and a lead wire 05 described later.

Reference numeral 07 denotes a lead wire for connecting the (−) pole, which is the other terminal of the DC power supply 06, to a cathode 08 made of iron or copper, and 09 denotes a conductive film 04.
010 is a direct current flowing between the cathode and the cathode 08, 010 is a bushing welded to the periphery of the inner end of the through hole formed in the outer plate 01, 01
Reference numeral 1 denotes a plug made of niobium, tantalum, titanium, or the like, which is plated with platinum to prevent an increase in contact resistance on the surface in contact with the conductive film 04 so that Faraday melting does not occur due to electric current. An external screw 012 is engraved at the tip of the current-carrying piece.

013 is a plastic washer made of polyethylene, a rubber sheet, a tetrafluoroethylene resin sheet, etc. for insulating and watertight between the outer plate 01 and the conductive piece 011. 014 and 015 are plastic washers for the conductive piece 011 and the outer plate 01 and the bushing 010, respectively. 016 is a rubber bush made of natural rubber, neoprene, butyl rubber, etc. inserted between the conductive piece 011 and the outer plate 01; Is an insulating washer made of polyethylene, a rubber sheet, a polytetrafluoroethylene resin sheet or the like for insulating the conductive piece 011 from the outer plate 01, and 018 is a conductive washer for connecting the conductive piece 011 to the outer plate 01.
A nut to be screwed with the outer screw 012 of the current-carrying piece 011 for fixing to the current-carrying piece 011, a current-carrying end protection cover 019 having an inner screw screwed into the bushing 010 and a lead wire outlet hole 020 drilled in the center, 021 Is the intermediate voltage output point provided in the DC power supply 06, 022
Is a lead wire connecting the DC power supply 06 and the outer plate 01.

In such an apparatus, as shown in FIG. 6, when a direct current 09 is caused to flow in seawater 02 with the conductive film 04 as an anode, the surface of the conductive film 04 is dense due to a reaction of 2Cl ⁻ + 2e → 2Cl _2. It is covered with a film of chlorine and prevents marine life from attaching to its surface.

Further, as shown in FIG. 7, the conductive film 04 is used as an anode,
Since the voltage is applied so that the outer plate 01 is used as a cathode, if the position of the intermediate voltage extraction point 021 of the DC power supply 06 is appropriate,
A part of the DC current 09 flowing out of the conductive film 04 is exposed on the outer plate.
023, which is cathodic protected.

If the position of the intermediate voltage output point 021 is shifted to the (-) side, the additional voltage between the conductive film 04 and the outer plate exposed portion 023 increases, so that the anticorrosion strength can be increased.

According to such a device, it is possible to perform antifouling and anticorrosion of the outer plate, but there are the following disadvantages.

(1) In a ship, a cathode is provided outside the outer plate 01 via a support structure.
The projecting 08 increases the hull resistance and increases installation costs.

(2) Since the intermediate voltage output point 021 of the DC power supply 06 is required, the power supply device becomes complicated and its manufacturing cost increases.

[Problems to be solved by the invention]

The present invention has been proposed in view of such circumstances, and it is possible to adjust the elution rate of antifouling components, does not require repainting work, and furthermore, can eliminate a sacrificial anode, and is a hull outer plate in contact with seawater. It is intended to provide an antifouling and anticorrosion method.

Another object of the present invention is to provide an antifouling and anticorrosion method for a hull outer panel that comes in contact with seawater, which causes little increase in hull resistance and equipment cost.

[Means for solving the problem]

For this purpose, the present invention relates to a conductive film (04) laid on a seawater contact surface of a hull outer plate (01) via an insulating film (03) and an electrode (1) installed in seawater to face the conductive film (04 ). And a DC power source (3) connected between the conductive film (04) and the electrode
(1) A method of protecting a seawater contact surface of the hull outer plate by flowing a direct current to the hull outer plate, wherein the conductive film (04) is formed of a lower conductive material having a relatively low resistance. An upper conductive film (9) having a relatively large resistance formed on the film (8) is used as an anode, and the hull outer plate (01) is used as an anode.
The bilge keel 1 itself projecting from the cathode (1)
It is characterized by flowing underwater current.

Further, the present invention is characterized in that the conductive film comprises a lower conductive film having a relatively low resistance and an upper conductive film having a relatively high resistance.

[Action]

According to the above configuration, (1) a DC current flows from the anode of the conductive film attached to the outer plate to the cathode of the bilge keel into the sea, so that the surface of the conductive film is covered with the film of the marine organism adhesion preventing active ingredient. An antifouling action is performed.

(2) When an underwater current flows with the conductive film as the anode and the outer plate as the cathode, a current flows through the outer plate exposed portion due to local damage of the insulating layer, thereby performing cathodic protection of the outer plate exposed portion.

(3) Since the bilge keel, which is a part of the hull structure, is used as it is as the cathode, there is no need to project the cathode on the outer plate via the support structure.

(4) Since the bilge keel of the cathode is at the same potential as the outer plate, an intermediate voltage extraction point of the DC power supply is unnecessary.

〔Example〕

One embodiment of the present invention will be described with reference to the drawings.
7 denote the same members as those in FIG.
First, in FIG. 1 front view and FIG. 2 partial cross-sectional view,
1) a bilge keel protruding from the outer plate 01 of the hull bending portion; 011 is connected via a lead wire 05, the (−) pole is connected to the outer plate 01 via a lead wire 4,
Reference numeral 5 denotes a DC current flowing between the conductive film 04 and the bilge keel 1 serving as a cathode.

Subsequently, in the partial cross-sectional view of FIG. 3, reference numeral 6 denotes an exposed portion of the outer plate formed by locally peeling off the insulating layer 03 and the conductive film 04 on the outer plate 01, and 7 denotes a conductive film 04 and the exposed portion of the outer plate. The direct current flows between the unit 6.

In such an apparatus, as shown in FIG. 2, when a direct current 5 is passed through seawater 02 using the conductive film 04 as an anode, the conductive film 04 is reacted by Cl ⁻ + 2OH ⁻ → ClO ⁻ + H ₂ O + e. Is coated with a film of an anti-marine organism adhesion component, preventing marine organisms from adhering to the surface.

Here, the conductive piece 011 (see FIG. 2) is a conductive film 04
Are provided at appropriate intervals depending on the thickness and area of the bilge keel 1 so that the direct current 5 flows uniformly from the conductive film 04 to the bilge keel 1.

At this time, the current density of the direct current 5 flowing out of the conductive film 04 is closely related to the chlorine concentration generated at the interface of the conductive film 04, and the magnitude thereof is determined by the temperature of the sea area, the flow state, the degree of seawater pollution, and the like. In general, it is economical to set the conductive film 04 to 1.0 A / m ² or less when the conductive film 04 is made of a carbon material and 0.1 A / m ² or less when made of a platinum material, although it depends on the type of the electrically conductive film 04. .

Further, as shown in FIG. 3, when the conductive film 04 is set to the (+) potential and the outer plate 01 is set to the (-) potential between the outer plate 01 and the conductive film 04, the outer plate exposed portion 6 is formed. Even if it occurs, the direct current 7 flowing out of the conductive film 04 flows into the outer plate exposed portion 6, where it is subjected to cathodic protection.

Next, a partial cross-sectional view of FIG. 4 shows a modification of FIG.
Reference numeral 8 denotes a lower conductive film formed of a thin metal plate or a metal spray film and provided on the surface of the insulating layer 03 and has relatively low resistance. Reference numeral 9 denotes a lower conductive film formed of the same material as the conductive film 04 and provided on the surface of the lower conductive film 8. The lower conductive film 8 and the upper conductive film having a relatively high resistance formed together form the conductive film 10.

Even in such a structure, substantially the same operation and effect as those of the present embodiment can be obtained, and the electric resistance can be reduced, so that a wide range of current can be supplied.

According to the method of the embodiment and the modified examples, the following operations and effects can be obtained.

(1) By operating the DC power supply, seasons, ocean currents,
Since the antifouling component elution rate can be adjusted according to the water quality, antifouling performance and economic efficiency are improved.

(2) If an electric current is supplied, the life of the antifouling component becomes permanent, so that it is not necessary to replace the antifouling paint, thereby improving the economy.

(3) Even if the conductive film and the insulating layer are locally damaged and an exposed portion of the outer plate occurs, a part of the DC current flowing out of the conductive film flows into the exposed portion of the outer plate and performs cathodic protection. The need for a sacrificial anode such as zinc is eliminated, thus improving the economic efficiency.

(4) Since the bilge keel, which is a part of the hull structure, is used as it is as the cathode, it is not necessary to protrude the cathode through the support structure on the outer plate, so that the hull resistance and the mounting cost are reduced.

(5) Since the bilge keel of the cathode is at the same potential as the outer plate, an intermediate voltage extraction point is not required in the DC power supply device, and thus the cost of the device is reduced.

〔The invention's effect〕

According to the method of the present invention, the following effects can be obtained, which is extremely useful industrially.

By operating the DC power source, the antifouling component elution rate can be adjusted according to the season, ocean current, and water quality, thereby improving antifouling performance and economic efficiency.

If an electric current is supplied, the life of the antifouling component becomes permanent, so that the trouble of repainting the antifouling paint is not required, and thus the economic efficiency is improved.

Even if the conductive film and the insulating device are locally damaged and the exposed portion of the outer plate occurs, a part of the DC current flowing out of the conductive film flows into the exposed portion of the outer plate and performs cathodic protection. The need for a sacrificial anode is eliminated, thus improving economics.

Since the bilge keel, which is a part of the hull structure, is used as the cathode, it is not necessary to protrude the cathode on the outer plate via the support structure, so that the hull resistance and the mounting cost are reduced.

Since the bilge keel of the cathode can be set to the same potential as the outer plate, the DC power supply does not need an intermediate voltage extraction point, and thus the cost of the apparatus is reduced.

As a result of the above, increases in hull resistance and equipment costs can be reduced.

[Brief description of the drawings]

FIG. 1 is a front view showing an embodiment of the present invention, and FIG.
FIG. 3 is a partial cross-sectional view showing the operation of the apparatus shown in FIG. 2, and FIG. 4 is a partial cross-sectional view showing a modification of FIG. FIG. 5 is a partial cross-sectional view showing an antifouling device for a structure that comes into contact with seawater proposed earlier by the present applicant, and FIGS. 6 and 7 show the antifouling and anticorrosion actions of the device of FIG. 5, respectively. It is a partial cross-sectional view. 1 ... bilge keel 2 ... insulating material 3 ... DC power supply
4 ... lead wire, 5 ... DC power supply, 6 ... exposed part of outer plate,
7: DC current, 8: Lower conductive film, 9: Upper conductive film, 10: Conductive film, 01: Outer plate, 02: Seawater, 03: Insulating layer, 04: Conductive film, 05 ... lead wire, 010 ... bushing, 011 ... energizing piece, 012 ... external thread, 013 ... plastic washer, 014,015 ... insulating filler, 016 ... rubber bush,
017 …… Insulated washer, 018 …… Nut, 019 …… Current-end protection cover, 020 …… Lead wire outlet hole,

──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Kiyomi Tomoshige 1-1, Akunouracho, Nagasaki City, Nagasaki Prefecture Mitsubishi Heavy Industries, Ltd. Nagasaki Research Laboratory (72) Inventor Kenji Ueda 5-7, Akunouracho, Nagasaki City, Nagasaki Prefecture Ryoko Building Annex, 5th floor, Nagaishi Engineering Co., Ltd. (56) References JP-A-63-103789 (JP, A) JP-B-47-10668 (JP, B1) (58) Fields investigated (Int. . ^6, DB name) B63B 59/04

Claims (2)

(57) [Claims] An insulating film (0) is provided on the surface of the hull shell (01) in contact with seawater.
A DC power supply (3) is connected between the conductive film (04) laid through 3) and the electrode (1) placed in seawater to face the conductive film (04), and the conductive film (04) is The above electrode (1)
In the method for preventing soiling and corrosion of a hull skin in contact with seawater, which protects the seawater contact surface of the hull skin by flowing a direct current to the hull skin, the conductive film (04) is provided with a lower conductive film (8) having a relatively small resistance. )), The upper conductive film (9) having a relatively high resistance is used as an anode, and the bilge keel 1 itself protruding from the hull outer plate (01) is used as a cathode (1) as a whole to serve as an underwater current. A method for antifouling and anticorrosion of a hull skin in contact with seawater, characterized by flowing water. 2. The hull outer panel according to claim 1, wherein the conductive film is composed of a lower conductive film having a relatively low resistance and an upper conductive film having a relatively high resistance. Soil and anticorrosion method.