JPH11106968A - Electric anticorrosion method by galvanic anode to marine structure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a means capable of cleaning the request for unprecedented long service life without fitting the means from the sea water side in continuing the electric anticorrosion by a galvanic anode at a water-contact part of a marine structure. SOLUTION: In a system where a tip of a galvanic anode 6 refillable according to the consumption is exposed in sea water in a cylindrical body 3 higher than the sea level 5 erected in a through holes of the prescribed number in a bottom of a water-contact part of a marine structure, the highest galvanic anode integrated with a cylinder lid 12 is suspended from an attachable/ detachable suspension piece 15 in a pulling-up and delivering manner, the galvanic anode 6 is refilled while monitoring the degree of consumption of the tip of the galvanic anode 6 from the inside of the marine structure, and the electric protection can be continued without any replacement from the sea water side by controlling the delivery quantity.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cathodic protection method using a galvanic anode material suitable for a water-contacting portion in a marine structure composed of a large floating body that cannot be docked, such as a marine airport.

[0002]

As a method for preventing corrosion of a water-contacting portion of an offshore structure, painting and electrolytic protection are generally used in combination. For example, in the case of a floating structure such as a ship, painting and installation of a galvanic anode are performed at the time of construction, and during periodic docking, the coating is repaired and the galvanic anode material is replaced to maintain corrosion prevention.

On the other hand, in harbor facilities such as piers and quays where docking is not possible, continuation of corrosion protection is mainly carried out using galvanic anodes (underwater painting is difficult). The current-carrying anode material is replaced by the work to maintain the cathodic protection. The installation of the galvanic anode described above is generally carried out by welding or bolting the core of the anode from the outside of the offshore structure, that is, from the water contact side, in order to delay the replacement time as much as possible. In designing the anode, the service life is generally as long as 20 to 30 years, and more recently, a larger one having a service life of 40 to 50 years has been designed.

However, recently, marine structures composed of large floating bodies such as marine airports have been constructed. Since such a facility has a vast area, its water contact area is extremely large as compared with conventional structures. Further, the service life of the structure itself is 100 years or more.

[0005] Such a difference in scale is not merely considered as an increase in the construction area, and there is a limit in applying the above anticorrosion design as it is. In other words, when painting and installing a galvanic anode with the conventional anticorrosion design during construction, it has a vast area, so in order to maintain the painting and galvanic anode, it is necessary to repair the paint on site with underwater work, It is almost impossible to replace and replace the current-carrying anode, as well as on a regular basis like a ship, and even if it is possible to do so, enormous labor and cost are required.

On the other hand, when designing a galvanic anode having a service life of 100 years or more in the same manner as a structure, its weight and shape are significantly larger than those of conventional ones.
As described above, the galvanic anode has the anode core metal attached to the structure by bolting or welding. Therefore, designing and constructing a galvanic anode having a service life of 100 years or more requires a great deal of labor and cost.

Further, even if a galvanic anode having a service life of 100 years or more can be designed and constructed, for example, in the case of using both a galvanic anode and a coating, the design of the galvanic anode depends on the coating damage rate. However, the conventional structure has no service life of more than 100 years, so there is no record of the paint damage rate. For this reason, at the design stage, it is necessary to set the paint damage rate for 100 years, but it is not possible to judge whether this set value is appropriate. Inspection and maintenance are required.

[0008] However, since such surveys and inspections involve underwater work, it is extremely difficult to maintain and manage marine structures having a large water contact area. The present invention was conceived in order to surely solve the problems with the galvanic anode expected in unknown fields where the application of the conventional method cannot guarantee the performance. Provides a novel method of cathodic protection of marine structures using galvanic anode materials for marine structures that can solve the unknown problems, solve the obstacles, is easy to construct and manage, and is much cheaper in terms of cost. It is in.

[0009]

In order to achieve the above-mentioned object, a method of the present invention is to provide a cylinder having a height higher than the sea level set up in a predetermined number of through holes at the bottom of a water-contacting portion of an offshore structure. In the body, the tip of the galvanic anode material, which can be replenished as it is consumed, is exposed in seawater. It was suspended so that it could be extended, and the current-carrying anode was added while monitoring the degree of wear at the tip of the current-carrying anode from inside the structure. By controlling the delivery amount, the cathodic protection was continued without replacement from the seawater side. Things.

[0010]

[Action] If the through-hole is designed to prevent seawater inflow by increasing the pressure inside the installation room, it can be perforated even in an existing offshore structure. Can be implemented. According to the method of the present invention, the exposed current-carrying anode is formed by exposing the current-carrying anode material, in which a plurality of units are combined, from the inside of the through-hole structure provided in the water-contacting portion of the marine structure to the water. Even when the material is depleted, by adding the galvanic anode material unit from inside the sequential structure,
Even for a current-carrying anode material with a service life of 20 to 30 years, it is extremely easy for marine structures requiring a service life of 100 years or more,
Fully applicable.

Further, since the wear state of the galvanic anode can be easily investigated and inspected (pulled up) from inside the structure, an unknown problem can be dealt with. Furthermore, in the corrosion protection method using a galvanic anode, the service life of the anode is usually determined by the magnitude of the corrosion protection current of the anode, and the corrosion protection current is determined by the potential difference between the galvanic anode and the body to be protected.
It is calculated from the water contact resistance between the galvanic anode and the body to be protected.

However, since the potential difference is substantially constant, the anticorrosion current depends on the size of the water contact resistance. The resistance becomes extremely small and is substantially dependent on the galvanic anode contact resistance. Therefore, according to the present invention, the water contact area of the galvanic anode can be arbitrarily changed, which is extremely effective in design.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described with reference to FIGS. In FIG. 1a, a through-hole 2 is provided in a water-contacting bottom plate surface 1 of an offshore structure, and a cylindrical or square tubular steel cylinder 3 is provided in the through-hole 2 so as to stand inside the structure.
Are welded 4.

The cylinder 3 must be higher than the sea level 5. In the cylindrical body 3, a current-flowing anode material 6 that can be replenished in accordance with wear is arranged in such a manner that its tip is exposed to seawater for corrosion protection. That is, as shown in detail in FIG. 2, the unit body 7 of the flowable anode material 6 which can be replenished in the illustrated example has a metal core 8 made of a steel pipe protruding from only one of the anodes to form a male screw 9. The other is formed as a female screw recess 10 into which the male screw 9 is screwed, and the male screw 9 and the female screw recess 1 are formed.
It is added by screwing with 0.

On the lower surface of the cylindrical lid 12 which covers the opening flange 11 of the cylindrical body 3, there is integrally provided a hanger 15 to which the uppermost unit 7 can be detachably attached. The hanging tool 15 is formed by welding a steel pipe 14 having a female screw 13 at the lower end thereof to which the male screw 9 of the uppermost unit body 7 is screw-fitted to the lower surface of the cylinder lid 12 in the same manner as the core metal 8 described above. It is. FIG.
“b” denotes a hanging tool 15 for each mechanism, and the through hole 1 is formed in the cylindrical lid 12.
6, a steel pipe 14 having a threaded shape 17 is inserted into the upper end and is suspended by a nut 18.

Further, in the case of FIG. 1C, the male screw 9 of the uppermost unit body 7 is directly screwed and screwed into the screw hole 19 formed in the cylindrical lid 12, and is hung. The unit body 7 is partially exposed to the atmosphere from the sea level 5. The continuity between the water-contacting bottom plate surface 1 and the anode may be made through the hanging member 15, the tube lid 12, and the steel tube 3, or may be connected through a wire.

The construction procedure of the above anticorrosion structure is shown in FIGS. First, as shown in FIG. 3, the lower end of a steel cylindrical body 3 is attached to a contact bottom plate surface 1 from the inside of a structure by welding 4 at a desired mounting position of a galvanic anode material. next,
As shown in FIG. 4, through holes 2 are provided from the inside of the structure in accordance with the cylindrical body 3. At this time, the pressure inside the structure is increased so that seawater or the like does not flow into the structure from the through hole 2.

Then, as shown in FIG. 5, the galvanic anode material 6 in which the steel pipe 14 is assembled to the uppermost unit body 7 is inserted into the cylinder 3 in advance from the inside of the structure. Finally, as shown in FIG. 6, the upper end of the steel pipe 14 is passed through the through hole 16 of the cylindrical lid 12 which covers the opening flange 11 of the cylindrical body 3 and the nut 18 is fixed to complete the suspension. In the drawing, reference numeral 20 denotes a run-out preventing spacer for stabilizing the current-flow anode material 6 when it is inserted.

As shown in FIG. 7, a groove 21 is formed on the upper part of the unit 7 to stabilize the fixing of the lower unit 7 which must be performed at the time of replenishment of the galvanic anode material 6.
It is preferable that a fall prevention member 22 be inserted into this groove 21 and locked.

[0020]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Another embodiment of the present invention will be described below. As shown in FIG. 8, a current-carrying anode material 6 of a type in which a male screw 9 protrudes from the upper end surface of the uppermost unit body 7 is made of a steel pipe core bar 23 as shown in FIG.
May be made to protrude from both front and rear end surfaces of the anode, and both protruding portions may be provided with threaded shapes 24, 24 so that they can be added via a joint steel pipe 25.

FIGS. 9 and 10 show a current-carrying anode material 6 'having a different core metal.
Is shown. That is, in a normal anode having a welding plate portion 26a attached to the tip of a rod-shaped metal core 26 protruding from both ends from the anode, the plate portion 26a is used, and joint bolt through holes 26b, 26b are drilled there. The stacked plate portions 26a, 26a are
It was decided to add 7 stops.

The hanging member 15 'in the upstream anode material 6'
May be configured in the same manner as the above-described hanging device 15. That is, as shown in FIGS. 11 to 13, the plate metal body 28 for joint, which is connected to the upper plate portion 26 a of the uppermost unit body 7 ′ and the bolt / nut 27, is welded to the lower surface of the cylinder lid 12 (FIG. 11).

Alternatively, the upper part of the sheet metal body 28 may be used as a screw rod part 28a, and the screw rod part 28a may be inserted through the through hole 16 of the cylindrical cover 12 and then suspended with the nut 18 fixed. (FIG. 12). Further, the screw rod portion 28a may be screwed into the screw hole 19 formed in the cylindrical lid 12 and suspended therefrom (FIG. 13).

FIG. 14 shows a galvanic anode material 6 "having a different replenishing mechanism. That is, a steel rod or a steel pipe core 29 at the front and rear ends of the anode is provided with bolt holes at one or more ends protruding beyond the anode diameter. 31 and 31 are welded with steel plate materials 30, 30 for drilling joints.
0 are added to each other by overlapping bolts and nuts 32, 32.

The hanging tool 15 "in the upstream anode material 6" can be formed in the same manner as described above. That is, as shown in FIG.
What is necessary is just to hang the steel plate 30 welded to the lower end of the rod-shaped steel 33 so that the uppermost unit body 7 ″ can be joined to the cylindrical lid 12. Specifically, FIGS.
The bar-shaped steel 33 is welded to the lower surface of the tube lid 12 (FIG. 16).

Alternatively, a threaded type 3
4 is passed through the through hole 16 of the cylindrical lid 12 and then fastened with a nut 18 (FIG. 17). Further, the threaded form 34 may be screwed to the screw 19 of the perforated hole in the cylindrical lid 12 (FIG. 18).

[0027]

Since the present invention is configured as described above, it has the following effects. The water contact area of the galvanic anode material that can be extended from the inside of the structure is
Since it can be changed arbitrarily, it is extremely effective in designing anticorrosion for unknown problems.

Further, the installation of the galvanic anode material to the structure can be easily performed without depending on the seawater side, and a plurality of galvanic anode material units can be added to each other so that simple work can be performed. The current-carrying anode material can be attached from inside the structure, and the unit itself can be used for structures requiring a service life of 100 years or more even with a current-carrying anode material of 20 to 30 years. Become.

Further, construction, maintenance and the like are easy,
An inexpensive galvanic anode material can be supplied in terms of cost.

[Brief description of the drawings]

BRIEF DESCRIPTION OF THE DRAWINGS FIGS. 1a to 1c are diagrams each showing a procedure for attaching a galvanic anode material according to the present invention.

FIG. 2 is an explanatory diagram of a unit body of a galvanic anode material of the present invention.

FIG. 3 is an explanatory diagram of a procedure for attaching a galvanic anode material according to the present invention.

FIG. 4 is an explanatory view of a procedure for attaching a galvanic anode material according to the present invention.

FIG. 5 is an explanatory view of a procedure for attaching a galvanic anode material according to the present invention.

FIG. 6 is an explanatory view of a procedure for attaching a galvanic anode material according to the present invention.

FIG. 7 is an explanatory view of prevention of falling when a current carrying anode material of the present invention is added.

FIG. 8 is an explanatory diagram showing the addition of the unit of the galvanic anode material of the present invention.

FIGS. 9A and 9B are plan and front views of a unit of a galvanic anode material of the present invention.

FIG. 10 is an explanatory diagram showing a replenishment of a unit body of a galvanic anode material of the present invention.

FIG. 11 is an explanatory view of a procedure for attaching a galvanic anode material of the present invention.

FIG. 12 is an explanatory view of a procedure for attaching a galvanic anode material of the present invention.

FIG. 13 is an explanatory view of how to attach the galvanic anode material of the present invention.

FIG. 14 is an explanatory view of a unit body of a galvanic anode material of the present invention.

FIG. 15 is an explanatory view of a hanging tool for a galvanic anode material of the present invention.

FIG. 16 is an explanatory view of a procedure for attaching a galvanic anode material of the present invention.

FIG. 17 is an explanatory view of a procedure for attaching a galvanic anode material of the present invention.

FIG. 18 is an explanatory view of a procedure for attaching a galvanic anode material of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Water contact bottom plate surface 2 Through-hole 3 Steel cylinder 4 Welding 5 Sea level 6 Galvanic anode material 7 Unit 8 Core metal 9 Male screw 10 Female screw recess 11 Opening flange 12 Cylindrical lid 13 Female screw 14 Steel pipe 15 Hanging tool Reference Signs List 16 through hole 17 threaded type 18 nut 19 screw hole 20 spacer 21 groove 22 fall prevention material 23 core bar 24 threaded type 25 steel pipe for joint 26 bar core bar 26a plate portion 26b bolt through hole 27 bolt nut 28 sheet metal body 28a screw Rod part 29 Metal core 30 Steel plate material 31 Bolt hole 32 Bolt / nut 33 Bar-shaped steel 34 Threaded type

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Toshiaki Nagata 1-12-112 Minami Kamata, Ota-ku, Tokyo Inside Japan Corrosion Prevention Industry Co., Ltd. (72) Inventor Sadao Takeda 1-12-112 Minami-Kamata, Ota-ku, Tokyo No. Japan Corrosion Protection Industry Co., Ltd.

Claims (5)

[Claims] 1. A current-carrying anode material, which can be added as needed according to wear, is placed in a cylindrical body, which is higher than the sea level and is provided in a predetermined number of through holes at the bottom of a water-contacting portion of an offshore structure, and the tip of which is made of seawater. In a manner that the top of the current-carrying anode integrated with the cylinder lid is detachably attached to the hanging device, it is lifted up and suspended so that it can be extended. A method of cathodic protection of a marine structure using a galvanic anode material, characterized in that the galvanic anode is added while monitoring the degree of wear and the cathodic protection is continued without replacement from the seawater side by controlling the feeding amount. . 2. A flowable anode unit body which can be replenished is provided with a male screw as a steel tube, a male screw protrusion on one of the front and rear end faces of the anode, and a female screw recess on which the screw protrusion fits. 2. The method according to claim 1, wherein the marine structure is provided with a galvanic anode material. 3. A flowable anode unit body that can be replenished, wherein the core metal is a steel pipe projecting from both front and rear end faces of the anode, the projecting section is formed with a screw, and the projecting section is a threaded joint steel pipe. 2. The method according to claim 1, wherein the corrosion protection is carried out by using a galvanic anode material on the marine structure. 4. A flowable anode unit body which can be added and replenished is provided with a plate portion formed by perforating joint bolt through holes in a welded plate portion attached to tips of rod-shaped metal cores protruding from both front and rear ends of the anode and superimposed. 2. The method according to claim 1, wherein the marine structure is provided with a galvanic anode material. 5. A flowable anode unit body which can be freely added is welded to a steel plate material for a joint which protrudes both ends from a diameter of an anode to a steel rod or a steel pipe core stopped at front and rear end faces of the anode,
2. The electric current generated by a galvanic anode material for an offshore structure according to claim 1, wherein the steel plate material superposed through bolt holes drilled at both ends of the steel plate material is added by bolts and nuts. Anticorrosion law.