JP7066465B2 - Method for forming anticorrosion electrodeposition coating on underwater metal structures - Google Patents

Description

The present disclosure relates to a method for forming an anticorrosion electrodeposition film on an underwater metal structure.

Generally, as an underwater metal structure, a steel sheet pile provided for berthing on a quay or the like, a steel pipe pile provided on a bridge or a pier, or a marine steel structure such as a steel caisson in which the surface of a concrete structure is covered with a steel member. Things are included. The underwater metal structure is seawater or brackish water (a liquid in which freshwater and seawater are mixed) in the so-called ebb and flow zone where submersion in the sea and exposure to the atmosphere are repeated, and in the underwater part which is constantly submerged regardless of the ebb and flow. It is provided in contact with the water, and is exposed to an environment where rust is very likely to occur.

Therefore, in such an underwater metal structure, rust is generated by long-term use, the wall thickness is reduced, and the strength is lowered. Therefore, it is necessary to perform reinforcement work or replacement work. However, since the reinforcement work or the replacement work requires a large amount of cost, the life of the underwater metal structure can be reduced by electrodeposition corrosion protection, electrocorrosion protection, or a combination thereof in the tidal zone and the underwater part of the underwater metal structure. Extensions are being made.

Conventionally, for example, an anode may be provided at a required interval between the ebb and flow zone and the underwater portion of the underwater metal structure, and a direct current power source may be provided between the anode and the underwater metal structure to energize a direct current. It is done. As a result, cations such as calcium ions (Ca ²⁺ ) and magnesium ions (Mg ²⁺ ) dissolved in seawater migrate in the seawater toward the underwater metal structure as a cathode, and electrons are obtained in the underwater metal structure. .. An anticorrosion electrodeposition coating (electrocoating layer) containing CaCO ₃ and Mg (OH) ₂ as main components is formed on the surface of the ebb and flow zone and the underwater portion of the underwater metal structure, and the anticorrosion electrodeposition coating is used to form the anticorrosion electrodeposition coating. The tidal zone and the underwater part of the underwater metal structure are protected against corrosion.

Further, as described above, after the anticorrosion electrodeposition coating is formed on the ebb and flow zone of the underwater metal structure and the surface of the underwater part, the anticorrosion current is allowed to flow between the electrolytic anticorrosion anode and the underwater metal structure. It has also been proposed to carry out electrocorrosion protection of underwater metal structures (for example, there is electrocorrosion protection of a current current anode method or electric corrosion protection of an external power source method).

As a general technical level related to electrocorrosion protection of underwater metal structures, for example, Patent Document 1 is available.

Japanese Unexamined Patent Publication No. 62-196384

However, in the conventional case, a DC power supply and a generator for the DC power supply are arranged in the vicinity of the underwater metal structure, wiring is laid between the DC power supply and the anode, and then the shape of the underwater metal structure is formed. It was necessary to install the combined electrodes at an appropriate distance from the underwater metal structure and energize them. Further, not only the refueling of the generator but also the confirmation and adjustment of the current value and the voltage value of the DC power source must be carried out each time, and it is difficult to lengthen the energization period. In addition, after the construction was completed, it was necessary to remove the anode, members for installing the anode, wiring, DC power supply, and generator. These operations were very laborious and time-consuming, and improvement was desired.

Further, in the conventional case, it may not be possible to precisely install the anodes according to the shape of the underwater metal structure at appropriate intervals, or it may not be possible to properly adjust and manage the DC power supply. This means that an appropriate current density distribution cannot be maintained in the electrodeposition film formation, and when the current is insufficient, the electrodeposition film is not formed. On the contrary, when an excessive current flows, a large amount of hydrogen gas is generated on the surface of the underwater metal structure, and there is also a problem that the electrodeposition coating is peeled off.

The present disclosure has been made in view of the above-mentioned conventional problems, and is an anticorrosion electrodeposition coating of an underwater metal structure capable of stably forming an electrodeposition coating while facilitating construction without the need for a DC power supply or wiring. It is intended to provide a forming method.

In order to achieve the above object, the anticorrosion electrodeposition film forming method of the underwater metal structure of the present disclosure includes a substrate adjusting step of removing deposits on the surface of the underwater metal structure.
A steel core material in which both ends are connected to the surface of the underwater metal structure on the surface of the underwater metal structure from which deposits have been removed in the substrate adjustment step, and a magnesium alloy coated on the core material. Perform the anode mounting process and mount the anode with
The underwater metal structure is a steel sheet pile that is connected and arranged so that a concave portion and a convex portion are formed.
In the anode mounting step, both ends of the core material are attached to the surface of the steel sheet pile so that the magnesium alloy of the anode extends in the water depth direction and is disposed between the convex portions adjacent to each other. ..

In the method for forming an anticorrosion electrodeposition film on an underwater metal structure, the anode mounting step is
The required film thickness setting step for setting the required film thickness t of the electrodeposition film to be formed on the surface of the steel sheet pile, and the required film thickness setting step.
A unit area energization amount calculation step for obtaining an energization amount i per unit area based on the required film thickness t set in the required film thickness setting step, and a unit area energization amount calculation step.
A surface area setting step for setting a surface area S on which an electrodeposition coating is to be formed on the surface of the steel sheet pile, and a surface area setting step.
The required energization amount calculation step of obtaining the required energization amount I based on the surface area S set in the surface area setting step and the energization amount i per unit area obtained in the unit area energization amount calculation step.
A recess setting step for setting the number n of recesses of the steel sheet piles to be connected and arranged, and a recess setting step.
Recessed energization amount calculation step for obtaining the recess energizing amount _Io per recess of the steel sheet pile based on the required energizing amount I obtained in the required energizing amount calculation step and the number n of recesses set in the recess setting step. When,
The anode generating current setting step of setting the generated current _yy per anode and the anode generating current setting step.
The number of anodes _Y to be attached to one recess of the steel sheet pile is obtained based on the recess energization amount _Io obtained in the recess energization amount calculation step and the generated current ii set in the anode generation current setting step. It can be included with the setting process.

In the method for forming an anticorrosion electrodeposition film on an underwater metal structure, both ends of the core material can be attached to the surface of the convex portion of the steel sheet pile in the anode attaching step.

In the method for forming an anticorrosion electrodeposition film on an underwater metal structure, both ends of the core material are detachably attached to a bracket fixed to the surface of the convex portion of the steel sheet pile by a fastening member in the anode mounting step. Can be done.

According to the method for forming an anticorrosion electrodeposition coating on an underwater metal structure of the present invention, it is possible to obtain an excellent effect that an electrodeposition coating can be stably formed while facilitating construction without the need for a DC power supply or wiring.

It is a flowchart which shows the Example of the anticorrosion electrodeposition film formation method of the underwater metal structure of this invention. It is a schematic structural plan view which shows the anode in the Example of the anticorrosion electrodeposition film formation method of the underwater metal structure of this invention. It is a schematic structural front view which shows the anode in the Example of the anticorrosion electrodeposition film formation method of the underwater metal structure of this invention. It is a diagram which shows the relationship between the required film thickness and the energization amount per unit area in the Example of the anticorrosion electrodeposition film formation method of the underwater metal structure of this invention. It is an enlarged front view of the main part which shows the modification about the installation of the anode in the Example of the anticorrosion electrodeposition film formation method of the underwater metal structure of this invention.

Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

1 to 4 are examples of the method for forming an anticorrosion electrodeposition film on an underwater metal structure of the present invention.

In the case of this embodiment, as shown in FIG. 1, the substrate adjusting step (step S100) and the anode mounting step (step S200) are performed.

The substrate adjusting step is a step of removing marine organisms such as shellfish and deposits such as rust on the surface of the underwater metal structure 10. In the substrate adjustment step, high-pressure water cleaning is performed by injecting high-pressure water from the nozzle onto the surface of the underwater metal structure 10, or a shot in which a polishing material such as sand or metal is injected from the nozzle onto the surface of the underwater metal structure 10. Blasting can be adopted.

The anode mounting step is a step of mounting the anode 20 on the surface of the underwater metal structure 10 from which deposits have been removed in the substrate adjusting step.

As shown in FIGS. 2 and 3, the anode 20 has a steel core material 21 whose both ends are connected to the surface of the underwater metal structure 10 and magnesium coated on the outer periphery of the intermediate portion of the core material 21. It is provided with an alloy 22. The core material 21 has a shape in which the upper and lower ends of the intermediate portion covered with the magnesium alloy 22 are bent. Further, in the embodiment of FIG. 2, a steel sheet pile 11 provided on the quay as an underwater metal structure 10 including a marine steel structure is shown. The quay has a wall surface extending in the vertical direction and extending in the width direction (horizontal direction) intersecting the vertical direction, and the steel sheet pile 11 has concave portions 11a and convex portions 11b alternating in the width direction along the wall surface. It is connected and arranged so as to be formed in the water, and as shown in FIG. 3, it hangs down in the depth direction of the water.

In the anode mounting step, the core material 21 is arranged so that the magnesium alloy 22 of the anode 20 extends in the water depth direction and is disposed between the convex portions 11b and the convex portions 11b, that is, between the convex portions 11b adjacent to each other. Both ends of the steel sheet pile 11 are attached to the surface of the steel sheet pile 11.

More specifically, as shown in FIG. 1, the anode mounting step requires a required film thickness setting step (step S210), a unit area energization amount calculation step (step S220), and a surface surface setting step (step S230). The energization amount calculation step (step S240), the recess setting step (step S250), the recess energization amount calculation step (step S260), the anode generation current setting step (step S270), and the number of anodes setting step (step S280). Includes.

The required film thickness setting step is a step of setting the required film thickness t of the electrodeposition film to be formed on the surface of the steel sheet pile 11.

The unit area energization amount calculation step is a step of obtaining the energization amount i per unit area based on the required film thickness t set in the required film thickness setting step.

The surface area setting step is a step of setting a surface area S on which an electrodeposition coating is to be formed on the surface of the steel sheet pile 11.

In the required energization amount calculation step, the required energization amount I (= i × S) is based on the surface area S set in the surface area setting step and the energization amount i per unit area obtained in the unit area energization amount calculation step. Is the process of finding.

The recess setting step is a step of setting the number n of the recesses 11a of the steel sheet pile 11 to be connected and arranged.

In the recess energization amount calculation step, the recesses per recess 11a of the steel sheet pile 11 are based on the required energization amount I obtained in the required energization amount calculation step and the number n of the recesses 11a set in the recess setting step. This is a step of obtaining the energization amount I _o (= I / n).

The anode generated current setting step is a step of setting the generated current _yy per anode 20.

The number of anodes setting step is attached to one recess 11a of the steel sheet pile 11 based on the recess energization amount _Io obtained in the recess energization amount calculation step and the generated current _i set in the anode generation current setting step. This is a step of obtaining the number Y (= I _o / i _y ) of the power anodes 20.

In the anode mounting step, both ends of the core material 21 are attached to the surface of the convex portion 11b of the steel sheet pile 11 by welding or the like, as shown in FIGS. 2 and 3. However, both ends of the core material 21 can be attached to the surface of the recess 11a of the steel sheet pile 11 as shown by the virtual line in FIG. In short, the position of the magnesium alloy 22 (the position extending in the water depth direction and arranged between the convex portions 11b and the convex portions 11b adjacent to each other) is important, and in principle, the core material 21 of the anode 20 It is sufficient that the steel sheet pile 11 is in electrical contact with the steel sheet pile 11, and the core material 21 may be attached at any position.

Next, the operation of the above embodiment will be described.

First, in the substrate adjusting step shown in step S100 of FIG. 1, deposits (for example, marine organisms such as shellfish and rust) on the surface of the steel sheet pile 11 which is the underwater metal structure 10 shown in FIGS. 2 and 3 are removed. Will be done. When, for example, high-pressure water washing is adopted in the substrate adjusting step, high-pressure water is sprayed onto the surface of the steel sheet pile 11 from a nozzle (not shown). Further, when, for example, shot blasting is adopted in the substrate adjusting step, a polishing material such as sand or metal is sprayed onto the surface of the steel sheet pile 11 from a nozzle (not shown).

Subsequently, in the anode mounting step shown in step S200 of FIG. 1, the anode 20 is mounted on the surface of the steel sheet pile 11 from which the deposits have been removed in the substrate adjusting step.

Regarding the number Y of the anodes 20 to be attached to one recess 11a of the steel sheet pile 11, the following steps, that is, a required film thickness setting step, a unit area energization amount calculation step, a surface surface setting step, and a required energization amount calculation step. , The recess setting step, the recess energization amount calculation step, the anode generation current setting step, and the number of anodes setting step are sequentially performed.

In the required film thickness setting step shown in step S210 of FIG. 1 in the anode mounting step, the required film thickness t of the electrodeposition film to be formed on the surface of the steel sheet pile 11 is set. The required film thickness t of the electrodeposition film may be, for example, about 500 [μm].

In the unit area energization amount calculation step shown in step S220 of FIG. 1 in the anode mounting step, the energization amount i per unit area is obtained based on the required film thickness t set in the required film thickness setting step.

Here, the relationship between the required film thickness t and the energization amount i per unit area is as shown in the diagram shown in FIG. Therefore, if the required film thickness is t = 500 [μm], the energization amount per unit area is i≈30 [A.day / m ² ].

In the surface area setting step shown in step S230 of FIG. 1 in the anode mounting step, the surface area S on which the electrodeposition film is to be formed on the surface of the steel sheet pile 11 is set. When it is assumed that the concave portion 11a and the convex portion 11b of the steel sheet pile 11 are stretched in a plane, the surface area is, for example, W = 20 [m] and the height is H = 5 [m]. S = WH = 20 × 5 = 100 [m ² ].

In the required energization amount calculation step shown in step S240 of FIG. 1 in the anode mounting step, the surface area S set in the surface area setting step and the energization amount i per unit area obtained in the unit area energization amount calculation step are set. Based on this, the required energization amount I is obtained. When the energization amount is i = 30 [A ・ day / m ² ] and the surface area is S = 100 [m ² ], the required energization amount is I = i × S = 30 × 100 = 3000 [A ・ day]. ].

In the recess setting step shown in step S250 of FIG. 1 in the anode mounting step, the number n of the recesses 11a of the steel sheet pile 11 to be connected and arranged is set. The number of recesses 11a of the steel sheet pile 11 is set to, for example, n = 20.

In the recess energization amount calculation step shown in step S260 of FIG. 1 in the anode mounting step, based on the required energization amount I obtained in the required energization amount calculation step and the number n of the recesses 11a set in the recess setting step. The recess energization amount _Io per recess 11a of the steel sheet pile 11 is obtained. When the required energization amount is I = 3000 [A · day] and the number of recesses 11a of the steel sheet pile 11 is n = 20, the recess energization amount per recess 11a of the steel sheet pile 11 is I _o = I. / N = 3000/20 = 150 [A · day].

In the anode generation current setting step shown in step S270 of FIG. 1 in the anode mounting step, the generated current _yy per anode 20 is set. The generated current per anode 20 is proportional to the physical quantity of the magnesium alloy 22, and is set, for example, i _y = 150 [A. Day].

In the process of setting the number of anodes shown in step S280 of FIG. 1 in the anode mounting step, the concave current energization amount _Io obtained in the concave energization amount calculation step and the generated current _i set in the anode generated current setting step are set. Based on this, the number Y of the anodes 20 to be attached to one recess 11a of the steel sheet pile 11 is obtained. When the concave energization amount is I _o = 150 [A · day] and the generated current is i _y = 150 [A · day], the number of the anodes 20 is Y = I _o / i _y = 150 /. 150 = 1 [book].

Then, when the number Y of the anodes 20 to be attached to one recess 11a of the steel sheet pile 11 is obtained in the anode number setting step in the anode attaching step, both ends of the core material 21 of the anode 20 are shown in FIGS. 2 and 2. As shown in 3, the steel sheet pile 11 is attached to the surface of the convex portion 11b by welding or the like. Note that FIG. 3 shows an example in which one anode 20 is attached to one recess 11a of the steel sheet pile 11. If the generated current is i _y = 75 [A · day], the number of the anodes 20 is Y = I _o / i _y = 150/75 = 2 [lines], so that the steel sheet pile 11 The anode 20 may be attached so that two anodes 20 are arranged in series in the vertical direction with respect to one recess 11a of the above. Further, when the generated current is i _y = 50 [A · day], the number of the anodes 20 is Y = I _o / i _y = 150/50 = 3 [lines], so that the steel sheet pile 11 The anode 20 may be attached so that three anodes 20 are arranged in series in the vertical direction with respect to one recess 11a.

Here, as an actual work, the core material 21 is attached to the steel sheet pile 11 by adjusting the surface of the steel sheet pile 11 by a diver or a dry method, welding in water, or the like. Therefore, it is preferable to attach the core material 21 to the surface of the convex portion 11b rather than attaching the core material 21 to the concave portion 11a of the steel sheet pile 11 in order to improve workability. Incidentally, the dry method is a method in which a water stop box is attached to the tidal zone of the steel sheet pile 11 and the water inside the water stop box is discharged by a pump so that the work can be performed in a dry state.

There are no deposits on the surface of the steel sheet pile 11 that has undergone the substrate adjustment step, and electricity flows uniformly through the anode 20 attached in the anode mounting step, so that the magnesium alloy 22 of the anode 20 melts and disappears. Until then, the current density distribution required for forming the electrodeposition film is stably maintained. As a result, the cathode current flows through the steel sheet pile 11 with a uniform current density distribution, and an electrodeposition film without cracking or peeling is formed until the required film thickness t is reached. Further, performing the substrate adjusting step is also effective in confirming the state of the steel sheet pile 11, that is, the change in thickness, the presence or absence of holes, and the like.

In the case of this embodiment, as compared with the conventional case, a DC power supply and a generator for the DC power supply are arranged in the vicinity of the underwater metal structure 10, wiring is laid between the DC power supply and the anode, and then the underwater metal is used. It is not necessary to install an anode matching the shape of the structure 10 at an appropriate distance from the underwater metal structure 10 to energize the structure 10. Further, it is not necessary to refuel the generator and check and adjust the current value and the voltage value of the DC power source each time, and there is no problem even if the energization period is lengthened. In addition, it is not necessary to remove the anode, members for installing the anode, wiring, DC power supply, and generator after the construction is completed. As described above, in this embodiment, the electrodeposition film can be formed only by attaching the anode 20 after adjusting the substrate of the surface of the underwater metal structure 10, and the work during energization is not required at all. There are no restrictions on the energization period for forming a film. Therefore, even if the current density on the surface of the underwater metal structure 10 varies and the current density is low, it is possible to stably obtain an electrodeposition coating having a required thickness t by extending the energization period. Become. Further, during the period of energization using the anode 20 provided with the magnesium alloy 22, the surface of the underwater metal structure 10 is formed at the same time as the electrodeposition film is formed by applying a current to the surface of the underwater metal structure 10. It is thought that electric corrosion protection is also provided.

Further, in the case of this embodiment, unlike the conventional case, anodes matching the shape of the underwater metal structure 10 are precisely installed at appropriate intervals, or the DC power supply is adjusted and managed. It is not necessary, and an appropriate current density distribution can be maintained in the formation of the electrodeposition film. Therefore, there is no concern that the electrodeposition film will not be formed due to insufficient current. On the contrary, there is no concern that an excessive current flows and a large amount of hydrogen gas is generated on the surface of the underwater metal structure 10 and the electrodeposition coating is peeled off.

Furthermore, if the anode 20 is installed without performing the substrate adjustment step, an electrodeposition film is formed on the rust, and there is a concern that the electrodeposition film may be peeled off together with the rust. It can be said that the adhesion is low. However, in the case of this embodiment, the deposits are removed from the surface of the steel sheet pile 11 by the base material adjusting step, so that an electrodeposition coating having sufficient adhesion can be formed on the base material surface of the steel sheet pile 11. It can exert a long-term anticorrosion effect. Further, by removing the rust that becomes an electric resistance, the dissolution of the magnesium alloy 22 of the anode 20 is promoted, the so-called useful life until the magnesium alloy 22 disappears is shortened, and the required film on the surface of the steel sheet pile 11 is shortened. The energization period until the electrodeposition film having a thickness of t is formed can be relatively short.

In this way, the electrodeposition coating can be stably formed while the construction can be easily performed without the need for a DC power supply or wiring.

FIG. 5 is a modified example of the installation of the anode in the embodiment of the method for forming an anticorrosion electrodeposition film of the underwater metal structure 10 of the present invention, and in the drawings, the portions with the same reference numerals as those in FIGS. 2 and 3 are the same. It represents an object.

In the modified example shown in FIG. 5, in the anode mounting step, both ends of the core material 21 are attached to the bracket 30 fixed to the surface of the convex portion 11b of the steel sheet pile 11 by a fastening member 40 such as a bolt or a nut. It is designed so that it can be attached and detached. Note that FIG. 5 shows only the upper end portion of the core material 21, and the lower end portion is omitted. Further, the fastening member 40 may be a member other than bolts and nuts as long as it can be attached and detached.

In the case of the modification shown in FIG. 5, after the magnesium alloy 22 of the anode 20 is melted and disappears, the core material 21 can be removed from the bracket 30 by loosening the fastening members 40 from both ends of the core material 21. Become. As a result, the anode 20 can be easily replaced, and workability can be improved.

Then, in the case of the embodiments of FIGS. 1 to 4, as shown in FIGS. 2 and 3, the underwater metal structure 10 is a steel sheet pile 11 which is connected and arranged so that the concave portion 11a and the convex portion 11b are formed. In the anode mounting step, both ends of the core material 21 are provided so that the magnesium alloy 22 of the anode 20 extends in the water depth direction and is disposed between the convex portions 11b and the convex portions 11b adjacent to each other. It is attached to the surface of the steel sheet pile 11. With this configuration, the electrodeposition film can be stably formed on the surface of the steel sheet pile 11 as the underwater metal structure 10.

Further, as shown in FIG. 1, the anode mounting step is set in the required film thickness setting step for setting the required film thickness t to be formed on the surface of the steel sheet pile 11 and the required film thickness setting step. A unit area energization amount calculation step for obtaining the energization amount i per unit area based on the required required film thickness t, and a surface area setting step for setting the surface surface S on which the electrodeposition film is to be formed on the surface of the steel sheet pile 11. The required energization amount calculation step of obtaining the required energization amount I (= i × S) based on the surface surface S set in the surface surface setting step and the energization amount i per unit area obtained in the unit area energization amount calculation step. , The number n of the recesses 11a of the steel sheet pile 11 to be connected and arranged, the required current amount I obtained in the recess setting step, the required current amount calculation step, and the number of recesses 11a set in the recess setting step. A recess energization amount calculation step for obtaining the recess energization amount I _o (= I / n) per recess 11a of the steel sheet pile 11 based on n, and an anode for setting the generated current _yy per recess 20. It should be attached to one recess 11a of the steel sheet pile 11 based on the generated current setting step, the recess energization amount _Io obtained in the recess energization amount calculation step, and the generated current _i set in the anode generated current setting step. It includes a step of setting the number of anodes for obtaining the number Y (= I _o / i _y ) of the number of anodes 20. With this configuration, the electrodeposition film having the required film thickness t can be stably obtained by appropriately selecting the number Y of the anodes 20 and attaching them to the surface of the steel sheet pile 11.

Further, in the anode mounting step, as shown in FIGS. 2 and 3, both ends of the core material 21 are mounted on the surface of the convex portion 11b of the steel sheet pile 11. With this configuration, workability can be improved as compared with attaching the core material 21 to the recess 11a of the steel sheet pile 11.

Furthermore, in the anode mounting step, as shown in FIG. 5, both ends of the core material 21 are detachably attached to the bracket 30 fixed to the surface of the convex portion 11b of the steel sheet pile 11 by the fastening member 40. Be done. With such a configuration, it is effective to easily replace the anode 20 and improve workability.

Incidentally, Patent Document 1 describes that a galvanic anode of an aluminum alloy, a zinc alloy, a magnesium alloy or the like is attached to the surface of a steel pipe pile in the sea by welding a steel core metal thereof. However, Patent Document 1 does not provide any description regarding substrate adjustment or installation of a specific anode on a steel sheet pile.

The method for forming an anticorrosion electrodeposition film on an underwater metal structure of the present invention is not limited to the above-described embodiment, and it goes without saying that various changes can be made without departing from the gist of the present invention. be.

10 Underwater metal structure 11 Steel sheet pile 11a Concave part 11b Convex part 20 Anode 21 Core material 22 Magnesium alloy 30 Bracket 40 Fastening member

Claims (4)

A substrate adjustment process that removes deposits on the surface of underwater metal structures,
A steel core material in which both ends are connected to the surface of the underwater metal structure on the surface of the underwater metal structure from which deposits have been removed in the substrate adjustment step, and a magnesium alloy coated on the core material. Perform the anode mounting process and mount the anode with
The underwater metal structure is a steel sheet pile that is connected and arranged so that a concave portion and a convex portion are formed.
In the anode mounting step, both ends of the core material are attached to the surface of the steel sheet pile so that the magnesium alloy of the anode extends in the water depth direction and is disposed between the convex portions adjacent to each other. A method for forming an anticorrosion electrodeposition film on an underwater metal structure. The anode mounting step is
The required film thickness setting step for setting the required film thickness t of the electrodeposition film to be formed on the surface of the steel sheet pile, and the required film thickness setting step.
A unit area energization amount calculation step for obtaining an energization amount i per unit area based on the required film thickness t set in the required film thickness setting step, and a unit area energization amount calculation step.
A surface area setting step for setting a surface area S on which an electrodeposition coating is to be formed on the surface of the steel sheet pile, and a surface area setting step.
The required energization amount calculation step of obtaining the required energization amount I based on the surface area S set in the surface area setting step and the energization amount i per unit area obtained in the unit area energization amount calculation step.
A recess setting step for setting the number n of recesses of the steel sheet piles to be connected and arranged, and a recess setting step.
Recessed energization amount calculation step for obtaining the recess energizing amount _Io per recess of the steel sheet pile based on the required energizing amount I obtained in the required energizing amount calculation step and the number n of recesses set in the recess setting step. When,
The anode generating current setting step of setting the generated current _yy per anode and the anode generating current setting step.
The number of anodes _Y to be attached to one recess of the steel sheet pile is obtained based on the recess energization amount _Io obtained in the recess energization amount calculation step and the generated current ii set in the anode generation current setting step. The method for forming an anticorrosion electrodeposition film on an underwater metal structure according to claim 1 , which includes a setting step. The method for forming an anticorrosion electrodeposition film on an underwater metal structure according to claim 2 , wherein both ends of the core material are attached to the surface of the convex portion of the steel sheet pile in the anode mounting step. The anticorrosion electrodeposition of the underwater metal structure according to claim 3 , wherein in the anode mounting step, both ends of the core material are detachably attached to a bracket fixed to the surface of the convex portion of the steel sheet pile by a fastening member. Film forming method.

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