JP5501171B2 - Anticorrosion construction method for steel pipe piles - Google Patents

Description

  The present invention relates to a corrosion prevention method for steel pipe piles.

Since the splash zone and tidal zone of steel pipe piles in offshore structures are rapidly corroded, an anticorrosion construction method in which an anticorrosion tape is wound around the surface or further covered with a protective sheet such as a synthetic resin is applied.
For example, in Patent Document 1, a rust preventive layer provided in close contact with the outer peripheral surface of a steel pipe pile, a foamed plastic layer covering the outer peripheral surface of the rust preventive layer, and pressurizing the foamed plastic layer from the outer periphery, An anticorrosion construction method for steel pipe piles, characterized in that a plurality of strip-shaped anticorrosion bands having a protective cover made of titanium or a titanium alloy thin plate are arranged in the vertical direction in the splash and tidal zones of the steel pipe piles. Have been described.

JP-A-9-302701

  According to the conventional method as described in the above-mentioned Patent Document 1, it is possible to perform the anticorrosion construction of the steel pipe pile. However, the adhesion between the steel pipe pile and each layer formed on the outer peripheral surface thereof becomes insufficient, and the corrosion prevention sometimes becomes insufficient.

  The inventor has intensively studied to solve the above-mentioned problems, and has completed the present invention.

The inventor diligently studied and found a method for solving the above-mentioned problems, and completed the present invention.
The present invention includes the following (1) to (6).
(1) An anticorrosion construction method for preventing corrosion by forming an anticorrosion layer including a rust prevention layer, a plastic layer and a protection layer on the outer peripheral surface of a splash zone / tidal zone of a steel pipe pile of an offshore structure,
A rust preventive layer forming step of forming a rust preventive layer in close contact with the outer peripheral surface of the steel pipe pile;
A plastic layer forming step of forming a plastic layer on the outer peripheral side of the rust preventive layer;
A protective layer forming step of forming a protective layer made of a corrosion-resistant metal thin plate on the outer peripheral side of the plastic layer;
An anti-corrosion construction method comprising: a pressing step of pressing the plastic layer inward with the protective layer.
(2) The protective layer has a folded portion formed by folding both ends of the thin plate outward, and further includes two auxiliary rods on the outer peripheral side of each thin plate forming the folded portion,
The pressing step includes
The protective layer is formed by approaching the two folded portions so as to abut each other, and tightening one auxiliary rod, two thin plates forming each folded portion, and the other auxiliary rod in this order with screws. The anticorrosion construction method according to the above (1), which is a step of pressurizing the plastic layer inward.
(3) The protective layer has a folded portion formed by folding both ends of the thin plate outward,
The pressing step includes
The two folded portions are brought close together so as to face each other, and the two folded portions are inserted together into a Saya tube having a C-shaped cross section having an opening on the side surface, and both ends of the protective layer are connected. The step of pressing the plastic layer inward by the protective layer by bringing the two folded portions closer together by tightening a screw attached to the side surface of the Saya tube extending to the opening side of the Saya tube The anticorrosion construction method according to (1) above.
(4) The protective layer has a folded portion formed by folding both ends of the thin plate outward,
The pressing step includes
By approaching the two folded portions so as to abut each other, inserting the two folded portions together into a S-shaped cross-section having an opening on the side surface and connecting the both ends of the protective layer The anticorrosion construction method according to (1), which is a step of pressurizing the plastic layer inward with the protective layer.
(5) The protective layer is formed by joining two or more of the thin plates, and when installed on the outer peripheral side of the plastic layer, a fastening portion that extends in a direction from the inner peripheral side to the outer peripheral side is provided. At both ends,
The pressing step includes
The anticorrosion construction according to the above (1), which is a step of pressing the plastic layer inward by the protective layer by bringing the two tightening portions close to each other and tightening them with screws. Method.
(6) The protective layer includes two or more thin plates, and when installed on the outer peripheral side of the plastic layer, the protective layer has tightening portions at both ends extending from the inner peripheral side to the outer peripheral side, , Having a folded portion formed by folding both ends of the thin plate outward,
The pressing step includes
The two folded portions are brought close together so as to face each other, and the two folded portions are inserted together into a Saya tube having a C-shaped cross section having an opening on the side surface, and both ends of the protective layer are connected. The anticorrosion according to (1), which is a step of pressing the plastic layer inward by the protective layer by bringing the two tightening parts close to each other and tightening them with screws. Construction method.

  ADVANTAGE OF THE INVENTION According to this invention, the steel pipe pile and each layer formed in the outer peripheral surface can fully be stuck, and the anticorrosion construction method which can perform corrosion prevention more highly can be provided.

It is the schematic which shows the state which gave the anticorrosion construction method of this invention to the splash zone and tidal zone of the steel pipe pile of an offshore structure. It is AA sectional drawing in FIG. It is a schematic perspective view of a Saya tube whose cross section is C-shaped. It is a schematic sectional drawing of the steel pipe pile and the anticorrosion layer in the case of aspect 1. It is a schematic sectional drawing of the steel pipe pile and the anticorrosion layer in the case of aspect 2. It is a schematic perspective view of another Saya tube having a C-shaped cross section. It is a schematic sectional drawing of the steel pipe pile and anticorrosion layer in the case of aspect 3. It is a schematic perspective view of a Saya tube having a B-shaped cross section. It is a schematic sectional view of a Saya tube having a B-shaped cross section. It is a schematic sectional drawing of the steel pipe pile and anticorrosion layer in the case of aspect 4. It is a schematic sectional drawing of the steel pipe pile and anticorrosion layer in the case of aspect 5.

The present invention will be described.
The present invention is an anticorrosion construction method for preventing corrosion by forming an anticorrosion layer including a rust prevention layer, a plastic layer and a protection layer on the outer peripheral surface of a splash zone / tidal zone of a steel pipe pile of an offshore structure, A rust preventive layer forming step for forming a rust preventive layer in close contact with the outer peripheral surface, a plastic layer forming step for forming a plastic layer on the outer peripheral side of the rust preventive layer, and a corrosion-resistant metal on the outer peripheral side of the plastic layer. It is an anticorrosion construction method comprising a protective layer forming step of forming a protective layer made of a thin plate and a pressurizing step of pressurizing the protective layer inward.

The rust preventive layer forming step of the present invention will be described.
In the rust preventive layer forming step of the present invention, the rust preventive layer is formed so as to be in close contact with the outer peripheral surface of the steel pipe pile.
The anticorrosive layer is not particularly limited, and for example, a conventionally known one can be used. For example, a strip-shaped cloth impregnated with a commercially available antirust agent (such as petrolatum, an oxidation polymerization resin, or an epoxy resin) can be used, A rust prevention layer can be formed by winding this around the outer peripheral surface of the steel pipe pile.
When constructing, for example, the surface deposits of steel pipe piles can be removed, the base is adjusted with sandblasting, etc., the petrolatum paste is applied, and then the tape impregnated with petrolatum is tightly wound to form a rust prevention layer. preferable.

The plastic layer forming process of the present invention will be described.
In the plastic layer forming step of the present invention, a plastic layer is formed on the outer peripheral side of the rust preventive layer. One or more other layers may be formed on the outer peripheral surface of the rust preventive layer, and a plastic layer may be formed on the outer peripheral surface. However, the plastic layer is formed so as to be in close contact with the outer peripheral surface of the rust preventive layer. It is preferable to do.
The plastic layer is preferably a foamed plastic layer. For example, a foamed plastic made of commercially available foamed polyethylene having a large number of holes communicating in a three-dimensional direction can be used.
A plastic layer can be formed by winding a belt-shaped sheet made of plastic around the outer periphery of the antirust layer.

The protective layer forming step of the present invention will be described.
In the protective layer forming step of the present invention, a protective layer made of a corrosion-resistant metal thin plate is formed on the outer peripheral side of the plastic layer. Corrosion-resistant metals have extremely high corrosion resistance in seawater, so they are not damaged by corrosion even when used for a long time.
One or more other layers may be formed on the outer peripheral surface of the plastic layer, and a protective layer may be formed on the outer peripheral surface, but the protective layer is formed so as to be in close contact with the outer peripheral surface of the plastic layer. Is preferred.
The corrosion resistant metal is not particularly limited. For example, examples of the corrosion-resistant metal include titanium, titanium alloy, and stainless steel, and titanium or titanium alloy is preferable.
As a thin plate of a corrosion-resistant metal, a plate having a thickness of 0.3 to 3.0 mm, preferably 0.6 to 1.0 mm is preferable because it is lightweight and easy to handle during construction.
Further, the thin plate may be obtained by joining two or more. When the steel pipe pile is a large-diameter pipe, the strip-like corrosion-resistant metal thin plate is also long, and handling in construction becomes troublesome. Therefore, it is preferable to use a thin plate obtained by joining two or more thin plates. That is, a plurality of short strip-shaped corrosion-resistant metal thin plates may be connected to each other in the circumferential direction. The joining method of a thin plate is not specifically limited, For example, the edge part of two thin plates can be joined by resistance welding. Further, the folded portions can be connected using a sheath tube, and a plurality of thin sheets of corrosion-resistant metal can be connected to each other.

  In addition, when constructing, a thin sheet of corrosion-resistant metal with a plastic sheet such as polyethylene foam stuck on one side in advance, and winding the plastic sheet inside on the outer peripheral side of the rust prevention layer, It is preferable because the plastic layer and the protective layer can be easily formed simultaneously.

The pressurizing process of the present invention will be described.
In the pressurizing step of the present invention, the plastic layer is pressed inward by the protective layer.
The means for pressing the plastic layer inward by the protective layer is not particularly limited, and for example, it can be pressed by a conventionally known method. For example, both ends of the thin plate forming the protective layer are folded outward with a width of 5 to 50 mm to form a folded portion, the two folded portions are brought close to each other, and a cross section having an opening on a side surface is formed. There is a method of connecting both ends of the protective layer by inserting two folded portions together into a C-shaped sheath tube. For example, using a commercially available belt binding machine as an auxiliary tool, when the belt is rotated around the outer circumference of a strip-shaped corrosion-resistant metal thin plate and the belt is tightened, the folded portions at both ends can be easily brought into contact with each other.

  In the present invention, it is preferable to install a plurality of strip-shaped anticorrosion layers side by side in the vertical direction in the splash zone / tidal zone of the steel pipe pile. This anticorrosion construction is preferably performed over a length of 2 to 5 m on the surface of the steel pipe pile. When the anticorrosion construction having a length of 2 to 5 m is formed as an integrated object that is not divided in the vertical direction, the construction is not easy because the members used are large and heavy. For this reason, it is preferable to use a plurality of strip-shaped anticorrosion layers divided in the vertical direction.

  When a plurality of anticorrosion layers are arranged side by side in this manner, it is preferable to provide a cradle below the lowermost anticorrosion layer and below the tidal zone of the steel pipe pile. Moreover, it is preferable to install the lowermost anticorrosion layer on the cradle so that there is no electrically connected portion between the steel pipe pile and the protective layer. For example, if the cradle is made of metal, the steel pipe pile and the protective layer are electrically connected. In this case, the steel pipe pile is easily corroded. Therefore, it is preferable to install, for example, a plastic plate on the upper part of the cradle and to install the lowermost anticorrosion layer thereon. Instead of the plastic plate, for example, an epoxy resin putty can be applied to the upper portion of the cradle and a lower anticorrosion layer can be placed thereon.

  When a plurality of anticorrosion layers are arranged side by side in the vertical direction as described above, the anticorrosion layers adjacent to each other in the vertical direction are preferably installed in an overlapping manner. When superposed, even if driftwood or a small boat collides with the vertical boundary of the anticorrosion layer, the anticorrosion zone is hardly damaged. Moreover, even if the plastic layer is aged over a long period of time, it will not fall off the lower part of the protective layer and will not easily dissipate.

Next, the specific example of the steel pipe pile after giving the anticorrosion construction method of this invention is demonstrated using FIGS. 1-3.
FIG. 1 is a schematic view showing a state where the anticorrosion construction method of the present invention is applied to a splash zone / tidal zone of a steel pipe pile 1 of an offshore structure, and FIG. 2 is a cross-sectional view taken along line AA in FIG. 3 is a schematic perspective view of a sheath tube 9 having a C-shaped cross section having an opening 91 on a side surface. Note that the size and balance of each part in each figure may be different from the actual one.
As shown in FIGS. 1 and 2, a rust prevention layer 3 is formed so as to be in close contact with the outer peripheral surface of the steel pipe pile 1, and a plastic layer 5 is formed so as to be in close contact with the outer peripheral surface thereof. A protective layer 7 is formed so as to be in close contact with the surface. In addition, the protective layer 7 has folded portions 71 and 72 formed by folding both ends outward, approached so that the folded portion 71 and the folded portion 72 abut each other, and a cross section having an opening 91 on the side surface. Are inserted into the C-shaped sheath tube 9 together with the two folded portions 71 and 72 so that both ends of the protective layer 7 are connected.
Moreover, in FIG. 1, two anticorrosion layers are arranged in the vertical direction on the steel pipe pile 1.
Further, the upper anticorrosion layer 10 and the lower anticorrosion layer 10 ′ are disposed so as to overlap each other.
A cradle 50 is provided below the bottom anticorrosion layer 10 ′ and below the tidal zone of the steel pipe pile 1. The cradle 50 has a plastic plate 52 at the top and a steel sleeve 51 at the bottom, and the bottom anticorrosion layer 10 ′ is placed on the cradle 50. In this case, the lowermost protective layer 7 ′ and the steel pipe pile 1 are not electrically connected.

  Preferred embodiments in the present invention will be described below.

<Aspect 1>
A first preferred embodiment of the present invention (hereinafter also referred to as “aspect 1”) will be described with reference to FIG. FIG. 4 is a schematic cross-sectional view of the steel pipe pile 1 and the anticorrosion layer 10 in the case of the aspect 1 (a view corresponding to FIG. 2, which is a cross-sectional view taken along line AA in FIG. 1).

  In the aspect 1, the protective layer 10 has the folded portions 71 and 72 formed by folding both ends of the thin plate outward, and is in close contact with the outer surface of each thin plate forming the folded portions 71 and 72. The thin plates 15 and 16 having a U-shaped cross section are provided, and two auxiliary rods 11 and 12 are provided so as to be in close contact with the outer surface of each of them. That is, as shown in FIG. 4, the auxiliary rod 11 is provided on the outer peripheral side of the folded portion 71, and the auxiliary rod 12 is provided on the outer peripheral side of the folded portion 72.

In the pressurizing step according to aspect 1, the two folded portions are brought close to each other, one auxiliary bar, one thin plate, two thin plates forming each folded portion, the other thin plate, and the other By tightening the auxiliary rods with screws in this order, the plastic layer is pressed inward by the protective layer.
That is, the folding part 71 and the folding part 72 are brought close to each other so that one auxiliary bar 11, the two thin plates forming the folding parts 71 and 72, and the other auxiliary bar 12 are screwed in this order. Tighten with 18 and tighten. Thereby, the plastic layer 5 can be pressurized inward by the protective layer 7.

Here, the strip-shaped thin plates 15 and 16 having a U-shaped cross section existing between the auxiliary rods 11 and 12 and the folded portions 71 and 72 may not be present, but are preferably present.
The auxiliary rod is preferably made of an insulating material (preferably engineering plastic or stainless steel (eg, 316L)). The strip-shaped thin plate having a U-shaped cross section is preferably made of FRP.

<Aspect 2>
A second preferred embodiment (hereinafter also referred to as “aspect 2”) in the present invention will be described with reference to FIGS. 5 and 6. FIG. 5 is a schematic cross-sectional view of the steel pipe pile 1 and the anticorrosion layer 10 in the case of the aspect 2 (a view corresponding to FIG. 2 which is a cross-sectional view taken along the line AA in FIG. 1), and FIG. FIG. 2 is a schematic perspective view of a shear tube 19 having a C-shaped cross section.

  In the aspect 2, the protective layer 10 has folded portions 71 and 72 formed by folding both ends of the thin plate outward.

In the pressurizing step according to aspect 2, the two folded portions are brought close to each other, and the two folded portions are inserted together into a sheath tube having a C-shaped cross section having an opening on the side surface. The two folded portions are further brought closer to each other by tightening a screw attached to the side surface of the Saya tube that extends to the opening side of the Saya tube and connects the plastic layer with the protective layer. Pressurize inward.
That is, as shown in FIG. 5, the folded portion 71 and the folded portion 72 are brought close to each other. Then, as shown in FIGS. 5 and 6, the two folded portions 71 and 72 are inserted together into the C-shaped Saya tube 29 having an opening 291 on the side surface, and both ends of the protective layer 7 are inserted. Connect the parts. Further, by tightening the screws 25 and 26 attached to the side surface of the Saya tube 29 extending to the opening side of the Saya tube 29, the two folded portions 71 and 72 are brought closer to each other, and the plastic layer 5 is placed inside by the protective layer 7 Pressurize toward.

  Here, it is preferable that the sheath tube 29 has a pair of screws so as to sandwich the opening 291. Moreover, although three pairs of screws are shown in FIG. 6, the number of screws is not limited.

<Aspect 3>
The 3rd suitable aspect (henceforth "aspect 3") in this invention is demonstrated using FIGS. FIG. 7 is a schematic cross-sectional view of the steel pipe pile 1 and the anticorrosion layer 10 in the case of the aspect 3 (a view corresponding to FIG. 2 which is an AA cross-sectional view in FIG. 1), and FIG. FIG. 9 is a schematic cross-sectional view for explaining a spring structure in a S-tube having a B-shaped cross section.

  In the aspect 3, the protective layer 10 has folded portions 71 and 72 formed by folding both ends of the thin plate outward.

In the pressurizing step according to aspect 3, the two folded portions are brought close to each other and the two folded portions are inserted together into a S-tube having a B-shaped cross section having an opening on the side surface, and the protective layer The plastic layer is pressed inward by the protective layer by connecting both ends of the protective layer.
That is, as shown in FIG. 7, the folded portion 71 and the folded portion 72 are brought close to each other. Then, the two folded portions 71 and 72 are inserted together into the Saya tube 39 having a B-shaped cross section having an opening 391 on the side surface to connect both ends of the protective layer 7.
Here, the Saya tube having a B-shaped cross section has a spring structure. That is, as shown in FIG. 9, when a force is applied in the direction in which the opening 391 is widened (in the direction of the solid line arrow in FIG. 9), the sheath tube 39 is deformed (for example, when it is deformed to the position indicated by the dotted line in FIG. 9). ) Like the spring, the sheath tube tries to return its deformation (dotted arrow in FIG. 9). By the force of returning the deformation, the folded portion 71 and the folded portion 72 are brought closer to each other, and the plastic layer 5 is pressed inward by the protective layer 7.

<Aspect 4>
A fourth preferred embodiment of the present invention (hereinafter also referred to as “embodiment 4”) will be described with reference to FIG. FIG. 10 is a schematic cross-sectional view of the steel pipe pile 1 and the anticorrosion layer 10 in the case of the aspect 4 (a view corresponding to FIG. 2, which is a cross-sectional view taken along line AA in FIG. 1).

  In the aspect 4, the protective layer 10 is obtained by joining two or more thin plates. In FIG. 10, the protective layer 10 is formed by welding (for example, resistance welding) two thin plates (protective layers 7a and 7b). Moreover, as shown in FIG. 10, when installed on the outer peripheral side of the plastic layer 5, it has tightening portions 40 at both ends that extend in the direction from the inner peripheral side to the outer peripheral side.

In the pressurizing step according to the aspect 4, the plastic layer is pressed inward by the protective layer by bringing the two tightening portions close to each other and tightening them with screws.
That is, as shown in FIG. 10, the tightening portion 41 and the tightening portion 42 are brought close to each other and tightened with bolts 43 and nuts 44 so that the plastic layer 5 is directed inward by the protective layer 7. Pressurize.
Here, the tightening portion can be formed by welding a thin plate having an L-shaped cross section and an end portion of the protective layer 7.

<Aspect 5>
A fifth preferred embodiment (hereinafter also referred to as “aspect 5”) in the present invention will be described with reference to FIG. 11 is a schematic cross-sectional view of the steel pipe pile 1 and the anticorrosion layer 10 in the case of the aspect 5 (a view corresponding to FIG. 2, which is a cross-sectional view taken along the line AA in FIG. 1).

In the aspect 5, the protective layer 10 includes two or more thin plates, and has folded portions 71 and 72 formed by folding both ends of the thin plates outward. Moreover, as shown in FIG. 11, when it installs in the outer peripheral side of the plastic layer 5, it has the clamping part 40 extended in the direction from an inner peripheral side to an outer peripheral side in the both ends.
Then, the folded portion 71 and the folded portion 72 are brought close to each other so that the two folded portions 71 and 72 are inserted together into the Saya tube 9 having the C-shaped cross section, and the protective layer 7 The both ends of are connected.

In the pressurizing process in the aspect 5, the plastic layer is pressed inward by the protective layer by bringing the two tightening portions close to each other and tightening them with screws.
That is, it is the same as that of the above-mentioned aspect 4, Comprising: As shown in FIG. 11, it closes so that the fastening part 41 and the fastening part 42 may face each other, and these are tightened with the volt | bolt 43 and the nut 44, and protection is carried out. The plastic layer 5 is pressed inward by the layer 7.
Here, the tightening portion can be formed by welding a thin plate having an L-shaped cross section and an end portion of the protective layer 7.

DESCRIPTION OF SYMBOLS 1 Steel pipe pile 3 Rust prevention layer 5 Plastic layer 7,7 ', 7a, 7b Protective layer 71,72 Folding part 9,19,29,39 Saya pipe 91,291,391 Opening 10,10' Anticorrosion layer 11,12 Auxiliary Bar 15, 16 Thin plate 18 Screw 25, 26 Screw 40, 41, 42 Tightening part 43 Bolt 44 Nut 50 Receiving base 51 Sleeve 52 Plate

Claims (2)

An anticorrosion construction method for preventing corrosion by forming an anticorrosive layer including a rust preventive layer, a plastic layer and a protective layer on the outer peripheral surface of a splash zone / tidal zone of a steel pipe pile of an offshore structure,
A rust preventive layer forming step of forming a rust preventive layer in close contact with the outer peripheral surface of the steel pipe pile;
A plastic layer forming step of forming a plastic layer on the outer peripheral side of the rust preventive layer;
On the outer peripheral side of the plastic layer, Ri Do a thin plate of corrosion resistant metal, and a protective layer forming step of forming a protective layer that have a fold-back portion formed by folding the ends of the sheet outwardly,
The two folded portions are brought close together so as to face each other, and the two folded portions are inserted together into a Saya tube having a C-shaped cross section having an opening on the side surface, and both ends of the protective layer are connected. , Pressurizing the plastic layer inward by the protective layer by tightening a screw attached to the side surface of the Saya tube that extends to the opening side of the Saya tube, bringing the two folded portions closer together The anticorrosion construction method provided with a process. An anticorrosion construction method for preventing corrosion by forming an anticorrosive layer including a rust preventive layer, a plastic layer and a protective layer on the outer peripheral surface of a splash zone / tidal zone of a steel pipe pile of an offshore structure,
A rust preventive layer forming step of forming a rust preventive layer in close contact with the outer peripheral surface of the steel pipe pile;
A plastic layer forming step of forming a plastic layer on the outer peripheral side of the rust preventive layer;
On the outer peripheral side of the plastic layer, Ri Do a thin plate of corrosion resistant metal, comprising two or more of said thin plate, when placed on the outer circumferential side of the plastic layer, clamping portion extending in the direction from the inner to the outer circumferential side the has at both ends thereof, further, a protective layer forming step of forming a protective layer that have a fold-back portion formed by folding the ends of the sheet outwardly,
The two folded portions are brought close together so as to face each other, and the two folded portions are inserted together into a Saya tube having a C-shaped cross section having an opening on the side surface, and both ends of the protective layer are connected. An anticorrosion construction method , comprising: a pressing step of pressing the plastic layer inward by the protective layer by tightening the two tightening portions close to each other and tightening them with screws .

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