JP7190372B2 - Anticorrosion construction method and thin plate used in the method - Google Patents

Description

TECHNICAL FIELD The present invention relates to an anticorrosion construction method and a thin plate used in the method.

Since corrosion progresses rapidly in the splash zone and tidal zone of steel pipe piles of offshore structures, anti-corrosion construction methods that form an anti-corrosion layer on the surface and a protective layer made of corrosion-resistant metal etc. are sometimes applied. . Further, methods for fixing the protective layer (protective cover) in such anticorrosion construction methods include flange type and flangeless type.

The former flange type is easy to fasten, so it is easy to fix the protective layer, but there are cases where waves and drifting objects collide with the flange and damage the flange. In addition, when the protective layer is fixed by tightening bolts and nuts at the flange, the flange opens in an inverted V shape. In some cases, gaps are formed through which seawater or the like enters, or the base of the flange portion damages the anticorrosion layer (rust prevention layer), resulting in a decrease in the anticorrosion function.
In relation to this, Patent Document 1 discloses a protective cover that protects an anti-corrosion material applied to the outer surface of a metal pipe such as a steel pipe by bolting the outward flange portions of the vertically split cover body together. A protective cover for a corrosion-resistant coating material such as a steel pipe is described, which is characterized in that the thickness of the cover body is gradually increased toward the flange portion. In such a protective cover, since the thickness of the cover body is gradually increased as it approaches the flange portion, the flexibility increases as the cover body approaches the abdomen, so that the flange portions are strongly bolted to each other. Also, it is described that the adhesion to the steel pipe is extremely good because there is no gap due to bending deformation in the vicinity of the flange portion as in the conventional art.
According to the method described in Patent Document 1, there is a possibility that it is possible to avoid the formation of a gap due to bending deformation in the vicinity of the flange portion. However, there is a possibility that the flange portion may be damaged due to the collision of waves or drifting objects.

On the other hand, the latter flangeless type can avoid adverse effects caused by collisions with waves and drifting objects, but it is difficult to reliably fix the protective layer against high wave forces. As a flangeless type conventional method, there is a method described in Patent Document 2.

Japanese Utility Model Laid-Open No. 62-190746 JP 2013-87539 A

As described above, conventionally, the protective layer (protective cover) can be securely fastened and fixed, the vicinity of the flange portion is not bent and deformed at the time of fastening, and a gap is not generated. However, no anti-corrosion construction method has been provided that is less likely to be adversely affected by corrosion.

The inventor of the present invention has made intensive studies, found a method for solving the above problems, and completed the present invention.
The present invention is the following (1) to (6).
(1) A corrosion prevention construction method for preventing corrosion by forming a corrosion prevention layer including a rust prevention layer, a plastic layer and a protective layer on the outer peripheral surface of the splash zone / tidal zone of a steel pipe pile of a marine 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 antirust layer;
a protective layer forming step of forming a protective layer on the outer peripheral side of the plastic layer;
with
The protective layer is made of a corrosion-resistant metal or plastic thin plate,
The thin plate is composed of joint portions at both ends thereof and a body portion other than the joint portions, the joint portions are connected to the body portion, and these are integrally formed,
The joint portion includes a flat portion that is parallel to the radial direction of the cross section in the longitudinal direction and the vertical direction of the steel pipe pile when the thin plate is arranged as the protective layer on the outer peripheral side of the plastic layer, and the and a sloped portion extending from the end of the flat portion located farthest from the steel pipe pile to the outer surface of the body portion, and the contact point between the body portion and the sloped portion is connected, and the There is a space inside the joint,
In the protective layer forming step, the protective layer is fixed by facing the flat portions of each of the two joint portions and fixing the protective layer by piercing and tightening them with screws.
(2) The anticorrosion protection according to (1) above, wherein in the protective layer forming step, the flat portions are opposed to each other, an elastic body is sandwiched between them, and screws are pierced and tightened to fix the protective layer. Construction method.
(3) The above (1) or (2), wherein the thin plate is made of a corrosion-resistant metal, both ends of the thin plate are folded outward, and the leading edge of the joint portion is fixed to the outer surface of the thin plate. Corrosion prevention construction method described.
(4) The anti-corrosion construction method according to any one of (1) to (3) above, wherein a protective layer is formed using two thin plates having joints formed in advance.
(5) The anti-corrosion construction method according to any one of (1) to (4) above, wherein the thin plate has a thickness of 0.3 to 3 mm.
(6) A thin plate used as a protective layer in the anticorrosion method according to any one of (1) to (5) above.

According to the present invention, the protective layer (protective cover) can be securely fastened and fixed, the vicinity of the flange portion is not bent and deformed at the time of fastening, and a gap is not generated. It is possible to provide a corrosion prevention construction method that is less likely to be adversely affected and a thin plate used in the method.

It is a schematic diagram showing a state where the anti-corrosion construction method of the present invention is applied to the outer peripheral surface of the splash body/tidal body of the steel pipe pile of the offshore structure. FIG. 2 is a cross-sectional view (schematic diagram) taken along the line AA in FIG. 1; FIG. 4 is a cross-sectional view (schematic diagram) taken along the line AA in the case of not having an elastic body; FIG. 4 is a cross-sectional view (schematic view) showing the thin plate in FIGS. 1 to 3;

The present invention will be described.
The present invention is a corrosion prevention construction method for preventing corrosion by forming a corrosion prevention layer including a rust prevention layer, a plastic layer and a protective layer on the outer peripheral surface of the splash zone / tidal zone of a steel pipe pile of a marine structure, wherein the steel pipe pile A rust-preventive layer forming step of forming a rust-preventive layer in close contact with the outer peripheral surface of the rust-preventive layer, a plastic layer forming step of forming a plastic layer on the outer peripheral side of the rust-preventive layer, and a protective layer on the outer peripheral side of the plastic layer. and a protective layer forming step, wherein the protective layer is made of a thin plate made of corrosion-resistant metal or plastic, the thin plate is composed of joints at both ends and a main body other than the joints, and the joint is the main body These are integrally formed, and the joint part is a cross section in the longitudinal direction and the vertical direction of the steel pipe pile when the thin plate is arranged as the protective layer on the outer peripheral side of the plastic layer and a sloped portion extending from the end located at the farthest position from the steel pipe pile in the flat portion in the cross section to the outer surface of the main body, and the main body and A contact point with the slant portion is connected, and a space exists inside the joint portion in the cross section. and fixing the protective layer by piercing them with screws and tightening them.

A steel pipe pile (anticorrosion coating) after being subjected to the anticorrosion construction method of the present invention will be described with specific examples (FIGS. 1 to 4).
FIG. 1 is a schematic diagram showing a state in which the anticorrosion construction method of the present invention is applied to the splash zone/tidal zone of a steel pipe pile 1 of a marine structure. Moreover, FIG. 2 is a cross-sectional view taken along line AA, which is a cross-section perpendicular to the longitudinal direction of the steel pipe pile in FIG. Further, FIG. 3 is a sectional view taken along the line A--A in FIG. 1 when there is no elastic body, and FIG. 4 is a schematic sectional view of the thin plate used in the embodiment of FIG. FIG. 4 can also be considered as a diagram in which only the thin plate portion in FIGS. 2 and 3 is taken out. Note that the size of each part in each drawing used to describe the present invention, including FIGS. 1 to 4, may differ from the actual size.

Although the offshore structure is not particularly limited in the present invention, examples thereof include piers and steel pipe piles as foundation piles.
The size of the steel pipe pile is not particularly limited, but the cross-sectional diameter may be, for example, 200 to 10000 mm, 300 to 2000 mm, or 400 to 1800 mm.

As shown in FIGS. 1 to 3, a rust preventive layer 3 is formed so as to adhere to the outer peripheral surface of the steel pipe pile 1. As shown in FIGS. In the specific examples shown in these figures, a plastic layer 5 is formed so as to adhere to the outer peripheral surface of the antirust layer 3, and a protective layer 7 is formed so as to adhere to the outer peripheral surface. .
The anticorrosive layer 3 , the plastic layer 5 and the protective layer 7 constitute the anticorrosive layer 10 .

1-3, the protective layer 7 consists of two thin plates 71 and 72 . Here, the thin plate 71 and the thin plate 72 have the same configuration.

The thin plate 71 is composed of joint portions 710 at both ends thereof and a body portion 711 other than the joint portions 710. The joint portions 710 are connected to the body portion 711, and these are integrally formed.
Also, joint portion 710 includes flat portion 710α and slope portion 710β.
Here, when the thin plate 71 is arranged as the protective layer 7 on the outer peripheral side of the plastic layer 5 as shown in FIGS. It is a portion including a plane parallel to the dotted line CL) shown in FIG. Note that this plane and the dotted line CL shown in FIG. 2 need not be strictly parallel, but should be approximately parallel (for example, the angle formed with the dotted line CL shown in FIG. 2 is approximately 10 degrees or less).
In addition, when the thin plate 71 is arranged as the protective layer 7 on the outer peripheral side of the plastic layer 5, the slope portion 710β is the end that is arranged at the farthest position from the steel pipe pile 1 in the plane portion 710α in FIG. 2 or FIG. and an inclined surface portion 710β extending from the portion ω to the outer surface 711s of the main body portion 711 . The outer surface 711s of the body portion 711 and the slope portion 710β are connected by a contact point φ. Therefore, as shown in FIG. 2 or FIG. 3, a space ρ exists within the cross section of the joint 710 .

The thin plate 72 is similar to the thin plate 71 .
That is, the thin plate 72 is composed of joint portions 720 at both ends thereof and a body portion 721 other than the joint portions 720. The joint portions 720 are connected to the body portion 721, and these are integrally formed.
Also, the joint portion 720 includes a flat portion 720α and a slope portion 7210β.
Here, when the thin plate 72 is arranged as the protective layer 7 on the outer peripheral side of the plastic layer 5 as shown in FIGS. It is a portion including a plane parallel to the dotted line CL) shown in FIG. Note that this plane and the dotted line CL shown in FIG. 2 need not be strictly parallel, but should be approximately parallel (for example, the angle formed with the dotted line CL shown in FIG. 2 is approximately 10 degrees or less).
In addition, when the thin plate 72 is arranged on the outer peripheral side of the plastic layer 5 as the protective layer 7, the slope portion 720β is the end that is arranged at the farthest position from the steel pipe pile 1 in the plane portion 720α in FIG. 2 or FIG. and a sloped portion 720β extending from the portion ω to the outer surface 721s of the main body portion 721 . The outer surface 721s of the body portion 721 and the slope portion 720β are connected by a contact point φ. Therefore, as shown in FIG. 2 or FIG. 3, a space ρ exists within the cross section of the joint 710 .

The inventors of the present application have found that if the joints 710 and 720 have a space ρ, the joints (especially bolts and the like) are less likely to be damaged even if waves or drifting objects collide with the joints. If the space ρ does not exist, it is presumed that when a wave or drifting object collides with the joint, the energy of the collision will concentrate on the bolts, etc., resulting in damage to the bolts, etc.

The method of connecting the body portions (711, 721) and the slope portions (710β, 720β) with the contact φ is not particularly limited. If the thin plate 7 is made of metal, it can be connected by welding. If the thin plate is made of plastic such as FRP, one or both of the plastics at the contact point φ is partially melted and solidified after the main body (711, 721) and the inclined surface (710β, 720β) are brought into contact with each other. Alternatively, the same kind of plastic material melted in advance is attached to the contact point φ, and after the body portions (711, 721) and the slope portions (710β, 720β) are brought into contact with each other, the body portions (711, 720β) are solidified. 721) and the slope portions (710β, 720β) can be connected by a contact φ.

The height of the plane portions (710α, 720α) in the cross-sectional view shown in FIG. 2 or FIG. , The distance (L1 in FIGS. 2 and 3) from the position closest to the steel pipe pile 1 to the farthest position (end ω) in the plane portion 720α in the cross section shown in FIG. 2 or 3 is 30 to 60 mm. is preferred, and 40 to 50 mm is more preferred.
In addition, the linear distance (L2 in FIGS. 2 and 3) from the position closest to the steel pipe pile 1 in the plane portions (710α, 720α) to the tip of the inclined portion is preferably 50 to 300 mm, and is about 100 mm. is more preferable.

Further, the thin plates 71 and 72 are made of corrosion-resistant metal, and both ends thereof face outward (as shown in FIGS. ), and the tips of the slanted portions 710β and 720β are connected and fixed to the outer surfaces 711s and 721s of the main body portions 711 and 721 at a contact point φ, thereby forming the joint portions 710 and 720 .

Then, as shown in FIG. 2, the planes of the plane portions (710α, 720α) of the two joint portions (710, 720) face each other, and are pierced with screws 9 and tightened with nuts. is fixed. Here, it is preferable that a gap of 5 to 40 mm (preferably about 20 mm) exists between the flat surfaces. This is to absorb the tolerance of the steel pipe pile diameter.

Here, as shown in FIG. 2 , the planes of the plane portions (710α, 720α) of the two joint portions (710, 720) are opposed to each other, and the elastic body 8 is sandwiched between them. is preferred. When the elastic body 8 is present, the flat portion 710α, the elastic body 8 and the flat portion 720α are penetrated by the screw 9 and are tightened and fixed using the nut.

In addition, on the steel pipe pile 1 side of the joints (710, 720) (more specifically, on the side of the steel pipe pile 1 closest to the steel pipe pile 1 in the plane portions (710α, 720α)), the joints (710, 720 ) is preferably arranged so as to be in contact with the backing plate 6 . If the elastic body 8 shown in FIG. 3 is not present, it is preferable to arrange the backing plate 6 at such a position.
The backing plate 6 plays a role of preventing seawater from directly entering the steel pipe pile main body from the vicinity between the flat portions of the protective layer.

The material of the backing plate 6 is not particularly limited, and may be the same material as the thin plate, for example.
The thickness of the backing plate 6 is also not particularly limited, and may be the same thickness as the thin plate, for example.
The size of the backing plate 6 is also not particularly limited. For example, the length in the width direction (the direction parallel to L2) in FIG. 3 is preferably 50 to 300 mm, more preferably about 100 mm.

As shown in FIG. 1 , a pedestal 50 is provided under the anticorrosion layer 10 and below the tidal zone of the steel pipe pile 1 . The pedestal 50 has a plastic plate 52 on the top and a steel sleeve 51 on the bottom, and the anti-corrosion layer 10 is placed on the pedestal 50 . In this case, the protective layer 7 (the thin plates 71 and 72) and the steel pipe pile 1 are not electrically connected.

The antirust layer forming step of the present invention will be described.
In the antirust layer forming step of the present invention, an antirust layer is formed so as to adhere to the outer peripheral surface of the steel pipe pile.
The rust-preventive layer is not particularly limited, and conventionally known ones can be used. A rust preventive layer can be formed by winding this around the outer peripheral surface of the steel pipe pile.
During construction, for example, deposits on the surface of steel pipe piles are removed, the surface is adjusted by sandblasting, etc., petrolatum paste is applied, and a petrolatum-impregnated tape is tightly wrapped around it to form a rust prevention layer. preferable.

Although the thickness of the antirust layer is not particularly limited, it is preferably 2 to 5 mm, more preferably 2.5 to 3.5 mm.

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 antirust layer. One or more other layers (for example, a waterproof sheet) may be formed on the outer peripheral surface of the antirust layer, and a plastic layer may be formed on the outer peripheral surface thereof, but the plastic layer is closely attached to the outer peripheral surface of the antirust layer. You may form a plastic layer like this.
Preferably, the plastic layer is a foamed plastic layer. For example, foamed plastic made of commercially available polyethylene foam having a large number of pores communicating in three-dimensional directions can be used.
A plastic layer can be formed by winding a belt-like sheet made of plastic around the outer peripheral side of the antirust layer.

Although the thickness of the plastic layer is not particularly limited, it is preferably 3 to 15 mm, more preferably 5 to 8 mm.

In addition, during construction, a thin plate with a plastic sheet such as foamed polyethylene attached to one side is prepared in advance, and the plastic sheet is placed inside and wrapped around the outer periphery of the anticorrosion layer. It is preferable because the protective layer can be easily formed at the same time.

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 is formed on the outer peripheral side of the plastic layer.
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. is preferred.

The protective layer consists of a sheet of corrosion-resistant metal or plastic.

Here, since the corrosion-resistant metal that constitutes the thin plate has extremely excellent corrosion resistance in seawater, it will not be damaged by corrosion even if it is used for a long period of time.
Corrosion-resistant metals are not particularly limited. For example, corrosion-resistant metals include titanium, titanium alloys, and stainless steel, with titanium or titanium alloys being preferred.
A thin plate made of corrosion-resistant metal having a plate thickness of 0.3 to 3.0 mm, preferably 0.6 to 1.0 mm, is light in weight, and in this case, it is preferable because it is easy to handle during construction. Moreover, even if the thickness is as thin as this, the strength of the joints is high, so it is difficult to break even if there is an impact from waves or drifting objects.

Moreover, the plastic constituting the thin plate may be any material as long as it has excellent corrosion resistance in seawater. Examples of such plastic include FRP and APC.
As the plastic thin plate, a plate thickness of 2 to 5 mm, preferably 2 to 3 mm is light, and in this case, it is preferable because it is easy to handle during construction.

In the present invention, it is preferable to prepare two thin plates having joints formed in advance, as shown in FIG. 4, and use them to form the protective layer. As shown in FIG. 4, the thin plate is preferably configured in a semicircular shape (arcuate shape) so as to fit the shape of the steel pipe pile to which it is fixed as a protective layer.

A specific example of a method of forming a protective layer using such two thin plates will be described below.

Thin plates 71 and 72 shown in FIG. 4 are arranged on the outer peripheral side of the plastic layer 5 formed in the plastic layer forming process described above.
Then, the plane portions (plane portion 710α and plane portion 720α) of the two joint portions (joint portion 710 and joint portion 720) are opposed to each other. It is preferable that the width between the flat portions is about 20 mm. Here, it is preferable to sandwich the elastic body 8 between them. Moreover, when the elastic body 8 is not used, it is preferable to arrange a backing plate as shown in FIG. A backing plate may be arranged when the elastic body 8 is used.

The elastic body 8 is preferably silicone rubber. In addition, EPDM or the like can also be used.
As for the size of the elastic body 8, for example, the thickness (the length in the width direction (the direction parallel to L2) in FIG. 2) may be 20 mm.

A screw 9 is passed through the plane portion 710α and the plane portion 720α, and a nut is used to fasten and fix them. When an elastic body is used, a screw 9 is inserted through the flat portion 710α, the elastic body 8 and the flat portion 720α with the flat portion 710α and the flat portion 720α sandwiching the flat portion 710α and the flat portion 720α. .
Here, the screw 9 and the nut are inserted into the space ρ inside the joint through the hole γ formed in the inclined portions (710β, 720β), and are tightened and fixed using a tool or the like.
The shape and size of the hole γ should be such that the screw 9 and the nut can be put into the space ρ, and the work can be done after putting the tool for tightening the screw 9 and the nut into the space ρ. is not particularly limited.

The screw and nut are preferably made of the same material as the aforementioned thin plate. That is, it is preferably made of corrosion-resistant metal or plastic.

The holes γ are preferably formed in the inclined portions (710β, 720β) at regular intervals. Specifically, it is preferably formed every 100 to 200 mm.

1 steel pipe pile 3 antirust layer 5 plastic layer 7 protective layer 71 thin plate 710 joint portion 710α plane portion 710β slope portion 711 body portion 711s outer surface 72 thin plate 720 joint portion 720α plane portion 720β slope portion 721 body portion 721s outer surface 50 pedestal 51 sleeve 52 plate 6 backing plate ω edge φ contact point ρ space 8 elastic body 9 screw

Claims (6)

A corrosion prevention construction method for preventing corrosion by forming a corrosion prevention layer including a rust prevention 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 a marine 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 antirust layer;
a protective layer forming step of forming a protective layer on the outer peripheral side of the plastic layer;
with
The protective layer is made of a corrosion-resistant metal or plastic thin plate,
The thin plate is composed of joint portions at both ends thereof and a body portion other than the joint portions, the joint portions are connected to the body portion, and these are integrally formed,
The joint portion includes a flat portion that is parallel to the radial direction of the cross section in the longitudinal direction and the vertical direction of the steel pipe pile when the thin plate is arranged as the protective layer on the outer peripheral side of the plastic layer, and the and a sloped portion extending from the end of the flat portion located farthest from the steel pipe pile to the outer surface of the body portion, and the contact point between the body portion and the sloped portion is connected, and the There is a space inside the joint,
In the protective layer forming step, the protective layer is fixed by facing the flat portions of each of the two joint portions and fixing the protective layer by piercing and tightening them with screws. 2. The anti-corrosion construction method according to claim 1, wherein in said protective layer forming step, said flat portions are opposed to each other, an elastic body is sandwiched between them, and screws are pierced and tightened to fix said protective layer. 3. The anti-corrosion construction method according to claim 1 or 2, wherein said thin plate is made of a corrosion-resistant metal, both ends of which are folded outward, and the tip portion of which has said joint portion fixed to the outer surface of said thin plate. The anti-corrosion construction method according to any one of claims 1 to 3, wherein a protective layer is formed using two said thin plates having said joints formed in advance. The anti-corrosion construction method according to any one of claims 1 to 4, wherein the thin plate has a thickness of 0.3 to 3 mm.
A thin plate used as a protective layer in the anticorrosion construction method according to any one of claims 1 to 5.

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