JP7135971B2 - Heavy-duty corrosion-resistant steel pipe sheet pile and its manufacturing method - Google Patents

Description

TECHNICAL FIELD The present invention relates to a heavy-duty corrosion-resistant steel pipe sheet pile coated with a urethane resin as a corrosion-resistant layer on the outer surface, and a method for manufacturing the same.

Steel pipe piles and steel pipe sheet piles used in severe marine corrosive environments are applied with a heavy anti-corrosion coating using a thick urethane resin of 2 mm or more from the viewpoint of corrosion resistance reliability. A urethane resin coating film is generally formed by spray coating a two-component urethane resin composition prepared by mixing a main agent containing various polyols and a curing agent mainly composed of an aromatic isocyanate without a solvent. formed by Since this urethane resin composition has a high viscosity and a high curing speed, it is possible to apply a thick coating of 2 mm or more in one coating. Therefore, in addition to steel pipe piles, it can also be applied to steel pipe sheet piles with complicated shapes.
A highly reliable anticorrosive layer requires that even if scratches occur in the anticorrosive layer due to some external force, these scratches do not reach the steel material, but this urethane resin anticorrosive layer is excellent in impact resistance and scratch resistance. Therefore, it is a standard anti-corrosion method in Japan. However, urethane resin heavy anti-corrosion coated steel requires surface treatment, coating equipment, and coating technology, so it is mainly produced in well-equipped factories.

Urethane resin heavy-duty anti-corrosion coating needs to be compatible with various coastal environments in Japan, and performance in various environments from low temperature to high temperature is required. However, in areas south of Okinawa where the corrosive environment is severe, corrosion is more intense in scratches and exposed steel parts such as the edges of the paint film, so peeling of the paint film starting from the scratches and edges is greater than in other areas. . However, since the damaged part can be repaired, steel pipe piles that do not have exposed ends of steel material in the severely corroded splash and tidal areas do not pose any major problems even when used in areas south of Okinawa.
Steel pipe sheet piles, on the other hand, have claws welded to the outer surface of the steel pipe (pile) to connect the steel pipe (pile) to the steel pipe (pile) in the direction perpendicular to the driving direction of the pile. It is a product that has both self-supporting and water stopping properties. Steel pipe sheet piles are classified into LT type, PP type, and PT type depending on the shape of the claws, and these are defined in JIS A5530 "Steel pipe sheet pile". -T form.

In Fig. 1, the LT type has two claws with an L-shaped cross section, which are arranged symmetrically with a gap that allows the T claws to be fitted, and the end of the upper part of the L is welded to a steel pipe (pile). It is composed of an L-claw 2 that is a female claw that is attached and a T-claw 3 that is a male claw that is T-shaped and has the lower end of the T welded to a steel pipe (pile).
If this LT type is coated with urethane resin, the current state will be as shown in FIG.
Therefore, some countermeasures are required for steel pipe sheet piles in which the exposed steel material is formed at the end of the coating film.
Similarly, for steel sheet piles with paint film ends, the coating specifications have been changed to a highly durable type that uses heat coating, but steel pipe sheet piles are painted the same as steel sheet piles, partly because they are difficult to heat. Specifications are difficult. In particular, it was difficult to paint the claw-fitting portion, which is the end portion of the coating film, due to its complicated shape, so the anti-peeling performance could not be improved. For this reason, there has been a demand for a technique for suppressing peeling from the edge of the coating film in steel pipe sheet piles, which can also be used in southern regions.

As shown in Patent Document 1, urethane resin coating on steel pipe sheet piles is generally performed from the outer surface using a spray gun after blasting. With this painting method, there is no problem with the steel pipe main body, but since blasting or painting cannot be performed on the inside of the fitting claw, there is a risk of corrosion peeling from the unpainted portion.
On the other hand, Patent Document 2 proposes a method of blasting and painting the steel pipe main tube portion inside the L claw of the steel pipe sheet pile, and the steel material of the steel pipe portion can be protected from corrosion even inside the claw. However, since it is difficult to coat the back surface from the edge surface of the nail with this method, corrosion occurs at the edge of the anticorrosive layer of urethane resin. For this reason, during long-term use, delamination progresses from the edge of the urethane resin coating that is in contact with the exposed steel material due to alkali generation due to electrical coupling between the corroded portion and the bottom of the coating.

Japanese Patent No. 1911901 Japanese Patent No. 1975122

The object of the present invention is to provide a coating specification that can suppress peeling of the coating film from the end of the urethane resin layer of the nail fitting part of the steel pipe sheet pile even in a severe corrosive environment such as the southern ocean area south of Okinawa. To provide a heavy corrosion-resistant steel pipe sheet pile and a method for manufacturing the same.

The gist of the present invention is as follows.
If corrosion occurs in the steel material exposed portion at the urethane resin-coated end, the cathodic portion of the macro-corrosion will be under the urethane resin coating, and cathodic detachment from the coating film end will occur. In order to improve the peeling resistance of the peeled edge of the urethane resin layer, it is effective to apply some kind of coating from the edge to prevent water from entering from the edge and to keep the steel corrosion site (anode) away. be.
However, until now, with steel pipe sheet piles, the claw-fitting portion had been painted after the claw was welded. It was in a lingering state. As a result, there is a problem that the durability of steel pipe sheet piles is not as good as that of steel pipe piles that do not have painted ends in the splash to tidal zone.

Since there was no realistic method of blasting the inside of the claw and coating the inside of the claw including thickness control, the present invention investigated a new method of providing a painted portion even inside the claw. As a result, in FIG. 3, it is effective to manufacture a pawl member having an epoxy resin layer 5 formed in advance on the part that will become the pawl interior, and then weld the parts 6 and 7 of this pawl member to the steel pipe (pile). I found
The two-liquid curing type epoxy resin used for coating the inside of the nail is hard and brittle, and therefore has poor impact resistance. On the other hand, the two-liquid curing type epoxy resin is excellent in heat resistance and scratch resistance, and is resistant to frictional heat and scratches during driving of steel pipe sheet piles, so epoxy resin coating is most suitable for coating the inside of nails. In addition, although the two-component curing type epoxy resin takes time to harden at room temperature, this method has the advantage that the welding process is performed after coating, and the welding heat accelerates the curing of the two-component curing type epoxy resin. Furthermore, since this method coats the claw members before welding, sufficient blasting and film thickness control of the coating are possible.

The coating range of the two-liquid curing type epoxy resin paint on the nail portion of the heavy corrosion-resistant steel pipe sheet pile of the present invention is the inside of the nail after nail welding, so it is difficult to paint the urethane resin. For example, in FIG. 3, it is the epoxy resin layer 5 on the inner side of the L for the L nail, and on the back side and the rising portion of the T for the T nail. However, since the steel pipe is welded in the longitudinal direction, the paint is not applied for at least 2 cm from the ends to be welded 6 and 7, where resin deterioration is expected due to the great influence of welding heat.
The urethane resin coating of the present invention must be applied so as to be continuous with the previously applied epoxy resin coating so as not to generate exposed steel parts. As a result, the urethane resin layer and the epoxy resin layer of the claw portion are continuously formed, so that peeling from the end portion of the urethane resin layer can be prevented. FIG. 4 shows an example of a partial cross-sectional view of the heavy-duty corrosion-resistant steel pipe sheet pile of the present invention in which the urethane resin layer 4 and the epoxy resin layer 5 are continuously formed at the claw portion.

By the above coating method, the urethane resin layer and the epoxy resin layer are formed continuously. method) is effective. FIG. 5 shows an example of a partial cross-sectional view of the heavy-duty corrosion-resistant steel pipe sheet pile of the present invention, in which the urethane resin layer 4 is partially overlapped with the epoxy resin layer 5 at the nail portion.
However, although this method is highly effective, it is necessary to ensure that the coating is repeated without variation, so control during manufacturing at the factory is important.

In many cases, it is actually difficult to form the urethane resin layer and the epoxy resin layer continuously without variation, and in particular, there are cases where the layers are not formed continuously at the ends of nails. Therefore, as a method of improving the continuity at the edge of the nail, these problems can be solved by applying seal coating 9 to the boundary between the urethane resin layer 4 and the epoxy resin layer 5 . FIG. 6 shows an example of a partial cross-sectional view of the heavy-duty corrosion-resistant steel pipe sheet pile of the present invention, in which the urethane resin layer 4 and the epoxy resin layer 5 are continuously formed at the claw portion and the boundary portion between them is seal-coated.
Epoxy resin paint is used as the paint used for the seal coating in consideration of corrosion resistance and adhesion between the urethane resin layer and the epoxy resin layer. As a result, even if the continuity between the urethane resin layer and the epoxy resin layer is insufficient, it is complemented by the seal layer, and a heavy corrosion-resistant steel pipe sheet pile having excellent corrosion resistance and peeling resistance can be formed.

Industrially, in consideration of variations in coating in the factory, the size of the labor involved in the work, restrictions on the work time, etc., the above-mentioned normal continuous coating method, the urethane resin layer is partially overcoated with the epoxy resin layer. It is important to select a combination of methods and seal coating methods for each factory.

According to the above aspect of the present invention, even in a severe corrosive environment in marine areas south of Okinawa, it is possible to significantly reduce steel material corrosion in the vicinity of the end of the coating film in the claw-fitting portion of the steel pipe sheet pile. . As a result, delamination from the urethane resin layer ends due to corrosion is suppressed, and steel pipe sheet piles can be handled in the same way as steel pipe piles. can do. In addition, it is possible to greatly improve the reliability even if it is applied to the conventional application sea area.

Sectional view of an LT-shaped claw fitting portion of a steel pipe sheet pile to which the present invention can be applied Partial cross-sectional view of LT-type heavy-duty corrosion-resistant steel pipe sheet piles coated with conventional urethane resin An example of a cross-sectional view of a claw member for a steel pipe sheet pile according to the present invention, in which an epoxy resin coating is applied to the portion that will become the inside of the claw before welding. An example of a partial cross-sectional view of the heavy-duty corrosion-resistant steel pipe sheet pile of the present invention in which a urethane resin layer and an epoxy resin layer are continuously formed in the claw portion An example of a partial cross-sectional view of a heavy-duty corrosion-resistant steel pipe sheet pile of the present invention in which a urethane resin layer is partially overlaid (overlapped) on an epoxy resin layer in the nail portion An example of a partial cross-sectional view of the heavy-duty corrosion-resistant steel pipe sheet pile of the present invention, in which a urethane resin layer and an epoxy resin layer are continuously formed in the claw portion, and seal coating is applied to the boundary between them.

Steel pipe sheet piles have various claw shapes such as LT type, PP type, PT type, and other Super Junction (LL) types defined in JIS A5530 “Steel pipe sheet piles”. In the conventional method of applying urethane coating from the outside surface after welding the mating claw to the steel pipe, it was not possible to apply urethane resin coating to the inside or back of the claw regardless of the shape of the claw. The edge of the nail with a crack was the edge of the urethane resin coating. In addition, rust-removal blasting treatment of the steel material tends to be insufficient at the nail end, and it is difficult to prevent paint film peeling from the nail due to macro-corrosion current due to corrosion of the end part paint adhesion and steel material exposed part.
Therefore, by changing the coating specification of the nail member used when forming the conventional steel pipe sheet pile, the coating specification that can greatly suppress the peeling from the urethane resin layer edge has been realized.

The nail shape of the steel pipe sheet pile to which the present invention can be applied requires that the inside of the nail after welding be painted before welding. Therefore, except for the PP and PT types, which are difficult to paint even before welding, the present invention mainly targets shapes that can be easily blasted and painted before welding, such as the LT type. . FIG. 1 shows a cross-section of the claw fitting portion of the LT type.
Next, the claw members for corrosion-resistant steel pipe sheet piles used in the present invention are coated by the following method.

In the L-claw or T-claw, blasting is performed on the part where the joint shape of the steel pipe sheet pile will be the inside of the claw after claw welding. Since the external portion is blasted after nail welding, no further treatment is required at this point. Check the coating control conditions (roughness, temperature, dew point, amount of salt deposit, etc.) after blasting. After that, an epoxy resin paint is applied with a thickness of 100 to 500 μm. If the thickness is less than 100 μm, coating defects tend to occur. Further, the epoxy resin paint has a high anticorrosion property, and there is no need to paint over 500 μm. The coating range of the epoxy resin coating is the portion of the epoxy resin layer 5 in FIG. If the coating is applied within 2 cm of the edges 6 and 7 to be welded, there is a possibility of burning, so it is necessary to avoid coating within 2 cm.
A two-liquid curing type is suitable for the epoxy resin coating, and as the epoxy resin component, bisphenol A or F type is used as the main agent, and an amine-based curing agent is used. Extender pigments such as silica, titanium oxide, calcium carbonate, talc and iron oxide are added to the resin component in an amount of 5 to 50% by weight as inorganic pigment components. Moreover, you may add the antirust pigment which mainly consists of a phosphoric acid compound and a zinc compound. Carbon black can also be used as a coloring pigment. For coating, known methods such as brush coating, roller coating, and spray coating are used.
As a result, a claw member for a heavy-duty corrosion-resistant steel pipe sheet pile coated with the two-liquid curing type epoxy resin paint of the present invention can be manufactured.
FIG. 3 shows an example of a cross-sectional view of a claw member for a steel pipe sheet pile according to the present invention, in which an epoxy resin coating is applied to the portion that will become the inside of the claw before welding.

A steel pipe sheet pile is formed by welding the nail member for a heavy corrosion-resistant steel pipe sheet pile coated with the two-liquid curing type epoxy resin paint to a steel pipe. A blasting treatment is performed on the outer surface of the steel pipe sheet pile to which the claw members are welded. After that, a primer is applied by spray coating so that the dry film thickness is 30 to 150 μm. This range is suitable because if the thickness is less than 30 μm, the anti-corrosion property is insufficient, and if the thickness is greater than 150 μm, the adhesiveness decreases.
After applying the primer, apply the urethane resin layer. The urethane resin paint used for the urethane resin layer includes conventionally known paints, for example, Permagard R137, Permagard R250, Permagard R601, Permagard R901, MACFLEX107, MACFLEX109 (manufactured by Daiichi Kogyo Seiyaku Co., Ltd.). , Mizeron (manufactured by Nippon Paint Anticorrosion Coatings Co., Ltd.), Elast #92 (manufactured by Nihon Paint Chemical Co., Ltd.), and other urethane resin paints. These paints are based on castor oil, polybutadiene, various epoxy-modified polyols, etc., and use isocyanates such as crude MDI as curing agents.The viscosity and curing speed are adjusted in order to spray paint several millimeters thick. It is what I did.
The urethane resin layer is adjusted to have a thickness of 2 to 5 mm. If the thickness is 2 mm or less, the scratch resistance and corrosion resistance are poor, and if the thickness exceeds 5 mm, low-temperature peeling increases due to coating film stress.

The urethane resin layer is applied so as to be continuous with the pre-applied epoxy resin coating such as the back surface of the nail. As a result, since there is no corroded portion of the steel material beside the urethane resin layer end portion, peeling of the urethane resin layer end portion can be suppressed. FIG. 4 shows an example of a partial cross-sectional view of the heavy-duty corrosion-resistant steel pipe sheet pile of the present invention in which the urethane resin layer 4 and the epoxy resin layer 5 are continuously formed at the claw portion.
The urethane resin layer and the epoxy resin layer are continuously formed by the above coating, but industrially, it is necessary to consider variations, so the urethane resin layer is partially overcoated (overlapped) on the epoxy resin layer. ) method is valid. FIG. 5 shows an example of a partial cross-sectional view of the heavy-duty corrosion-resistant steel pipe sheet pile of the present invention, in which the urethane resin layer 4 is partially overlapped with the epoxy resin layer 5 at the nail portion.
This method has the advantage of saving labor in the factory, but it is necessary to apply coatings in layers.

However, in reality, it is often difficult to form the urethane resin layer and the epoxy resin layer continuously without variation, and in particular, there are cases where the layers are not formed continuously at the ends of nails. Therefore, as a method of improving the continuity at the edge of the nail, these problems can be solved by applying seal coating 9 to the boundary between the urethane resin layer 4 and the epoxy resin layer 5 . FIG. 6 shows an example of a partial cross-sectional view of the heavy-duty corrosion-resistant steel pipe sheet pile of the present invention, in which the urethane resin layer 4 and the epoxy resin layer 5 are continuously formed at the claw portion and the boundary portion between them is seal-coated.
Epoxy resin paint is used as the paint used for the seal coating in consideration of corrosion resistance and adhesion between the urethane resin layer and the epoxy resin layer. As a result, even if the continuity between the urethane resin layer and the epoxy resin layer is insufficient, it is complemented by the seal layer, and a heavy corrosion-resistant steel pipe sheet pile having excellent corrosion resistance and peeling resistance can be formed.

A heavy corrosion-resistant steel pipe sheet pile according to an embodiment of the present invention will be described in detail below.
Steel pipe sheet piles applied to the present invention are mainly JIS A5530 steel pipe sheet piles (outer diameter 500A to 2000A, plate thickness 9 to 25 mm), but are not particularly limited to this standard.
Next, Fig. 1 shows the claw shape of the steel pipe sheet pile according to the embodiment of the present invention. FIG. 1 is a partial cross-sectional view of an LT shape, in which an L-shaped claw 2 and a T-shaped claw 3 are welded to a steel pipe 1, which are connected during driving.
The LT type will now be described in detail.
The LT-shaped claws are composed of L-claws and T-claws that are combined with each other.
The T-claw 3 has a base end portion 31 and an engaging portion 32 . The base end portion 31 is provided so as to project outward from the outer surface of the steel pipe 1 along the radial direction of the steel pipe 1, and the bottom portion is welded to the outer surface of the steel pipe. The engaging portion 32 is provided so as to extend to both sides in a direction orthogonal to the base end portion 31 from the protruding tip of the base end portion.
The L-claw 2 engages with the T-claw 3 by combining two L-claws 2 . The L claw is composed of a first side 21 forming one side of the L shape and a second side 22 forming the other side. The first side 21 protrudes outward from the outer surface of the steel pipe 1 and is welded to the outer surface of the steel pipe 1 at its bottom. The second side 22 extends from the upper end of the first side 21 in a direction orthogonal to the first side 21 . The two L-claws 2 are provided on the outer surface of the steel pipe 1 so that the second sides 22 face each other, and form engaged portions.
The T-claw 3 and the L-claw 2 are engaged by inserting the engaging portion 32 of the T-claw 3 into the second sides 22 of the two L-claws 2 .

In the present invention, a two-liquid curing type epoxy resin paint is applied to the rear surface of the claw member before welding. At that time, as a preliminary surface treatment, sand, alumina, grid, or blasting using shot is performed to remove scales, contaminants, etc. on the surface of the steel material. Then apply epoxy resin paint. For painting, as shown in FIG. 3, after masking with tape a portion of 2 cm from the ends 6 and 7 to be welded, a two-liquid curing type epoxy resin paint is spray-coated with a target thickness of 300 μm. NS Pile Primer manufactured by Nichinuri Kagaku Co., Ltd. was used for this two-liquid curing type epoxy resin coating. As a result, L claws and T claws of the coated claw members for heavy corrosion-resistant steel pipe sheet piles of the present invention were manufactured.

The claw member was axially welded to the outer surface of a 600A spiral steel pipe to produce a steel pipe sheet pile. The temperature of the epoxy resin layer 5 rises to 100° C. or higher due to the welding heat when the claw member is welded to the spiral steel pipe. .
Next, the outer surface of the steel pipe sheet pile main pipe and claw portion was blasted by an impeller blasting device using a grid to achieve a degree of rust removal of Sa2.1/2 or more. Apply primer after blasting. The primer layer contains at least one selected from the group consisting of urethane resins and epoxy resins, and was spray-coated with an R primer manufactured by Nippon Paint Anti-corrosion Coatings Co., Ltd. with a target thickness of 50 μm. After curing for 3 hours, Mizeron urethane resin paint manufactured by Nippon Paint Anti-Corrosion Coatings Co., Ltd. was applied with an airless high-pressure spray coating machine, aiming at 3 mm or more on the steel pipe surface and 2 mm or more on the nail.

FIG. 2 is a partial cross-sectional view showing a conventional coating form in which a urethane resin layer 4 is coated from the outer surface of a steel pipe sheet pile having LT-shaped claws. Since it is difficult to paint the back surface of the T-claw or the inside of the L-claw in the conventional method, the coated end of the urethane resin layer is formed at the end of the nail. As a result, the non-coated portion corrodes and peels off easily.
On the other hand, FIG. 4 is an example of a partial cross-sectional view of a heavy corrosion-resistant steel pipe sheet pile according to the present invention in which a urethane resin layer 4 is coated from the outer surface after welding the coated nail member for heavy corrosion-resistant steel pipe sheet pile shown in FIG. 3 to the steel pipe 1. The urethane resin layer 4 is formed continuously with the epoxy resin layer 5. As a result, the edge of the urethane resin layer disappears, and peeling from the edge, which is the greatest weak point of the coating film, can be prevented.

The edge of the urethane resin layer can also be completely eliminated by a method of partially coating (overlapping) the urethane resin layer 4 on the epoxy resin layer 5 . Specifically, as shown in FIG. 5, a member coated with an epoxy resin layer over a slightly wider range than that shown in FIG. This situation is illustrated in FIG. The urethane resin layer 4 is overcoated completely over the edge of the epoxy resin layer 5, completely eliminating the continuous edge.
This method is an industrially excellent manufacturing method, but it is essential to ensure that the coating is overlaid. It is important to establish and control during painting.

Further, seal coating is applied to the boundary between the urethane resin layer 4 and the epoxy resin layer 5 which are continuously formed. The seal painting range is a slightly wider part so as to cover the end side that is not welded for the L claw, and for the T claw, a slightly wider part so as to cover the end side in the lateral direction of T as described above. , the welding side is a portion that covers the intersection of the rising portion of the T claw and the direction portion of T.
FIG. 5 is an example of a cross-sectional view of a heavy-duty corrosion-resistant steel pipe sheet pile of the present invention in which seal coating 9 is applied to the boundary between the urethane resin layer 4 and the epoxy resin layer 5 after the urethane resin layer 4 of FIG. 4 is formed. For the seal coating, it is appropriate to use an epoxy paint with excellent adhesion for both the urethane resin layer 4 and the epoxy resin layer 5, and the NS pile primer was applied by brush coating to a film thickness of 100 μm or more.
As a result, the edges of the urethane resin layer can be completely eliminated, and long-term durability can be maintained even under severe conditions.

As described above, in the present invention, the urethane resin layer and the epoxy resin layer are continuous, the urethane resin layer partially overlaps the epoxy resin layer to form a continuous coating film, and the continuous boundary surface There are three types: one in which a sealant is applied to the
Heavy corrosion-resistant steel pipe sheet piles can be manufactured using only one of these methods, but these three methods can be used in combination in consideration of variations in the coating of the manufacturing plant, the size of the labor involved in the work, the restrictions on the work time, etc. can do
For example, both ends of the T-claw and the end of the L-claw are coated with a sealant, and the welded end of the T-claw and the welded end of the L-claw are a continuous urethane resin layer and epoxy resin layer. can be considered.

Provided is a heavy-duty anti-corrosion steel pipe sheet pile that prevents anti-corrosion coating from peeling off from claws over a long period of time even under extremely severe corrosive environments such as the southern ocean.

1 steel pipe 2 L claw of steel pipe sheet pile fitting portion 21 first side of L claw 22 second side of L claw 3 T claw of steel pipe sheet pile fitting portion 31 base end of T claw 32 engaging portion of T claw 4 urethane resin layer 5 Epoxy resin layer 6 Welding planned end of T claw 7 Welding planned end of L claw 9 Seal painted part with epoxy paint

Claims (7)

A steel pipe sheet pile in which claws for connecting steel pipe piles in a direction perpendicular to the driving direction of the piles are formed by welding on the outer surface of the steel pipe, and the cross-sectional shape of the steel pipe sheet pile is a T-shaped male claw. In the LT-shaped claw of JIS A5530 “Steel pipe sheet pile”, which is composed of a T-claw and an L-shaped claw that is a female claw in which two L-shaped claws are arranged symmetrically, the lateral part of the T-claw Back side (the side where the vertical part of the T is formed), the front side of the horizontal part of the T nail, and the steel pipe welding of the vertical part of the T nail continuously to the epoxy resin layer coated on the vertical part of the T nail and the inner part of the L nail. A heavy-duty corrosion-resistant steel pipe sheet pile, characterized in that a urethane resin layer is coated on the neighboring part and the outer part of the L-claw. 2. The heavy-duty corrosion-resistant steel pipe sheet pile according to claim 1, wherein the urethane resin layer partially overlaps and is continuous with the epoxy resin layer in the claw portion. 3. The heavy duty steel pipe sheet pile according to claim 1, wherein a sealant is applied to a boundary portion where the urethane resin layer and the epoxy resin layer are continuous in the claw portion. 4. The method according to any one of claims 1 to 3, wherein after blasting, a claw member is pre-coated with a two-liquid curing type epoxy resin paint, and the claw member is welded to the steel pipe. A method for manufacturing the heavy-duty corrosion-resistant steel pipe sheet pile according to the above item. The claw member is welded to a steel pipe to form a claw portion, and the outer surface of the steel pipe including the claw portion is subjected to blasting, primer coating, and urethane resin coating to form a continuous urethane resin layer on the epoxy resin. The method for manufacturing a heavy-duty corrosion-resistant steel pipe sheet pile according to claim 4, characterized in that: When the urethane resin layer is formed by blasting, primer coating, and urethane resin coating on the outer surface including the claw portion, the urethane resin layer is partially overlaid on the epoxy resin layer, and the urethane resin layer and the epoxy resin layer are coated. 6. The method for manufacturing a heavy-duty corrosion-resistant steel pipe sheet pile according to claim 5, characterized in that the coating film is continuous. 7. The method for manufacturing a heavy-duty corrosion-resistant steel pipe sheet pile according to claim 5, further comprising applying a sealant to a continuous boundary between said urethane resin layer and said epoxy resin layer.

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