JP2014025551A - Pipe line constituent member subjected to outer surface anticorrosion coating and method for manufacturing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a pipe line constituent member subjected to outer surface anticorrosion coating which can obtain anti-corrosion performance markedly superior than the conventional pipe line constituent member subjected to outer surface coating by forming a pseudo alloy coating film, a pore-sealing treatment coating film and a synthetic resin coating film on an outer surface of a pipe line constituent member such as a metal pipe or valve of cast iron, iron or the like, therefore, can maintain high anti-corrosion performance over a long period and, because of the high anti-corrosion performance, makes the covering of polyethylene sleeve or the like unnecessary and improves the on-site constructibility markedly, and to provide a method for manufacturing the pipe line constituent member subjected to outer surface anticorrosion coating.SOLUTION: A pipe line constituent member subjected to outer surface anticorrosion coating includes: a cast iron pipe main body 1; a pseudo alloy coating film 2 formed by arc spraying using a spraying wire made of zinc and a spraying wire made of aluminum-magnesium-silicon alloy; a pore-sealing treatment coating film 3 formed on the pseudo alloy coating film 2; and a synthetic resin coating film 4 formed on the pore-sealing treatment coating film 3.

Description

  The present invention relates to a pipe component having an anti-corrosion coating on the outer surface and a manufacturing method thereof, in particular, a pseudo alloy film is formed on the outer surface of the pipe component member main body, and a sealing treatment film is formed on the pseudo alloy film. Further, the present invention relates to a pipe component such as a cast pipe or a metal pipe or a valve made of a synthetic resin film formed on a sealing treatment film, and a manufacturing method thereof.

  2. Description of the Related Art In pipes and valves, which are conventionally used for pipes for water supply or sewerage, etc., and used as metallic pipe components such as cast iron or iron with external coating, external coating is generally used for pipes. In this case, it is composed of a zinc rich paint or a zinc coating as a primer formed to a thickness of about 20 to 30 μm by thermal spraying, and an acrylic resin paint applied to the thickness of about 80 μm as a primer coating. Yes. On the other hand, in the case of a valve, it consists of a powder coating of epoxy resin coated to a thickness of 150 μm or more.

  However, in the case of pipes, the above exterior coating can only be expected to prevent the occurrence of red rust from the pipe outer surface during the storage period until construction, and if the pipe is buried underground for a long period of time, the pipe will be shortened depending on the soil environment. In some cases, it corroded in the middle, and the life of the outer surface coated tube was completed.

  Currently, the construction method of covering the outer surface of the outer painted tube with a polyethylene sleeve is the mainstream, but this construction method is complicated in process, and the polyethylene sleeve is scratched. May not be able to demonstrate.

  On the other hand, in the case of a valve, there is a case where the powder coating film of the epoxy resin is hard and weak against impact, and the coating film is damaged and peels off. In some cases, the corrosion progresses starting from the peeling damage point, and the life is finished in a short time. At present, the construction method of covering the outer sleeve with the polyethylene sleeve is the mainstream as with the outer surface coating tube, but there are the same problems as the outer surface coating tube.

  Accordingly, an object of the present invention is to withstand a severe corrosive environment that cannot be expected with conventional pipe components such as cast iron or iron-made metal pipes or valves with an outer surface coating, and a polyethylene sleeve. Is basically not required, and therefore, it is intended to provide a pipe-constituting member having a good workability and subjected to an outer surface anticorrosion coating, and a manufacturing method thereof.

  The inventor of the present application has made extensive studies in order to achieve the above object. As a result, the following findings were obtained.

  A special alloy in which a pseudo-alloy film made of zinc and aluminum-magnesium-silicon alloy is formed as an anticorrosion layer on the outer surface of a metal pipe or valve such as cast iron or iron, and special resin and powdered inorganic material are blended on it. A sealing treatment film is formed by coating a sealing agent composed of a special acrylic resin or an alkyl silicate mixed with a special resin and a powdered inorganic material, and a specially modified acrylic resin paint is applied to the top layer. By forming the synthetic resin coating, it is possible to obtain a much better anticorrosion performance than the existing outer coating tubes and valves and the anti-corrosion layer of the pseudo-alloy coating made of an aluminum-magnesium alloy. As a result, it is possible to obtain remarkably superior workability by basically eliminating the need to cover the polyethylene sleeve. Findings were obtained such.

  The present invention has been made on the basis of the above findings, and is characterized by the following.

  The invention according to claim 1 uses a pipe component member main body, and a spray wire made of zinc and a spray wire made of an aluminum-magnesium-silicon alloy formed on the outer surface of the pipe component member main body. Characterized by comprising a pseudoalloy film formed by arc spraying, a sealing treatment film formed on the pseudoalloy coating, and a synthetic resin coating formed on the sealing treatment film It is.

  The invention according to claim 2 is the pipe constituent member according to claim 1, wherein the outer surface is subjected to anticorrosion coating, and the magnesium content in the pseudo-alloy coating is in the range of 0.1 to 5 wt%. It has the characteristics.

  A third aspect of the present invention is the pipe component having the outer surface anticorrosive coating according to the first or second aspect, wherein the silicon content in the pseudo alloy film is within a range of 0.1 to 3 wt%. It has a characteristic in certain things.

According to a fourth aspect of the present invention, there is provided the pipe component having an outer surface anticorrosive coating according to any one of the first to third aspects, wherein the spray coating amount of the pseudo alloy film is 50 to 400 g / m. It is characterized by being within the range of ² .

  The invention according to claim 5 is the pipe constituent member according to any one of claims 1 to 4, wherein the outer surface anticorrosion coating is applied, and the sealing treatment coating has a solid content of 5 to 30 wt%. An acrylic resin paint in which a phosphoric acid-modified epoxy resin and a powdered inorganic material are blended, or an alkyl silicate in which a solid content is 5 to 30 wt% and a phosphoric acid-modified epoxy resin and a powdered inorganic material are blended, The film thickness of the treatment coating is characterized by being in the range of 5 to 30 μm.

According to a sixth aspect of the present invention, in the pipe line component having an outer surface anticorrosive coating according to any one of the first to fifth aspects, the synthetic resin film is an epoxy-modified acrylic resin paint or an acrylic resin paint. The coating amount of the synthetic resin film paint is characterized by being in the range of 50 to 300 g / m ² .

  The invention according to claim 7 is the pipe component having an outer surface anticorrosive coating according to any one of claims 1 to 6, wherein the pipe component is a pipe or a valve. Alternatively, the valve is characterized by being made of cast iron or iron.

  In the invention according to claim 8, surface finishing treatment is performed on the outer surface of the pipe component member main body, and then, on the outer surface of the pipe component member main body, a spray wire made of zinc and an aluminum-magnesium-silicon alloy are used. A pseudo alloy film is formed by arc spraying using a thermal spray wire, and then the pipe component member body is preheated, and a sealing agent is coated on the pseudo alloy film to form a seal treatment film. Forming, and then forming a synthetic resin film on the sealing film.

  The invention according to claim 9 is the method of manufacturing a pipe component having an outer surface anticorrosive coating according to claim 8, wherein the magnesium content in the pseudo-alloy coating is in the range of 0.1 to 5 wt%. It is characterized by being.

  The invention according to claim 10 is the method of manufacturing a pipe component having an outer surface anticorrosive coating according to claim 8 or 9, wherein the silicon content in the pseudoalloy film is 0.1 to 3 wt%. It is characterized by being within the range of.

Invention of Claim 11 is a manufacturing method of the pipe line component which gave the outer surface corrosion-resistant coating of Claims 8-10, The thermal spraying adhesion amount of the said pseudo alloy film is 50-400 g / m < ² >. It is characterized by being within the range.

  Invention of Claim 12 is a manufacturing method of the pipe line component which gave the outer surface corrosion-resistant coating according to any one of Claims 8 to 11, The solid content of the sealing treatment film is 5 to 5. An acrylic resin paint in which a phosphoric acid-modified epoxy resin and a powdered inorganic material are blended at 30 wt%, or an alkyl silicate in which a solid content is 5 to 30 wt% and a phosphoric acid-modified epoxy resin and a powdered inorganic material are blended, The sealing treatment film has a thickness in the range of 5 to 30 μm.

The invention described in claim 13 is the method of manufacturing a pipe component having an outer surface anticorrosive coating according to any one of claims 8 to 12, wherein the synthetic resin film is made of an epoxy-modified acrylic resin paint. Thus, the coating amount of the epoxy-modified acrylic resin paint is characterized by being in the range of 50 to 300 g / m ² .

  A fourteenth aspect of the present invention is the method for manufacturing a pipe constituent member having an outer surface anticorrosive coating according to any one of the eighth to thirteenth aspects, wherein the pipe constituent member is a pipe or a valve. The pipe or the valve is characterized by being made of cast iron or iron.

  According to the present invention, the outer surface coating is performed by forming the pseudoalloy film, the sealing treatment film, and the synthetic resin film on the outer surface of the pipe constituent member such as a metal pipe such as cast iron or iron or a valve. Therefore, it is possible to maintain a high anti-corrosion performance over a long period of time and to cover the polyethylene sleeve or the like without covering the polyethylene sleeve. This will improve the workability on site.

It is a fragmentary sectional view which shows the cast iron pipe in which the outer surface corrosion-resistant coating was given of this invention. It is process drawing which shows the manufacturing method of the cast iron pipe in which the outer surface corrosion-resistant coating was given of this invention.

  Next, an embodiment of the pipe constituent member to which the outer surface corrosion-resistant coating is applied according to the present invention will be described with reference to the drawings, taking a cast iron pipe as an example of the pipe constituent member.

  FIG. 1 is a partial sectional view showing a cast iron pipe to which an outer surface corrosion-resistant coating is applied according to the present invention.

  As shown in FIG. 1, a cast iron pipe with an outer surface anticorrosive coating according to the present invention includes a cast iron pipe body (metal pipe) 1 and a spray wire made of zinc formed on the outer surface of the cast iron pipe body 1. And a pseudo-alloy coating 2 as an anticorrosion layer formed by arc spraying using a spray wire made of an aluminum-magnesium-silicon alloy, a sealing treatment coating 3 formed on the pseudo-alloy coating 2, and a sealing The synthetic resin film 4 is formed on the treatment film 3.

  The magnesium content in the pseudoalloy film 2 is in the range of 0.1 to 5 wt%. If the magnesium content is less than 0.1 wt%, the initial sacrificial anodic action of zinc as an anticorrosive action is poor. On the other hand, if the magnesium content exceeds 5 wt%, the action becomes rate limiting and becomes harder and the sprayed wire becomes It becomes easy to cut.

  Further, the silicon content in the pseudoalloy coating 2 is in the range of 0.1 to 3 wt%. If the silicon content is less than 0.1 wt%, the zinc corrosion product stabilizing action as an anticorrosive action is poor, whereas if the silicon content exceeds 3 wt%, the action becomes rate limiting and the hardness increases. It is easy to cut the thermal spray wire.

The amount of spray coating of the pseudoalloy film 2 is in the range of 50 to 400 g / m ² . If the thermal spray deposition amount is less than 50 g / m ^2, it is difficult to maintain the sacrificial anodic action of zinc for a long time and to stabilize the corrosion products. On the other hand, when the amount of sprayed coating exceeds 400 g / m ² , the thickness of the pseudoalloy film 2 becomes too thick, and there is a risk that the pseudoalloy film 2 is floated or peeled off due to impact or the like.

  The sealing treatment coating 3 has an acrylic resin paint in which a phosphoric acid-modified epoxy resin and a powdered inorganic material are blended in a solid content of 5 to 30 wt%, or a phosphoric acid-modified epoxy resin and a powder in a solid content of 5 to 30 wt%. It consists of an alkyl silicate blended with an inorganic material.

  If the solid content is less than 5 wt%, an appropriate film thickness range of 5 to 30 μm of the sealing treatment film 3 cannot be obtained, and voids remaining in the pseudoalloy film 2 cannot be sealed. On the other hand, if the solid content exceeds 30 wt%, the film thickness of the sealing treatment film 3 becomes too thick and the adhesion with the pseudoalloy film 2 is lowered. Therefore, the solid content is in the range of 5 to 30 wt%, preferably 10 to 20 wt%.

  The phosphoric acid-modified epoxy resin has an effect of improving the adhesion to the pseudoalloy film 2 and improving the anticorrosion performance by forming a chemical conversion film of zinc phosphate on the surface of the pseudoalloy film 2.

  Further, the powdery inorganic material has a function of sealing the void holes remaining in the pseudoalloy film 2. As the powdery inorganic material, silica, zirconium, tourmaline and the like are preferable. By blending the phosphoric acid-modified epoxy resin and the powdered inorganic material, the anticorrosion performance is remarkably improved.

  The film thickness of the sealing treatment film 3 is in the range of 5 to 30 μm. If the film thickness is less than 5 μm, the film thickness is too thin to obtain the above effect. On the other hand, if the film thickness exceeds 30 μm, the film thickness is too thick, and elution of zinc in the pseudo-alloy film 2 is suppressed, and improvement in anticorrosion performance cannot be expected.

  The synthetic resin film 4 is made of an epoxy-modified acrylic resin paint. This epoxy-modified acrylic resin paint is a resin paint obtained by modifying an acrylic resin with an epoxy resin having excellent adhesion to an object to be coated. Thereby, there is no generation | occurrence | production of peeling of the synthetic resin film 4, a floating, etc., and it can anticipate long-term durability. Further, the synthetic resin film 4 has an action of suppressing excessive elution of zinc, whereby a long-term sacrificial anodic action is continued and a long life can be achieved.

The film thickness of the synthetic resin coating 4 is 50 to 300 g / m ² , preferably 150 to 250 g / m ² . If the film thickness is less than 50 g / m ² , the film thickness is too thin to obtain the above effect. On the other hand, if the film thickness is more than 300 g / m ² , the film thickness is too thick and the adhesion is lowered.

  The above is a case where the present invention is applied to a cast iron pipe, but the case where the present invention is applied to a metal pipe such as an iron pipe or a metal valve such as cast iron or iron is the same as in the case of a cast iron pipe.

  Next, an embodiment of a method for manufacturing a pipe constituent member having an outer surface anticorrosive coating according to the present invention will be described with reference to the drawings, taking a cast iron pipe as an example of the pipe constituent member.

  FIG. 2 is a process diagram showing a method of manufacturing a cast iron pipe to which an outer surface corrosion-resistant coating is applied according to the present invention.

  As shown in FIG. 2, in order to manufacture the cast iron pipe to which the outer surface anticorrosion coating is applied according to the present invention, first, a surface finish treatment is applied to the cast iron base pipe. The surface finishing treatment of the cast iron base pipe is important, and the surface is blasted with grit blasting to remove rust, oxide scale, etc. from the outer surface of the cast iron base pipe. The finishing degree is set to be Sa21 / 2 or more.

Next, the outer surface of the cast iron base tube subjected to the surface finishing treatment was subjected to the surface finishing treatment by performing the arc spraying using the spraying wire made of zinc and the spraying wire made of the aluminum-magnesium-silicon alloy. A pseudoalloy film is formed on the outer surface of the cast iron tube. At this time, the magnesium content is 0.1 to 5 wt%, the silicon content is 0.1 to 3 wt%, and the thermal spray deposition amount is 50 to 400 g / m ² .

  Next, the cast iron element pipe having the pseudo alloy film formed on the outer surface is preheated to a temperature in the range of 50 to 90 ° C. When the preheating temperature is less than 50 ° C., the sealing agent and the synthetic resin coating described later are not completely dried, so that the effect of the original sealing and the synthetic resin film cannot be obtained, and the anticorrosion performance is adversely affected. On the other hand, if the preheating temperature exceeds 90 ° C., the sealing agent and the synthetic resin coating described later are heated to a high temperature, and the original sealing and synthetic resin coating effects cannot be obtained.

  Next, a sealing agent film is formed by coating a sealing agent on the preheated pseudo-alloy alloy pipe. The sealing agent is an acrylic resin paint in which a phosphoric acid-modified epoxy resin and a powdered inorganic material are blended with a solid content of 5 to 30 wt%, or a phosphoric acid-modified epoxy resin and a powdered inorganic material with a solid content of 5 to 30 wt% It consists of an alkyl silicate composed of methyl silicate, ethyl silicate or propyl silicate, with which the ingredients are blended.

Next, an epoxy-modified acrylic resin paint is applied on the sealing treatment film to form a synthetic resin film. The application amount of the epoxy-modified acrylic resin paint at this time is set in the range of 50 to 300 g / m ² .

  In this way, a cast iron pipe having an outer surface anticorrosive coating as a product having high anticorrosion performance can be produced.

  The above is the case where the present invention is applied to a method for manufacturing a cast iron pipe, but the case where the present invention is applied to a method for manufacturing a metal valve such as a steel pipe or a metal valve such as cast iron or iron is the same as in the case of a cast iron pipe. is there.

(Example)
Next, the present invention will be further described with reference to examples.

  Rust and oxide scale were removed from the outer surface of the ductile cast iron pipe by grit blasting on the outer surface of the ductile cast iron pipe having a diameter of 100 mm, a wall thickness of 7.5 mm, and a length of 700 mm.

Next, on the outer surface of the surface-treated ductile cast iron pipe, using an automatic arc spraying apparatus, a spray wire composed of zinc, 5 wt% magnesium and 1 wt% so that the amount of spray coating becomes 250 g / m ^2. Arc spraying was performed using a thermal spraying wire made of an aluminum-magnesium-silicon alloy containing silicon, thereby forming a pseudoalloy film. At this time, the magnesium content in the pseudo alloy film was 1 wt%, and the silicon content was 0.5 wt%.

Next, the ductile cast iron tube on which the pseudo alloy film is formed is placed in a heating furnace and preheated to 80 ° C., and then the acrylic resin paint in which phosphoric acid-modified epoxy resin and powdered silica are blended on the pseudo alloy film. The sealing agent thus formed is coated so as to have a film thickness of 10 μm to form a sealing treatment film. Further, a water-based epoxy-modified acrylic resin emulsion paint is applied onto the sealing treatment film at a coating amount of 200 g / m ^2. The paint was applied and dried.

  Thus, the cast iron pipe (Example of this invention) which gave the outer surface corrosion-resistant coating was manufactured.

(Comparative Example 1)
As in the above example, an outer surface automatic arc spraying apparatus is used on the outer surface of a ductile cast iron pipe having a diameter of φ100 mm, a wall thickness of 7.5 mm, and a length of 700 mm, which has been subjected to a surface finishing treatment, and the amount of spray coating is 130 g. Arc spraying was performed using a spray wire made of zinc so as to be / m ² .

Next, the outer surface sprayed tube was placed in a heating furnace and preheated to 80 ° C., and an aqueous acrylic resin emulsion paint was applied to the outer surface so that the coating amount was 250 g / m ² .

(Comparative Example 2)
As in the above example, an outer surface automatic arc spraying apparatus is used on the outer surface of a ductile cast iron pipe having a surface finish of caliber φ100 mm, wall thickness 7.5 mm, and length 700 mm. Arc spraying was performed using a spray wire made of zinc and a spray wire made of an aluminum-magnesium alloy containing 5% magnesium so as to be / m ² .

Next, the ductile cast iron tube on which the pseudo alloy film is formed is placed in a heating furnace and preheated to 80 ° C., and then the acrylic resin paint in which phosphoric acid-modified epoxy resin and powdered silica are blended on the pseudo alloy film. The sealing agent thus formed is coated so as to have a film thickness of 10 μm to form a sealing treatment film. Further, a water-based epoxy-modified acrylic resin emulsion paint is applied onto the sealing treatment film at a coating amount of 200 g / m ^2. The paint was applied and dried.

  And the combined cycle test was done with respect to the said Example, the comparative example 1, and the comparative example 2. FIG. The test conditions are as follows.

Combined cycle test device: CPY-90 type, salt water spray test manufactured by Suga Test Instruments Co., Ltd., which satisfies the performance specified in JIS Z 2371.
Drying test:
(A) Temperature conditions: (RT + 10 ° C.) to 70 ± 1 ° C.
(B) Humidity condition: 25 ± 5% rh at a temperature of 60 ° C.
Wet test (high temperature):
(A) Temperature conditions: (RT + 10 ° C.) to 50 ± 1 ° C.
(B) Humidity condition: 95% rh or more at a temperature of 50 ° C. Outside air introduction test: About outside air temperature / temperature / humidity control Test cycle: Cycle A in Annex C (normative) of JIS K 5600-7-9
Number of test cycles: 450 cycles

  The combined cycle test results are shown in Table 1.

  In Table 1, ◯ indicates that the crosscut portion is not red rust, Δ indicates that the crosscut portion is red rusted, and X indicates that red rust is generated as a whole.

  As is apparent from Table 1, according to the ductile cast iron pipe with the outer surface anticorrosive coating of the present invention, the first layer is coated with a thermal spray coating of a pseudo alloy made of zinc and an aluminum-magnesium-silicon alloy. The second layer is coated with a sealing agent containing a special resin and a powdered inorganic material, and the top layer is coated with a specially modified synthetic resin paint mainly composed of acrylic resin. It was confirmed that high anticorrosion performance (10 times or more) was maintained over a long period of time compared to the outer surface coated tube (Comparative Example 1).

  Moreover, even if compared with (Comparative Example 2), it was confirmed that higher anticorrosion performance was maintained over a long period of time.

  From this, it was found that the construction property can be improved because it can withstand a severe corrosive environment which cannot be expected with a conventional outer surface coated pipe and a polyethylene sleeve is basically unnecessary.

1: Cast iron pipe body 2: Pseudo-alloy coating 3: Sealing coating 4: Synthetic resin coating

Claims (13)

  Pseudo-alloy coating formed by arc spraying using a pipe constituent member main body and a thermal spraying wire made of zinc and a thermal spraying wire made of an aluminum-magnesium-silicon alloy formed on the outer surface of the pipe constituent member main body A pipe structure with an anti-corrosion coating on the outer surface, comprising: a sealing treatment film formed on the pseudo-alloy coating; and a synthetic resin coating formed on the sealing treatment film Element.   The pipe component according to claim 1, wherein the magnesium content in the pseudo-alloy coating is in the range of 0.1 to 5 wt%.   3. The pipe component according to claim 1, wherein a content of silicon in the pseudoalloy film is in a range of 0.1 to 3 wt%. 4. The pipe component having an outer surface anticorrosive coating according to claim 1, wherein the spray coating amount of the pseudo alloy film is in a range of 50 to 400 g / m ² .   The sealing treatment film is an acrylic resin paint in which a solid content is 5 to 30 wt% and a phosphoric acid-modified epoxy resin and a powdered inorganic material are blended, or a solid content is 5 to 30 wt% and a phosphoric acid-modified epoxy resin and a powder form. It consists of an alkyl silicate blended with an inorganic material, and the film thickness of the sealing treatment film is in the range of 5 to 30 μm, according to any one of claims 1 to 4, Pipe component with anti-corrosion coating on the outside. The synthetic resin film is made of an epoxy-modified acrylic resin paint, and the coating amount of the synthetic resin film paint is in the range of 50 to 300 g / m ^2. The pipe line constituent member which gave the outer surface anti-corrosion painting.   The outer pipe anticorrosion coating according to any one of claims 1 to 6, wherein the pipe constituent member is a pipe or a valve, and the pipe or the valve is made of cast iron or iron. Pipe line component.   Surface finishing treatment is performed on the outer surface of the pipe constituent member body, and then arc spraying is performed on the outer surface of the pipe constituent member body using a spray wire made of zinc and a spray wire made of an aluminum-magnesium-silicon alloy. Then, the pipe component member body is preheated, a sealing agent is coated on the pseudoalloy film to form a sealing treatment film, and then the sealing treatment is performed. A synthetic resin coating is formed on the coating, and the method for producing a pipe component having an anti-corrosion coating on the outer surface is provided.   The outer surface anticorrosive coating according to claim 8, wherein the pseudo alloy film has a magnesium content of 0.1 to 5 wt% and a silicon content of 0.1 to 3 wt%. The manufacturing method of the pipe line constituent member which performed. The spray deposition amount of pseudo alloy coating is characterized in that it is in the range of 50 to 400 g / m ^2, according to claim 8 or 9, the manufacturing method of the conduit component having been subjected to outer surface corrosion paint.   The sealing treatment film is an acrylic resin paint in which a solid content is 5 to 30 wt% and a phosphoric acid-modified epoxy resin and a powdered inorganic material are blended, or a solid content is 5 to 30 wt% and a phosphoric acid-modified epoxy resin and a powder form. It consists of the alkyl silicate mix | blended with the inorganic material, The film thickness of the said sealing treatment film is in the range of 5-30 micrometers, It is characterized by the above-mentioned. A method of manufacturing a pipe component having an outer surface anticorrosive coating. The synthetic resin film is made of an epoxy-modified acrylic resin paint, and an application amount of the epoxy-modified acrylic resin paint is in a range of 50 to 300 g / m ² . The manufacturing method of the pipe line structural member which gave the outer surface corrosion-resistant coating as described in one.   The outer pipe anticorrosion coating according to any one of claims 8 to 12, wherein the pipe line constituting member is a pipe or a valve, and the pipe or the valve is made of cast iron or iron. Manufacturing method of the pipe line constituting member.

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