TW201008762A - A method for manufacturing an internally polyolefin coated steel pipe - Google Patents

Abstract

The present invention is intended to provide a method for manufacturing an internally polyolefin coated steel pipe, which is resistant to the detachment of a polyolefin tube and has high water resistance and adhesive properties when in an environment with freeze-thaw cycles or when being filled with hot-water constantly. The method includes grinding the inner coated layer of a molten zinc coated steel pipe applied with a molten zinc coating internally and externally using a steel wire brush, and coating a polyolefin tube after exposing an iron-zinc alloy layer including 6% or more of Fe by mass. The wire brush is cylindrical and has steel wires arranged radically to a radius direction from a central axis of the cylindrical column. The wire brush is inserted into the molten zinc coated steel pipe while spinning around the central axis of the wire brush, thereby grinding the internally coated layer of the pipe.

Description

201008762 VI. Description of the Invention: [Technical Field of the Invention] [Technical Field] The present invention relates to a method for producing a steel pipe coated with an inner surface of a polyolefin tube coated with a polyolefin tube on the inner surface and the outer surface of the steel tube 0 This case claims priority based on the special wish 2GG8-184988 filed in Japan on July 16, 2008, and its content is referred to this W case.

C. The background of the invention is used in the steel pipe for water supply or drainage, and the synthetic resin tube 1 made of the synthetic surface of the inner surface of the steel pipe can be used. Steel pipe. Since the inner surface of the resin-coated steel pipe is to be used for a long period of time, it is necessary to have sufficient φ between the inner surface of the steel pipe and the synthetic resin pipe. In particular, in the case where the temperature or the temperature of the water fluctuates greatly and the freezing and melting occurs in the pipe, the sag of the synthetic resin pipe and the steel pipe which is covered with the inner surface is insufficient, and the expansion of the synthetic resin pipe may occur. The disengagement force caused by shrinkage causes the synthetic resin tube to be peeled off from the steel pipe, and if the peeling progresses greatly, the pipe is blocked. Therefore, in particular, when the inner surface of the inner surface of the galvanized steel pipe is coated with a synthetic resin made of a synthetic resin such as polyolefin*, in order to obtain sufficient adhesion between the zinc and the synthetic resin, the inner surface of the preheated copper pipe is used. The method of pre-treatment of the zinc surface. For example, Patent Document 1 teaches a method of performing polishing to remove and clean rust or impurities and oil and fat components of white 3 201008762. Further, Patent Document 2 discloses a pretreatment of a galvanized steel pipe by grinding the inner surface of the steel pipe with a wire brush to remove a pure zinc layer to expose an iron-zinc alloy layer containing more than 63⁄4 of iron, and if the polyolefin pipe is coated, The polyolefin tube was not easily peeled off during the freeze-thaw test. [PRIOR ART DOCUMENT] [Patent Document 1] JP-A-58-87-45 (Patent Document 2) PCT/JP2007/061256 SUMMARY OF INVENTION Summary of the Invention In Patent Document 1, the specific polishing method and the degree of polishing to the extent that the inner synthetic resin tube is difficult to peel off in a freeze-thaw test or the like are not disclosed at all. Further, in Patent Document 2, the shape and size of a specific wire brush, the appropriate conditions for polishing, and the inspection methods after polishing are not disclosed at all. In order to solve the above problems, it is an object of the present invention to provide a polyolefin tube which is difficult to be peeled off even in a state in which freezing and melting are repeated, or in a state in which it is often filled with warm water, and the water-tightness is good. A method of producing a steel pipe coated with polyolefin on the inside. Means for Solving the Problem As a result of intensive research to solve the above problems, the inventors of the present invention have obtained a content of 6% in the base material of the steel pipe, that is, the surface of the base metal and the zinc oxide layer of 201008762. In the inner surface of the above-mentioned iron-zinc alloy layer of the Fe alloy, the inner surface of the steel pipe is covered with a binder, and the inner surface of the steel pipe coated with the thin smoke is used to improve the adhesion of the polyolefin. The iron alloy-containing alloy layer containing 6% by mass or more of Fe is exposed, and the specific conditions of the ore layer on the inner surface of the molten bell'_tube are polished by a wire brush. The present invention has been completed based on the above findings, and the gist thereof is as follows. (1) A method for producing a steel pipe coated with a polyolefin on the inner surface, which is an inner surface layer of a molten steel pipe which is melted on the inner surface and the outer surface by a wire brush, and is made of iron containing 6 mass% or more of Fe. - After the alloy layer is exposed, the method of manufacturing a steel pipe coated with polyolefin on the inner surface of the polyolefin pipe is arranged in a radial shape in the radial direction from the central axis of the steel pipe. The steel wire is formed by polishing the inner surface plating layer of the steel pipe by inserting the steel fresh brush while rotating the shaft as the rotating shaft and inserting the molten galvanized steel into the tube. (2) The method for producing a steel pipe coated with polyolefin on the inner surface according to (1), characterized in that the steel wire has a Vickers hardness of 500 or more. (3) The method for producing a polyolefin-coated steel pipe according to (1) or (2), characterized in that the chemical composition of the steel wire is C: 0.6 to 1.2 mass. /. , Μη: 0.2~1.2 mass. /〇, Si : 〇.1 to 1.5% by mass, P: 〇.05% by mass or less 'S: 〇.〇4 mass. /. Hereinafter, the remainder is Fe and unavoidable impurities. (4) The method for producing a steel lining of the inner surface of the polyaniline according to any one of (1) to (3) characterized in that the surface of the steel wire is plated with brass. (5) A method for producing a steel pipe coated with a polyolefin-coated inner surface, in the method of manufacturing the inner-coated polyolefin steel pipe according to any one of (1) to (4), in the method of manufacturing a steel pipe 10 201008762, The condition of Formula 5 is characterized. [Number 1] Factory (1)=

Kx(Db-Dpi)xDw3 Lw Equation 1 h(l) = LbxJl + (

π 乂 π 乂 Dpi, V J

S

Lb2x nx πx Dpi

V type 3 type 4 F(l)x^(l)xA^x^

KxS 2.6 <^<85.4..... Equation 5 F (1). Scraping force per wire of wire brush h(l): When the wire brush advances its brush length (Lb) portion, the wire The length of the inner surface of a steel wire polished steel pipe (mm) φ: when the inner surface of the hot-dip galvanized steel pipe is passed through the inner surface of the hot-dip galvanized steel pipe m times, the total length of the wire brush grinding per unit area and the rubbing of the steel wire Product of force K: proportional coefficient

Dpi: inner diameter (mm) of hot-dip galvanized steel pipe

Db: outer diameter of the wire brush (mm)

Lb: length of the wire brush (mm)

Dw : outer diameter (mm) of wire brush wire

Lw : Wire length of wire brush (mm) 201008762 • Number of wires of wire brush (root) 11 : Number of revolutions of wire brush (rpm) V . 'Feed speed of wire brush (mm/min) Number of passes of wire brush ( (S) 'When the wire brush advances its brush length (Lb) portion, the area of the inner surface of the steel pipe that is polished by the wire brush (mm2) (6) is recorded in any one of items (1) to (5). The inner surface of the coated polyolefin steel is made of the above-mentioned grinding, and the inner surface of the steel pipe is scraped with a metal needle having a Vickers hardness of 60 100 to determine whether the grinding state is good or not. (7) The manufacturer of the inner-coated polyolefin steel pipe as described in (6) * The metal needle is made of copper. According to the present invention, the inner surface of the hot-dip galvanized steel pipe is polished by a wire brush to remove the pure layer "because the iron-zinc φ gold layer containing Fe of 6 mass% or more can be surely removed" The adhesion of the olefin tube is stabilized and strengthened. Even in the pipeline where the freeze-thaw is formed, the inner surface of the polyolefin tube is not easily peeled off, and the inner surface of the polyolefin-coated steel tube can be industrially produced. BRIEF DESCRIPTION OF THE DRAWINGS [Fig. 1] is a cross-sectional view of a molten steel plate and a cross-sectional view and a side view of a wire brush. [Fig. 2] is a schematic diagram showing the relationship between the length h(l) and the brush length Lb of the inside surface of a molten steel zinc-steel steel bar when the wire brush advances the length Lb portion of the brush. ^方包] 7 201008762 The best mode for carrying out the invention. The inventors of the present invention, on the inner surface of a molten zinc-coated steel pipe, are coated with a polysulfide-coated steel pipe with the inner surface of the polyolefin pipe covered with a sword. In the production, the chain layer of the inner surface of the hot-dip galvanized steel pipe is polished by a wire brush to expose a specific condition of exposing the iron-iron alloy layer containing 6 mass% or more of Fe. In order to expose the yttrium-zinc alloy layer containing 6 mass% or more of the inner surface of the molten zinc-coated steel pipe, it is necessary to uniformly and surely grind the inner surface of the hot-dip galvanized steel pipe. Therefore, as shown in Fig. 1, the steel wire is passed through a .VL semi-column brush, and the steel wire is radially disposed from the center of the cylinder in the '/cr radial direction, and the wire is placed. The brush edge is inserted into the molten galvanized steel pipe by rotating the middle brake as a rotating shaft, thereby achieving the grinding of the inner surface of the molten steel pipe. This is because the steel wire of the wire brush conforms to the microscopic unevenness of the inner surface of the molten bell zinc steel pipe uniformly. If the Vickers hardness of the above-mentioned steel wire is 500 or more, the polishing efficiency is good. This is because the difference between the Vickers hardness of the steel wire and the Vickers hardness of the word is as large as the grinding efficiency of zinc. The chemical composition of the steel wire is C: 0.6 to 1.2% by mass, Μη: 0.2 to 1.2% by mass, and Si: 0.1 to 1.5 by mass. /〇, Ρ : 〇.〇5 mass% or less, S: 0.04 mass% The remainder is preferably composed of Fe and unavoidable impurities. When the lower limit of C and Si ' Μη is less than the above value, the necessary high hardness cannot be obtained. If the upper limit value exceeds the above value, the toughness is lowered, so these values are set. In addition, if the upper limit of Ρ and S exceeds the above value, embrittlement may occur due to segregation, and these upper limits are set. The focus is on high hardness and resistance to breakage. 201008762 The combination is necessary for the wire brush, and as long as it contains such other elements as the trace amount, it will not damage the invention. The steel wire should be plated with brass as a rust preventive means for the aforementioned steel wire. This is to prevent rust from entering the inner surface of the molten galvanized steel pipe. When the inner surface of the molten zinc-containing steel pipe is ground under the conditions of the following formulas 1 to 5, an iron-zinc alloy layer containing 6 mass% or more of Fe can be exposed. [Number 2]

Corpse (1) = Kx (Db-Dpi) x Dw3.....

Ml): Call 1 + (^^2.....式 2 s =

Lb2 χηχ πχ Dpi V Equation 3, _F(1) χ Λ(1) x iV x wj λ φ =... Equation 4

KxS 2.6 <^<85.4..... Equation 5

The symbols in the above formula are defined as follows, and the partial symbols are also shown in the first and second figures. F (1). The wiping force h(l) of each wire of the wire brush: When the wire brush advances its brush length (Lb), the length of the inner surface of the steel wire of the wire brush (mm) Φ : When the inner surface of the galvanized steel pipe is passed through the inner surface of the hot-dip galvanized steel pipe m times, the total extension length of the steel wire brush 9 201008762 per unit area and the scraping force of the steel wire κ: proportional coefficient

Dpi: inner diameter (mm) of the molten steel tube

Db: outer diameter of the wire brush (mm)

Lb: length of the wire brush (mm)

Dw : outer diameter of the wire of the wire brush (mm)

Lw : length of wire of wire brush (mm) N : number of wires of wire brush (root) η : number of revolutions of wire brush (rpm) V : feed rate of wire brush (mm/min) m : wire brush Number of passes (times) S : When the wire brush advances its brush length (Lb) portion, the wire brush grinds the area of the molten zinc-zinc steel pipe (mm2). One wire scraping of the wire brush and the force F of the inner surface of the molten galvanized steel pipe ( l) is as shown in Equation 1. When the wire brush advances only the brush length Lb, the length h(l) of the inner surface of the wire-polished molten steel pipe of the wire brush is as shown in Formula 2. When the wire brush advances only the brush length Lb, the area S of the inner surface of the wire brush-polished molten galvanized steel pipe is as shown in Formula 3. When the inner surface of the molten zinc steel pipe is melted by the wire brush of N steel wires m times, the product of the total length of the wire grinding of the wire brush per unit area and the scraping force of the steel wire is as shown in the following formula 4. As shown in the first embodiment to the seventh embodiment, it was confirmed that the φ value of the formula 4 is 2.6 or more and 85.4 or less, and the iron-containing alloy layer containing 6 mass% or more of Fe is exposed to 201008762, and the polished surface and the aggregate are ensured. The stability of the stability of the dilute hydrocarbon tube. In other words, in the case where the φ value in the formula 4 is less than the polishing condition of 2.6, even if the inner surface of the hot-dip galvanized steel pipe is polished by a wire brush, the pure zinc layer remains, and the iron-containing alloy layer containing 6 mass% or more of Fe is exposed. Become inadequate. When the φ value of the formula 4 exceeds the polishing condition of 85.4, the inner surface of the wire brush and the galvanized steel pipe becomes high temperature due to frictional heat generation, the polishing efficiency is remarkably lowered, and the pure layer remains, and the iron-zinc alloy containing 6 mass% or more of Fe is contained. The exposure of the layer is insufficient. In addition, the inventors of the present invention paid attention to the difference in the Vickers hardness of the surface layer of the molten plating layer and the iron-spelling alloy layer, and used it to judge the iron containing 6 mass% or more of Fe by the wire brush. - The inspection of the alloy layer on the inside of the molten zinc steel pipe. That is, since the Vickers hardness of the pure zinc layer is less than 60, and the Vickers hardness of the iron-containing alloy layer containing 6% by mass or more of Fe exceeds 1 〇〇, the Vickers hardness in the meantime is 60 〜 The metal needle of 100 is scraped and inspected by the inner surface of the steel pipe polished by the wire brush. When the polishing is insufficient, since a pure zinc layer which is softer than the Vickers hardness of the metal needle remains, the groove can be formed on the inner surface of the bell-zinc steel pipe when the surface is scratched by the inspection needle. On the other hand, when the polishing is sufficient, 'the iron-zinc alloy layer containing Fe of 6 mass% or more harder than the Vickers hardness of the metal needle is exposed, so if the surface is scratched with the metal needle' The metal powder to be cut off is attached to the surface of the iron-zinc alloy layer containing 6% by mass or more of Fe. Metals with a Vickers hardness of 60 to 60 are known, and are available in copper, brass, and brass. Since the color of aluminum and galvanized is the same as silver, it is difficult to judge 11 2〇1〇〇8762 aluminum and zinc by visual observation, which is not suitable as a material for inspection metal needles. Copper, yellow copper and Wei zinc have different color tones. It is suitable as a material for metal needles for inspection. p is, because brass will have different copper and rhyme mixing ratios depending on the source, Vickers hardness is prone to high and low, so it is best to obtain copper with a certain Vickers hardness. Check the material of the metal needle - quality. - [Embodiment] An embodiment of the present invention will be described. The conditions of the examples are the conditions used to confirm the implementation possibilities and effects of the present invention. The present invention is not limited to these conditions. The present invention can adopt various conditions without departing from the gist of the present invention to achieve the object of the present invention. (Example 1) A galvanized steel pipe was obtained by performing smelting and galvanizing on the inner surface and the outer surface of a steel pipe (SGPl 〇〇 Ax 6000 mm length). At this time, the content of aluminum contained in the galvanizing was - 0.01% by mass. From the inner surface of the zinc-coated steel pipe, the outer diameter of the inner diameter of the galvanized steel pipe is larger, and the shape is a columnar shape, and the steel wire is radially arranged in the semi-diameter direction from the central axis of the cylinder. The wire brush is rotated and inserted into the galvanized steel pipe to grind the inner surface of the key. The wire brush wire used in the experiment has a Vickers hardness of 500, and the chemical composition of the wire is C: 〇.81% by mass ' Μ η : 0.47 mass %, Si : 〇.2 〇 mass %, p : 〇. 〇5 mass% ' S : 0. 〇 4 mass%. The grinding conditions are shown in Table 1. In this embodiment, the feed rate of the wire brush is changed, and 10 pieces of molten ore zinc steel pipe are internally ground for each type of reference, and 12 201008762 is used to implement five kinds of standards. The surface temperature of the wire brush shaft was measured immediately after the inner surface was ground and the first and the tenth branch were examined to investigate the frictional heat. Use a copper metal needle to rub the inner surface of the inner surface of the steel pipe that has been ground. 'Check the quality of the grinding. * Next, a small-density polyethylene pipe of maleic anhydride-modified polyethylene having a thickness of ΙΟΟμηη is prepared in a smaller area than the inner diameter of the zinc-coated steel pipe. The high density polyethylene has a thickness of 2.0 mm and a melting point of 125 °C. β Insert the high-density polyethylene pipe into the inner surface of the polished steel pipe, cover it at both ends, press air inside the high-density polyethylene pipe and seal it, then heat it to 160 ° C in a heating furnace. The high density polyethylene pipe is melted and pressed against the inner surface of the galvanized steel pipe. Then, the galvanized pipe was taken out from the heating furnace to be cooled, and at the time when the temperature became 70 ° C, the sealed air was taken out to obtain a plated steel pipe (the steel pipe a of the present invention) having the inner surface covered with the high-density polyethylene pipe. After the steel pipe a of the present invention was cut, the cross section was polished and observed with an optical microscope, and subjected to a freeze-thaw test and a warm water dipping test. When observing with an optical microscope, a 20 mm wide circumferential section was taken as a test piece, and after re-polishing the cross section by resin embedding, the plated layer was etched with a 3% nitric acid-alcohol solution, and galvanized was observed with an optical microscope. In the layer, it was investigated whether or not the iron-containing alloy layer containing 6% by mass or more of Fe was exposed to the outermost layer. In the knot-knot test, the test piece cut into a length of 150 mm is placed in a container filled with tap water in a state of about 1/3 of the length of the water, and placed in a low-temperature tank together with the container at -10 ° C. It was allowed to freeze for 23 hours, and then, 13 201008762 was placed in a high-temperature tank at 60 ° C for 1 hour, and the freeze-thaw operation was one cycle, and 100 cycles were repeated. In the warm water subcrush test, the test piece obtained by cutting the length of 15 〇 111111 was immersed in a container filled with tap water, and placed in a thermostat at 40 ° C together with the container, and left for 3 months. After the freeze-thaw test and the warm water dipping test, the test piece was investigated for the presence or absence of high-density polyethylene tube. According to Table 1, only the case where the φ value of the formula 4 falls within the range of the above formula 5 'In the inspection with the metal needle made of copper, the case where the surface of the polished galvanized steel tube @ has copper adhesion is confirmed. In the observation of the galvanized layer section by the microscope, it was confirmed that the iron-zinc alloy layer containing 6 mass% or more of Fe was exposed to the outermost layer. In addition, in the results of the freeze-thaw test and the warm water dipping test, it was also found that the polyethylene pipe was not peeled off. Friction and heat generation of the wire brush In all of the five references, the surface temperature of the wire brush shaft was measured immediately after the first and the tenth grinding, and the result was less than 150 C, and the grinding efficiency was good. (Example 2) _ A molten steel bond was obtained on the inner surface and the outer surface of a steel pipe (SGP1 〇〇 AX60 〇〇 min length) to obtain a mineral zinc steel pipe. At this time, the content of the inscription contained in the zinc bond was 0.01% by mass. A steel wire having a larger outer diameter than the inner diameter of the plated steel pipe and having a cylindrical shape from the inner surface of the galvanized steel pipe, and a steel wire radially arranged from the central axis of the cylinder The brush rotates and is inserted into the mineral zinc pipe to grind the inner zinc. 14 201008762 The wire brush wire used in the experiment has a Vickers hardness of 500. The chemical composition of the wire is C: 0.81% by mass, Μη: 0.47 mass%, Si: 0.20 mass%, and P: 0.05 mass. /〇, S : 0.04% by mass. The grinding conditions are shown in Table 2. In the present embodiment, the number of passes of the wire brush is changed, and 10 sets of galvanized steel pipes are internally ground for each type of reference, and five types of standards are collectively implemented. The surface temperature of the wire brush shaft was measured immediately after the inner surface was ground and the first and the tenth branch were examined to investigate the frictional heat. Scratch the inner surface of the inner surface of the galvanized steel pipe with a copper metal needle to check the quality of the grinding. Next, it was prepared to have a slightly smaller inner diameter than the galvanized steel pipe, and a high-density polyethylene pipe of maleic anhydride-modified polyethylene having a thickness of ΙΟΟμηι was laminated on the outer surface. The high density polyethylene has a thickness of 2.0 mm and a melting point of 125 °C. Insert a high-density polyethylene pipe into the inside of the internally ground galvanized steel pipe, cover at both ends, press air inside the high-density polyethylene pipe and seal it, and then heat it to 160 ° C in a heating furnace. The high density polyethylene pipe is melted and pressed against the inner surface of the galvanized steel pipe. Then, the galvanized pipe is taken out from the heating furnace and cooled, and the sealed air is taken out at a temperature of 70 ° C to obtain a plated steel pipe coated with a high-density polyethylene pipe on the inner surface (the steel pipe of the present invention) b). After the steel pipe b of the present invention was cut, the polished cross section was observed by an optical microscope, and subjected to a freeze-thaw test and a warm water dipping test. When observing with an optical microscope, a 20 mm wide circumferential section was taken as a test piece, and after re-polishing the section by resin, the galvanized layer was etched with a 3% nitrate 15 201008762 acid-alcohol solution. In the galvanized layer, it was investigated whether or not the iron-zinc alloy layer containing 6% by mass or more of Fe was exposed to the outermost layer. The freeze-thaw test is a test piece obtained by cutting into a length of 150 mm and immersed in water in a state of about 1/3 of the length in a container filled with tap water, and placed in a low-temperature tank at -10 ° C together with the container. It was allowed to freeze for 23 hours, and the freezing and thawing operation of thawing was carried out for 1 hour in a high-temperature tank at 60 ° C for one cycle, and 100 cycles were repeated. In the warm water immersion test, the test piece obtained by cutting into a length of 150 mm was immersed in a container containing tap water, and placed in a 40 〇c constant temperature ® tank together with the container for 3 months. After the Kangjie melt test and the warm water dipping test, the high density polyethylene pipe of the test piece was investigated for peeling. According to Table 2, only the case where the value of φ of the formula 4 exceeds 2.4, the result of the inspection made with a copper metal needle is 'lighting the surface of the zinc-coated steel pipe on the surface of the polished zinc-coated steel pipe, and the optical microscope of the section of the galvanized layer In the observation results, the iron-containing alloy layer containing 6 mass% or more of Fe was exposed to the outermost layer. In the ♦ knot melting test, warm water dipping test thief fruit towel, also strong u section does not have a shape. The frictional heating of the wire brush was achieved in all of the five benchmarks, and the surface temperature of the first and the first GG of the continuous grinding was immediately unicorned, and the results were all below 150 ° C, and the grinding efficiency was good. ~ Know W 1 Let the value of φ of Equation 4 fall within the range of Equation 5 above to set the number of passes of the wire brush. (Example 3) 16 201008762 Melt galvanizing was performed on the inner surface and the outer surface of a steel pipe (SGP100Ax6000 mm length) to obtain a plated steel pipe. At this time, the aluminum content contained in the galvanizing was 0.01% by mass. From the inner surface of the zirconia steel pipe, an outer diameter having a larger inner diameter than that of the ore pipe is formed in a cylindrical shape, and a steel wire is radially arranged from the central axis of the cylinder in the semi-diameter direction. The wire brush rotates and is inserted into the plated steel pipe to polish the inner surface of the plate. The wire brush wire used in the experiment has a Vickers hardness of 500. The chemical composition of the wire is C: 0.81% by mass, Μη: 0.47 mass%, Si: 0.20 mass%, P: 0.05 mass%, S: 0.04% by mass. The grinding conditions are shown in Table 3. In the present embodiment, the number of revolutions of the wire brush was changed, and 10 sets of hot-dip galvanized steel pipes were subjected to inner surface polishing for each type of reference, and five types of standards were collectively implemented. The surface temperature of the wire brush shaft was measured immediately after the inner surface was ground and the first and the tenth branch were examined to investigate the frictional heat. Scratch the inner surface of the inner surface of the minered zinc steel pipe with a copper metal needle to check the quality of the grinding. Next, a smaller density of the inner diameter of the zinc-coated steel pipe was prepared, and a high-density polyethylene pipe of maleic anhydride-modified polyethylene having a thickness of ΙΟΟμηη was laminated on the outer surface. The high density polyethylene has a thickness of 2.0 mm and a melting point of 125 °C. Insert the high-density polyethylene pipe into the inner surface of the plated steel pipe, cover both ends, press air inside the high-density polyethylene pipe and seal it, then heat it to 160 ° C in a heating furnace to make it high. The density polyethylene tube is melted and pressed against the inner surface of the bell zinc steel pipe. 17 201008762 Then, the zinc coated tube was taken out from the heating furnace and allowed to cool, and the temperature became 70. At the time of (:, the enclosed air is taken out, and the galvanized steel pipe (the steel pipe c of the present invention) coated with the high-density polyethylene pipe is obtained. The steel pipe of the present invention is cut off by the moxibustion section and then observed by an optical microscope. Freeze-thaw test and warm-water impregnation test. In the observation with an optical microscope, a 20 mm wide circumferential _ direction section was taken as a test piece, and the resin was embedded and fixed to re-grind the section, and then 3% nitric acid was used. The alcohol layer was etched and plated, and the galvanized layer was observed with an optical microscope to investigate whether or not the iron-zinc alloy layer containing 6 mass% or more of Fe was exposed to the most surface layer. The freeze-thaw test was a test piece obtained by cutting into a length of 150 mm. Approximately 1/3 of the length is immersed in water and placed in a container filled with tap water, and placed in a low temperature tank at -10 ° C for 23 hours together with the container, and then placed in a 60 C high temperature bath. The bundle unwinding operation for 1 hour is 1 cycle, and 100 cycles are repeated. The warm water immersion test is a test piece obtained by cutting into a length of 150 mm, immersed in a container containing tap water, together with the container. Put them together in a constant temperature tank of 40t: for 3 months. After the freeze-thaw test and the warm water dipping test, investigate whether the high-density polyethylene pipe of the test piece is peeled off. According to Table 3, only the formula 4 (| In the case where the value is within the range of the above formula 5, the inspection towel made of the copper metal needle is confirmed to be deposited on the surface of the ground steel tube, and the optical microscope observation of the cross section of the plating layer is confirmed to contain The iron-zinc alloy layer of Fe of 6 mass% or more is exposed to the outermost layer. In addition, the result of the knot melting test and the warm money stain test on 18 201008762 also found that the polyethylene tube was not peeled off. In all of the five types of reference sheets, the surface temperature of the wire brush shaft was measured immediately after the first and tenth grindings, and the result was less than 150 ° C, and the polishing efficiency was good. (Example 4) In the steel pipe ( SGPl〇〇Ax6〇〇〇mm length) inside and outside

The molten zinc is melted and the steel pipe is obtained. At this time, the content of (4) contained in the ride was 0.01% by mass. From the inner surface of the zirconia steel pipe, a steel wire having a larger outer diameter than the inner diameter of the zirconia steel pipe is formed in a cylindrical shape, and a wire is radially arranged from the central axis of the cylinder in a radial direction. The brush is rotated and inserted into the galvanized steel pipe to grind the inner surface. The wire brush made in the experiment has a Vickers hardness of 500, and the steel 4 has a knives of c. 〇 81 mass. ,. , Μη : 〇 47% by mass, & ·· 0·20% by mass% P: 0.0S mass%, s: 〇.〇4 mass %. The grinding conditions are shown in Table 4. In this case, the length of the wire of the wire brush is changed. The inner surface of each of the 1 to 1 set of molten clock zinc steel pipes is subjected to internal grinding, and a total of five standards are implemented. Immediately after grinding the first branch and the IMG branch, the surface temperature of the wire brush shaft was measured to investigate the frictional heat. Scratch the inner surface of the inner surface of the minered zinc steel pipe with a copper metal needle to check the quality of the grinding. Then prepare a high-density polyethylene pipe of maleic anhydride-modified polyethylene with a thickness of 2010μιη. The high density polyethylene has a thickness of 2.0 mm and a melting point of 125 °C. Insert the high-density polyethylene pipe into the inner surface of the galvanized steel pipe, cover both ends, press the air inside the high-density polyethylene pipe and seal it, then heat it to 160 ° C in a heating furnace to make it high. The density polyethylene tube is melted and pressed against the inner surface of the galvanized steel pipe. Then, the zinc-coated tube was taken out from the heating furnace and cooled, and the sealed air was taken out at a temperature of 70 ° C to obtain a plated steel pipe coated with a high-density polyethylene pipe (the steel pipe d of the present invention) . After the steel pipe d of the present invention was cut, the polished cross section was observed by an optical microscope, and subjected to a freeze-thaw test and a warm water dipping test. When observing with an optical microscope, a 20 mm-wide circumferential section was taken as a test piece, and after re-polishing the cross section by resin embedding, the galvanized layer was etched with a 3% nitric acid-alcohol solution, and the galvanized layer was observed with an optical microscope. It was investigated whether or not the iron-containing alloy layer containing 6% by mass or more of Fe was exposed to the outermost layer. The freeze-thaw test is a test piece obtained by cutting into a length of 150 mm and immersed in water in a state of about 1/3 of the length in a container filled with tap water, and placed in a low-temperature tank at -10 ° C together with the container. It was allowed to freeze for 23 hours, and then it was placed in a high-temperature tank at 60 ° C for 1 hour to carry out thawing and freeze-thaw operation in one cycle, and 100 cycles were repeated. The warm water immersion test is a test piece obtained by cutting into a length of 150 mm, immersed in a container containing tap water, placed in a constant temperature bath at 40 ° C together with the container, and left for 3 months. After the freeze-thaw test and the warm water dipping test, the high-density 201008762 degree polyethylene pipe of the test piece was investigated for peeling. According to Table 4, only in the case where the value of φ of Formula 4 is within the range of the above Formula 5, it was confirmed in the inspection with a copper metal needle that copper adhered to the surface of the ground galvanized steel pipe, in the galvanized layer section. In the optical microscopic observation, it was confirmed that the iron-containing alloy layer containing 6 mass% or more of Fe was exposed to the outermost layer. In addition, in the results of the freeze-thaw test and the warm water dipping test, it was also found that the polyethylene pipe did not peel. 0 Friction and heat generation of wire brush In all five types of standards, the surface temperature of the wire brush shaft was measured immediately after continuous grinding of the first and tenth branches, and the results were all below 150 ° C, and the polishing efficiency was good. (Example 5) A galvanized steel pipe was obtained by performing smelting and galvanizing on the inner surface and the outer surface of a steel pipe (SGP100Ax 6000 mm length). At this time, the content of aluminum contained in the galvanizing is 〇.〇1% by mass. The inner surface of the galvanized steel pipe is formed in a cylindrical shape having a larger outer diameter than the inner diameter of the galvanized steel pipe, and the wire is radially arranged in the half-direction from the central axis of the cylindrical steel pipe. The wire brush is rotated and inserted into the galvanized steel pipe to grind the inner surface of the galvanized steel. The steel wire used in the experiment has a Vickers hardness of 500, and the chemical composition of the steel wire is C: 〇·8ΐ mass%, Mn: 0.47 mass °/〇, Si: 〇'2〇 mass%, P: 0. 〇 5 quality. /〇, S : 0.04% by mass. The grinding conditions are shown in Table 5. In the present embodiment, the steel wire of the wire brush is externally changed, and 10 sets of molten galvanized steel pipes are ground for each type of reference, and a total of five standards are implemented. 21 201008762 Continuously, the surface temperature of the wire brush shaft was measured immediately after grinding the first and tenth sides on the inner surface to investigate the frictional heat. Use a copper metal needle to scrape the inner surface of the inner surface of the plated steel pipe and check the quality of the grinding. Next, a smaller density inner diameter of the zinc-coated steel pipe was prepared, and a high-density polyethylene pipe of maleic anhydride-modified polyethylene having a thickness of ΙΟΟμηι was laminated on the outer surface. The high density polyethylene has a thickness of 2.0 mm and a melting point of 125 °C. Insert the high-density polyethylene pipe into the inner surface of the galvanized steel pipe, cover both ends, press the air inside the high-density polyethylene pipe and seal it, then heat it to 160 ° C in a heating furnace to make it high. The density polyethylene tube is melted and pressed against the inner surface of the galvanized steel pipe. Then, the plated tube was taken out from the heating furnace and cooled, and the sealed air was taken out at a temperature of 70 ° C to obtain a galvanized steel pipe coated with a high-density polyethylene pipe (the steel pipe of the present invention) ). After the steel pipe e of the present invention was cut, the polished section was observed by an optical microscope, and subjected to a freeze-thaw test and a warm water dipping test. When observing with an optical microscope, a 20 mm wide circumferential section was taken as a test piece, and the cross section was fixed by resin embedding, and then the galvanized layer was etched with a 3% nitric acid-alcohol solution, and the galvanized layer was observed with an optical microscope. It was investigated whether or not the iron-containing alloy layer containing 6% by mass or more of Fe was exposed to the outermost layer. The freeze-thaw test is a test piece obtained by cutting into a length of 150 mm and immersed in water in a state of about 1/3 of the length in a container filled with tap water, and placed in a low-temperature tank at -10 ° C together with the container. It was allowed to freeze for 23 hours, and then it was placed in a high-temperature tank at 60 ° C for 1 hour to carry out thawing freezing and melting operation for 201008762 for one cycle, and loo cycles were repeated. The water immersion test is a test piece obtained by cutting into a length of 15 〇 mm, immersed in a container containing tap water, and placed in a constant temperature bath of 4 〇〇c together with the container, and left for 3 months. After the bundle melting test and the warm water dipping test, the high density polyethylene tube of the test piece was investigated for peeling. According to Table 5, in the case where the value of φ of Formula 4 is within the range of the above Formula 5, it was confirmed in the inspection with the copper metal needle that the copper adhered to the surface of the ground galvanized steel pipe, in the galvanized layer section. In the optical microscopic observation, it was confirmed that the iron-zinc alloy layer containing 6 mass% or more of Fe was exposed to the outermost layer. In addition, in the results of the freeze-thaw test and the warm water dipping test, it was also found that the polyethylene pipe was not peeled off. Friction and heat generation of the wire brush In all of the five types of standards, the surface temperature of the wire brush shaft was measured immediately after the first and tenth sections were continuously polished, and the result was less than 150 ° C, and the polishing efficiency was good. (Example 6) Melt galvanizing was performed on the inner surface and the outer surface of a steel pipe (SGPl 〇〇 Ax 6000 mm length) to obtain a steel pipe. At this time, the content of the inscription contained in the mineral zinc is 0.01% by mass. The outer diameter of the inner surface of the zinc-coated steel pipe is a cylindrical shape having an outer diameter larger than the inner diameter of the steel pipe, and the steel wire is radially arranged from the central axis of the cylinder in the radial direction. The brush is rotated and inserted into a galvanized steel pipe to grind the inner surface of the zinc. The wire brush wire used in the experiment has a Vickers hardness of 500 '. 23 201008762 The chemical composition of the steel wire is C: 0.81% by mass, Μη: 0.47 mass%, Si: 0.20 mass%, P: 0.05 mass%, S : 0·04% by mass. The grinding conditions are shown in Table 6. In the present embodiment, the outer diameter of the wire brush was changed, and 10 hot-dip galvanized steel pipes were ground for each type of reference, and five kinds of standards were collectively implemented. The surface temperature of the wire brush shaft was measured immediately after the first and tenth branches were ground on the inner surface to investigate the frictional heat. Use a copper metal needle to polish the inner surface of the steel pipe that has been ground on the inner surface to check whether the grinding condition is good or not. Next, a high-density polyethylene pipe of maleic anhydride-modified polyethylene having a thickness of ΙΟΟμηι was prepared to be slightly smaller than the inner diameter of the galvanized steel pipe. The high density polyethylene has a thickness of 2.0 mm and a melting point of 125 °C. Insert the high-density polyethylene pipe into the inner surface of the galvanized steel pipe, cover both ends, press the air inside the high-density polyethylene pipe and seal it, then heat it to 160 ° C in a heating furnace to make it high. The density polyethylene tube is melted and pressed against the inner surface of the galvanized steel pipe. Then, the zinc-coated tube was taken out from the heating furnace to be cooled, and at the time when the temperature was changed to 70 ° C, the sealed air was taken out to obtain a zinc-zinc steel pipe having a high-density polyethylene pipe inside (the steel pipe of the present invention was cut. After breaking the steel pipe f of the present invention, the polished section was observed by an optical microscope, and subjected to a freeze-thaw test and a warm water dipping test. When observing with an optical microscope, a 20 mm-wide circumferential section was taken as a test piece, which was packaged in resin. After burying and re-polishing the cross section, the galvanized layer was etched with a 3% nitric acid-alcohol solution, and the galvanized layer was observed with an optical microscope to investigate whether or not the iron-zinc alloy layer containing 6 mass% or more of Fe, containing 201008762 was exposed to the outermost layer. In the melting test, the test piece obtained by cutting into a length of 150 mni is placed in a container filled with tap water in a state of about 1/3 of the length of the water, and placed in a low temperature tank of -10 ° C together with the container. It was frozen for 23 hours, and then placed in a high-temperature tank at 60 ° C for 1 hour to perform thawing freezing and melting operation for one cycle, and repeated operations for 100 cycles. The warm water immersion test was to cut into a length of 150 mm. The test piece obtained was immersed in a container filled with tap water, placed in a constant temperature bath of 4 ° C together with the container, and left for 3 months. After the melting test and the warm water dipping test, the height of the test piece was investigated. Whether or not the density polyethylene tube is peeled off. According to Table 6, only the φ value of the formula 4 is within the range of the above formula 5, and it is confirmed in the inspection with the copper metal needle that the copper adheres to the ground galvanized steel pipe. In the optical microscopic observation of the cross section of the plated layer, it was confirmed that the iron layer containing 6% by mass or more of Fe was exposed to the outermost layer. In addition, in the results of the special melting test and the warm water dipping test, It is known that the polyethylene pipe is not peeled off. The friction heat of the wire brush is measured in all five kinds of standards, and the surface temperature of the wire brush shaft is measured immediately after the first and the tenth branches are continuously polished, and the result is less than 150 C, and the grinding efficiency is low. (Example 7) The galvanized steel pipe was obtained by performing hot-dip galvanization on the inner surface and the outer surface of the steel pipe (SGP1〇〇AX60〇〇mrn length). At this time, the content of aluminum contained in the plating was 0.01% by mass. 201008762 Within the money zinc steel pipe In addition, the outer diameter of the outer diameter of the zinc-coated steel pipe is a plate shape, and the wire is radially arranged in the semi-red direction from the central axis of the m-shaped steel pipe. The brush is rotated, and it is inserted into the zinc alloy of the key zinc steel tube (4). The steel wire used in the experiment has a Vickers hardness of 5 〇〇, and the chemical composition of the steel wire is C: 0.81% by mass, Μη: 0.47 mass%, Si: 〇·20 ft./〇' P. 0. 〇5 mass%, S: 0.04 mass%. The polishing conditions are as shown in Table 7. In this example, the number of revolutions of the wire brush was changed. 'Insulin polishing was carried out on 10 sets of hot-dip galvanized steel pipes for each type of reference, and a total of five types of standards were implemented. The surface temperature of the wire brush shaft was measured immediately after the inner surface was ground and the first and the tenth branch were examined to investigate the frictional heat. Use a copper metal needle to scrape the inner surface of the inner surface of the galvanized steel pipe, and check the quality of the grinding. Next, a high-density polyethylene pipe of maleic anhydride-modified polyethylene having a thickness smaller than the outer diameter of the galvanized steel pipe was prepared. The high density polyethylene has a thickness of 2.0 mm and a melting point of 125 °C. A high-density polyethylene pipe was inserted into the internally-polished steel plate, and both ends were capped, and air was sealed and sealed inside the high-density polyethylene pipe, and then heated to 160 by a heating furnace. (:, the high-density polyethylene pipe is melted and pressed against the inner surface of the galvanized steel pipe. Then, the zinc pipe is taken out from the heating furnace and cooled, and the temperature is taken out at a time point of 7 ° C. The enclosed air is obtained by a plated steel pipe (the steel pipe g of the present invention) coated with a high-density polyethylene pipe. 26 201008762 After cutting the steel pipe g of the present invention, the polished section is observed by an optical microscope, and the beam melting test and the temperature are performed. Water immersion test. When observing with an optical microscope, take a 2 〇 mm wide circumferential section as a test piece, embed the resin and fix the cross section, and then etch the layer with 3% nitric acid-alcohol solution. The galvanized layer was observed under an optical microscope, and it was investigated whether or not the iron-zinc alloy layer containing 6 mass% or more of Fe was exposed to the outermost layer. The freeze-thaw test was performed by cutting the test piece obtained by cutting into a length of 15 mm to about 1/3 of the length. The state in the water is placed in a container filled with tap water, and placed in a low temperature tank of _10 ° C together with the container to be frozen for 23 hours, and then placed in a high temperature bath at 60 ° C for 1 hour to be thawed. Freeze and melt the operation for 1 cycle Repeated operation for 100 cycles. The warm water dipping test is to pour the test piece obtained by cutting into a length of 150 mm into a container filled with tap water, and put it in a thermostat bath at 40 ° C together with the container for 3 months. After the freeze-thaw test and the warm water dipping test, the high-density polyethylene pipe of the test piece was investigated for peeling. According to Table 7, only the φ value of the formula 4 is within the range of the above formula 5, and the metal needle is made of copper. In the inspection, it was confirmed that copper adhered to the surface of the polished steel pipe, and it was confirmed by optical microscopic observation of the cross section of the plated layer that the iron-containing alloy layer containing 6 mass% or more of Fe was exposed to the outermost layer. In the results of the freeze-thaw test and the warm water dipping test, it was found that the polyethylene tube was not peeled off. The friction heat of the wire brush was measured in all five kinds of standards, and the wire brush was measured immediately after the j-th and the 10th pieces were continuously polished. The surface temperature of the shaft was not as high as 27 201008762 to 150 ° C, and the polishing efficiency was good. [Table 1] Comparative Example Comparative Example Comparative Example Comparative Example Comparative Example The inner diameter of the hot-dip galvanized steel pipe was Dpi 106.0 106.0 106.0 106.0 106.0 Wire brush outer diameter Db 111.0 111.0 111.0 111.0 111.0 Wire brush lengthwise length Lb 70 70 70 70 70 Wire brush wire outer diameter Dw 0.25 0.25 0.25 0.25 0.25 Wire brush wire length Lw 30 30 30 30 30 Wire brush wire Number of roots N 7,500 7,500 7,500 7,500 7,500 Number of revolutions of wire brush n 100 100 100 100 100 Feed rate of wire brush V 1,000 3,000 5,000 10,000 20,000 Number of passes of wire brush m 2 2 2 2 2 S 23,311 23,311 23,311 23,311 23,311 F( l)/K 0.002604 0.002604 0.002604 0.002604 0.002604 (h(l)xNxm)/S 1,501 502 303 157 87 Φ 3.9 1.3 0.8 0.4 0.2 Exposed to contain 6% by mass of "Fe side - ί♦ alloy layer with copper metal needle inspection copper Microscopic observation of the cross section of the zinc layer containing 6Fe alloy layer containing 6% by mass or more in the grooved groove (Note 1) Surface temperature of the wire brush shaft after grinding the inner surface of the 〇XXXX wire brush (Note 2) The surface temperature of the wire brush shaft after the grinding of the inner surface of the 〇〇〇〇〇 wire brush (Note 2) 〇〇〇〇〇 Freezing and melting test Alkenyl release tube Yes Yes Yes Yes No peeling test warm water polyethylene pipe collapse No Yes Yes Yes Yes

(Note 1) 〇: It contains 6 mass ° /. The iron-zinc alloy layer of the above Fe is exposed, X: not exposed (Note 2) 〇: the surface temperature of the brush shaft is less than 150 ° C, X: 150 ° C or more 28 201008762 [Table 2] Comparative Example The present invention The inner diameter of the molten forged steel pipe of the present invention is Dpi 106.0 106.0 106.0 106.0 106.0 The outer diameter of the wire brush Db 111.0 111.0 111.0 1Π.0 111.0 The long length of the wire brush Lb 70 70 70 70 70 The wire outer diameter of the wire brush Dw 0.25 0.25 Wire length of 0.25 0.25 0.25 wire brush Lw 30 30 30 30 30 Wire number of wire brush N 7,500 7,500 7,500 ,7,500 7,500 Number of turns of wire brush n 100 100 100 100 100 Feed rate of wire brush V 3,000 3,000 3,000 3,000 3,000 Number of passes of the wire brush m 2 4 6 8 10 S 23,311 23,311 23,311 23,311 23,311 F(l)/K 0.002604 0.002604 0.002604 0.002604 0.002604 (h(l)xNxm)/S 502 1,004 1,506 2,008 2,510 Φ 1.3 2.6 3.9 5.2 6.5 Exposed inclusion 6% by mass or more of Fe iron-known alloy layer, copper metal needle inspection, copper adhesion, copper adhesion, copper adhesion, copper adhesion, and galvanized layer of iron-zinc alloy layer containing 6 mass% or more of Fe Microscope observation (Note 1) The surface temperature of the wire brush shaft after grinding the first branch of the X 〇〇〇〇 wire brush (Note 2) 摩擦 The friction heat of the wire brush is ground after the 10th branch The surface temperature of the wire brush shaft (Note 2) The peeling of the polyethylene pipe after the freeze-thaw test is carried out without or without the peeling of the polyethylene pipe after the warm water dipping test.

(Note 1) 〇: The iron-zinc alloy layer containing 6 mass% or more of Fe is exposed, x: not exposed (Note 2) 〇: the surface temperature of the brush shaft is less than 150 ° C, X: 150 ° C or more 29 201008762 [Table 3] Comparative Example The present invention - The inner diameter of the molten galvanized steel pipe of the present invention Dpi 106.0 106.0 106.0 106.0 106.0 The outer diameter of the wire brush Db 111.0 111.0 111.0 111.0 111.0 The long direction of the wire brush Length Lb 70 70 70 70 70 Wire brush outer diameter Dw 0.25 0.25 0.25 0.25 0.25 Wire brush wire length Lw 30 30 30 30 30 Wire brush wire number N 7,500 7,500 7,500 7,500 7,500 Wire brush rotation n 100 300 Feed rate of 500 700 1,000 wire brush V 3,000 3,000 3,000 3,000 3,000 Number of passes of wire brush m 2 2 2 2 2 S 23,311 23,311 23,311 23,311 23,311 F(l)/K 0.002604 0.002604 0.002604 0.002604 0.002604 (h(l)xNxm) /S 502 1,501 2,500 3,500 5,000 Φ 1.3 3.9 6.5 9.1 13.0 Exposure of iron containing 6 mass% or more of Fe-known alloy layer with copper metal needle inspection groove copper adhesion copper adhesion copper adhesion copper adhesion exposure containing 6 mass% 6^) Microscopic observation of the cross section of the galvanized layer of the iron alloy layer of Fe (Note 1) The surface temperature of the wire brush shaft after the grinding of the inner surface of the X 〇〇〇〇 wire brush (Note 2) 〇〇〇〇 The surface temperature of the wire brush shaft after the grinding of the inner surface of the 〇 wire brush is carried out. The peeling of the polyethylene pipe after the freeze-thaw test is carried out without or without the polyethylene pipe after the warm water immersion test. Whether there is no peeling or not (Note 1) 〇: The alloy layer containing 6% by mass or more is exposed, χ ·· is not exposed (Note 2) 〇: The surface temperature of the brush shaft is less than 15 〇. Hey, hey: 15 years old. 0 or more 201008762 [Table 4] The present invention Comparative Example Comparative Example Comparative Example The inner diameter of the hot-dip galvanized steel pipe Dpi ------- - 106.0 106.0 106.0 106.0 106.0 The outer diameter of the wire brush Db - 111.0 111.0 111.0 111.0 111.0 Longitudinal length of wire brush Lb 70 70 70 70 70 Wire brush outer diameter Dw '------ 1— 0.25 0.25 0.25 0.25 0.25 Wire brush wire length Lw 10 15 20 25 30 Wire brush wire root Number N -----___ 7,500 7,500 7,500 7,500 7,500 Number of revolutions of wire brush n ——__ 100 100 100 100 100 Feed rate of wire brush V 3,000 3,000 3,000 3,000 3,000 Number of passes of wire brush -- m 2 2 2 2 2 S 23,311 23,311 23,311 23,311 23,311 F(l)/K 0.007813 0.005208 0.003906 0.003125 0.002604 (h(l)xNxm)/S 502 502 502 502 502 —-—__ Φ ---___ 3.9 2.6 2.0 1.6 1.3 Exposed contains 6 Quality ° / 〇 or more ^ | Fe by - ί ♦ alloy layer 镗 metal needle copper adhesion copper adhesion groove trench exposed containing more than 6% by mass ^ (Fe Zhiwei alloy layer galvanized layer section of the observation mirror observation ( Note 1) 〇〇XXX wire brush friction heating Surface temperature of the steel squeegee shaft after the inner surface grinding of the first branch (Note 2) 摩擦The frictional heat of the 〇〇〇〇〇 wire brush is polished on the inner surface of the steel wire after the 10th branch (Note 2) 〇〇〇〇 There is no peeling of the polyethylene pipe after the hot water immersion test. (Note 1) 〇·· There is iron containing 6% by mass or more of Fe. - The zinc alloy layer is exposed, x: not exposed (Note 2) 〇: The surface temperature of the brush shaft is less than 150 t, X: 15 〇 ° C or more 31 201008762 [Table 5] Comparative Example ------ The present invention The inner diameter of the molten galvanized steel pipe of the present invention is Dpi 106.0 106.0 106.0 106.0 106.0 The outer diameter of the wire brush Db 111.0 111.0 111.0 111.0 111.0 The long length of the wire brush Lb 70 70 70 70 70 The outer diameter of the wire brush Dw 0.15 0.25 0.38 0.55 0.80 Wire length of wire brush Lw 30 30 30 30 30 Wire number of wire brush N 7,500 7,500 7,500 7,500 7,500 Number of turns of wire brush n 100 100 100 100 100 Feed rate of wire brush V 3,000 3,000 3,000 3,000 3,000 Wire brush Pass times m 2 2 2 2 2 S 23,311 23,311 23,311 23,311 23,311 F(l)/K 0.000563 0.002604 0.009145 0.027729 0.085333 (h(l)xNxm)/S 502 502 502 502 502 Φ 0.3 1.3 4.6 13.9 42.8 Exposed to contain 6% by mass or more Microscopic observation of the cross section of the galvanized layer of the iron-zinc alloy layer containing Fe in an amount of 6% by mass or more by using a copper metal needle to inspect the copper of the copper and the adhesion of copper to the copper. (Note 1) XX 〇〇〇 The frictional heat of the wire brush is ground on the inner surface of the steel 鲦 _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ 2) Whether the peeling of the polyethylene pipe after the freeze-thaw test is carried out with or without the peeling of the polyethylene pipe after the warm water dipping test (Note 1) 〇: Containing 6% by mass or more The iron-zinc alloy layer of Fe is exposed, χ: not exposed (Note 2) 〇: the surface temperature of the brush shaft is less than 150 ° C, X: 150 ° C or higher 201008762 [Table 6] Comparative Example Comparative Example Comparative Example The present invention The inner diameter of the hot-dip galvanized steel pipe Dpi 106 .0 106.0 106.0 106.0 106.0 Outer diameter of wire brush Db 109.0 111.0 113.0 115.0 117.0 Length of wire brush length Lb 70 70 70 70 70 Wire brush wire outer diameter Dw 0.25 0.25 0.25 0.25 0.25 Wire brush wire length Lw 30 30 30 30 30 Wire number of wire brush N 7,500 7,500 7,500 7,500 7,500 Number of turns of wire brush n 100 100 100 100 100 Feed rate of wire brush V 3,000 3,000 3,000 3,000 3,000 Number of passes of wire brush m 2 2 2 2 2 S 23,311 23,311 23,311 23,311 23,311 F(l)/K 0.001563 0.002604 0.003646 0.004688 0.005729 (h(l)xNxm)/S 502 502 502 502 502 Φ 0.8 1.3 1.8 2.4 2.9 Exposing a salty alloy layer containing 6% by mass or more of yttrium Fe Metal needle inspection of copper in the trench groove to expose a section of the galvanized layer of the alloy layer containing 6 mass% or more of fine e (microscope observation) (X) The frictional heat of the XXXX wire brush is ground and the wire brush shaft of the first branch is ground. Surface temperature (Note 2) The surface temperature of the wire brush shaft after the grinding of the inner surface of the wire brush (Note 2) Peeling of polyethylene pipe after knot melting test, presence or absence of peeling of polyethylene pipe after warm water impregnation test

(Note 1) 〇: The iron-containing alloy layer containing 6% by mass or more of Fe is exposed, x: not exposed (Note 2) 〇: The surface temperature of the brush shaft is less than 150 ° C, X : 15 〇〇 C or more 33 201008762 [Table 7] The present invention Comparative Example Comparative Example Comparative Example The inner diameter of a molten zinc steel pipe Dpi 106.0 106.0 106.0 106.0 106.0 The outer diameter of the wire brush Db 111.0 111.0 111.0 111.0 111.0 The long length of the wire brush Lb 70 70 70 70 70 Wire brush outer diameter Dw 0.8 0.8 0.8 0.8 0.8 Wire brush wire length Lw 30 30 30 30 30 Wire brush wire number N 7,500 7,500 7,500 7,500 7,500 Wire brush rotation n 100 200 300 400 500 Wire brush Feed rate V 3,000 3,000 3,000 3,000 3,000 Number of passes of the wire brush m 2 2 2 2 2 S 23,311 23,311 23,311 23,311 23,311 F(l)/K 0.085333 0.085333 0.085333 0.085333 0.085333 (h(l)xNxm)/S 502 1,001 1,501 2,001 2,500 Φ 42.8 85.4 128.1 170.7 213.4 Exposed iron-zinc alloy layer containing 6% by mass or more of Fe. Copper-based metal needle is used to inspect copper-attached copper-attached groove trenches to expose iron containing 6% by mass or more. Microscopic observation of the cross section of the bond layer of the alloy layer (Note 1) 〇〇 XXX The surface temperature of the wire brush shaft after grinding the inner surface of the wire brush (Note 2) 〇〇 XXX The friction heat of the wire brush is ground. The surface temperature of the wire brush shaft after 10 (>i2) 〇〇XXX The peeling of the polyethylene pipe after the freeze-thaw test is not the case. There is no peeling of the polyethylene pipe after the warm water dipping test.

(Note 1) 〇: The iron-zinc alloy layer containing 6 mass% or more of Fe is exposed, x: not exposed (Note 2) 〇: the surface temperature of the brush shaft is less than i5 〇 ° C, X : 150 ° C or more 34 201008762 INDUSTRIAL APPLICABILITY According to the present invention, since the inner surface of the hot-dip galvanized steel pipe is polished by a wire brush and the pure zinc layer is removed, the iron alloy containing 6 mass% or more of Fe can be surely exposed. The adhesion between the surface and the polyolefin tube is stable and enhanced. It can be industrially produced. Even in the pipeline where freezing and melting occurs, the inner surface of the polyolefin pipe is not easily peeled off, and the inner surface of the polyolefin pipe is coated, which is extremely useful in the industry. [Graphic succinct _ say ^ Ming] [Fig. 1] is a cross-sectional view of the molten steel tube and a cross-sectional view and a side view of the wire brush. [Fig. 2] A relationship between the length h(i) of the inner surface of the molten steel tube and the brush length Lb of a steel wire is drilled when the wire brush advances its brush length Lb portion. [Explanation of main component symbols] l.-·Solved mineral zinc steel pipe 2···Wire brush 2'...Wire brush (shows the mode position of the wire brush when advancing its brush length (Lb) part) 35

Claims (1)

201008762 VII. Patent application scope: 1. A method for manufacturing a steel pipe coated with polyolefin on the inner surface, which is coated on the inner surface of the hot-dip galvanized steel pipe which has been subjected to hot-dip galvanizing on the inner surface and the outer surface, so as to contain 6% by mass or more. After exposing the iron-zinc alloy layer of Fe and then coating the inner surface of the polyolefin tube with the polyolefin-coated steel pipe, the manufacturing method is characterized in that the wire brush is cylindrical and the central axis of the cylinder is The wire is radially arranged in the radial direction, and the inner surface layer of the steel pipe is ground by inserting the wire brush into the molten galvanized steel pipe while rotating the wire shaft with the central axis as a rotating shaft. 2. The method for producing an inner-coated polyolefin steel pipe according to the first aspect of the invention, wherein the steel wire has a Vickers hardness of 500 or more. 3. The method for producing a steel pipe coated with an inner surface according to the first or second aspect of the invention, wherein the chemical composition of the steel wire is C: 0.6 to 1.2 mass%, and Μη: 0.2 to 1.2 mass%, Si: 0.1 to 1.5% by mass, P: 0.05% by mass or less, and S: 0.04% by mass or less, and the remainder is Fe and unavoidable impurities. 4. The method for producing an inner-coated polyolefin steel pipe according to any one of claims 1 to 3, wherein the surface of the steel wire is plated with brass. 5. The method for producing a steel pipe coated with a polyolefin inner surface according to any one of claims 1 to 4, which satisfies the following formula 1 The condition of ~5, [1] 36 201008762 Explanation) = Kx(Db-Dpi)xDw3 Lw Equation 1 s = Lb2xn χπχ Dpi V Equation 3 F(l)xh(\)xNxm KxS 4 2.6 <^<85.4.....Form 5 F(l): Scraping force per wire of the wire brush h(l): When the wire brush advances its brush length (Lb) portion, the wire brush The length of the inner surface of a steel wire polished steel pipe (mm) Φ : When the wire brush of N steel wire passes through the inner surface of the galvanized steel pipe m times, the total length of the wire brush grinding per unit area and the product of the wire to the rubbing force K: proportional coefficient Dpi: smelting bond zinc Inner diameter of steel pipe (mm) Db: outer diameter of wire brush (mm) Lb: length of wire brush (mm) Dw: wire diameter of wire brush (mm) Lw: wire length of wire brush (mm) N : Number of wires of wire brush (root) η : Number of revolutions of wire brush (rpm) 37 201008762 V : Feeding speed of wire brush (mm/min) m : Number of passes of wire brush (times) S : Wire brush advances When the length (Lb) portion is brushed, the wire brush grinds the area (mm2) of the molten galvanized steel pipe. 6. The method for producing an inner-coated polyolefin steel pipe according to any one of claims 1 to 5, wherein after the grinding, the steel pipe is scraped with a Vickers hardness of 60 to 100. The inner surface is used to judge the quality of the grinding state. 7. The method for producing a steel pipe coated with an inner surface of a polyolefin according to claim 6, wherein the metal needle is made of copper. 38