WO2010008025A1 - Process for production of steel tube having polyolefin-coated inside surface - Google Patents

Process for production of steel tube having polyolefin-coated inside surface Download PDF

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Publication number
WO2010008025A1
WO2010008025A1 PCT/JP2009/062828 JP2009062828W WO2010008025A1 WO 2010008025 A1 WO2010008025 A1 WO 2010008025A1 JP 2009062828 W JP2009062828 W JP 2009062828W WO 2010008025 A1 WO2010008025 A1 WO 2010008025A1
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WIPO (PCT)
Prior art keywords
steel wire
steel pipe
wire brush
mass
polyolefin
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PCT/JP2009/062828
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French (fr)
Japanese (ja)
Inventor
博幸 三村
義久 仮屋園
真一 船津
哲 佐藤
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新日本製鐵株式会社
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Application filed by 新日本製鐵株式会社 filed Critical 新日本製鐵株式会社
Priority to CN2009801263001A priority Critical patent/CN102089120A/en
Priority to KR1020117000300A priority patent/KR101279334B1/en
Publication of WO2010008025A1 publication Critical patent/WO2010008025A1/en

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    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16L—PIPES; JOINTS OR FITTINGS FOR PIPES; SUPPORTS FOR PIPES, CABLES OR PROTECTIVE TUBING; MEANS FOR THERMAL INSULATION IN GENERAL
    • F16L58/00—Protection of pipes or pipe fittings against corrosion or incrustation
    • F16L58/02—Protection of pipes or pipe fittings against corrosion or incrustation by means of internal or external coatings
    • F16L58/04—Coatings characterised by the materials used
    • F16L58/10—Coatings characterised by the materials used by rubber or plastics
    • F16L58/1009—Coatings characterised by the materials used by rubber or plastics the coating being placed inside the pipe
    • F16L58/1045—Coatings characterised by the materials used by rubber or plastics the coating being placed inside the pipe the coating being an extruded or a fused layer
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B24—GRINDING; POLISHING
    • B24B—MACHINES, DEVICES, OR PROCESSES FOR GRINDING OR POLISHING; DRESSING OR CONDITIONING OF ABRADING SURFACES; FEEDING OF GRINDING, POLISHING, OR LAPPING AGENTS
    • B24B5/00—Machines or devices designed for grinding surfaces of revolution on work, including those which also grind adjacent plane surfaces; Accessories therefor
    • B24B5/02—Machines or devices designed for grinding surfaces of revolution on work, including those which also grind adjacent plane surfaces; Accessories therefor involving centres or chucks for holding work
    • B24B5/06—Machines or devices designed for grinding surfaces of revolution on work, including those which also grind adjacent plane surfaces; Accessories therefor involving centres or chucks for holding work for grinding cylindrical surfaces internally
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
    • B05D—PROCESSES FOR APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
    • B05D7/00—Processes, other than flocking, specially adapted for applying liquids or other fluent materials to particular surfaces or for applying particular liquids or other fluent materials
    • B05D7/22—Processes, other than flocking, specially adapted for applying liquids or other fluent materials to particular surfaces or for applying particular liquids or other fluent materials to internal surfaces, e.g. of tubes
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
    • B05D—PROCESSES FOR APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
    • B05D7/00—Processes, other than flocking, specially adapted for applying liquids or other fluent materials to particular surfaces or for applying particular liquids or other fluent materials
    • B05D7/22—Processes, other than flocking, specially adapted for applying liquids or other fluent materials to particular surfaces or for applying particular liquids or other fluent materials to internal surfaces, e.g. of tubes
    • B05D7/222—Processes, other than flocking, specially adapted for applying liquids or other fluent materials to particular surfaces or for applying particular liquids or other fluent materials to internal surfaces, e.g. of tubes of pipes
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B24—GRINDING; POLISHING
    • B24B—MACHINES, DEVICES, OR PROCESSES FOR GRINDING OR POLISHING; DRESSING OR CONDITIONING OF ABRADING SURFACES; FEEDING OF GRINDING, POLISHING, OR LAPPING AGENTS
    • B24B29/00—Machines or devices for polishing surfaces on work by means of tools made of soft or flexible material with or without the application of solid or liquid polishing agents
    • B24B29/02—Machines or devices for polishing surfaces on work by means of tools made of soft or flexible material with or without the application of solid or liquid polishing agents designed for particular workpieces
    • B24B29/04—Machines or devices for polishing surfaces on work by means of tools made of soft or flexible material with or without the application of solid or liquid polishing agents designed for particular workpieces for rotationally symmetrical workpieces, e.g. ball-, cylinder- or cone-shaped workpieces
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B24—GRINDING; POLISHING
    • B24B—MACHINES, DEVICES, OR PROCESSES FOR GRINDING OR POLISHING; DRESSING OR CONDITIONING OF ABRADING SURFACES; FEEDING OF GRINDING, POLISHING, OR LAPPING AGENTS
    • B24B5/00—Machines or devices designed for grinding surfaces of revolution on work, including those which also grind adjacent plane surfaces; Accessories therefor
    • B24B5/36—Single-purpose machines or devices
    • B24B5/40—Single-purpose machines or devices for grinding tubes internally
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B24—GRINDING; POLISHING
    • B24D—TOOLS FOR GRINDING, BUFFING OR SHARPENING
    • B24D13/00—Wheels having flexibly-acting working parts, e.g. buffing wheels; Mountings therefor
    • B24D13/02—Wheels having flexibly-acting working parts, e.g. buffing wheels; Mountings therefor acting by their periphery
    • B24D13/10—Wheels having flexibly-acting working parts, e.g. buffing wheels; Mountings therefor acting by their periphery comprising assemblies of brushes
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/02—Ferrous alloys, e.g. steel alloys containing silicon
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/04—Ferrous alloys, e.g. steel alloys containing manganese
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16L—PIPES; JOINTS OR FITTINGS FOR PIPES; SUPPORTS FOR PIPES, CABLES OR PROTECTIVE TUBING; MEANS FOR THERMAL INSULATION IN GENERAL
    • F16L9/00—Rigid pipes
    • F16L9/14—Compound tubes, i.e. made of materials not wholly covered by any one of the preceding groups
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16L—PIPES; JOINTS OR FITTINGS FOR PIPES; SUPPORTS FOR PIPES, CABLES OR PROTECTIVE TUBING; MEANS FOR THERMAL INSULATION IN GENERAL
    • F16L9/00—Rigid pipes
    • F16L9/14—Compound tubes, i.e. made of materials not wholly covered by any one of the preceding groups
    • F16L9/147—Compound tubes, i.e. made of materials not wholly covered by any one of the preceding groups comprising only layers of metal and plastics with or without reinforcement
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
    • B05D—PROCESSES FOR APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
    • B05D2202/00—Metallic substrate
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
    • B05D—PROCESSES FOR APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
    • B05D2254/00—Tubes
    • B05D2254/04—Applying the material on the interior of the tube
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
    • B05D—PROCESSES FOR APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
    • B05D2350/00—Pretreatment of the substrate
    • B05D2350/60—Adding a layer before coating
    • B05D2350/65—Adding a layer before coating metal layer
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
    • B05D—PROCESSES FOR APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
    • B05D2507/00—Polyolefins
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
    • B05D—PROCESSES FOR APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
    • B05D3/00—Pretreatment of surfaces to which liquids or other fluent materials are to be applied; After-treatment of applied coatings, e.g. intermediate treating of an applied coating preparatory to subsequent applications of liquids or other fluent materials
    • B05D3/12—Pretreatment of surfaces to which liquids or other fluent materials are to be applied; After-treatment of applied coatings, e.g. intermediate treating of an applied coating preparatory to subsequent applications of liquids or other fluent materials by mechanical means

Definitions

  • the present invention relates to a method for producing an inner surface polyolefin coated steel pipe in which an inner surface of a steel pipe whose inner surface and outer surface are galvanized is coated with a polyolefin tube.
  • inner surface resin-coated steel pipes that are coated with a synthetic resin pipe made of a synthetic resin such as polyolefin on the inner surface of the steel pipe to prevent corrosion are used. Since the inner surface resin-coated steel pipe is used for a long period of time, sufficient adhesion is required between the inner surface of the steel pipe and the synthetic resin pipe. In particular, when the temperature and water temperature fluctuate greatly and the pipe line freezes and thaws, if the adhesion between the synthetic resin pipe coated on the inner surface and the steel pipe is insufficient, the synthetic resin pipe will expand or contract. When the synthetic resin pipe is peeled off from the steel pipe by the peeling force caused by, and the peeling progresses greatly, the pipe may be blocked.
  • Patent Document 1 discloses a method of polishing and removing white rust, impurities, and oil and fat, and cleaning.
  • Patent Document 2 as a pretreatment of a galvanized steel pipe, the inner surface of the steel pipe is polished with a wire brush to remove a pure zinc layer to expose an iron-zinc alloy layer containing 6% or more of iron, It is disclosed that if a polyolefin tube is coated, the polyolefin tube is difficult to peel off in a freeze-thaw test.
  • Patent Document 1 does not disclose any specific polishing method or how much polishing is required to make it difficult to peel the inner synthetic resin tube in a freeze-thaw test or the like.
  • Patent Document 2 does not disclose any specific wire brush shape, size, appropriate conditions for scouring, and inspection method after scouring.
  • the present invention is an environment where freezing and thawing repeatedly occurs, and even in a state where the hot water is always filled, the polyolefin tube is hardly peeled off and has excellent water-resistant adhesion. It aims at providing the manufacturing method of an inner surface polyolefin covering steel pipe.
  • the present inventors have an iron-zinc alloy layer containing 6 mass% or more of Fe between the surface of the steel pipe base material and the galvanized layer.
  • an iron-zinc alloy layer containing 6 mass% or more of Fe is exposed in order to increase the adhesion of polyolefin.
  • the steel wire brush has a columnar shape, and the steel wires are radially arranged from the central axis of the column, A method for producing an inner surface polyolefin-coated steel pipe, wherein the steel pipe inner surface plating layer is ground by inserting a steel wire brush into the hot dip galvanized steel pipe while rotating the central axis as a rotation axis.
  • the chemical composition of the steel wire is C: 0.6 to 1.2% by mass, Mn: 0.2 to 1.2% by mass, Si: 0.1 to 1.5% by mass, P: 0.0.
  • the ground state is judged by scratching the inner surface of the steel pipe with a metal needle having a Vickers hardness of 60 to 100 after the grinding.
  • the inner surface of a hot-dip galvanized steel pipe can be ground with a steel wire brush to remove a pure zinc layer, and an iron-zinc alloy layer containing 6 mass% or more of Fe can be reliably exposed. Therefore, the adhesion between the ground surface and the polyolefin pipe is stably enhanced, and industrial production of the inner surface polyolefin coated steel pipe in which the inner surface polyolefin pipe is difficult to peel off even in a pipe line where freeze-thaw occurs.
  • the inner surface of the hot-dip galvanized steel pipe is ground with a steel wire brush. Then, specific conditions for exposing an iron-zinc alloy layer containing 6 mass% or more of Fe were found.
  • a steel wire brush having a columnar shape, and steel wires are arranged radially from the central axis of the column, and the steel wire brush is rotated about the central axis. This can be achieved by grinding the inner surface of the hot dip galvanized steel pipe by inserting it into the hot dip galvanized steel pipe while rotating as a shaft. This is because the steel wire of the steel wire brush follows the microscopic irregularities on the inner surface of the hot dip galvanized steel pipe and grinds uniformly and reliably.
  • the grinding efficiency of the steel wire is 500 or more, the grinding efficiency is good. This is because the grinding efficiency of zinc is good when the difference between the Vickers hardness of the steel wire and that of zinc is large.
  • the chemical composition of the steel wire is C: 0.6 to 1.2 mass%, Mn: 0.2 to 1.2 mass%, Si: 0.1 to 1.5 mass%, P: 0.05 mass%
  • S 0.04% by mass and the balance being Fe and inevitable impurities are preferable. If the lower limit values of C, Si, and Mn are less than that, the required high hardness cannot be obtained, and if the upper limit value is exceeded, the toughness decreases, so these values are set. Moreover, since the upper limit of P and S will cause embrittlement etc. by segregation when it exceeds it, these upper limits are set. In short, the steel wire needs to have both high hardness and fracture resistance, and even if a small amount of other elements are contained within that range, the present invention is not impaired.
  • the steel wire is preferably subjected to brass plating. This is to prevent iron rust from being brought into the inner surface of the hot-dip galvanized steel pipe.
  • the present inventors ground an inner surface of a hot-dip galvanized steel tube under the conditions satisfying the following formulas 1 to 5, and an iron-zinc alloy containing 6 mass% or more of Fe: It has been found that the layer can be exposed.
  • Equation 1 The force F (1) that one steel wire of a steel wire brush scratches the inner surface of a hot-dip galvanized steel pipe can be expressed as shown in Equation 1.
  • Equation 4 The product of the total extension length of the steel wire brush ground per unit area and the scratching force of the steel wire when the steel wire passes the inner surface of the galvanized steel pipe m times with N steel wire brushes ⁇ Can be expressed as Equation 4.
  • Example 1 to Example 7 if the value of ⁇ in Formula 4 is 2.6 or more and 85.4 or less, the iron-zinc alloy layer containing 6% by mass or more of Fe is exposed and the grinding is performed. It was confirmed that stable adhesion between the surface and the polyolefin tube was ensured. In other words, in the case of the grinding conditions in which the value of ⁇ in formula 4 is less than 2.6, even if the inner surface of the hot dip galvanized steel pipe is ground with a steel wire brush, the pure zinc layer remains and Fe is 6 mass. The exposure of the iron-zinc alloy layer containing at least% is insufficient.
  • the present inventors pay attention to the fact that the pure zinc layer and the iron-zinc alloy layer on the surface layer of the hot dip galvanizing differ in Vickers hardness, and Fe on the inner surface of the hot dip galvanized steel pipe with a steel wire brush is 6 mass%. It used for the inspection which judges that the iron-zinc alloy layer contained above was exposed.
  • the Vickers hardness of the pure zinc layer is less than 60
  • the Vickers hardness of the iron-zinc alloy layer containing 6% by mass or more of Fe exceeds 100.
  • the inner surface of a hot-dip galvanized steel pipe ground with a steel wire brush is scratched and inspected.
  • a pure zinc layer whose Vickers hardness is softer than that of the metal needle remains. Therefore, when the surface is scratched with the inspection needle, a groove is formed on the inner surface of the galvanized steel pipe.
  • the iron-zinc alloy layer containing 6 mass% or more of Fe having a Vickers hardness higher than that of the metal needle is exposed. The tip is shaved and the shaved metal powder adheres to the surface of the iron-zinc alloy layer containing 6 mass% or more of Fe.
  • Aluminum, copper, and brass are known as metals having a Vickers hardness of 60 to 100. Since aluminum has the same color as galvanized silver, it is difficult to judge aluminum and zinc by visual observation, making it unsuitable as a metal needle material for inspection. Copper and brass are different in color tone from galvanized, and are suitable as materials for inspection metal needles. However, since the blend ratio of copper and zinc may vary depending on the supplier and the Vickers hardness varies easily, brass with a certain Vickers hardness is the most suitable metal needle for inspection regardless of the supplier. It is a material.
  • the conditions of the examples are condition examples adopted to confirm the feasibility and effects of the present invention, and the present invention is not limited to these conditions.
  • the present invention can adopt various conditions as long as the object of the present invention is achieved without departing from the gist of the present invention.
  • Example 1 The inner surface and outer surface of a steel pipe (SGP100AX ⁇ 6000 mm length) were hot dip galvanized to obtain a galvanized steel pipe. At this time, the content of aluminum contained in the zinc plating was set to 0.01% by mass.
  • the inner galvanizing was ground by inserting it into a galvanized steel pipe while rotating.
  • the steel wire brush used in the experiment had a Vickers hardness of 500, and the chemical composition of the steel wire was C: 0.81% by mass, Mn: 0.47% by mass, Si: 0.20% by mass. , P: 0.05% by mass, S: 0.04% by mass.
  • the grinding conditions are as shown in Table 1.
  • the feed speed of the steel wire brush was changed, and 10 hot-dip galvanized steel pipes per one level were ground on the inner surface for a total of 5 levels.
  • the surface temperature of the steel wire brush shaft was measured immediately after the first and tenth inner surfaces were continuously ground to investigate the state of frictional heat generation.
  • the inner surface of the galvanized steel pipe ground with a copper metal needle was scratched to inspect the quality of the ground state.
  • a high-density polyethylene pipe was prepared in which maleic anhydride-modified polyethylene having a thickness slightly smaller than the inner diameter of the galvanized steel pipe and having a thickness of 100 ⁇ m 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 galvanized steel pipe whose inner surface is ground, cover both ends, press-fit air into the high-density polyethylene pipe, seal it, and then heat to 160 ° C in a heating furnace, The high-density polyethylene pipe was melted and pressure-bonded to the inner surface of the galvanized steel pipe.
  • the galvanized pipe is taken out from the heating furnace and cooled.
  • the temperature reaches 70 ° C.
  • the enclosed air is removed to obtain a galvanized steel pipe (invented steel pipe a) having a high-density polyethylene pipe coated on the inner surface. It was.
  • the cross section was polished and observed with an optical microscope, and a freeze-thaw test and a hot water immersion test were performed.
  • a 20 mm wide circumferential section was taken as a test piece, embedded and fixed with a resin, the section was polished, the galvanized layer was etched with a 3% nitric acid-ethanol solution, and galvanized.
  • the layer was observed with an optical microscope to investigate whether an iron-zinc alloy layer containing 6 mass% or more of Fe was exposed on the outermost layer.
  • a specimen obtained by cutting to a length of 150 mm is placed in a container filled with tap water so that about 1/3 of the length is immersed in water.
  • the freezing and thawing operation of freezing and thawing in a high-temperature bath at 60 ° C. for 1 hour was repeated for 100 cycles.
  • a test piece obtained by cutting to a length of 150 mm was immersed in a container containing tap water, and the container was placed in a constant temperature bath at 40 ° C. and left for 3 months. After the freeze-thaw test and the hot water immersion test, the test piece was examined for the presence or absence of peeling of the high-density polyethylene tube.
  • Example 2 The inner surface and outer surface of a steel pipe (SGP100AX ⁇ 6000 mm length) were hot dip galvanized to obtain a galvanized steel pipe. At this time, the content of aluminum contained in the zinc plating was set to 0.01% by mass.
  • the inner galvanizing was ground by inserting it into a galvanized steel pipe while rotating.
  • the steel wire brush used in the experiment had a Vickers hardness of 500, and the chemical composition of the steel wire was C: 0.81% by mass, Mn: 0.47% by mass, Si: 0.20% by mass. , P: 0.05% by mass, S: 0.04% by mass.
  • the grinding conditions are as shown in Table 2.
  • the number of passes of the steel wire brush was changed, and 10 hot-dip galvanized steel pipes were internally ground per level, for a total of 5 levels.
  • the surface temperature of the steel wire brush shaft was measured immediately after the first and tenth inner surfaces were continuously ground to investigate the state of frictional heat generation.
  • the inner surface of the galvanized steel pipe ground with a copper metal needle was scratched to inspect the quality of the ground state.
  • a high-density polyethylene pipe was prepared in which maleic anhydride-modified polyethylene having a thickness slightly smaller than the inner diameter of the galvanized steel pipe and having a thickness of 100 ⁇ m 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 galvanized steel pipe whose inner surface is ground, cover both ends, press-fit air into the high-density polyethylene pipe, seal it, and then heat to 160 ° C in a heating furnace, The high-density polyethylene pipe was melted and pressure-bonded to the inner surface of the galvanized steel pipe.
  • the galvanized pipe is taken out from the heating furnace and cooled, and when the temperature reaches 70 ° C., the enclosed air is removed to obtain a galvanized steel pipe whose inner surface is coated with a high-density polyethylene pipe (present invention steel pipe b). It was.
  • the cross section was polished and observed with an optical microscope, and a freeze-thaw test and a hot water immersion test were performed.
  • a 20 mm wide circumferential section was taken as a test piece, embedded and fixed with a resin, the section was polished, the galvanized layer was etched with a 3% nitric acid-ethanol solution, and galvanized.
  • the layer was observed with an optical microscope to investigate whether an iron-zinc alloy layer containing 6 mass% or more of Fe was exposed on the outermost layer.
  • a specimen obtained by cutting to a length of 150 mm is placed in a container filled with tap water so that about 1/3 of the length is immersed in water.
  • the freezing and thawing operation of freezing and thawing in a high-temperature bath at 60 ° C. for 1 hour was repeated for 100 cycles.
  • a test piece obtained by cutting to a length of 150 mm was immersed in a container containing tap water, and the container was placed in a constant temperature bath at 40 ° C. and left for 3 months. After the freeze-thaw test and the hot water immersion test, the test piece was examined for the presence or absence of peeling of the high-density polyethylene tube.
  • Example 3 The inner surface and outer surface of a steel pipe (SGP100AX ⁇ 6000 mm length) were hot dip galvanized to obtain a galvanized steel pipe. At this time, the content of aluminum contained in the zinc plating was set to 0.01% by mass.
  • the inner galvanizing was ground by inserting it into a galvanized steel pipe while rotating.
  • the steel wire brush used in the experiment had a Vickers hardness of 500, and the chemical composition of the steel wire was C: 0.81% by mass, Mn: 0.47% by mass, Si: 0.20% by mass. , P: 0.05% by mass, S: 0.04% by mass.
  • the grinding conditions are as shown in Table 3.
  • the number of rotations of the steel wire brush was changed, and 10 hot-dip galvanized steel pipes were internally ground per level, for a total of 5 levels.
  • the surface temperature of the steel wire brush shaft was measured immediately after the first and tenth inner surfaces were continuously ground to investigate the state of frictional heat generation.
  • the inner surface of the galvanized steel pipe ground with a copper metal needle was scratched to inspect the quality of the ground state.
  • a high-density polyethylene pipe was prepared in which maleic anhydride-modified polyethylene having a thickness slightly smaller than the inner diameter of the galvanized steel pipe and having a thickness of 100 ⁇ m 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 galvanized steel pipe whose inner surface is ground, cover both ends, press-fit air into the high-density polyethylene pipe, seal it, and then heat to 160 ° C in a heating furnace, The high-density polyethylene pipe was melted and pressure-bonded to the inner surface of the galvanized steel pipe.
  • the galvanized pipe is taken out from the heating furnace and cooled, and when the temperature reaches 70 ° C., the enclosed air is removed to obtain a galvanized steel pipe (invented steel pipe c) whose inner surface is covered with a high-density polyethylene pipe. It was.
  • the cross section was polished and observed with an optical microscope, and a freeze-thaw test and a hot water immersion test were performed.
  • a 20 mm wide circumferential section was taken as a test piece, embedded and fixed with a resin, the section was polished, the galvanized layer was etched with a 3% nitric acid-ethanol solution, and galvanized.
  • the layer was observed with an optical microscope to investigate whether an iron-zinc alloy layer containing 6 mass% or more of Fe was exposed on the outermost layer.
  • a specimen obtained by cutting to a length of 150 mm is placed in a container filled with tap water so that about 1/3 of the length is immersed in water.
  • the freezing and thawing operation of freezing and thawing in a high-temperature bath at 60 ° C. for 1 hour was repeated for 100 cycles.
  • a test piece obtained by cutting to a length of 150 mm was immersed in a container containing tap water, and the container was placed in a constant temperature bath at 40 ° C. and left for 3 months. After the freeze-thaw test and the hot water immersion test, the test piece was examined for the presence or absence of peeling of the high-density polyethylene tube.
  • Example 4 The inner surface and outer surface of a steel pipe (SGP100AX ⁇ 6000 mm length) were hot dip galvanized to obtain a galvanized steel pipe. At this time, the content of aluminum contained in the zinc plating was set to 0.01% by mass.
  • the inner galvanizing was ground by inserting it into a galvanized steel pipe while rotating.
  • the steel wire brush used in the experiment had a Vickers hardness of 500, and the chemical composition of the steel wire was C: 0.81% by mass, Mn: 0.47% by mass, Si: 0.20% by mass. , P: 0.05% by mass, S: 0.04% by mass.
  • the grinding conditions are as shown in Table 4.
  • the length of the steel wire brush steel wire was changed, and 10 hot-dip galvanized steel pipes were internally ground per level, and a total of 5 levels were carried out.
  • the surface temperature of the steel wire brush shaft was measured immediately after the first and tenth inner surfaces were continuously ground to investigate the state of frictional heat generation.
  • the inner surface of the galvanized steel pipe ground with a copper metal needle was scratched to inspect the quality of the ground state.
  • a high-density polyethylene pipe was prepared in which maleic anhydride-modified polyethylene having a thickness slightly smaller than the inner diameter of the galvanized steel pipe and having a thickness of 100 ⁇ m 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 galvanized steel pipe whose inner surface is ground, cover both ends, press-fit air into the high-density polyethylene pipe, seal it, and then heat to 160 ° C in a heating furnace, The high-density polyethylene pipe was melted and pressure-bonded to the inner surface of the galvanized steel pipe.
  • the galvanized pipe is taken out from the heating furnace and cooled, and when the temperature reaches 70 ° C., the enclosed air is removed to obtain a galvanized steel pipe (invented steel pipe d) whose inner surface is covered with a high-density polyethylene pipe. It was.
  • the cross section was polished and observed with an optical microscope, and a freeze-thaw test and a hot water immersion test were performed.
  • a 20 mm wide circumferential section was taken as a test piece, embedded and fixed with a resin, the section was polished, the galvanized layer was etched with a 3% nitric acid-ethanol solution, and galvanized.
  • the layer was observed with an optical microscope to investigate whether an iron-zinc alloy layer containing 6 mass% or more of Fe was exposed on the outermost layer.
  • a specimen obtained by cutting to a length of 150 mm is placed in a container filled with tap water so that about 1/3 of the length is immersed in water.
  • the freezing and thawing operation of freezing and thawing in a high-temperature bath at 60 ° C. for 1 hour was repeated for 100 cycles.
  • a test piece obtained by cutting to a length of 150 mm was immersed in a container containing tap water, and the container was placed in a constant temperature bath at 40 ° C. and left for 3 months. After the freeze-thaw test and the hot water immersion test, the test piece was examined for the presence or absence of peeling of the high-density polyethylene tube.
  • Example 5 The inner surface and outer surface of a steel pipe (SGP100AX ⁇ 6000 mm length) were hot dip galvanized to obtain a galvanized steel pipe. At this time, the content of aluminum contained in the zinc plating was set to 0.01% by mass.
  • the inner galvanizing was ground by inserting it into a galvanized steel pipe while rotating.
  • the steel wire brush used in the experiment had a Vickers hardness of 500, and the chemical composition of the steel wire was C: 0.81% by mass, Mn: 0.47% by mass, Si: 0.20% by mass. , P: 0.05% by mass, S: 0.04% by mass.
  • the grinding conditions are as shown in Table 5.
  • the outer diameter of the steel wire of the steel wire brush was changed, and 10 hot-dip galvanized steel pipes per one level were internally ground, for a total of 5 levels.
  • the surface temperature of the steel wire brush shaft was measured immediately after the first and tenth inner surfaces were continuously ground to investigate the state of frictional heat generation.
  • the inner surface of the galvanized steel pipe ground with a copper metal needle was scratched to inspect the quality of the ground state.
  • a high-density polyethylene pipe was prepared in which maleic anhydride-modified polyethylene having a thickness slightly smaller than the inner diameter of the galvanized steel pipe and having a thickness of 100 ⁇ m 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 galvanized steel pipe whose inner surface is ground, cover both ends, press-fit air into the high-density polyethylene pipe, seal it, and then heat to 160 ° C in a heating furnace, The high-density polyethylene pipe was melted and pressure-bonded to the inner surface of the galvanized steel pipe.
  • the galvanized pipe is taken out from the heating furnace and cooled, and when the temperature reaches 70 ° C., the enclosed air is removed to obtain a galvanized steel pipe whose inner surface is coated with a high-density polyethylene pipe (present steel pipe e). It was.
  • the cross section was polished and observed with an optical microscope, and a freeze-thaw test and a hot water immersion test were performed. In observation with an optical microscope, a 20 mm wide circumferential section was taken as a test piece, embedded and fixed with a resin, the section was polished, the galvanized layer was etched with a 3% nitric acid-ethanol solution, and galvanized.
  • the layer was observed with an optical microscope to investigate whether an iron-zinc alloy layer containing 6 mass% or more of Fe was exposed on the outermost layer.
  • a specimen obtained by cutting to a length of 150 mm is placed in a container filled with tap water so that about 1/3 of the length is immersed in water.
  • the freezing and thawing operation of freezing and thawing in a high-temperature bath at 60 ° C. for 1 hour was repeated for 100 cycles.
  • a test piece obtained by cutting to a length of 150 mm was immersed in a container containing tap water, and the container was placed in a constant temperature bath at 40 ° C. and left for 3 months. After the freeze-thaw test and the hot water immersion test, the test piece was examined for the presence or absence of peeling of the high-density polyethylene tube.
  • Example 6 The inner surface and outer surface of a steel pipe (SGP100AX ⁇ 6000 mm length) were hot dip galvanized to obtain a galvanized steel pipe. At this time, the content of aluminum contained in the zinc plating was set to 0.01% by mass.
  • the inner galvanizing was ground by inserting it into a galvanized steel pipe while rotating.
  • the steel wire brush used in the experiment had a Vickers hardness of 500, and the chemical composition of the steel wire was C: 0.81% by mass, Mn: 0.47% by mass, Si: 0.20% by mass. , P: 0.05% by mass, S: 0.04% by mass.
  • the grinding conditions are as shown in Table 6.
  • the outer diameter of the steel wire brush was changed, and 10 hot-dip galvanized steel pipes were ground on the inner surface per level, for a total of 5 levels.
  • the surface temperature of the steel wire brush shaft was measured immediately after the first and tenth inner surfaces were continuously ground to investigate the state of frictional heat generation.
  • the inner surface of the galvanized steel pipe ground with a copper metal needle was scratched to inspect the quality of the ground state.
  • a high-density polyethylene pipe was prepared in which maleic anhydride-modified polyethylene having a thickness slightly smaller than the inner diameter of the galvanized steel pipe and having a thickness of 100 ⁇ m 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 galvanized steel pipe whose inner surface is ground, cover both ends, press-fit air into the high-density polyethylene pipe, seal it, and then heat to 160 ° C in a heating furnace, The high-density polyethylene pipe was melted and pressure-bonded to the inner surface of the galvanized steel pipe.
  • the galvanized pipe is taken out from the heating furnace and cooled, and when the temperature reaches 70 ° C., the enclosed air is removed to obtain a galvanized steel pipe whose inner surface is coated with a high-density polyethylene pipe (present invention steel pipe f). It was.
  • the cross section was polished and observed with an optical microscope, and a freeze-thaw test and a hot water immersion test were performed. In observation with an optical microscope, a 20 mm wide circumferential section was taken as a test piece, embedded and fixed with a resin, the section was polished, the galvanized layer was etched with a 3% nitric acid-ethanol solution, and galvanized.
  • the layer was observed with an optical microscope to investigate whether an iron-zinc alloy layer containing 6 mass% or more of Fe was exposed on the outermost layer.
  • a specimen obtained by cutting to a length of 150 mm is placed in a container filled with tap water so that about 1/3 of the length is immersed in water.
  • the freezing and thawing operation of freezing and thawing in a high-temperature bath at 60 ° C. for 1 hour was repeated for 100 cycles.
  • a test piece obtained by cutting to a length of 150 mm was immersed in a container containing tap water, and the container was placed in a constant temperature bath at 40 ° C. and left for 3 months. After the freeze-thaw test and the hot water immersion test, the test piece was examined for the presence or absence of peeling of the high-density polyethylene tube.
  • Example 7 The inner surface and outer surface of a steel pipe (SGP100AX ⁇ 6000 mm length) were hot dip galvanized to obtain a galvanized steel pipe. At this time, the content of aluminum contained in the zinc plating was set to 0.01% by mass.
  • the inner galvanizing was ground by inserting it into a galvanized steel pipe while rotating.
  • the steel wire brush used in the experiment had a Vickers hardness of 500, and the chemical composition of the steel wire was C: 0.81% by mass, Mn: 0.47% by mass, Si: 0.20% by mass. , P: 0.05% by mass, S: 0.04% by mass.
  • the grinding conditions are as shown in Table 7.
  • the number of rotations of the steel wire brush was changed, and 10 hot-dip galvanized steel pipes were internally ground per level, for a total of 5 levels.
  • the surface temperature of the steel wire brush shaft was measured immediately after the first and tenth inner surfaces were continuously ground to investigate the state of frictional heat generation.
  • the inner surface of the galvanized steel pipe ground with a copper metal needle was scratched to inspect the quality of the ground state.
  • a high-density polyethylene pipe was prepared in which maleic anhydride-modified polyethylene having a thickness slightly smaller than the inner diameter of the galvanized steel pipe and having a thickness of 100 ⁇ m 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 galvanized steel pipe whose inner surface is ground, cover both ends, press-fit air into the high-density polyethylene pipe, seal it, and then heat to 160 ° C in a heating furnace, The high-density polyethylene pipe was melted and pressure-bonded to the inner surface of the galvanized steel pipe.
  • the galvanized pipe is taken out from the heating furnace and cooled, and when the temperature reaches 70 ° C., the enclosed air is removed to obtain a galvanized steel pipe whose inner surface is coated with a high-density polyethylene pipe (present steel pipe g). It was.
  • the cross section was polished and observed with an optical microscope, and a freeze-thaw test and a hot water immersion test were performed. In observation with an optical microscope, a 20 mm wide circumferential section was taken as a test piece, embedded and fixed with a resin, the section was polished, the galvanized layer was etched with a 3% nitric acid-ethanol solution, and galvanized.
  • the layer was observed with an optical microscope to investigate whether an iron-zinc alloy layer containing 6 mass% or more of Fe was exposed on the outermost layer.
  • a specimen obtained by cutting to a length of 150 mm is placed in a container filled with tap water so that about 1/3 of the length is immersed in water.
  • the freezing and thawing operation of freezing and thawing in a high-temperature bath at 60 ° C. for 1 hour was repeated for 100 cycles.
  • a test piece obtained by cutting to a length of 150 mm was immersed in a container containing tap water, and the container was placed in a constant temperature bath at 40 ° C. and left for 3 months. After the freeze-thaw test and the hot water immersion test, the test piece was examined for the presence or absence of peeling of the high-density polyethylene tube.
  • the surface temperature of the steel wire brush shaft measured immediately after the first and tenth grinding was less than 150 ° C, and the grinding efficiency was good. It was.
  • the inner surface of a hot-dip galvanized steel pipe can be ground with a steel wire brush to remove a pure zinc layer, and an iron-zinc alloy layer containing 6 mass% or more of Fe can be reliably exposed. Therefore, the adhesion between the ground surface and the polyolefin pipe is stably enhanced, and industrial production of the inner polyolefin coated steel pipe in which the inner polyolefin pipe is hardly peeled even in a pipe where freezing and thawing occurs is extremely useful industrially.

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Abstract

Provided is a process for the production of a steel tube of which the inside surface is coated with a polyolefin, in which the polyolefin tube on the inside surface rarely peels off even in an environment where freezing and thawing occur repeatedly or in a case where the steel tube is always filled with warm water, and which is also excellent in water-resistant adhesion.  A process for the production of a steel tube of which the inside surface is coated with a polyolefin, which comprises subjecting a hot-dip zinc-plated steel tube, of which the inside and outside surfaces are plated with zinc by hot dipping, to grinding of the plating layer covering the inside surface with a steel wire brush to expose an iron-zinc alloy layer containing at least 6mass % of Fe, and then coating the resulting inside surface with a polyolefin, characterized in that the wire brush has a cylinder-like shape and is provided with steel wires arranged in radial directions radiately from the central axis of the cylinder and that the wire brush is inserted into the hot-dip zinc-plated steel tube while rotating on the central axis of the brush to grind the plating layer covering the inside surface.

Description

内面ポリオレフィン被覆鋼管の製造方法Manufacturing method of inner surface polyolefin coated steel pipe
　本願発明は、内面と外面に亜鉛めっきを施した鋼管の内面にポリオレフィン管を被覆した内面ポリオレフィン被覆鋼管の製造方法に関する。
　本願は、２００８年７月１６日に、日本に出願された特願２００８－１８４９８８号に基づき優先権を主張し、その内容をここに援用する。 The present invention relates to a method for producing an inner surface polyolefin coated steel pipe in which an inner surface of a steel pipe whose inner surface and outer surface are galvanized is coated with a polyolefin tube.
This application claims priority on July 16, 2008 based on Japanese Patent Application No. 2008-184988 for which it applied to Japan, and uses the content here.
　給水や排水に用いられる鋼管には、鋼管内面にポリオレフィン等の合成樹脂からなる合成樹脂管を被覆して防食した内面樹脂被覆鋼管が用いられる。該内面樹脂被覆鋼管は長期に渡って供用されるので、鋼管の内面と合成樹脂管の間には十分な密着性が必要である。特に、気温や水温の変動が大きく、管路に凍結融解が起こるような場合には、内面被覆した合成樹脂管と鋼管の間の密着性が不十分であると、合成樹脂管の膨張又は収縮による引き剥がし力で合成樹脂管が鋼管から剥離し、剥離が大きく進展すると管路の閉塞に到ることがある。そのため、特に内面に亜鉛めっきを有する鋼管の内面にポリオレフィン等の合成樹脂からなる合成樹脂管を被覆する際、亜鉛と合成樹脂の間に十分な密着性を得るために、予め鋼管内面の亜鉛表面を前処理する方法が用いられる。 For steel pipes used for water supply and drainage, inner surface resin-coated steel pipes that are coated with a synthetic resin pipe made of a synthetic resin such as polyolefin on the inner surface of the steel pipe to prevent corrosion are used. Since the inner surface resin-coated steel pipe is used for a long period of time, sufficient adhesion is required between the inner surface of the steel pipe and the synthetic resin pipe. In particular, when the temperature and water temperature fluctuate greatly and the pipe line freezes and thaws, if the adhesion between the synthetic resin pipe coated on the inner surface and the steel pipe is insufficient, the synthetic resin pipe will expand or contract. When the synthetic resin pipe is peeled off from the steel pipe by the peeling force caused by, and the peeling progresses greatly, the pipe may be blocked. Therefore, in particular, when coating the inner surface of a steel pipe having zinc plating on the inner surface with a synthetic resin pipe made of synthetic resin such as polyolefin, in order to obtain sufficient adhesion between zinc and the synthetic resin, the zinc surface on the inner surface of the steel pipe is previously Is used.
　例えば、特許文献１では、研磨して白さびや不純物、油脂分を除去、清掃する方法が示されている。
　また、特許文献２では、亜鉛めっき鋼管の前処理として、当該鋼管の内面をワイヤーブラシで研掃して、純亜鉛層を除去して鉄含有６％以上の鉄―亜鉛合金層を露出させ、ポリオレフィン管を被覆すれば、凍結融解試験でポリオレフィン管が剥離し難くなることが公開されている。 For example, Patent Document 1 discloses a method of polishing and removing white rust, impurities, and oil and fat, and cleaning.
Further, in Patent Document 2, as a pretreatment of a galvanized steel pipe, the inner surface of the steel pipe is polished with a wire brush to remove a pure zinc layer to expose an iron-zinc alloy layer containing 6% or more of iron, It is disclosed that if a polyolefin tube is coated, the polyolefin tube is difficult to peel off in a freeze-thaw test.
特開昭５８－８７０４５号公報JP 58-87045 A ＰＣＴ／ＪＰ２００７／０６１２５６号公報PCT / JP2007 / 061256
　しかし、特許文献１では、具体的な研磨方法や、どの程度研磨すれば、凍結融解試験などで内面の合成樹脂管が剥離し難くなるか等は一切公開されていない。また、特許文献２では、具体的なワイヤーブラシの形状、寸法、研掃の適切な条件や研掃後の検査方法については一切公開されていない。 However, Patent Document 1 does not disclose any specific polishing method or how much polishing is required to make it difficult to peel the inner synthetic resin tube in a freeze-thaw test or the like. Further, Patent Document 2 does not disclose any specific wire brush shape, size, appropriate conditions for scouring, and inspection method after scouring.
　本願発明は、上記問題点を解決するために、凍結・融解が繰り返し起きる環境や、常時、温水が充満している状態においても、ポリオレフィン管の剥離が起こりにくく、且つ、耐水密着性に優れた内面ポリオレフィン被覆鋼管の製造方法を提供することを目的とする。 In order to solve the above-mentioned problems, the present invention is an environment where freezing and thawing repeatedly occurs, and even in a state where the hot water is always filled, the polyolefin tube is hardly peeled off and has excellent water-resistant adhesion. It aims at providing the manufacturing method of an inner surface polyolefin covering steel pipe.
　本発明者らは、上記課題を解決するために鋭意研究を行った結果、鋼管母材である地鉄表面と亜鉛めっき層の間にＦｅを６質量％以上含有する鉄―亜鉛合金層を有する溶融亜鉛めっき鋼管の内面に、接着剤を介して、ポリオレフィンを被覆する内面ポリオレフィン被覆鋼管の製造において、ポリオリフィンの密着性を高めるため、Ｆｅを６質量％以上含有する鉄―亜鉛合金層を露出させて当該溶融亜鉛めっき鋼管の内面のめっき層を鋼製ワイヤーブラシで研削する具体的な条件に関する知見を得た。本発明は、前記知見に基づいて成されたものであり、その要旨は、以下のとおりである。 As a result of intensive studies to solve the above problems, the present inventors have an iron-zinc alloy layer containing 6 mass% or more of Fe between the surface of the steel pipe base material and the galvanized layer. In the production of an inner surface polyolefin coated steel pipe coated with polyolefin via an adhesive on the inner surface of a hot dip galvanized steel pipe, an iron-zinc alloy layer containing 6 mass% or more of Fe is exposed in order to increase the adhesion of polyolefin. Thus, the inventors have obtained knowledge about specific conditions for grinding the plating layer on the inner surface of the hot dip galvanized steel pipe with a steel wire brush. This invention is made | formed based on the said knowledge, The summary is as follows.
（１）内面及び外面に溶融亜鉛めっきを施した溶融亜鉛めっき鋼管の、内面のめっき層を鋼製ワイヤーブラシで研削し、Ｆｅを６質量％以上含有する鉄―亜鉛合金層を露出させた後に、ポリオレフィン管を被覆する内面ポリオレフィン被覆鋼管の製造方法において、前記鋼製ワイヤーブラシが、円柱状であり、且つ、鋼線を当該円柱の中心軸から半径方向に放射状に配置したものであり、当該鋼製ワイヤーブラシを前記中心軸を回転軸として回転させながら前記溶融亜鉛めっき鋼管に挿入することにより前記鋼管内面めっき層を研削することを特徴とする内面ポリオレフィン被覆鋼管の製造方法。 (1) After the inner surface plating layer of a hot dip galvanized steel pipe with hot dip galvanized inner and outer surfaces is ground with a steel wire brush to expose an iron-zinc alloy layer containing 6 mass% or more of Fe In the method for producing an inner surface polyolefin-coated steel pipe for coating a polyolefin pipe, the steel wire brush has a columnar shape, and the steel wires are radially arranged from the central axis of the column, A method for producing an inner surface polyolefin-coated steel pipe, wherein the steel pipe inner surface plating layer is ground by inserting a steel wire brush into the hot dip galvanized steel pipe while rotating the central axis as a rotation axis.
（２）前記鋼線のビッカース硬さが５００以上であることを特徴とする（１）に記載の内面ポリオレフィン被覆鋼管の製造方法。 (2) The method for producing an inner surface polyolefin-coated steel pipe according to (1), wherein the steel wire has a Vickers hardness of 500 or more.
（３）前記鋼線の化学成分がＣ：０．６～１．２質量％、Ｍｎ：０．２～１．２質量％、Ｓｉ：０．１～１．５質量％、P：０．０５質量％以下、S：０．０４質量％以下、残部がＦｅおよび不可避的不純物であることを特徴とする（１）または（２）に記載の内面ポリオレフィン被覆鋼管の製造方法。 (3) The chemical composition of the steel wire is C: 0.6 to 1.2% by mass, Mn: 0.2 to 1.2% by mass, Si: 0.1 to 1.5% by mass, P: 0.0. The method for producing an internally polyolefin-coated steel pipe according to (1) or (2), characterized in that the content is 05% by mass or less, S: 0.04% by mass or less, and the balance is Fe and inevitable impurities.
（４）前記鋼線の表面にブラスメッキを施したことを特徴とする（１）～（３）のいずれか一項に記載の内面ポリオレフィン被覆鋼管の製造方法。 (4) The method for producing an inner surface polyolefin-coated steel pipe according to any one of (1) to (3), wherein the surface of the steel wire is subjected to brass plating.
（５）（１）～（４）のいずれか一項に記載の内面ポリオレフィン被覆鋼管の製造方法において、下記の式１～式５の条件を満足することを特徴とする内面ポリオレフィン被覆鋼管の製造方法。
Figure JPOXMLDOC01-appb-M000002
 　　　F(1)　：　鋼製ワイヤーブラシの鋼線１本あたりの引っ掻き力
　　　h(1)　：　鋼製ワイヤーブラシがそのブラシ長さ（Lb）分を進む際、
　　　　　　　　該ワイヤーブラシの１本の鋼線が鋼管内面を研削する長さ（ｍｍ）
　　　φ　　：　鋼線がN本の鋼製ワイヤーブラシで溶融亜鉛めっき鋼管内面をｍ回通過した際、単位面積あたりの該ワイヤーブラシで研削する総延長長さと鋼線の引っ掻き力の積
　　　K　　 ：　比例係数
　　　Dpi　 ：　溶融亜鉛めっき鋼管の内径（ｍｍ）
　　　Db　　：　鋼製ワイヤーブラシの外径（ｍｍ）
　　　Lb　　：　鋼製ワイヤーブラシの長手方向の長さ（ｍｍ）
　　　Dw　　：　鋼製ワイヤーブラシの鋼線の外径（ｍｍ）
　　　Lw　　：　鋼製ワイヤーブラシの鋼線の長さ（ｍｍ）
　　　N　　 ：　鋼製ワイヤーブラシの鋼線の本数（本）
　　　n　　 ：　鋼製ワイヤーブラシの回転数（ｒｐｍ）
　　　V　　 ：　鋼製ワイヤーブラシの送り速度（ｍｍ／分）
　　　ｍ　　：　鋼製ワイヤーブラシの通過回数（回）
　　　S　　 ：　鋼製ワイヤーブラシがそのブラシ長さ（Lb）分を進む際、該ワイヤーブラシが溶融亜鉛めっき鋼管内面を研削する面積（ｍｍ２） (5) In the method for producing an inner surface polyolefin-coated steel pipe according to any one of (1) to (4), the production of an inner surface polyolefin-coated steel pipe characterized by satisfying the following formulas 1 to 5: Method.
Figure JPOXMLDOC01-appb-M000002
 F (1): Scratch force per steel wire of steel wire brush h (1): When the steel wire brush advances the length of the brush (Lb),
Length (mm) by which one steel wire of the wire brush grinds the inner surface of a steel pipe
φ: product of the total length of the wire to be ground with the wire brush per unit area when the steel wire passes through the inner surface of the hot-dip galvanized steel pipe m times with N steel wire brushes K: proportional coefficient Dpi: inner diameter of hot-dip galvanized steel pipe (mm)
Db: Outer diameter of steel wire brush (mm)
Lb: Length in the longitudinal direction of the steel wire brush (mm)
Dw: Outer diameter of steel wire brush (mm)
Lw: Length of steel wire brush steel wire (mm)
N: Number of steel wire brush steel wires
n: Rotation speed of steel wire brush (rpm)
V: Feed speed of steel wire brush (mm / min)
m: Number of times the steel wire brush passes (times)
S: Area where the wire brush grinds the inner surface of the hot-dip galvanized steel pipe (mm 2 ) when the steel wire brush advances the length of the brush (Lb)
（６）前記研削した後、前記鋼管内表面をビッカース硬度が６０～１００の金属針で引っ掻くことにより研削状態の良否を判定することを特徴とする（１）～（５）のいずれか一項に記載の内面ポリオレフィン被覆鋼管の製造方法。 (6) The ground state is judged by scratching the inner surface of the steel pipe with a metal needle having a Vickers hardness of 60 to 100 after the grinding. The manufacturing method of the inner surface polyolefin covering steel pipe as described in 1 ..
（７）前記金属針が銅製であることを特徴とする（６）に記載の内面ポリオレフィン被覆鋼管の製造方法。 (7) The method for producing an inner surface polyolefin-coated steel pipe according to (6), wherein the metal needle is made of copper.
　本発明によれば、溶融亜鉛めっき鋼管の内面を鋼製ワイヤーブラシで研削して、純亜鉛層を除去し、Ｆｅを６質量％以上含有する鉄―亜鉛合金層を確実に露出させることができるので、当該研削面とポリオレフィン管の密着性が安定して強化され、凍結融解が起こる管路でも内面ポリオレフィン管が剥離し難い内面ポリオレフィン被覆鋼管の工業生産が可能になった。 According to the present invention, the inner surface of a hot-dip galvanized steel pipe can be ground with a steel wire brush to remove a pure zinc layer, and an iron-zinc alloy layer containing 6 mass% or more of Fe can be reliably exposed. Therefore, the adhesion between the ground surface and the polyolefin pipe is stably enhanced, and industrial production of the inner surface polyolefin coated steel pipe in which the inner surface polyolefin pipe is difficult to peel off even in a pipe line where freeze-thaw occurs.
は、融亜鉛めっき鋼管の断面図と鋼製ワイヤーブラシの断面図及び側面図である。These are sectional drawing of a hot-dip galvanized steel pipe, and sectional drawing and side view of a steel wire brush. は、鋼製ワイヤーブラシがそのブラシ長さLb分を進む際、１本の鋼線が溶融亜鉛めっき鋼管内面を研削する長さｈ（１）とブラシ長さLbの関係を示す図である。These are figures which show the relationship between length h (1) and the brush length Lb which one steel wire grinds the inner surface of a hot-dip galvanized steel pipe, when a steel wire brush advances the brush length Lb.
　本発明者らは、溶融亜鉛めっき鋼管の内面に、接着剤を介して、ポリオレフィン管を被覆する内面ポリオレフィン被覆鋼管の製造において、当該溶融亜鉛めっき鋼管の内面のめっき層を鋼製ワイヤーブラシで研削し、Ｆｅを６質量％以上含有する鉄―亜鉛合金層を露出させる具体的な条件を見出した。 In the manufacture of an inner surface polyolefin-coated steel pipe that covers an inner surface of a hot-dip galvanized steel pipe with an adhesive, the inner surface of the hot-dip galvanized steel pipe is ground with a steel wire brush. Then, specific conditions for exposing an iron-zinc alloy layer containing 6 mass% or more of Fe were found.
　溶融亜鉛めっき鋼管の内面にＦｅを６質量％以上含有する鉄―亜鉛合金層を露出させるためには、溶融亜鉛めっき鋼管の内面の微視的な凹凸に追従し、均一かつ確実に研削しなければならない。そのためには、図１に示すように、円柱状の鋼製ワイヤーブラシで、かつ、鋼線を当該円柱の中心軸から半径方向に放射状に配置し、当該鋼製ワイヤーブラシを前記中心軸を回転軸として回転させながら前記溶融亜鉛めっき鋼管に挿入することにより前記溶融亜鉛めっき鋼管の内面研削することにより達成できる。それは当該鋼製ワイヤーブラシの鋼線が溶融亜鉛めっき鋼管の内面の微視的な凹凸に追従し、均一かつ確実に研削するからである。 In order to expose an iron-zinc alloy layer containing 6 mass% or more of Fe on the inner surface of a hot-dip galvanized steel pipe, it must follow the microscopic irregularities on the inner surface of the hot-dip galvanized steel pipe and grind it uniformly and reliably. I must. For this purpose, as shown in FIG. 1, a steel wire brush having a columnar shape, and steel wires are arranged radially from the central axis of the column, and the steel wire brush is rotated about the central axis. This can be achieved by grinding the inner surface of the hot dip galvanized steel pipe by inserting it into the hot dip galvanized steel pipe while rotating as a shaft. This is because the steel wire of the steel wire brush follows the microscopic irregularities on the inner surface of the hot dip galvanized steel pipe and grinds uniformly and reliably.
　前記鋼線のビッカース硬さは５００以上であれば研削効率が良い。それは当該鋼線のビッカース硬さと亜鉛のそれとの差が大きいと亜鉛の研削効率が良いからである。
　前記鋼線の化学成分はＣ：０．６～１．２質量％、Ｍｎ：０．２～１．２質量％、Ｓｉ：０．１～１．５質量％、P：０．０５質量％以下、S：０．０４質量％、残部がＦｅおよび不可避的不純物から成るものが良い。Ｃ、Ｓｉ，Ｍｎの下限値は、それ未満だと必要な高硬度を得られないし、上限値は、それを超えると靭性が低下するため、これらの値が設定されている。また、Ｐ、Ｓの上限値は、それを超えると偏析により脆化などを引き起こすため、これらの上限値が設定されている。要は鋼線には高硬度と耐破断性の両立が必要であり、その範囲で例えばその他の元素が微量含有されても本願発明を損なうものではない。 If the Vickers hardness of the steel wire is 500 or more, the grinding efficiency is good. This is because the grinding efficiency of zinc is good when the difference between the Vickers hardness of the steel wire and that of zinc is large.
The chemical composition of the steel wire is C: 0.6 to 1.2 mass%, Mn: 0.2 to 1.2 mass%, Si: 0.1 to 1.5 mass%, P: 0.05 mass% Hereinafter, S: 0.04% by mass and the balance being Fe and inevitable impurities are preferable. If the lower limit values of C, Si, and Mn are less than that, the required high hardness cannot be obtained, and if the upper limit value is exceeded, the toughness decreases, so these values are set. Moreover, since the upper limit of P and S will cause embrittlement etc. by segregation when it exceeds it, these upper limits are set. In short, the steel wire needs to have both high hardness and fracture resistance, and even if a small amount of other elements are contained within that range, the present invention is not impaired.
　前記鋼線の錆防止として当該鋼線にブラスメッキを施すのが良い。それは、溶融亜鉛めっき鋼管の内面への鉄錆持込を防止するためである。 ¡To prevent rust of the steel wire, the steel wire is preferably subjected to brass plating. This is to prevent iron rust from being brought into the inner surface of the hot-dip galvanized steel pipe.
　さらに、本発明者らは上記鋼製ワイヤーブラシを用いた際、以下の式１～式５を満足する条件で溶融亜鉛めっき鋼管の内面を研削するとＦｅを６質量％以上含有する鉄―亜鉛合金層を露出させることができることを見出した。 Furthermore, when using the steel wire brush, the present inventors ground an inner surface of a hot-dip galvanized steel tube under the conditions satisfying the following formulas 1 to 5, and an iron-zinc alloy containing 6 mass% or more of Fe: It has been found that the layer can be exposed.
Figure JPOXMLDOC01-appb-M000003
Figure JPOXMLDOC01-appb-M000003
　上記式中の記号の定義は以下の通りであり、また一部の記号を図１及び図２にも示している。
　　　F(1)　：　鋼製ワイヤーブラシの鋼線１本あたりの引っ掻き力
　　　h(1)　：　鋼製ワイヤーブラシがそのブラシ長さ（Lb）分を進む際、該ワイヤーブラシの１本の鋼線が鋼管内面を研削する長さ（ｍｍ）
　　　φ　　：　鋼線がN本の鋼製ワイヤーブラシで溶融亜鉛めっき鋼管内面をｍ回通過した際、単位面積あたりの該ワイヤーブラシで研削する総延長長さと鋼線の引っ掻き力の積
　　　K　　 ：　比例係数
　　　Dpi　 ：　溶融亜鉛めっき鋼管の内径（ｍｍ）
　　　Db　　：　鋼製ワイヤーブラシの外径（ｍｍ）
　　　Lb　　：　鋼製ワイヤーブラシの長手方向の長さ（ｍｍ）
　　　Dw　　：　鋼製ワイヤーブラシの鋼線の外径（ｍｍ）
　　　Lw　　：　鋼製ワイヤーブラシの鋼線の長さ（ｍｍ）
　　　N　　 ：　鋼製ワイヤーブラシの鋼線の本数（本）
　　　n　　 ：　鋼製ワイヤーブラシの回転数（ｒｐｍ）
　　　V　　 ：　鋼製ワイヤーブラシの送り速度（ｍｍ／分）
　　　ｍ　　：　鋼製ワイヤーブラシの通過回数（回）
　　　S　　 ：　鋼製ワイヤーブラシがそのブラシ長さ（Lb）分を進む際、該ワイヤーブラシが溶融亜鉛めっき鋼管内面を研削する面積（ｍｍ２） The definitions of the symbols in the above formula are as follows, and some symbols are also shown in FIGS.
F (1): Scratch force per steel wire of a steel wire brush h (1): When a steel wire brush advances its length (Lb), one steel wire of the wire brush Length to grind the inner surface of steel pipe (mm)
φ: product of the total extension length per unit area ground by the wire brush and the scratching force of the steel wire when the steel wire passes through the inner surface of the hot-dip galvanized steel pipe m times with N steel wire brushes K: proportional coefficient Dpi: inner diameter of hot-dip galvanized steel pipe (mm)
Db: Outer diameter of steel wire brush (mm)
Lb: Length in the longitudinal direction of the steel wire brush (mm)
Dw: Outer diameter of steel wire brush (mm)
Lw: Length of steel wire brush steel wire (mm)
N: Number of steel wire brush steel wires
n: Rotation speed of steel wire brush (rpm)
V: Feed speed of steel wire brush (mm / min)
m: Number of times the steel wire brush passes (times)
S: Area where the wire brush grinds the inner surface of the hot-dip galvanized steel pipe (mm 2 ) when the steel wire brush advances the length of the brush (Lb)
　鋼製ワイヤーブラシの鋼線１本が、溶融亜鉛めっき鋼管の内面を引っ掻く力F（1）は式１のように表せる。 The force F (1) that one steel wire of a steel wire brush scratches the inner surface of a hot-dip galvanized steel pipe can be expressed as shown in Equation 1.
　鋼製ワイヤーブラシがそのブラシ長さLbだけ進む際、該ワイヤーブラシの１本の鋼線が溶融亜鉛めっき鋼管内面を研削する長さｈ（1）は式２のように表せる。 When the steel wire brush advances by the brush length Lb, the length h (1) at which one steel wire of the wire brush grinds the inner surface of the hot-dip galvanized steel pipe can be expressed by Equation 2.
　鋼製ワイヤーブラシがそのブラシ長さLbだけ進む際、該ワイヤーブラシが溶融亜鉛めっき鋼管内面を研削する面積Sは式３のように表せる。 When the steel wire brush advances by the brush length Lb, the area S where the wire brush grinds the inner surface of the hot-dip galvanized steel pipe can be expressed as shown in Equation 3.
　鋼線がN本の鋼製ワイヤーブラシで溶融亜鉛めっき鋼管内面をｍ回通過した際、単位面積あたりの当該鋼製ワイヤーブラシの鋼線が研削する総延長長さと鋼線の引っ掻き力の積φは式４のように表せる。 The product of the total extension length of the steel wire brush ground per unit area and the scratching force of the steel wire when the steel wire passes the inner surface of the galvanized steel pipe m times with N steel wire brushes φ Can be expressed as Equation 4.
　実施例１から実施例７に示すように、式４のφの値が２．６以上８５．４以下であれば、Ｆｅを６質量％以上含有する鉄―亜鉛合金層が露出し、当該研削面とポリオレフィン管の安定した密着性が確保されることが確認された。言葉を変えると、式４のφの値が２．６未満となる研削条件の場合、溶融亜鉛めっき鋼管の内面を鋼製ワイヤーブラシで研削しても、純亜鉛層が残り、Ｆｅを６質量％以上含有する鉄―亜鉛合金層の露出が不十分になる。式４のφの値が８５．４を超える研削条件の場合、鋼製ワイヤーブラシが亜鉛めっき鋼管の内面との摩擦発熱で高温になり、研削効率が著しく低下し、純亜鉛層が残り、Ｆｅを６質量％以上含有する鉄―亜鉛合金層の露出が不十分になる。 As shown in Example 1 to Example 7, if the value of φ in Formula 4 is 2.6 or more and 85.4 or less, the iron-zinc alloy layer containing 6% by mass or more of Fe is exposed and the grinding is performed. It was confirmed that stable adhesion between the surface and the polyolefin tube was ensured. In other words, in the case of the grinding conditions in which the value of φ in formula 4 is less than 2.6, even if the inner surface of the hot dip galvanized steel pipe is ground with a steel wire brush, the pure zinc layer remains and Fe is 6 mass. The exposure of the iron-zinc alloy layer containing at least% is insufficient. In the case of grinding conditions in which the value of φ in Equation 4 exceeds 85.4, the steel wire brush becomes hot due to frictional heat generation with the inner surface of the galvanized steel pipe, the grinding efficiency is remarkably reduced, the pure zinc layer remains, and Fe The iron-zinc alloy layer containing 6% by mass or more is not sufficiently exposed.
　また、本発明者らは溶融亜鉛めっきの表層の純亜鉛層と鉄―亜鉛合金層ではビッカース硬さが異なることに着目し、鋼製ワイヤーブラシによる溶融亜鉛めっき鋼管の内面にＦｅを６質量％以上含有する鉄―亜鉛合金層が露出したことを判断する検査に利用した。 Further, the present inventors pay attention to the fact that the pure zinc layer and the iron-zinc alloy layer on the surface layer of the hot dip galvanizing differ in Vickers hardness, and Fe on the inner surface of the hot dip galvanized steel pipe with a steel wire brush is 6 mass%. It used for the inspection which judges that the iron-zinc alloy layer contained above was exposed.
　すなわち、純亜鉛層のビッカース硬さは６０未満である一方、Ｆｅを６質量％以上含有する鉄―亜鉛合金層のビッカース硬さは１００を超えることから、その間のビッカース硬さが６０～１００である金属針にて、鋼製ワイヤーブラシで研削した溶融亜鉛めっき鋼管の内面を引っ掻いて検査する。研削が不十分な場合、当該金属針よりもビッカース硬さが柔らかい純亜鉛層が残っているので、当該検査針で表面を引っ掻くと亜鉛めっき鋼管の内面の表面に溝ができる。一方、研削が十分な場合、当該金属針よりもビッカース硬さが硬いＦｅを６質量％以上含有する鉄―亜鉛合金層が露出しているので、当該金属針で表面を引っ掻くと該金属針の先端が削られて、削れた金属粉末がＦｅを６質量％以上含有する鉄―亜鉛合金層の表面に付着する。 That is, while the Vickers hardness of the pure zinc layer is less than 60, the Vickers hardness of the iron-zinc alloy layer containing 6% by mass or more of Fe exceeds 100. Using a metal needle, the inner surface of a hot-dip galvanized steel pipe ground with a steel wire brush is scratched and inspected. When grinding is insufficient, a pure zinc layer whose Vickers hardness is softer than that of the metal needle remains. Therefore, when the surface is scratched with the inspection needle, a groove is formed on the inner surface of the galvanized steel pipe. On the other hand, when the grinding is sufficient, the iron-zinc alloy layer containing 6 mass% or more of Fe having a Vickers hardness higher than that of the metal needle is exposed. The tip is shaved and the shaved metal powder adheres to the surface of the iron-zinc alloy layer containing 6 mass% or more of Fe.
　ビッカース硬さが６０から１００の金属は、アルミ、銅、真鍮が知られている。アルミは亜鉛めっきと色調が同じ銀色のため、目視観察ではアルミと亜鉛の判断が困難であり検査用の金属針の材質として不適当である。銅、真鍮は亜鉛めっきと色調が異なり、検査用の金属針の材質としては適切である。しかし、真鍮は入手先により銅と亜鉛のブレンド比が異なることがありビッカース硬さにバラツキが出易いので、入手先によらず一定のビッカース硬さを持つ銅が最も適切な検査用の金属針の材質である。 Aluminum, copper, and brass are known as metals having a Vickers hardness of 60 to 100. Since aluminum has the same color as galvanized silver, it is difficult to judge aluminum and zinc by visual observation, making it unsuitable as a metal needle material for inspection. Copper and brass are different in color tone from galvanized, and are suitable as materials for inspection metal needles. However, since the blend ratio of copper and zinc may vary depending on the supplier and the Vickers hardness varies easily, brass with a certain Vickers hardness is the most suitable metal needle for inspection regardless of the supplier. It is a material.
　本発明の実施例について説明する。実施例の条件は、本発明の実施可能性及び効果を確認するために採用した条件例であり、本発明は、これらの条件に限定されるものではない。本発明は、本発明の主旨を逸脱せず、本発明の目的を達成する限りにおいて、種々の条件を採用し得るものである。 Examples of the present invention will be described. The conditions of the examples are condition examples adopted to confirm the feasibility and effects of the present invention, and the present invention is not limited to these conditions. The present invention can adopt various conditions as long as the object of the present invention is achieved without departing from the gist of the present invention.
（実施例１）
　鋼管（ＳＧＰ１００AＸ６０００ｍｍ長さ）の内面及び外面を溶融亜鉛めっきして、亜鉛めっき鋼管を得た。この時、亜鉛めっきに含まれるアルミニウムの含有量を０．０１質量％とした。 Example 1
The inner surface and outer surface of a steel pipe (SGP100AX × 6000 mm length) were hot dip galvanized to obtain a galvanized steel pipe. At this time, the content of aluminum contained in the zinc plating was set to 0.01% by mass.
　この亜鉛めっき鋼管の内面を亜鉛めっき鋼管の内径よりも大きい外径を持ち、形状が円柱状であり、且つ、鋼線を当該円柱の中心軸から半径方向に放射状に配置した鋼製ワイヤーブラシを回転させながら、亜鉛めっき鋼管に挿入することで内面の亜鉛めっきを研削した。
　実験に用いた鋼製ワイヤーブラシの鋼線のビッカース硬さは５００であり、その鋼線の化学成分はＣ：０．８１質量％、Ｍｎ：０．４７質量％、Ｓｉ：０．２０質量％、P：０．０５質量％、S：０．０４質量％であった。
　研削条件は表１に示した通りである。本実施例では、鋼製ワイヤーブラシの送り速度を変化させ、１水準あたり溶融亜鉛めっき鋼管を１０本づつ内面研削し、合計５水準実施した。
　連続して内面研削した１本目と１０本目の直後に鋼製ワイヤーブラシ軸の表面温度を測定して摩擦発熱の状況を調査した。
　銅製の金属針を用いて内面研削した亜鉛めっき鋼管の内面を引っ掻いて、研削状態の良否を検査した。 A steel wire brush in which the inner surface of the galvanized steel pipe has an outer diameter larger than the inner diameter of the galvanized steel pipe, the shape is cylindrical, and the steel wires are radially arranged from the central axis of the cylinder. The inner galvanizing was ground by inserting it into a galvanized steel pipe while rotating.
The steel wire brush used in the experiment had a Vickers hardness of 500, and the chemical composition of the steel wire was C: 0.81% by mass, Mn: 0.47% by mass, Si: 0.20% by mass. , P: 0.05% by mass, S: 0.04% by mass.
The grinding conditions are as shown in Table 1. In this example, the feed speed of the steel wire brush was changed, and 10 hot-dip galvanized steel pipes per one level were ground on the inner surface for a total of 5 levels.
The surface temperature of the steel wire brush shaft was measured immediately after the first and tenth inner surfaces were continuously ground to investigate the state of frictional heat generation.
The inner surface of the galvanized steel pipe ground with a copper metal needle was scratched to inspect the quality of the ground state.
　次に、この亜鉛めっき鋼管の内径よりも僅かに小さく、外面に厚さ１００μｍの無水マレイン酸変性ポリエチレンを積層した高密度ポリエチレン管を用意した。高密度ポリエチレンの厚みは２．０ｍｍ、融点は１２５℃である。
　高密度ポリエチレン管を内面研削した亜鉛めっき鋼管の内部に挿入し、その両端に蓋をし、高密度ポリエチレン管の内部に空気を圧入して封印し、次いで、加熱炉で１６０℃に加熱し、高密度ポリエチレン管を溶融し、亜鉛めっき鋼管の内面に圧着させた。
　その後、亜鉛めっき管を加熱炉から取り出して冷却し、温度が７０℃になった時点で、封入空気を抜いて、内面に高密度ポリエチレン管を被覆した亜鉛めっき鋼管（本発明鋼管a）を得た。 Next, a high-density polyethylene pipe was prepared in which maleic anhydride-modified polyethylene having a thickness slightly smaller than the inner diameter of the galvanized steel pipe and having a thickness of 100 μm 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 galvanized steel pipe whose inner surface is ground, cover both ends, press-fit air into the high-density polyethylene pipe, seal it, and then heat to 160 ° C in a heating furnace, The high-density polyethylene pipe was melted and pressure-bonded to the inner surface of the galvanized steel pipe.
Thereafter, the galvanized pipe is taken out from the heating furnace and cooled. When the temperature reaches 70 ° C., the enclosed air is removed to obtain a galvanized steel pipe (invented steel pipe a) having a high-density polyethylene pipe coated on the inner surface. It was.
　本発明鋼管aを切断した後、断面を研磨して光学顕微鏡で観察し、凍結融解試験および温水浸漬試験を行った。
　光学顕微鏡による観察では、試験片として２０ｍｍ幅の円周方向断面を採取し、樹脂で埋め込みして固定してから断面を研磨後、３％硝酸―エタノール溶液で亜鉛めっき層をエッチングし、亜鉛めっき層を光学顕微鏡で観察して、Ｆｅを６質量％以上含有する鉄―亜鉛合金層が最表層に露出しているか調査した。
　凍結融解試験は、１５０ｍｍの長さに切断して得た試験片を、水道水を入れた容器の中に、長さの約１／３が水に漬かる状態にして立て、容器ごとー１０℃の低温槽に入れて２３時間凍結させ、次に、６０℃の高温槽に１時間入れて解氷する凍結融解作業を１サイクルとして、１００サイクル繰り返した。
　温水浸漬試験は、１５０ｍｍの長さに切断して得た試験片を、水道水を入れた容器の中に浸漬し、容器ごと、４０℃の恒温槽に入れて、３ケ月間放置した。
　凍結融解試験と温水浸漬試験の後、試験片について、高密度ポリエチレン管の剥離の有無を調査した。 After cutting the steel pipe a of the present invention, the cross section was polished and observed with an optical microscope, and a freeze-thaw test and a hot water immersion test were performed.
In observation with an optical microscope, a 20 mm wide circumferential section was taken as a test piece, embedded and fixed with a resin, the section was polished, the galvanized layer was etched with a 3% nitric acid-ethanol solution, and galvanized. The layer was observed with an optical microscope to investigate whether an iron-zinc alloy layer containing 6 mass% or more of Fe was exposed on the outermost layer.
In the freeze-thaw test, a specimen obtained by cutting to a length of 150 mm is placed in a container filled with tap water so that about 1/3 of the length is immersed in water. The freezing and thawing operation of freezing and thawing in a high-temperature bath at 60 ° C. for 1 hour was repeated for 100 cycles.
In the warm water immersion test, a test piece obtained by cutting to a length of 150 mm was immersed in a container containing tap water, and the container was placed in a constant temperature bath at 40 ° C. and left for 3 months.
After the freeze-thaw test and the hot water immersion test, the test piece was examined for the presence or absence of peeling of the high-density polyethylene tube.
　表１から式４のφの値が前記式５の範囲内に入る場合だけ、銅製の金属針による検査で、研削した亜鉛めっき鋼管の表面に銅付着が認められ、亜鉛めっき層の断面の顕微鏡による観察でＦｅを６質量％以上含有する鉄―亜鉛合金層が最表層に露出していることが確認された。更には、凍結融解試験、温水浸漬試験の結果においてもポリエチレン管の剥離の無いことが判った。
　鋼製ワイヤーブラシの摩擦発熱は全５水準とも、連続研削１本目と１０本目の研削直後に鋼製ワイヤーブラシ軸の表面温度を測定した結果はともに１５０℃未満であり、研削効率は良好であった。 Only when the value of φ in Table 1 is within the range of Formula 5 from Table 1, copper adhesion was observed on the surface of the ground galvanized steel pipe by inspection with a copper metal needle, and a cross-sectional microscope of the galvanized layer It was confirmed that the iron-zinc alloy layer containing 6 mass% or more of Fe was exposed on the outermost layer by observation by the above. Furthermore, it was found that there was no peeling of the polyethylene tube in the results of the freeze / thaw test and the hot water immersion test.
In all five levels of frictional heat generation of steel wire brushes, the surface temperature of the steel wire brush shaft measured immediately after the first and tenth grinding was less than 150 ° C, and the grinding efficiency was good. It was.
（実施例２）
　鋼管（ＳＧＰ１００AＸ６０００ｍｍ長さ）の内面及び外面を溶融亜鉛めっきして、亜鉛めっき鋼管を得た。この時、亜鉛めっきに含まれるアルミニウムの含有量を０．０１質量％とした。 (Example 2)
The inner surface and outer surface of a steel pipe (SGP100AX × 6000 mm length) were hot dip galvanized to obtain a galvanized steel pipe. At this time, the content of aluminum contained in the zinc plating was set to 0.01% by mass.
　この亜鉛めっき鋼管の内面を亜鉛めっき鋼管の内径よりも大きい外径を持ち、形状が円柱状であり、且つ、鋼線を当該円柱の中心軸から半径方向に放射状に配置した鋼製ワイヤーブラシを回転させながら、亜鉛めっき鋼管に挿入することで内面の亜鉛めっきを研削した。
　実験に用いた鋼製ワイヤーブラシの鋼線のビッカース硬さは５００であり、その鋼線の化学成分はＣ：０．８１質量％、Ｍｎ：０．４７質量％、Ｓｉ：０．２０質量％、P：０．０５質量％、S：０．０４質量％であった。
　研削条件は表２に示した通りである。本実施例では、鋼製ワイヤーブラシの通過回数を変化させ、１水準あたり溶融亜鉛めっき鋼管を１０本づつ内面研削し、合計５水準実施した。
　連続して内面研削した１本目と１０本目の直後に鋼製ワイヤーブラシ軸の表面温度を測定して摩擦発熱の状況を調査した。
　銅製の金属針を用いて内面研削した亜鉛めっき鋼管の内面を引っ掻いて、研削状態の良否を検査した。 A steel wire brush in which the inner surface of the galvanized steel pipe has an outer diameter larger than the inner diameter of the galvanized steel pipe, the shape is cylindrical, and the steel wires are radially arranged from the central axis of the cylinder. The inner galvanizing was ground by inserting it into a galvanized steel pipe while rotating.
The steel wire brush used in the experiment had a Vickers hardness of 500, and the chemical composition of the steel wire was C: 0.81% by mass, Mn: 0.47% by mass, Si: 0.20% by mass. , P: 0.05% by mass, S: 0.04% by mass.
The grinding conditions are as shown in Table 2. In this example, the number of passes of the steel wire brush was changed, and 10 hot-dip galvanized steel pipes were internally ground per level, for a total of 5 levels.
The surface temperature of the steel wire brush shaft was measured immediately after the first and tenth inner surfaces were continuously ground to investigate the state of frictional heat generation.
The inner surface of the galvanized steel pipe ground with a copper metal needle was scratched to inspect the quality of the ground state.
　次に、この亜鉛めっき鋼管の内径よりも僅かに小さく、外面に厚さ１００μｍの無水マレイン酸変性ポリエチレンを積層した高密度ポリエチレン管を用意した。高密度ポリエチレンの厚みは２．０ｍｍ、融点は１２５℃である。
　高密度ポリエチレン管を内面研削した亜鉛めっき鋼管の内部に挿入し、その両端に蓋をし、高密度ポリエチレン管の内部に空気を圧入して封印し、次いで、加熱炉で１６０℃に加熱し、高密度ポリエチレン管を溶融し、亜鉛めっき鋼管の内面に圧着させた。
　その後、亜鉛めっき管を加熱炉から取り出して冷却し、温度が７０℃になった時点で、封入空気を抜いて、内面に高密度ポリエチレン管を被覆した亜鉛めっき鋼管（本発明鋼管ｂ）を得た。 Next, a high-density polyethylene pipe was prepared in which maleic anhydride-modified polyethylene having a thickness slightly smaller than the inner diameter of the galvanized steel pipe and having a thickness of 100 μm 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 galvanized steel pipe whose inner surface is ground, cover both ends, press-fit air into the high-density polyethylene pipe, seal it, and then heat to 160 ° C in a heating furnace, The high-density polyethylene pipe was melted and pressure-bonded to the inner surface of the galvanized steel pipe.
Thereafter, the galvanized pipe is taken out from the heating furnace and cooled, and when the temperature reaches 70 ° C., the enclosed air is removed to obtain a galvanized steel pipe whose inner surface is coated with a high-density polyethylene pipe (present invention steel pipe b). It was.
　本発明鋼管ｂを切断した後、断面を研磨して光学顕微鏡で観察し、凍結融解試験および温水浸漬試験を行った。
　光学顕微鏡による観察では、試験片として２０ｍｍ幅の円周方向断面を採取し、樹脂で埋め込みして固定してから断面を研磨後、３％硝酸―エタノール溶液で亜鉛めっき層をエッチングし、亜鉛めっき層を光学顕微鏡で観察して、Ｆｅを６質量％以上含有する鉄―亜鉛合金層が最表層に露出しているか調査した。
　凍結融解試験は、１５０ｍｍの長さに切断して得た試験片を、水道水を入れた容器の中に、長さの約１／３が水に漬かる状態にして立て、容器ごとー１０℃の低温槽に入れて２３時間凍結させ、次に、６０℃の高温槽に１時間入れて解氷する凍結融解作業を１サイクルとして、１００サイクル繰り返した。
　温水浸漬試験は、１５０ｍｍの長さに切断して得た試験片を、水道水を入れた容器の中に浸漬し、容器ごと、４０℃の恒温槽に入れて、３ケ月間放置した。
　凍結融解試験と温水浸漬試験の後、試験片について、高密度ポリエチレン管の剥離の有無を調査した。 After cutting the steel pipe b of the present invention, the cross section was polished and observed with an optical microscope, and a freeze-thaw test and a hot water immersion test were performed.
In observation with an optical microscope, a 20 mm wide circumferential section was taken as a test piece, embedded and fixed with a resin, the section was polished, the galvanized layer was etched with a 3% nitric acid-ethanol solution, and galvanized. The layer was observed with an optical microscope to investigate whether an iron-zinc alloy layer containing 6 mass% or more of Fe was exposed on the outermost layer.
In the freeze-thaw test, a specimen obtained by cutting to a length of 150 mm is placed in a container filled with tap water so that about 1/3 of the length is immersed in water. The freezing and thawing operation of freezing and thawing in a high-temperature bath at 60 ° C. for 1 hour was repeated for 100 cycles.
In the warm water immersion test, a test piece obtained by cutting to a length of 150 mm was immersed in a container containing tap water, and the container was placed in a constant temperature bath at 40 ° C. and left for 3 months.
After the freeze-thaw test and the hot water immersion test, the test piece was examined for the presence or absence of peeling of the high-density polyethylene tube.
　表２から式４のφの値が２．４を超える場合だけ、銅製の金属針による検査結果では、研削した亜鉛めっき鋼管の表面に銅付着が認められ、亜鉛めっき層の断面の顕微鏡による観察結果では、Ｆｅを６質量％以上含有する鉄―亜鉛合金層が最表層に露出していた。更には、凍結融解試験、温水浸漬試験の結果においてもポリエチレン管の剥離の無いことが判った。
　鋼製ワイヤーブラシの摩擦発熱は全５水準とも、連続研削１本目と１０本目の研削直後に鋼製ワイヤーブラシ軸の表面温度を測定した結果はともに１５０℃未満であり、研削効率は良好であった。 From Table 2, only when the value of φ in Formula 4 exceeds 2.4, copper was observed on the surface of the ground galvanized steel pipe, and the cross section of the galvanized layer was observed with a microscope. As a result, an iron-zinc alloy layer containing 6 mass% or more of Fe was exposed on the outermost layer. Furthermore, it was found that there was no peeling of the polyethylene tube in the results of the freeze / thaw test and the hot water immersion test.
In all five levels of frictional heat generation of steel wire brushes, the surface temperature of the steel wire brush shaft measured immediately after the first and tenth grinding was less than 150 ° C, and the grinding efficiency was good. It was.
　式４のφの値が前記式５の範囲内に入るように鋼製ワイヤーブラシの通過回数を設定することが好ましいことが判った。 It has been found that it is preferable to set the number of passes of the steel wire brush so that the value of φ in Equation 4 falls within the range of Equation 5.
（実施例３）
　鋼管（ＳＧＰ１００AＸ６０００ｍｍ長さ）の内面及び外面を溶融亜鉛めっきして、亜鉛めっき鋼管を得た。この時、亜鉛めっきに含まれるアルミニウムの含有量を０．０１質量％とした。 (Example 3)
The inner surface and outer surface of a steel pipe (SGP100AX × 6000 mm length) were hot dip galvanized to obtain a galvanized steel pipe. At this time, the content of aluminum contained in the zinc plating was set to 0.01% by mass.
　この亜鉛めっき鋼管の内面を亜鉛めっき鋼管の内径よりも大きい外径を持ち、形状が円柱状であり、且つ、鋼線を当該円柱の中心軸から半径方向に放射状に配置した鋼製ワイヤーブラシを回転させながら、亜鉛めっき鋼管に挿入することで内面の亜鉛めっきを研削した。
　実験に用いた鋼製ワイヤーブラシの鋼線のビッカース硬さは５００であり、その鋼線の化学成分はＣ：０．８１質量％、Ｍｎ：０．４７質量％、Ｓｉ：０．２０質量％、P：０．０５質量％、S：０．０４質量％であった。
　研削条件は表３に示した通りである。本実施例では、鋼製ワイヤーブラシの回転数を変化させ、１水準あたり溶融亜鉛めっき鋼管を１０本づつ内面研削し、合計５水準実施した。
　連続して内面研削した１本目と１０本目の直後に鋼製ワイヤーブラシ軸の表面温度を測定して摩擦発熱の状況を調査した。
　銅製の金属針を用いて内面研削した亜鉛めっき鋼管の内面を引っ掻いて、研削状態の良否を検査した。 A steel wire brush in which the inner surface of the galvanized steel pipe has an outer diameter larger than the inner diameter of the galvanized steel pipe, the shape is cylindrical, and the steel wires are radially arranged from the central axis of the cylinder. The inner galvanizing was ground by inserting it into a galvanized steel pipe while rotating.
The steel wire brush used in the experiment had a Vickers hardness of 500, and the chemical composition of the steel wire was C: 0.81% by mass, Mn: 0.47% by mass, Si: 0.20% by mass. , P: 0.05% by mass, S: 0.04% by mass.
The grinding conditions are as shown in Table 3. In this example, the number of rotations of the steel wire brush was changed, and 10 hot-dip galvanized steel pipes were internally ground per level, for a total of 5 levels.
The surface temperature of the steel wire brush shaft was measured immediately after the first and tenth inner surfaces were continuously ground to investigate the state of frictional heat generation.
The inner surface of the galvanized steel pipe ground with a copper metal needle was scratched to inspect the quality of the ground state.
　次に、この亜鉛めっき鋼管の内径よりも僅かに小さく、外面に厚さ１００μｍの無水マレイン酸変性ポリエチレンを積層した高密度ポリエチレン管を用意した。高密度ポリエチレンの厚みは２．０ｍｍ、融点は１２５℃である。
　高密度ポリエチレン管を内面研削した亜鉛めっき鋼管の内部に挿入し、その両端に蓋をし、高密度ポリエチレン管の内部に空気を圧入して封印し、次いで、加熱炉で１６０℃に加熱し、高密度ポリエチレン管を溶融し、亜鉛めっき鋼管の内面に圧着させた。
　その後、亜鉛めっき管を加熱炉から取り出して冷却し、温度が７０℃になった時点で、封入空気を抜いて、内面に高密度ポリエチレン管を被覆した亜鉛めっき鋼管（本発明鋼管ｃ）を得た。 Next, a high-density polyethylene pipe was prepared in which maleic anhydride-modified polyethylene having a thickness slightly smaller than the inner diameter of the galvanized steel pipe and having a thickness of 100 μm 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 galvanized steel pipe whose inner surface is ground, cover both ends, press-fit air into the high-density polyethylene pipe, seal it, and then heat to 160 ° C in a heating furnace, The high-density polyethylene pipe was melted and pressure-bonded to the inner surface of the galvanized steel pipe.
Thereafter, the galvanized pipe is taken out from the heating furnace and cooled, and when the temperature reaches 70 ° C., the enclosed air is removed to obtain a galvanized steel pipe (invented steel pipe c) whose inner surface is covered with a high-density polyethylene pipe. It was.
　本発明鋼管ｃを切断した後、断面を研磨して光学顕微鏡で観察し、凍結融解試験および温水浸漬試験を行った。
　光学顕微鏡による観察では、試験片として２０ｍｍ幅の円周方向断面を採取し、樹脂で埋め込みして固定してから断面を研磨後、３％硝酸―エタノール溶液で亜鉛めっき層をエッチングし、亜鉛めっき層を光学顕微鏡で観察して、Ｆｅを６質量％以上含有する鉄―亜鉛合金層が最表層に露出しているか調査した。
　凍結融解試験は、１５０ｍｍの長さに切断して得た試験片を、水道水を入れた容器の中に、長さの約１／３が水に漬かる状態にして立て、容器ごとー１０℃の低温槽に入れて２３時間凍結させ、次に、６０℃の高温槽に１時間入れて解氷する凍結融解作業を１サイクルとして、１００サイクル繰り返した。
　温水浸漬試験は、１５０ｍｍの長さに切断して得た試験片を、水道水を入れた容器の中に浸漬し、容器ごと、４０℃の恒温槽に入れて、３ケ月間放置した。
　凍結融解試験と温水浸漬試験の後、試験片について、高密度ポリエチレン管の剥離の有無を調査した。 After cutting the steel pipe c of the present invention, the cross section was polished and observed with an optical microscope, and a freeze-thaw test and a hot water immersion test were performed.
In observation with an optical microscope, a 20 mm wide circumferential section was taken as a test piece, embedded and fixed with a resin, the section was polished, the galvanized layer was etched with a 3% nitric acid-ethanol solution, and galvanized. The layer was observed with an optical microscope to investigate whether an iron-zinc alloy layer containing 6 mass% or more of Fe was exposed on the outermost layer.
In the freeze-thaw test, a specimen obtained by cutting to a length of 150 mm is placed in a container filled with tap water so that about 1/3 of the length is immersed in water. The freezing and thawing operation of freezing and thawing in a high-temperature bath at 60 ° C. for 1 hour was repeated for 100 cycles.
In the warm water immersion test, a test piece obtained by cutting to a length of 150 mm was immersed in a container containing tap water, and the container was placed in a constant temperature bath at 40 ° C. and left for 3 months.
After the freeze-thaw test and the hot water immersion test, the test piece was examined for the presence or absence of peeling of the high-density polyethylene tube.
　表３から式４のφの値が前記式５の範囲内に入る場合だけ、銅製の金属針による検査で研削した亜鉛めっき鋼管の表面に銅付着が認められ、亜鉛めっき層の断面の顕微鏡による観察でＦｅを６質量％以上含有する鉄―亜鉛合金層が最表層に露出していることが確認された。更には、凍結融解試験、温水浸漬試験の結果においてもポリエチレン管の剥離の無いことが判った。
　鋼製ワイヤーブラシの摩擦発熱は全５水準とも、連続研削１本目と１０本目の研削直後に鋼製ワイヤーブラシ軸の表面温度を測定した結果はともに１５０℃未満であり、研削効率は良好であった。 Only when the value of φ in Table 3 is within the range of Formula 5 from Table 3, copper adhesion was observed on the surface of the galvanized steel pipe ground by inspection with a copper metal needle, and the cross section of the galvanized layer was observed by a microscope. It was confirmed by observation that an iron-zinc alloy layer containing 6 mass% or more of Fe was exposed on the outermost layer. Furthermore, it was found that there was no peeling of the polyethylene tube in the results of the freeze / thaw test and the hot water immersion test.
In all five levels of frictional heat generation of steel wire brushes, the surface temperature of the steel wire brush shaft measured immediately after the first and tenth grinding was less than 150 ° C, and the grinding efficiency was good. It was.
（実施例４）
　鋼管（ＳＧＰ１００AＸ６０００ｍｍ長さ）の内面及び外面を溶融亜鉛めっきして、亜鉛めっき鋼管を得た。この時、亜鉛めっきに含まれるアルミニウムの含有量を０．０１質量％とした。 Example 4
The inner surface and outer surface of a steel pipe (SGP100AX × 6000 mm length) were hot dip galvanized to obtain a galvanized steel pipe. At this time, the content of aluminum contained in the zinc plating was set to 0.01% by mass.
　この亜鉛めっき鋼管の内面を亜鉛めっき鋼管の内径よりも大きい外径を持ち、形状が円柱状であり、且つ、鋼線を当該円柱の中心軸から半径方向に放射状に配置した鋼製ワイヤーブラシを回転させながら、亜鉛めっき鋼管に挿入することで内面の亜鉛めっきを研削した。
　実験に用いた鋼製ワイヤーブラシの鋼線のビッカース硬さは５００であり、その鋼線の化学成分はＣ：０．８１質量％、Ｍｎ：０．４７質量％、Ｓｉ：０．２０質量％、P：０．０５質量％、S：０．０４質量％であった。
　研削条件は表４に示した通りである。本実施例では、鋼製ワイヤーブラシの鋼線の長さを変化させ、１水準あたり溶融亜鉛めっき鋼管を１０本づつ内面研削し、合計５水準実施した。
　連続して内面研削した１本目と１０本目の直後に鋼製ワイヤーブラシ軸の表面温度を測定して摩擦発熱の状況を調査した。
　銅製の金属針を用いて内面研削した亜鉛めっき鋼管の内面を引っ掻いて、研削状態の良否を検査した。 A steel wire brush in which the inner surface of the galvanized steel pipe has an outer diameter larger than the inner diameter of the galvanized steel pipe, the shape is cylindrical, and the steel wires are radially arranged from the central axis of the cylinder. The inner galvanizing was ground by inserting it into a galvanized steel pipe while rotating.
The steel wire brush used in the experiment had a Vickers hardness of 500, and the chemical composition of the steel wire was C: 0.81% by mass, Mn: 0.47% by mass, Si: 0.20% by mass. , P: 0.05% by mass, S: 0.04% by mass.
The grinding conditions are as shown in Table 4. In this example, the length of the steel wire brush steel wire was changed, and 10 hot-dip galvanized steel pipes were internally ground per level, and a total of 5 levels were carried out.
The surface temperature of the steel wire brush shaft was measured immediately after the first and tenth inner surfaces were continuously ground to investigate the state of frictional heat generation.
The inner surface of the galvanized steel pipe ground with a copper metal needle was scratched to inspect the quality of the ground state.
　次に、この亜鉛めっき鋼管の内径よりも僅かに小さく、外面に厚さ１００μｍの無水マレイン酸変性ポリエチレンを積層した高密度ポリエチレン管を用意した。高密度ポリエチレンの厚みは２．０ｍｍ、融点は１２５℃である。
　高密度ポリエチレン管を内面研削した亜鉛めっき鋼管の内部に挿入し、その両端に蓋をし、高密度ポリエチレン管の内部に空気を圧入して封印し、次いで、加熱炉で１６０℃に加熱し、高密度ポリエチレン管を溶融し、亜鉛めっき鋼管の内面に圧着させた。
　その後、亜鉛めっき管を加熱炉から取り出して冷却し、温度が７０℃になった時点で、封入空気を抜いて、内面に高密度ポリエチレン管を被覆した亜鉛めっき鋼管（本発明鋼管ｄ）を得た。 Next, a high-density polyethylene pipe was prepared in which maleic anhydride-modified polyethylene having a thickness slightly smaller than the inner diameter of the galvanized steel pipe and having a thickness of 100 μm 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 galvanized steel pipe whose inner surface is ground, cover both ends, press-fit air into the high-density polyethylene pipe, seal it, and then heat to 160 ° C in a heating furnace, The high-density polyethylene pipe was melted and pressure-bonded to the inner surface of the galvanized steel pipe.
Thereafter, the galvanized pipe is taken out from the heating furnace and cooled, and when the temperature reaches 70 ° C., the enclosed air is removed to obtain a galvanized steel pipe (invented steel pipe d) whose inner surface is covered with a high-density polyethylene pipe. It was.
　本発明鋼管ｄを切断した後、断面を研磨して光学顕微鏡で観察し、凍結融解試験および温水浸漬試験を行った。
　光学顕微鏡による観察では、試験片として２０ｍｍ幅の円周方向断面を採取し、樹脂で埋め込みして固定してから断面を研磨後、３％硝酸―エタノール溶液で亜鉛めっき層をエッチングし、亜鉛めっき層を光学顕微鏡で観察して、Ｆｅを６質量％以上含有する鉄―亜鉛合金層が最表層に露出しているか調査した。
　凍結融解試験は、１５０ｍｍの長さに切断して得た試験片を、水道水を入れた容器の中に、長さの約１／３が水に漬かる状態にして立て、容器ごとー１０℃の低温槽に入れて２３時間凍結させ、次に、６０℃の高温槽に１時間入れて解氷する凍結融解作業を１サイクルとして、１００サイクル繰り返した。
　温水浸漬試験は、１５０ｍｍの長さに切断して得た試験片を、水道水を入れた容器の中に浸漬し、容器ごと、４０℃の恒温槽に入れて、３ケ月間放置した。
　凍結融解試験と温水浸漬試験の後、試験片について、高密度ポリエチレン管の剥離の有無を調査した。 After cutting the steel pipe d of the present invention, the cross section was polished and observed with an optical microscope, and a freeze-thaw test and a hot water immersion test were performed.
In observation with an optical microscope, a 20 mm wide circumferential section was taken as a test piece, embedded and fixed with a resin, the section was polished, the galvanized layer was etched with a 3% nitric acid-ethanol solution, and galvanized. The layer was observed with an optical microscope to investigate whether an iron-zinc alloy layer containing 6 mass% or more of Fe was exposed on the outermost layer.
In the freeze-thaw test, a specimen obtained by cutting to a length of 150 mm is placed in a container filled with tap water so that about 1/3 of the length is immersed in water. The freezing and thawing operation of freezing and thawing in a high-temperature bath at 60 ° C. for 1 hour was repeated for 100 cycles.
In the warm water immersion test, a test piece obtained by cutting to a length of 150 mm was immersed in a container containing tap water, and the container was placed in a constant temperature bath at 40 ° C. and left for 3 months.
After the freeze-thaw test and the hot water immersion test, the test piece was examined for the presence or absence of peeling of the high-density polyethylene tube.
　表４から式４のφの値が前記式５の範囲内に入る場合だけ、銅製の金属針による検査で研削した亜鉛めっき鋼管の表面に銅付着が認められ、亜鉛めっき層の断面の顕微鏡による観察でＦｅを６質量％以上含有する鉄―亜鉛合金層が最表層に露出していることが確認された。更には、凍結融解試験、温水浸漬試験の結果においてもポリエチレン管の剥離の無いことが判った。
　鋼製ワイヤーブラシの摩擦発熱は全５水準とも連続研削１本目と１０本目の研削直後に鋼製ワイヤーブラシ軸の表面温度を測定した結果はともに１５０℃未満であり、研削効率は良好であった。 Only when the value of φ in Formula 4 falls within the range of Formula 5 from Table 4, copper adhesion was observed on the surface of the galvanized steel pipe ground by inspection with a copper metal needle, and the cross section of the galvanized layer was observed by a microscope. It was confirmed by observation that an iron-zinc alloy layer containing 6 mass% or more of Fe was exposed on the outermost layer. Furthermore, it was found that there was no peeling of the polyethylene tube in the results of the freeze / thaw test and the hot water immersion test.
As for the frictional heat generation of the steel wire brush, the results of measuring the surface temperature of the steel wire brush shaft immediately after the first grinding and the tenth grinding were all below 150 ° C., and the grinding efficiency was good. .
（実施例５）
　鋼管（ＳＧＰ１００AＸ６０００ｍｍ長さ）の内面及び外面を溶融亜鉛めっきして、亜鉛めっき鋼管を得た。この時、亜鉛めっきに含まれるアルミニウムの含有量を０．０１質量％とした。 (Example 5)
The inner surface and outer surface of a steel pipe (SGP100AX × 6000 mm length) were hot dip galvanized to obtain a galvanized steel pipe. At this time, the content of aluminum contained in the zinc plating was set to 0.01% by mass.
　この亜鉛めっき鋼管の内面を亜鉛めっき鋼管の内径よりも大きい外径を持ち、形状が円柱状であり、且つ、鋼線を当該円柱の中心軸から半径方向に放射状に配置した鋼製ワイヤーブラシを回転させながら、亜鉛めっき鋼管に挿入することで内面の亜鉛めっきを研削した。
　実験に用いた鋼製ワイヤーブラシの鋼線のビッカース硬さは５００であり、その鋼線の化学成分はＣ：０．８１質量％、Ｍｎ：０．４７質量％、Ｓｉ：０．２０質量％、P：０．０５質量％、S：０．０４質量％であった。
　研削条件は表５に示した通りである。本実施例では、鋼製ワイヤーブラシの鋼線の外径を変化させ、１水準あたり溶融亜鉛めっき鋼管を１０本づつ内面研削し、合計５水準実施した。
　連続して内面研削した１本目と１０本目の直後に鋼製ワイヤーブラシ軸の表面温度を測定して摩擦発熱の状況を調査した。
　銅製の金属針を用いて内面研削した亜鉛めっき鋼管の内面を引っ掻いて、研削状態の良否を検査した。 A steel wire brush in which the inner surface of the galvanized steel pipe has an outer diameter larger than the inner diameter of the galvanized steel pipe, the shape is cylindrical, and the steel wires are radially arranged from the central axis of the cylinder. The inner galvanizing was ground by inserting it into a galvanized steel pipe while rotating.
The steel wire brush used in the experiment had a Vickers hardness of 500, and the chemical composition of the steel wire was C: 0.81% by mass, Mn: 0.47% by mass, Si: 0.20% by mass. , P: 0.05% by mass, S: 0.04% by mass.
The grinding conditions are as shown in Table 5. In this example, the outer diameter of the steel wire of the steel wire brush was changed, and 10 hot-dip galvanized steel pipes per one level were internally ground, for a total of 5 levels.
The surface temperature of the steel wire brush shaft was measured immediately after the first and tenth inner surfaces were continuously ground to investigate the state of frictional heat generation.
The inner surface of the galvanized steel pipe ground with a copper metal needle was scratched to inspect the quality of the ground state.
　次に、この亜鉛めっき鋼管の内径よりも僅かに小さく、外面に厚さ１００μｍの無水マレイン酸変性ポリエチレンを積層した高密度ポリエチレン管を用意した。高密度ポリエチレンの厚みは２．０ｍｍ、融点は１２５℃である。
　高密度ポリエチレン管を内面研削した亜鉛めっき鋼管の内部に挿入し、その両端に蓋をし、高密度ポリエチレン管の内部に空気を圧入して封印し、次いで、加熱炉で１６０℃に加熱し、高密度ポリエチレン管を溶融し、亜鉛めっき鋼管の内面に圧着させた。
　その後、亜鉛めっき管を加熱炉から取り出して冷却し、温度が７０℃になった時点で、封入空気を抜いて、内面に高密度ポリエチレン管を被覆した亜鉛めっき鋼管（本発明鋼管e）を得た。
　本発明鋼管eを切断した後、断面を研磨して光学顕微鏡で観察し、凍結融解試験および温水浸漬試験を行った。
　光学顕微鏡による観察では、試験片として２０ｍｍ幅の円周方向断面を採取し、樹脂で埋め込みして固定してから断面を研磨後、３％硝酸―エタノール溶液で亜鉛めっき層をエッチングし、亜鉛めっき層を光学顕微鏡で観察して、Ｆｅを６質量％以上含有する鉄―亜鉛合金層が最表層に露出しているか調査した。
　凍結融解試験は、１５０ｍｍの長さに切断して得た試験片を、水道水を入れた容器の中に、長さの約１／３が水に漬かる状態にして立て、容器ごとー１０℃の低温槽に入れて２３時間凍結させ、次に、６０℃の高温槽に１時間入れて解氷する凍結融解作業を１サイクルとして、１００サイクル繰り返した。
　温水浸漬試験は、１５０ｍｍの長さに切断して得た試験片を、水道水を入れた容器の中に浸漬し、容器ごと、４０℃の恒温槽に入れて、３ケ月間放置した。
　凍結融解試験と温水浸漬試験の後、試験片について、高密度ポリエチレン管の剥離の有無を調査した。 Next, a high-density polyethylene pipe was prepared in which maleic anhydride-modified polyethylene having a thickness slightly smaller than the inner diameter of the galvanized steel pipe and having a thickness of 100 μm 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 galvanized steel pipe whose inner surface is ground, cover both ends, press-fit air into the high-density polyethylene pipe, seal it, and then heat to 160 ° C in a heating furnace, The high-density polyethylene pipe was melted and pressure-bonded to the inner surface of the galvanized steel pipe.
Thereafter, the galvanized pipe is taken out from the heating furnace and cooled, and when the temperature reaches 70 ° C., the enclosed air is removed to obtain a galvanized steel pipe whose inner surface is coated with a high-density polyethylene pipe (present steel pipe e). It was.
After cutting the steel pipe e of the present invention, the cross section was polished and observed with an optical microscope, and a freeze-thaw test and a hot water immersion test were performed.
In observation with an optical microscope, a 20 mm wide circumferential section was taken as a test piece, embedded and fixed with a resin, the section was polished, the galvanized layer was etched with a 3% nitric acid-ethanol solution, and galvanized. The layer was observed with an optical microscope to investigate whether an iron-zinc alloy layer containing 6 mass% or more of Fe was exposed on the outermost layer.
In the freeze-thaw test, a specimen obtained by cutting to a length of 150 mm is placed in a container filled with tap water so that about 1/3 of the length is immersed in water. The freezing and thawing operation of freezing and thawing in a high-temperature bath at 60 ° C. for 1 hour was repeated for 100 cycles.
In the warm water immersion test, a test piece obtained by cutting to a length of 150 mm was immersed in a container containing tap water, and the container was placed in a constant temperature bath at 40 ° C. and left for 3 months.
After the freeze-thaw test and the hot water immersion test, the test piece was examined for the presence or absence of peeling of the high-density polyethylene tube.
　表５から式４のφの値が前記式５の範囲内に入る場合だけ、銅製の金属針による検査で研削した亜鉛めっき鋼管の表面に銅付着が認められ、亜鉛めっき層の断面の顕微鏡による観察でＦｅを６質量％以上含有する鉄―亜鉛合金層が最表層に露出していることが確認された。更には、凍結融解試験、温水浸漬試験の結果においてもポリエチレン管の剥離の無いことが判った。
　鋼製ワイヤーブラシの摩擦発熱は全５水準とも、連続研削１本目と１０本目の研削直後に鋼製ワイヤーブラシ軸の表面温度を測定した結果はともに１５０℃未満であり、研削効率は良好であった。 Only when the value of φ in Formula 4 falls within the range of Formula 5 from Table 5, copper adhesion was observed on the surface of the galvanized steel pipe ground by inspection with a copper metal needle, and the cross section of the galvanized layer was observed by a microscope. It was confirmed by observation that an iron-zinc alloy layer containing 6 mass% or more of Fe was exposed on the outermost layer. Furthermore, it was found that there was no peeling of the polyethylene tube in the results of the freeze / thaw test and the hot water immersion test.
In all five levels of frictional heat generation of steel wire brushes, the surface temperature of the steel wire brush shaft measured immediately after the first and tenth grinding was less than 150 ° C, and the grinding efficiency was good. It was.
（実施例６）
　鋼管（ＳＧＰ１００AＸ６０００ｍｍ長さ）の内面及び外面を溶融亜鉛めっきして、亜鉛めっき鋼管を得た。この時、亜鉛めっきに含まれるアルミニウムの含有量を０．０１質量％とした。 (Example 6)
The inner surface and outer surface of a steel pipe (SGP100AX × 6000 mm length) were hot dip galvanized to obtain a galvanized steel pipe. At this time, the content of aluminum contained in the zinc plating was set to 0.01% by mass.
　この亜鉛めっき鋼管の内面を亜鉛めっき鋼管の内径よりも大きい外径を持ち、形状が円柱状であり、且つ、鋼線を当該円柱の中心軸から半径方向に放射状に配置した鋼製ワイヤーブラシを回転させながら、亜鉛めっき鋼管に挿入することで内面の亜鉛めっきを研削した。
　実験に用いた鋼製ワイヤーブラシの鋼線のビッカース硬さは５００であり、その鋼線の化学成分はＣ：０．８１質量％、Ｍｎ：０．４７質量％、Ｓｉ：０．２０質量％、P：０．０５質量％、S：０．０４質量％であった。
　研削条件は表６に示した通りである。本実施例では、鋼製ワイヤーブラシの外径を変化させ、１水準あたり溶融亜鉛めっき鋼管を１０本づつ内面研削し、合計５水準実施した。
　連続して内面研削した１本目と１０本目の直後に鋼製ワイヤーブラシ軸の表面温度を測定して摩擦発熱の状況を調査した。
　銅製の金属針を用いて内面研削した亜鉛めっき鋼管の内面を引っ掻いて、研削状態の良否を検査した。 A steel wire brush in which the inner surface of the galvanized steel pipe has an outer diameter larger than the inner diameter of the galvanized steel pipe, the shape is cylindrical, and the steel wires are radially arranged from the central axis of the cylinder. The inner galvanizing was ground by inserting it into a galvanized steel pipe while rotating.
The steel wire brush used in the experiment had a Vickers hardness of 500, and the chemical composition of the steel wire was C: 0.81% by mass, Mn: 0.47% by mass, Si: 0.20% by mass. , P: 0.05% by mass, S: 0.04% by mass.
The grinding conditions are as shown in Table 6. In this example, the outer diameter of the steel wire brush was changed, and 10 hot-dip galvanized steel pipes were ground on the inner surface per level, for a total of 5 levels.
The surface temperature of the steel wire brush shaft was measured immediately after the first and tenth inner surfaces were continuously ground to investigate the state of frictional heat generation.
The inner surface of the galvanized steel pipe ground with a copper metal needle was scratched to inspect the quality of the ground state.
　次に、この亜鉛めっき鋼管の内径よりも僅かに小さく、外面に厚さ１００μｍの無水マレイン酸変性ポリエチレンを積層した高密度ポリエチレン管を用意した。高密度ポリエチレンの厚みは２．０ｍｍ、融点は１２５℃である。
　高密度ポリエチレン管を内面研削した亜鉛めっき鋼管の内部に挿入し、その両端に蓋をし、高密度ポリエチレン管の内部に空気を圧入して封印し、次いで、加熱炉で１６０℃に加熱し、高密度ポリエチレン管を溶融し、亜鉛めっき鋼管の内面に圧着させた。
　その後、亜鉛めっき管を加熱炉から取り出して冷却し、温度が７０℃になった時点で、封入空気を抜いて、内面に高密度ポリエチレン管を被覆した亜鉛めっき鋼管（本発明鋼管ｆ）を得た。
　本発明鋼管ｆを切断した後、断面を研磨して光学顕微鏡で観察し、凍結融解試験および温水浸漬試験を行った。
　光学顕微鏡による観察では、試験片として２０ｍｍ幅の円周方向断面を採取し、樹脂で埋め込みして固定してから断面を研磨後、３％硝酸―エタノール溶液で亜鉛めっき層をエッチングし、亜鉛めっき層を光学顕微鏡で観察して、Ｆｅを６質量％以上含有する鉄―亜鉛合金層が最表層に露出しているか調査した。
　凍結融解試験は、１５０ｍｍの長さに切断して得た試験片を、水道水を入れた容器の中に、長さの約１／３が水に漬かる状態にして立て、容器ごとー１０℃の低温槽に入れて２３時間凍結させ、次に、６０℃の高温槽に１時間入れて解氷する凍結融解作業を１サイクルとして、１００サイクル繰り返した。
　温水浸漬試験は、１５０ｍｍの長さに切断して得た試験片を、水道水を入れた容器の中に浸漬し、容器ごと、４０℃の恒温槽に入れて、３ケ月間放置した。
　凍結融解試験と温水浸漬試験の後、試験片について、高密度ポリエチレン管の剥離の有無を調査した。 Next, a high-density polyethylene pipe was prepared in which maleic anhydride-modified polyethylene having a thickness slightly smaller than the inner diameter of the galvanized steel pipe and having a thickness of 100 μm 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 galvanized steel pipe whose inner surface is ground, cover both ends, press-fit air into the high-density polyethylene pipe, seal it, and then heat to 160 ° C in a heating furnace, The high-density polyethylene pipe was melted and pressure-bonded to the inner surface of the galvanized steel pipe.
Thereafter, the galvanized pipe is taken out from the heating furnace and cooled, and when the temperature reaches 70 ° C., the enclosed air is removed to obtain a galvanized steel pipe whose inner surface is coated with a high-density polyethylene pipe (present invention steel pipe f). It was.
After cutting the steel pipe f of the present invention, the cross section was polished and observed with an optical microscope, and a freeze-thaw test and a hot water immersion test were performed.
In observation with an optical microscope, a 20 mm wide circumferential section was taken as a test piece, embedded and fixed with a resin, the section was polished, the galvanized layer was etched with a 3% nitric acid-ethanol solution, and galvanized. The layer was observed with an optical microscope to investigate whether an iron-zinc alloy layer containing 6 mass% or more of Fe was exposed on the outermost layer.
In the freeze-thaw test, a specimen obtained by cutting to a length of 150 mm is placed in a container filled with tap water so that about 1/3 of the length is immersed in water. The freezing and thawing operation of freezing and thawing in a high-temperature bath at 60 ° C. for 1 hour was repeated for 100 cycles.
In the warm water immersion test, a test piece obtained by cutting to a length of 150 mm was immersed in a container containing tap water, and the container was placed in a constant temperature bath at 40 ° C. and left for 3 months.
After the freeze-thaw test and the hot water immersion test, the test piece was examined for the presence or absence of peeling of the high-density polyethylene tube.
　表６から式４のφの値が前記式５の範囲内に入る場合だけ、銅製の金属針による検査で研削した亜鉛めっき鋼管の表面に銅付着が認められ、亜鉛めっき層の断面の顕微鏡による観察でＦｅを６質量％以上含有する鉄―亜鉛合金層が最表層に露出していることが確認された。更には、凍結融解試験、温水浸漬試験の結果においてもポリエチレン管の剥離の無いことが判った。
　鋼製ワイヤーブラシの摩擦発熱は全５水準とも、連続研削１本目と１０本目の研削直後に鋼製ワイヤーブラシ軸の表面温度を測定した結果はともに１５０℃未満であり、研削効率は良好であった。 Only when the value of φ in Equation 4 falls within the range of Equation 5 from Table 6, copper adhesion was observed on the surface of the galvanized steel pipe ground by inspection with a copper metal needle, and the cross section of the galvanized layer was observed by a microscope. It was confirmed by observation that an iron-zinc alloy layer containing 6 mass% or more of Fe was exposed on the outermost layer. Furthermore, it was found that there was no peeling of the polyethylene tube in the results of the freeze / thaw test and the hot water immersion test.
In all five levels of frictional heat generation of steel wire brushes, the surface temperature of the steel wire brush shaft measured immediately after the first and tenth grindings was less than 150 ° C, and the grinding efficiency was good. It was.
（実施例７）
　鋼管（ＳＧＰ１００AＸ６０００ｍｍ長さ）の内面及び外面を溶融亜鉛めっきして、亜鉛めっき鋼管を得た。この時、亜鉛めっきに含まれるアルミニウムの含有量を０．０１質量％とした。 (Example 7)
The inner surface and outer surface of a steel pipe (SGP100AX × 6000 mm length) were hot dip galvanized to obtain a galvanized steel pipe. At this time, the content of aluminum contained in the zinc plating was set to 0.01% by mass.
　この亜鉛めっき鋼管の内面を亜鉛めっき鋼管の内径よりも大きい外径を持ち、形状が円柱状であり、且つ、鋼線を当該円柱の中心軸から半径方向に放射状に配置した鋼製ワイヤーブラシを回転させながら、亜鉛めっき鋼管に挿入することで内面の亜鉛めっきを研削した。
　実験に用いた鋼製ワイヤーブラシの鋼線のビッカース硬さは５００であり、その鋼線の化学成分はＣ：０．８１質量％、Ｍｎ：０．４７質量％、Ｓｉ：０．２０質量％、P：０．０５質量％、S：０．０４質量％であった。
　研削条件は表７に示した通りである。本実施例では、鋼製ワイヤーブラシの回転数を変化させ、１水準あたり溶融亜鉛めっき鋼管を１０本づつ内面研削し、合計５水準実施した。
　連続して内面研削した１本目と１０本目の直後に鋼製ワイヤーブラシ軸の表面温度を測定して摩擦発熱の状況を調査した。
　銅製の金属針を用いて内面研削した亜鉛めっき鋼管の内面を引っ掻いて、研削状態の良否を検査した。 A steel wire brush in which the inner surface of the galvanized steel pipe has an outer diameter larger than the inner diameter of the galvanized steel pipe, the shape is cylindrical, and the steel wires are radially arranged from the central axis of the cylinder. The inner galvanizing was ground by inserting it into a galvanized steel pipe while rotating.
The steel wire brush used in the experiment had a Vickers hardness of 500, and the chemical composition of the steel wire was C: 0.81% by mass, Mn: 0.47% by mass, Si: 0.20% by mass. , P: 0.05% by mass, S: 0.04% by mass.
The grinding conditions are as shown in Table 7. In this example, the number of rotations of the steel wire brush was changed, and 10 hot-dip galvanized steel pipes were internally ground per level, for a total of 5 levels.
The surface temperature of the steel wire brush shaft was measured immediately after the first and tenth inner surfaces were continuously ground to investigate the state of frictional heat generation.
The inner surface of the galvanized steel pipe ground with a copper metal needle was scratched to inspect the quality of the ground state.
　次に、この亜鉛めっき鋼管の内径よりも僅かに小さく、外面に厚さ１００μｍの無水マレイン酸変性ポリエチレンを積層した高密度ポリエチレン管を用意した。高密度ポリエチレンの厚みは２．０ｍｍ、融点は１２５℃である。
　高密度ポリエチレン管を内面研削した亜鉛めっき鋼管の内部に挿入し、その両端に蓋をし、高密度ポリエチレン管の内部に空気を圧入して封印し、次いで、加熱炉で１６０℃に加熱し、高密度ポリエチレン管を溶融し、亜鉛めっき鋼管の内面に圧着させた。
　その後、亜鉛めっき管を加熱炉から取り出して冷却し、温度が７０℃になった時点で、封入空気を抜いて、内面に高密度ポリエチレン管を被覆した亜鉛めっき鋼管（本発明鋼管ｇ）を得た。
　本発明鋼管ｇを切断した後、断面を研磨して光学顕微鏡で観察し、凍結融解試験および温水浸漬試験を行った。
　光学顕微鏡による観察では、試験片として２０ｍｍ幅の円周方向断面を採取し、樹脂で埋め込みして固定してから断面を研磨後、３％硝酸―エタノール溶液で亜鉛めっき層をエッチングし、亜鉛めっき層を光学顕微鏡で観察して、Ｆｅを６質量％以上含有する鉄―亜鉛合金層が最表層に露出しているか調査した。
　凍結融解試験は、１５０ｍｍの長さに切断して得た試験片を、水道水を入れた容器の中に、長さの約１／３が水に漬かる状態にして立て、容器ごとー１０℃の低温槽に入れて２３時間凍結させ、次に、６０℃の高温槽に１時間入れて解氷する凍結融解作業を１サイクルとして、１００サイクル繰り返した。
　温水浸漬試験は、１５０ｍｍの長さに切断して得た試験片を、水道水を入れた容器の中に浸漬し、容器ごと、４０℃の恒温槽に入れて、３ケ月間放置した。
　凍結融解試験と温水浸漬試験の後、試験片について、高密度ポリエチレン管の剥離の有無を調査した。 Next, a high-density polyethylene pipe was prepared in which maleic anhydride-modified polyethylene having a thickness slightly smaller than the inner diameter of the galvanized steel pipe and having a thickness of 100 μm 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 galvanized steel pipe whose inner surface is ground, cover both ends, press-fit air into the high-density polyethylene pipe, seal it, and then heat to 160 ° C in a heating furnace, The high-density polyethylene pipe was melted and pressure-bonded to the inner surface of the galvanized steel pipe.
Thereafter, the galvanized pipe is taken out from the heating furnace and cooled, and when the temperature reaches 70 ° C., the enclosed air is removed to obtain a galvanized steel pipe whose inner surface is coated with a high-density polyethylene pipe (present steel pipe g). It was.
After cutting the steel pipe g of the present invention, the cross section was polished and observed with an optical microscope, and a freeze-thaw test and a hot water immersion test were performed.
In observation with an optical microscope, a 20 mm wide circumferential section was taken as a test piece, embedded and fixed with a resin, the section was polished, the galvanized layer was etched with a 3% nitric acid-ethanol solution, and galvanized. The layer was observed with an optical microscope to investigate whether an iron-zinc alloy layer containing 6 mass% or more of Fe was exposed on the outermost layer.
In the freeze-thaw test, a specimen obtained by cutting to a length of 150 mm is placed in a container filled with tap water so that about 1/3 of the length is immersed in water. The freezing and thawing operation of freezing and thawing in a high-temperature bath at 60 ° C. for 1 hour was repeated for 100 cycles.
In the warm water immersion test, a test piece obtained by cutting to a length of 150 mm was immersed in a container containing tap water, and the container was placed in a constant temperature bath at 40 ° C. and left for 3 months.
After the freeze-thaw test and the hot water immersion test, the test piece was examined for the presence or absence of peeling of the high-density polyethylene tube.
　表７から式４のφの値が前記式５の範囲内に入る場合だけ、銅製の金属針による検査で研削した亜鉛めっき鋼管の表面に銅付着が認められ、亜鉛めっき層の断面の顕微鏡による観察でＦｅを６質量％以上含有する鉄―亜鉛合金層が最表層に露出していることが確認された。更には、凍結融解試験、温水浸漬試験の結果においてもポリエチレン管の剥離の無いことが判った。 Only when the value of φ in Formula 4 falls within the range of Formula 5 from Table 7, copper adhesion was observed on the surface of the galvanized steel pipe ground by inspection with a copper metal needle, and the cross section of the galvanized layer was observed by a microscope. It was confirmed by observation that an iron-zinc alloy layer containing 6 mass% or more of Fe was exposed on the outermost layer. Furthermore, it was found that there was no peeling of the polyethylene tube in the results of the freeze / thaw test and the hot water immersion test.
　鋼製ワイヤーブラシの摩擦発熱は全５水準とも、連続研削１本目と１０本目の研削直後に鋼製ワイヤーブラシ軸の表面温度を測定した結果はともに１５０℃未満であり、研削効率は良好であった。 In all five levels of frictional heat generation of steel wire brushes, the surface temperature of the steel wire brush shaft measured immediately after the first and tenth grinding was less than 150 ° C, and the grinding efficiency was good. It was.
Figure JPOXMLDOC01-appb-T000004
Figure JPOXMLDOC01-appb-T000004
Figure JPOXMLDOC01-appb-T000005
Figure JPOXMLDOC01-appb-T000005
Figure JPOXMLDOC01-appb-T000006
Figure JPOXMLDOC01-appb-T000006
Figure JPOXMLDOC01-appb-T000007
Figure JPOXMLDOC01-appb-T000007
Figure JPOXMLDOC01-appb-T000008
Figure JPOXMLDOC01-appb-T000008
Figure JPOXMLDOC01-appb-T000009
Figure JPOXMLDOC01-appb-T000009
Figure JPOXMLDOC01-appb-T000010
Figure JPOXMLDOC01-appb-T000010
本発明によれば、溶融亜鉛めっき鋼管の内面を鋼製ワイヤーブラシで研削して、純亜鉛層を除去し、Ｆｅを６質量％以上含有する鉄―亜鉛合金層を確実に露出させることができるので、当該研削面とポリオレフィン管の密着性が安定して強化され、凍結融解が起こる管路でも内面ポリオレフィン管が剥離し難い内面ポリオレフィン被覆鋼管の工業生産が可能となり、産業上極めて有用である。 According to the present invention, the inner surface of a hot-dip galvanized steel pipe can be ground with a steel wire brush to remove a pure zinc layer, and an iron-zinc alloy layer containing 6 mass% or more of Fe can be reliably exposed. Therefore, the adhesion between the ground surface and the polyolefin pipe is stably enhanced, and industrial production of the inner polyolefin coated steel pipe in which the inner polyolefin pipe is hardly peeled even in a pipe where freezing and thawing occurs is extremely useful industrially.
　１　　溶融亜鉛めっき鋼管
　２　　鋼製ワイヤーブラシ
　２’　鋼製ワイヤーブラシ（そのブラシ長さ（Lb）分を進んだ際の該ワイヤーブラシの模式的位置を示す） DESCRIPTION OF SYMBOLS 1 Hot-dip galvanized steel pipe 2 Steel wire brush 2 'Steel wire brush (The schematic position of this wire brush when it advances the brush length (Lb) part is shown.)

Claims (7)

  1. 　内面及び外面に溶融亜鉛めっきを施した溶融亜鉛めっき鋼管の、内面のめっき層を鋼製ワイヤーブラシで研削し、Ｆｅを６質量％以上含有する鉄―亜鉛合金層を露出させた後に、ポリオレフィン管を被覆する内面ポリオレフィン被覆鋼管の製造方法において、前記鋼製ワイヤーブラシが、円柱状であり、且つ、鋼線を当該円柱の中心軸から半径方向に放射状に配置したものであり、当該鋼製ワイヤーブラシを前記中心軸を回転軸として回転させながら前記溶融亜鉛めっき鋼管に挿入することにより前記鋼管内面めっき層を研削することを特徴とする内面ポリオレフィン被覆鋼管の製造方法。 After galvanized steel pipe with hot-dip galvanized inner and outer surfaces, the inner plating layer is ground with a steel wire brush to expose an iron-zinc alloy layer containing 6 mass% or more of Fe, and then a polyolefin pipe In the method of manufacturing an inner surface polyolefin-coated steel pipe for coating the steel wire brush, the steel wire brush is cylindrical, and the steel wires are radially arranged from the central axis of the column, and the steel wire A method for producing an inner surface polyolefin-coated steel pipe, comprising grinding a steel pipe inner surface plating layer by inserting a brush into the hot dip galvanized steel pipe while rotating the central axis as a rotation axis.
  2. 　前記鋼線のビッカース硬さが５００以上であることを特徴とする請求項１記載の内面ポリオレフィン被覆鋼管の製造方法。 The method for producing an inner surface polyolefin-coated steel pipe according to claim 1, wherein the steel wire has a Vickers hardness of 500 or more.
  3. 　前記鋼線の化学成分がＣ：０．６～１．２質量％、Ｍｎ：０．２～１．２質量％、Ｓｉ：０．１～１．５質量％、P：０．０５質量％以下、S：０．０４質量％以下、残部がＦｅおよび不可避的不純物であることを特徴とする請求項１または２に記載の内面ポリオレフィン被覆鋼管の製造方法。 The chemical composition of the steel wire is C: 0.6 to 1.2 mass%, Mn: 0.2 to 1.2 mass%, Si: 0.1 to 1.5 mass%, P: 0.05 mass% The method for producing an internally polyolefin coated steel pipe according to claim 1 or 2, wherein S: 0.04% by mass or less, and the balance is Fe and inevitable impurities.
  4. 　前記鋼線の表面にブラスメッキを施したことを特徴とする請求項１乃至３のいずれか一項に記載の内面ポリオレフィン被覆鋼管の製造方法。 The method for producing an inner surface polyolefin-coated steel pipe according to any one of claims 1 to 3, wherein the surface of the steel wire is subjected to brass plating.
  5. 　請求項１乃至４のいずれか一項に記載の内面ポリオレフィン被覆鋼管の製造方法において、下記の式１～式５の条件を満足することを特徴とする内面ポリオレフィン被覆鋼管の製造方法。
    Figure JPOXMLDOC01-appb-M000001
     　　　F(1)　：　鋼製ワイヤーブラシの鋼線１本あたりの引っ掻き力
    　　　h(1)　：　鋼製ワイヤーブラシがそのブラシ長さ（Lb）分を進む際、該ワイヤーブラシの１本の鋼線が鋼管内面を研削する長さ（ｍｍ）
    　　　φ　　：　鋼線がN本の鋼製ワイヤーブラシで溶融亜鉛めっき鋼管内面をｍ回通過した際、単位面積あたりの該ワイヤーブラシで研削する総延長長さと鋼線の引っ掻き力の積
    　　　K　　 ：　比例係数
    　　　Dpi　 ：　溶融亜鉛めっき鋼管の内径（ｍｍ）
    　　　Db　　：　鋼製ワイヤーブラシの外径（ｍｍ）
    　　　Lb　　：　鋼製ワイヤーブラシの長手方向の長さ（ｍｍ）
    　　　Dw　　：　鋼製ワイヤーブラシの鋼線の外径（ｍｍ）
    　　　Lw　　：　鋼製ワイヤーブラシの鋼線の長さ（ｍｍ）
    　　　N　　 ：　鋼製ワイヤーブラシの鋼線の本数（本）
    　　　n　　 ：　鋼製ワイヤーブラシの回転数（ｒｐｍ）
    　　　V　　 ：　鋼製ワイヤーブラシの送り速度（ｍｍ／分）
    　　　ｍ　　：　鋼製ワイヤーブラシの通過回数（回）
    　　　S　　 ：　鋼製ワイヤーブラシがそのブラシ長さ（Lb）分を進む際、該ワイヤーブラシが溶融亜鉛めっき鋼管内面を研削する面積（ｍｍ２）     The method for producing an inner surface polyolefin-coated steel pipe according to any one of claims 1 to 4, wherein the conditions of the following formulas 1 to 5 are satisfied.
    Figure JPOXMLDOC01-appb-M000001
     F (1): Scratch force per steel wire of a steel wire brush h (1): When a steel wire brush advances its length (Lb), one steel wire of the wire brush Length to grind the inner surface of steel pipe (mm)
    φ: product of the total length of the wire to be ground with the wire brush per unit area when the steel wire passes through the inner surface of the hot-dip galvanized steel pipe m times with N steel wire brushes K: proportional coefficient Dpi: inner diameter of hot-dip galvanized steel pipe (mm)
    Db: Outer diameter of steel wire brush (mm)
    Lb: Length in the longitudinal direction of the steel wire brush (mm)
    Dw: Outer diameter of steel wire brush (mm)
    Lw: Length of steel wire brush steel wire (mm)
    N: Number of steel wire brush steel wires
    n: Rotation speed of steel wire brush (rpm)
    V: Feed speed of steel wire brush (mm / min)
    m: Number of times the steel wire brush passes (times)
    S: Area where the wire brush grinds the inner surface of the hot-dip galvanized steel pipe (mm 2 ) when the steel wire brush advances the length of the brush (Lb)
  6. 　前記研削した後、前記鋼管内表面をビッカース硬度が６０～１００の金属針で引っ掻くことにより研削状態の良否を判定することを特徴とする請求項１乃至５のいずれか一項に記載の内面ポリオレフィン被覆鋼管の製造方法。 6. The inner surface polyolefin according to claim 1, wherein after the grinding, the quality of the ground state is judged by scratching the inner surface of the steel pipe with a metal needle having a Vickers hardness of 60 to 100. Manufacturing method of coated steel pipe.
  7. 　前記金属針が銅製であることを特徴とする請求項６に記載の内面ポリオレフィン被覆鋼管の製造方法。 The method for producing an inner surface polyolefin-coated steel pipe according to claim 6, wherein the metal needle is made of copper.
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