JP6819568B2 - Manufacturing method of partially plated steel pipe and manufacturing method of inner surface coated steel pipe - Google Patents
Manufacturing method of partially plated steel pipe and manufacturing method of inner surface coated steel pipe Download PDFInfo
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- JP6819568B2 JP6819568B2 JP2017251730A JP2017251730A JP6819568B2 JP 6819568 B2 JP6819568 B2 JP 6819568B2 JP 2017251730 A JP2017251730 A JP 2017251730A JP 2017251730 A JP2017251730 A JP 2017251730A JP 6819568 B2 JP6819568 B2 JP 6819568B2
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- 229910000831 Steel Inorganic materials 0.000 title claims description 168
- 239000010959 steel Substances 0.000 title claims description 168
- 238000004519 manufacturing process Methods 0.000 title claims description 49
- 238000000034 method Methods 0.000 claims description 58
- 238000007747 plating Methods 0.000 claims description 51
- 239000003973 paint Substances 0.000 claims description 25
- 238000005554 pickling Methods 0.000 claims description 22
- 238000005238 degreasing Methods 0.000 claims description 10
- 239000003822 epoxy resin Substances 0.000 claims description 4
- 229920000647 polyepoxide Polymers 0.000 claims description 4
- 238000005422 blasting Methods 0.000 description 22
- 239000010410 layer Substances 0.000 description 17
- 229920005989 resin Polymers 0.000 description 17
- 239000011347 resin Substances 0.000 description 17
- 238000000576 coating method Methods 0.000 description 14
- 238000010438 heat treatment Methods 0.000 description 14
- 239000011248 coating agent Substances 0.000 description 13
- 239000000843 powder Substances 0.000 description 11
- 238000012545 processing Methods 0.000 description 11
- 239000002987 primer (paints) Substances 0.000 description 9
- 239000000126 substance Substances 0.000 description 9
- 238000006243 chemical reaction Methods 0.000 description 7
- 230000000052 comparative effect Effects 0.000 description 7
- 239000011247 coating layer Substances 0.000 description 6
- 238000001816 cooling Methods 0.000 description 6
- 239000007788 liquid Substances 0.000 description 6
- 238000004140 cleaning Methods 0.000 description 4
- 238000011156 evaluation Methods 0.000 description 4
- 230000006698 induction Effects 0.000 description 4
- 239000003921 oil Substances 0.000 description 4
- 239000000463 material Substances 0.000 description 3
- 238000004904 shortening Methods 0.000 description 3
- VEXZGXHMUGYJMC-UHFFFAOYSA-N Hydrochloric acid Chemical compound Cl VEXZGXHMUGYJMC-UHFFFAOYSA-N 0.000 description 2
- 229910019142 PO4 Inorganic materials 0.000 description 2
- 239000002253 acid Substances 0.000 description 2
- 230000015572 biosynthetic process Effects 0.000 description 2
- 238000007796 conventional method Methods 0.000 description 2
- 238000001035 drying Methods 0.000 description 2
- 238000002844 melting Methods 0.000 description 2
- 230000008018 melting Effects 0.000 description 2
- 235000014593 oils and fats Nutrition 0.000 description 2
- NBIIXXVUZAFLBC-UHFFFAOYSA-K phosphate Chemical compound [O-]P([O-])([O-])=O NBIIXXVUZAFLBC-UHFFFAOYSA-K 0.000 description 2
- 239000010452 phosphate Substances 0.000 description 2
- 238000005498 polishing Methods 0.000 description 2
- 229920013716 polyethylene resin Polymers 0.000 description 2
- 239000002904 solvent Substances 0.000 description 2
- 239000002345 surface coating layer Substances 0.000 description 2
- VEXZGXHMUGYJMC-UHFFFAOYSA-M Chloride anion Chemical compound [Cl-] VEXZGXHMUGYJMC-UHFFFAOYSA-M 0.000 description 1
- 239000004593 Epoxy Substances 0.000 description 1
- 229920001971 elastomer Polymers 0.000 description 1
- 239000003925 fat Substances 0.000 description 1
- 238000000227 grinding Methods 0.000 description 1
- DLMVDBDHOIWEJZ-UHFFFAOYSA-N isocyanatooxyimino(oxo)methane Chemical compound O=C=NON=C=O DLMVDBDHOIWEJZ-UHFFFAOYSA-N 0.000 description 1
- 229920005749 polyurethane resin Polymers 0.000 description 1
- 239000000758 substrate Substances 0.000 description 1
- 238000012360 testing method Methods 0.000 description 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 1
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Description
本発明は、外面はめっきをし、内面はめっきをしない部分めっき鋼管の製造方法およびその部分めっき鋼管を用いた内面被覆鋼管の製造方法に関するものである。 The present invention relates to a method for manufacturing a partially plated steel pipe whose outer surface is plated and whose inner surface is not plated, and a method for manufacturing an inner coated steel pipe using the partially plated steel pipe.
外面をめっきし、内面を樹脂で被覆した鋼管（以下、「内面被覆鋼管」という）を製造する際には、まず、前段プロセスとして、外面はめっきをし、内面はめっきをしない鋼管（以下、「部分めっき鋼管」という）を製造し、次に、後段プロセスとして、その部分めっき鋼管を用いて、内面被覆鋼管を製造する（例えば、特許文献１）。 When manufacturing a steel pipe whose outer surface is plated and whose inner surface is coated with resin (hereinafter referred to as "inner surface coated steel pipe"), first, as a pre-stage process, the outer surface is plated and the inner surface is not plated (hereinafter, "inner surface coated steel pipe"). A "partially plated steel pipe") is manufactured, and then, as a subsequent process, the inner surface coated steel pipe is manufactured using the partially plated steel pipe (for example, Patent Document 1).
図４に、従来の部分めっき鋼管の製造方法（製造工程）と内面被覆鋼管の製造方法（製造工程）を示す。 FIG. 4 shows a conventional method for manufacturing a partially plated steel pipe (manufacturing process) and a method for manufacturing an inner coated steel pipe (manufacturing process).
まず、図４（ａ）に示すように、前段プロセスでは、原鋼管（例えば、鍛接鋼管）の両管端部の内面に栓を嵌める栓打ち工程と、原鋼管の外面の油脂およびスケールを除去する脱脂・酸洗工程と、原鋼管の両管端部の内面に嵌めた栓を抜く栓抜き工程と、原鋼管をめっき浴に浸漬し、原鋼管の外面にめっき層を形成するめっき工程とをその順に経て、部分めっき鋼管が製造される。 First, as shown in FIG. 4A, in the pre-stage process, a plugging step of fitting plugs on the inner surfaces of both pipe ends of the raw steel pipe (for example, forged steel pipe) and removing oils and fats and scale on the outer surface of the raw steel pipe are removed. The degreasing / pickling step, the plug removal step of removing the plugs fitted on the inner surfaces of both pipe ends of the raw steel pipe, and the plating step of immersing the raw steel pipe in a plating bath to form a plating layer on the outer surface of the raw steel pipe. A partially plated steel pipe is manufactured through the above steps.
ここで、原鋼管の外面と内面にはスケールが付着している。そこで、めっき工程によって、原鋼管の外面にめっき層を形成するためには、脱脂・酸洗工程によって、原鋼管の外面の油脂およびスケールを除去する必要がある。ただし、めっき工程において、原鋼管の内面にめっき層が形成されてしまうと、そのめっき層の影響で、後段プロセスで部分めっき鋼管の内面に形成される樹脂被覆層に必要とされるピール強度（詳細は後述する）が確保できない。そこで、栓打ち工程で、原鋼管の両管端内面に栓を嵌めておき、あえて、脱脂・酸洗工程では、原鋼管の内面の油脂およびスケールが残るようにして、めっき工程で、原鋼管の内面にめっき層が形成されないようにしている。ちなみに、原鋼管の両管端内面に栓を嵌めたままで、原鋼管の外面にめっき層を形成しようとした場合、原鋼管内の空気がめっき浴の熱で膨張して暴発する可能性がある。そのため、めっき工程の前には、原鋼管の両管端の内面に嵌めた栓を抜く栓抜き工程を行う。 Here, scales are attached to the outer and inner surfaces of the raw steel pipe. Therefore, in order to form a plating layer on the outer surface of the raw steel pipe by the plating step, it is necessary to remove oils and fats and scale on the outer surface of the raw steel pipe by the degreasing / pickling step. However, if a plating layer is formed on the inner surface of the raw steel pipe in the plating process, the peel strength required for the resin coating layer formed on the inner surface of the partially plated steel pipe in the subsequent process due to the influence of the plating layer ( Details will be described later) cannot be secured. Therefore, in the plugging process, plugs are fitted on the inner surfaces of both pipe ends of the raw steel pipe, and in the degreasing / pickling process, the oil and fat and scale on the inner surface of the raw steel pipe remain, and in the plating process, the raw steel pipe is used. The plating layer is not formed on the inner surface of the pipe. By the way, if you try to form a plating layer on the outer surface of the raw steel pipe with the stoppers on the inner surfaces of both ends of the raw steel pipe, the air inside the raw steel pipe may expand due to the heat of the plating bath and explode. .. Therefore, before the plating process, a bottle opener step is performed to remove the stoppers fitted on the inner surfaces of both pipe ends of the raw steel pipe.
次に、図４（ｂ）に示すように、後段プロセスでは、部分めっき鋼管の内面のスケール等を除去するショットブラスト工程と、リン酸塩系化成処理液を用いて化成処理層を形成する化成処理工程、前記化成処理層の上に、平均厚さが１０〜４０μｍであるプライマー液を塗装してプライマー層を形成するプライマー塗布工程と、前記プライマー層に含まれる溶剤を揮発させるために、誘導加熱を用いて鋼管を加熱する第１加熱工程と、誘導加熱を用いて粉体塗装に必要な温度まで鋼管を加熱する第２加熱工程と、ポリエチレン樹脂粉末を粉体塗装により部分めっき鋼管の内面に付着させる内面粉体塗装工程と、前記粉体工程で部分めっき鋼管の内面に付着させた樹脂を、保熱炉により溶融させ、内周均一な内面被覆層を形成するために、鋼管温度を１５０〜２５０℃の間で保持する保熱工程と、前記保熱炉から出てきた鋼管を冷却する冷却工程とをその順に経て、内面被覆鋼管が製造される。 Next, as shown in FIG. 4 (b), in the subsequent process, a shot blast step of removing scale and the like on the inner surface of the partially plated steel pipe and a chemical formation using a phosphate-based chemical conversion treatment liquid to form a chemical conversion treatment layer. A treatment step, a primer coating step of coating a primer solution having an average thickness of 10 to 40 μm on the chemical conversion treatment layer to form a primer layer, and an induction to volatilize the solvent contained in the primer layer. The first heating step of heating the steel pipe using heating, the second heating step of heating the steel pipe to the temperature required for powder coating using induction heating, and the inner surface of the partially plated steel pipe by powder coating the polyethylene resin powder. In order to form a uniform inner surface coating layer by melting the resin adhered to the inner surface of the partially plated steel pipe in the inner surface powder coating step and the powder step, the steel pipe temperature is adjusted. An inner surface-coated steel pipe is manufactured through a heat-retaining step of holding the temperature between 150 and 250 ° C. and a cooling step of cooling the steel pipe coming out of the heat-retaining furnace in that order.
ここで、前述したように、内面被覆鋼管の品質要求事項の一つにピール強度がある。ピール強度とは、内面被覆鋼管の管端から管長方向に１００ｍｍ入った位置を起点とし、管端から管長方向に２００ｍｍ入った位置を終点として、長さ１００ｍｍの試験管を採取して半割りし、管軸方向に平行に、１０ｍｍ幅で内面素地まで被覆樹脂にスリットを入れた後、スリット端を掴んで被覆樹脂を引き剥がしたときの、必要荷重のことを指す。ピール強度は（公社）日本水道協会による下限規定があり、３０Ｎ／１０ｍｍ幅以上なければならない。 Here, as described above, one of the quality requirements for the inner coated steel pipe is peel strength. The peel strength is defined by taking a test tube with a length of 100 mm and dividing it in half, starting from the position 100 mm in the pipe length direction from the pipe end of the inner coated steel pipe and starting from the position 200 mm in the pipe length direction from the pipe end. It refers to the required load when a slit is made in the coating resin to the inner surface substrate with a width of 10 mm parallel to the pipe axis direction, and then the coating resin is peeled off by grasping the slit end. There is a lower limit for peel strength by the Japan Water Works Association, and it must be 30N / 10mm wide or more.
そこで、後段プロセスでは、ショットブラスト工程によって、部分めっき鋼管の内面に残存しているスケール等を除去して、部分めっき鋼管の内面を清浄化するようにしている。 Therefore, in the subsequent process, the scale and the like remaining on the inner surface of the partially plated steel pipe are removed by the shot blasting step to clean the inner surface of the partially plated steel pipe.
そして、その後、上述したように、化成処理工程と、プライマー塗布工程と、第１加熱工程と、第２加熱工程と、内面粉体塗装工程と、保熱工程と、冷却工程とによって、内面被覆鋼管を製造するようにしている。 Then, as described above, the inner surface is coated by the chemical conversion treatment step, the primer coating step, the first heating step, the second heating step, the inner surface powder coating step, the heat retention step, and the cooling step. I try to manufacture steel pipes.
しかしながら、図４に示した従来の従来の部分めっき鋼管の製造方法と内面被覆鋼管の製造方法においては、以下のような問題があった。 However, the conventional method for manufacturing a partially plated steel pipe and the method for manufacturing an inner coated steel pipe shown in FIG. 4 have the following problems.
すなわち、前段プロセスの脱脂・酸洗工程において、原鋼管と栓の間から、僅かに酸洗液が漏れるため、めっき工程において、原鋼管の両管端部の内面に、めっきが付着してしまい、後段プロセスのショットブラスト工程において、部分めっき鋼管の内面を清浄化するために、スケールや油脂に加えて、付着しためっきも除去する必要があり、ショットブラスト工程の処理時間が長くなって（例えば、２０分）、生産性を落とす要因となっていた。逆に言えば、生産性を上げようとして、短時間のショットブラストを行うと、部分めっき鋼管の内面が清浄化されず、被覆樹脂層に必要とされるピール強度（３０Ｎ／１０ｍｍ幅以上）が確保できない。 That is, in the degreasing / pickling process of the previous process, a slight pickling solution leaks between the raw steel pipe and the stopper, so that the plating adheres to the inner surfaces of both pipe ends of the raw steel pipe in the plating process. In the shot blasting process of the subsequent process, in order to clean the inner surface of the partially plated steel pipe, it is necessary to remove the adhered plating in addition to the scale and oil, which increases the processing time of the shot blasting process (for example). , 20 minutes), which was a factor that reduced productivity. Conversely, if shot blasting is performed for a short time in order to increase productivity, the inner surface of the partially plated steel pipe is not cleaned, and the peel strength (30 N / 10 mm width or more) required for the coating resin layer is increased. Cannot be secured.
本発明は、上記のような事情に鑑みてなされたものであり、外面をめっきした部分めっき鋼管を製造し、その部分めっき鋼管を用いて、内面を樹脂で被覆した内面被覆鋼管を製造する際に、製造した部分めっき鋼管の内面の清浄化を行う処理時間を短縮しながら、製造した内面被覆鋼管に必要とされる樹脂被覆層のピール強度（３０Ｎ／１０ｍｍ幅以上）を確保することができる部分めっき鋼管の製造方法および内面被覆鋼管の製造方法を提供することを目的とするものである。 The present invention has been made in view of the above circumstances, and when manufacturing a partially plated steel pipe whose outer surface is plated and using the partially plated steel pipe to manufacture an inner coated steel pipe whose inner surface is coated with a resin. In addition, the peel strength (30 N / 10 mm width or more) of the resin coating layer required for the manufactured inner surface coated steel pipe can be secured while shortening the processing time for cleaning the inner surface of the manufactured partially plated steel pipe. An object of the present invention is to provide a method for manufacturing a partially plated steel pipe and a method for manufacturing an inner coated steel pipe.
本発明者らは、上記課題を解決するために鋭意検討した結果、前段プロセスにおいて、脱脂・酸洗工程で、原鋼管と栓の間から酸洗液が漏れても、めっき工程で、原鋼管の両管端部の内面に、漏れてきためっきが付着しなければよいと考え、栓打ち工程の前に、原鋼管の両管端部の内面に不めっき塗料を塗布する不めっき塗料塗布工程を設けることを着想した。 As a result of diligent studies to solve the above problems, the present inventors have conducted a diligent study, and even if the pickling liquid leaks between the raw steel pipe and the stopper in the degreasing / pickling process in the previous process, the raw steel pipe is used in the plating process. Non-plating paint application process of applying non-plating paint to the inner surfaces of both pipe ends of the raw steel pipe before the plugging process, considering that the leaked plating should not adhere to the inner surfaces of both pipe ends. Was conceived to provide.
本発明は、上記の着想に基づいており、以下のような特徴を有している。 The present invention is based on the above idea and has the following features.
［１］外面をめっきした部分めっき鋼管の製造方法であって、
原鋼管の両管端部の内面に不めっき塗料を塗布する不めっき塗料塗布工程と、
原鋼管の両管端部の内面に栓を嵌める栓打ち工程と、
原鋼管の外面の油脂およびスケールを除去する脱脂・酸洗工程と、
原鋼管の両管端部の内面に嵌めた栓を抜く栓抜き工程と、
原鋼管をめっき浴に浸漬し、鋼管の外面にめっき層を形成するめっき工程と
をその順に備えていることを特徴とする部分めっき鋼管の製造方法。
[1] A method for manufacturing a partially plated steel pipe whose outer surface is plated.
The non-plating paint application process of applying non-plating paint to the inner surfaces of both pipe ends of the raw steel pipe,
The plugging process of fitting the plugs on the inner surfaces of both ends of the raw steel pipe,
A degreasing / pickling process that removes oil and scale from the outer surface of the raw steel pipe,
A bottle opener process to remove the stopper fitted on the inner surface of both pipe ends of the raw steel pipe,
A method for manufacturing a partially plated steel pipe, which comprises a plating step of immersing the raw steel pipe in a plating bath and forming a plating layer on the outer surface of the steel pipe in that order.
［２］不めっき塗料は、エポキシ系樹脂からなることを特徴とする前記［１］に記載の部分めっき鋼管の製造方法。 [2] The method for producing a partially plated steel pipe according to the above [1], wherein the non-plated paint is made of an epoxy resin.
［３］原鋼管のそれぞれの管端部において、管端を起点とし、管端から管長方向に２００〜３００ｍｍ入った位置を終点とする範囲に、不めっき塗料を塗布することを特徴とする前記［１］または［２］に記載の部分めっき鋼管の製造方法。 [3] The non-plated paint is applied to each pipe end portion of the raw steel pipe in a range starting from the pipe end and ending at a position 200 to 300 mm in the pipe length direction from the pipe end. The method for manufacturing a partially plated steel pipe according to [1] or [2].
［４］ローラーまたは刷毛を用いて、不めっき塗料を塗布することを特徴とする前記［１］〜［３］のいずれかに記載の部分めっき鋼管の製造方法。 [4] The method for producing a partially plated steel pipe according to any one of [1] to [3] above, wherein the non-plating paint is applied using a roller or a brush.
［５］原鋼管が鍛接鋼管であることを特徴とする前記［１］〜［４］のいずれかに記載の部分めっき鋼管の製造方法。 [5] The method for producing a partially plated steel pipe according to any one of [1] to [4] above, wherein the raw steel pipe is a forge welded steel pipe.
［６］前記［１］〜［５］のいずれかに記載の部分めっき鋼管の製造方法によって製造された部分めっき鋼管を用いて内面被覆鋼管を製造することを特徴とする内面被覆鋼管の製造方法。 [6] A method for producing an inner surface-coated steel pipe, which comprises producing an inner surface-coated steel pipe using the partially-plated steel pipe produced by the method for producing a partially plated steel pipe according to any one of [1] to [5]. ..
本発明においては、外面をめっきした部分めっき鋼管を製造し、その部分めっき鋼管を用いて、内面を樹脂で被覆した内面被覆鋼管を製造する際に、製造した部分めっき鋼管の内面の清浄化を行う処理時間を短縮しながら、製造した内面被覆鋼管に必要とされる樹脂被覆層のピール強度（３０Ｎ／１０ｍｍ幅以上）を確保することができる。 In the present invention, when a partially plated steel pipe having a plated outer surface is manufactured and the inner surface coated steel pipe whose inner surface is coated with a resin is manufactured using the partially plated steel pipe, the inner surface of the manufactured partially plated steel pipe is cleaned. It is possible to secure the peel strength (30 N / 10 mm width or more) of the resin coating layer required for the manufactured inner surface coated steel pipe while shortening the processing time to be performed.
本発明の一実施形態を図面に基づいて説明する。 An embodiment of the present invention will be described with reference to the drawings.
本発明の一実施形態においては、外面をめっきし、内面を樹脂で被覆した内面被覆鋼管を製造する際に、まず、前段プロセスとして、外面はめっきをし、内面はめっきをしない部分めっき鋼管を製造し、次に、後段プロセスとして、その部分めっき鋼管を用いて、内面被覆鋼管を製造するようにしている。 In one embodiment of the present invention, when manufacturing an inner surface-coated steel pipe whose outer surface is plated and whose inner surface is coated with resin, first, as a pre-stage process, a partially plated steel pipe whose outer surface is plated and whose inner surface is not plated is used. It is manufactured, and then, as a subsequent process, the partially plated steel pipe is used to manufacture the inner surface coated steel pipe.
図１に、本発明の一実施形態における部分めっき鋼管の製造方法（製造工程）と内面被覆鋼管の製造方法（製造工程）を示す。 FIG. 1 shows a manufacturing method (manufacturing process) of a partially plated steel pipe and a manufacturing method (manufacturing process) of an inner coated steel pipe according to an embodiment of the present invention.
まず、図１（ａ）に示すように、前段プロセスでは、原鋼管（例えば、鍛接鋼管）の両管端部の内面に不めっき塗料を塗布する不めっき塗料塗布工程と、原鋼管の両管端部の内面に栓を嵌める栓打ち工程と、原鋼管の外面の油脂およびスケールを除去する脱脂・酸洗工程と、原鋼管の両管端の内面に嵌めた栓を抜く栓抜き工程と、原鋼管をめっき浴に浸漬し、原鋼管の外面にめっき層を形成するめっき工程とをその順に経て、部分めっき鋼管を製造するようにしている。 First, as shown in FIG. 1A, in the pre-stage process, a non-plating paint application step of applying a non-plating paint to the inner surfaces of both pipe ends of a raw steel pipe (for example, a forged steel pipe) and both pipes of the raw steel pipe. A plugging step of fitting a plug on the inner surface of the end, a degreasing / pickling step of removing oil and scale on the outer surface of the raw steel pipe, and a plug removal step of removing the plug fitted on the inner surface of both pipe ends of the raw steel pipe. A partially plated steel pipe is manufactured by immersing the raw steel pipe in a plating bath and performing a plating step of forming a plating layer on the outer surface of the raw steel pipe in that order.
すなわち、この実施形態においては、前段プロセスとして、図４（ａ）に示した従来の部分めっき鋼管の製造工程（栓打ち工程〜めっき工程）に加えて、栓打ち工程の前に、不めっき塗料塗布工程を備えている。 That is, in this embodiment, as a pre-stage process, in addition to the conventional partially plated steel pipe manufacturing process (capping process to plating process) shown in FIG. 4 (a), the non-plated paint is applied before the capping process. It has a coating process.
このように、不めっき塗料塗布工程を備えていることによって、脱脂・酸洗工程で、原鋼管と栓の間から酸洗液が漏れても、めっき工程で、原鋼管の両管端部の内面に、漏れてきためっきが付着しなくなる。その結果、製造した部分めっき鋼管の内面の清浄化を行うショットブラスト工程（後述）の処理時間を短縮できるとともに、製造した内面被覆鋼管に必要とされる樹脂被覆層のピール強度（３０Ｎ／１０ｍｍ幅以上）を確保することができるようになる。 In this way, by providing the non-plating paint application process, even if the pickling liquid leaks between the raw steel pipe and the stopper in the degreasing / pickling process, in the plating process, both pipe ends of the raw steel pipe The leaked plating will not adhere to the inner surface. As a result, the processing time of the shot blasting step (described later) for cleaning the inner surface of the manufactured partially plated steel pipe can be shortened, and the peel strength (30 N / 10 mm width) of the resin coating layer required for the manufactured inner surface coated steel pipe can be shortened. The above) can be secured.
ここで、図２は、不めっき塗料塗布工程において、原鋼管１の両管端部の内面に不めっき塗料２を塗布した状態を示す図であり、図２（ａ）は縦断面、図２（ｂ）は横断面である。 Here, FIG. 2 is a view showing a state in which the non-plating paint 2 is applied to the inner surfaces of both pipe end portions of the raw steel pipe 1 in the non-plating paint coating step, and FIG. 2A is a vertical cross section and FIG. (B) is a cross section.
不めっき塗料２を塗布する範囲Ｓは、脱脂・酸洗工程で、原鋼管１と栓の間から酸洗液が漏れてくる範囲を考慮して定めればよいが、例えば、原鋼管１のそれぞれの管端部において、管端を起点とし、管端から管長方向に２００〜３００ｍｍ入った位置を終点とする範囲にするとよい。 The range S to which the non-plating paint 2 is applied may be determined in consideration of the range in which the pickling liquid leaks from between the raw steel pipe 1 and the stopper in the degreasing / pickling step. For example, the raw steel pipe 1 At each pipe end, the range may be such that the pipe end is the starting point and the end point is a position 200 to 300 mm in the pipe length direction from the pipe end.
その際、不めっき塗料２の乾燥後の膜厚が１０〜３００μｍとなるように、ローラーまたは刷毛を用いて不めっき塗料２を塗布すればよい。 At that time, the non-plating paint 2 may be applied using a roller or a brush so that the film thickness of the non-plating paint 2 after drying is 10 to 300 μm.
そして、ここでの不めっき塗料２は、速乾性や耐酸性が優れていればよいので、エポキシ系樹脂によるものを用いればよい。例えば、塩化ゴム系、ポリウレタン樹脂系、一液反応硬化形エポキシ、エポキシイソシアネートが挙げられる。 The non-plating paint 2 here may be made of an epoxy resin because it may be excellent in quick-drying property and acid resistance. Examples thereof include rubber chloride-based, polyurethane resin-based, one-component reaction-curable epoxy, and epoxy isocyanate.
なお、めっき工程の後に、製造した部分めっき鋼管の内面の清浄化を行うショットブラスト工程の事前処理工程として、鋼管内面を軽く酸洗する軽酸洗工程を設けてもよい。例えば、酸洗液の酸濃度は０．５質量％程度、酸洗温度は２０℃程度、酸洗温度は５分程度にして行えばよい。 After the plating step, a light pickling step of lightly pickling the inner surface of the steel pipe may be provided as a pretreatment step of the shot blasting step of cleaning the inner surface of the manufactured partially plated steel pipe. For example, the acid concentration of the pickling solution may be about 0.5% by mass, the pickling temperature may be about 20 ° C., and the pickling temperature may be about 5 minutes.
次に、図１（ｂ）に示すように、後段プロセスでは、部分めっき鋼管の内面のスケール等を除去するショットブラスト工程と、リン酸塩系化成処理液を用いて化成処理層を形成する化成処理工程、前記化成処理層の上に、平均厚さが１０〜４０μｍであるプライマー液を塗装してプライマー層を形成するプライマー塗布工程と、前記プライマー層に含まれる溶剤を揮発させるために、誘導加熱を用いて鋼管を加熱する第１加熱工程と、誘導加熱を用いて粉体塗装に必要な温度まで鋼管を加熱する第２加熱工程と、ポリエチレン樹脂粉末を粉体塗装により部分めっき鋼管の内面に付着させる内面粉体塗装工程と、前記粉体工程で部分めっき鋼管の内面に付着させた樹脂を、保熱炉により溶融させ、内周均一な内面被覆層を形成するために、鋼管温度を１５０〜２５０℃の間で保持する保熱工程と、前記保熱炉から出てきた鋼管を冷却する冷却工程とをその順に経て、内面被覆鋼管を製造するようにしている。 Next, as shown in FIG. 1 (b), in the subsequent process, a shot blast step of removing scale and the like on the inner surface of the partially plated steel pipe and a chemical formation using a phosphate-based chemical conversion treatment liquid to form a chemical conversion treatment layer. A treatment step, a primer coating step of coating a primer solution having an average thickness of 10 to 40 μm on the chemical conversion treatment layer to form a primer layer, and an induction to volatilize the solvent contained in the primer layer. The first heating step of heating the steel pipe using heating, the second heating step of heating the steel pipe to the temperature required for powder coating using induction heating, and the inner surface of the partially plated steel pipe by powder coating the polyethylene resin powder. In order to form a uniform inner surface coating layer by melting the resin adhered to the inner surface of the partially plated steel pipe in the inner surface powder coating step and the powder step, the steel pipe temperature is adjusted. The inner surface-coated steel pipe is manufactured through a heat-retaining step of holding the temperature between 150 and 250 ° C. and a cooling step of cooling the steel pipe coming out of the heat-retaining furnace in that order.
すなわち、この実施形態においては、後段プロセスとして、図４（ｂ）に示した従来の内面被覆鋼管の製造工程（ショットブラスト工程〜冷却工程）と同じ製造工程を備えている。 That is, in this embodiment, as the subsequent process, the same manufacturing process as the conventional manufacturing process (shot blasting step to cooling step) of the inner surface coated steel pipe shown in FIG. 4B is provided.
ここで、図３は、ショットブラスト工程において用いるショットブラスト装置を示すものである。図３に示すように、ショットブラスト装置は、部分めっき鋼管３の両管端をクランプし、一方の管端より研掃材（スチールグリット等）４を投入し、他方の管端よりブロワー５によって研掃材（スチールグリット等）４を負圧吸引することで、部分めっき鋼管３の内面を研掃するようになっている。 Here, FIG. 3 shows a shot blasting apparatus used in the shot blasting process. As shown in FIG. 3, in the shot blasting apparatus, both pipe ends of the partially plated steel pipe 3 are clamped, a polishing material (steel grit or the like) 4 is charged from one pipe end, and a blower 5 is used from the other pipe end. The inner surface of the partially plated steel pipe 3 is cleaned by suctioning the polishing material (steel grit or the like) 4 under negative pressure.
なお、ショットブラスト装置に替えて、内面酸洗装置を用いてもよい。内面酸洗装置は、部分めっき鋼管３の両管端をクランプし、部分めっき鋼管３の内部に酸洗液（塩酸）を注入・通過させるものである。 An internal pickling device may be used instead of the shot blasting device. The inner surface pickling device clamps both ends of the partially plated steel pipe 3 and injects and passes the pickling liquid (hydrochloric acid) into the partially plated steel pipe 3.
このようにして、この実施形態においては、外面をめっきした部分めっき鋼管を製造し、その部分めっき鋼管を用いて、内面を樹脂で被覆した内面被覆鋼管を製造する際に、製造した部分めっき鋼管の内面の清浄化を行う処理時間を短縮しながら、製造した内面被覆鋼管に必要とされる樹脂被覆層のピール強度（３０Ｎ／１０ｍｍ幅以上）を確保することができる。 In this way, in this embodiment, when a partially plated steel pipe having a plated outer surface is manufactured and the partially plated steel pipe is used to manufacture an inner coated steel pipe whose inner surface is coated with a resin, the manufactured partially plated steel pipe is used. It is possible to secure the peel strength (30 N / 10 mm width or more) of the resin coating layer required for the manufactured inner surface-coated steel pipe while shortening the processing time for cleaning the inner surface of the steel pipe.
本発明の実施例として、外面をめっきした部分めっき鋼管を製造し、その部分めっき鋼管を用いて内面を樹脂で被覆した内面被覆鋼管を製造した。 As an example of the present invention, a partially plated steel pipe whose outer surface was plated was manufactured, and an inner surface coated steel pipe whose inner surface was coated with a resin was manufactured using the partially plated steel pipe.
原鋼管の寸法は、呼び径５０Ａ、外径φ６０．５ｍｍ、肉厚３．５ｍｍ、管長４０２０ｍｍである。 The dimensions of the raw steel pipe are a nominal diameter of 50 A, an outer diameter of φ60.5 mm, a wall thickness of 3.5 mm, and a pipe length of 4020 mm.
その際に、本発明例として、図１に示した本発明の一実施形態における製造工程に基づいて、部分めっき鋼管と内面被覆鋼管を製造した。ショットブラスト工程の処理時間（ショットブラスト処理時間）は５分とした。不めっき塗料は、エポキシ系樹脂のものを用いた。 At that time, as an example of the present invention, a partially plated steel pipe and an inner surface coated steel pipe were manufactured based on the manufacturing process in one embodiment of the present invention shown in FIG. The processing time of the shot blasting step (shot blasting processing time) was set to 5 minutes. The non-plating paint used was an epoxy resin.
これに対して、比較例（比較例１、２）として、図４に示した従来の製造工程に基づいて、部分めっき鋼管と内面被覆鋼管を製造した。ショットブラスト工程の処理時間（ショットブラスト処理時間）は、比較例１では１０分、比較例２では１５分とした。 On the other hand, as comparative examples (Comparative Examples 1 and 2), a partially plated steel pipe and an inner surface coated steel pipe were manufactured based on the conventional manufacturing process shown in FIG. The processing time of the shot blasting step (shot blasting processing time) was 10 minutes in Comparative Example 1 and 15 minutes in Comparative Example 2.
また、従来例として、図４に示した従来の製造工程に基づいて、部分めっき鋼管と内面被覆鋼管を製造した。ショットブラスト工程の処理時間（ショットブラスト処理時間）は、従来通り、２０分とした。 Further, as a conventional example, a partially plated steel pipe and an inner surface coated steel pipe were manufactured based on the conventional manufacturing process shown in FIG. The processing time of the shot blasting process (shot blasting processing time) was set to 20 minutes as before.
そして、それぞれの例（本発明例、比較例１、２、従来例）について、製造された内面被覆鋼管の樹脂被覆層のピール強度を測定した。その結果を表１に示す。 Then, for each of the examples (Examples of the present invention, Comparative Examples 1, 2 and Conventional Examples), the peel strength of the resin coating layer of the manufactured inner surface coated steel pipe was measured. The results are shown in Table 1.
まず、比較例１は、ショットブラスト処理時間が１０分と短かったが、そのために、ピール強度が１７Ｎ／１０ｍｍ幅となり、必要なピール強度（３０Ｎ／１０ｍｍ幅以上）が得られなかった。したがって、評価は不良（×）となった。 First, in Comparative Example 1, the shot blasting treatment time was as short as 10 minutes, but for that reason, the peel strength was 17 N / 10 mm width, and the required peel strength (30 N / 10 mm width or more) could not be obtained. Therefore, the evaluation was poor (x).
同じく、比較例２は、ショットブラスト処理時間が１５分と短かったが、そのために、ピール強度が２５Ｎ／１０ｍｍ幅となり、必要なピール強度（３０Ｎ／１０ｍｍ幅以上）が得られなかった。したがって、評価は不良（×）となった。 Similarly, in Comparative Example 2, the shot blasting treatment time was as short as 15 minutes, but for that reason, the peel strength was 25 N / 10 mm width, and the required peel strength (30 N / 10 mm width or more) could not be obtained. Therefore, the evaluation was poor (x).
一方、従来例は、ピール強度が５６Ｎ／１０ｍｍ幅となり、必要なピール強度（３０Ｎ／１０ｍｍ幅以上）が得られたが、ショットブラスト処理時間が２０分と長かった。したがって、評価は不良（×）となった。 On the other hand, in the conventional example, the peel strength was 56 N / 10 mm width, and the required peel strength (30 N / 10 mm width or more) was obtained, but the shot blasting treatment time was as long as 20 minutes. Therefore, the evaluation was poor (x).
これに対して、本発明例は、ショットブラスト処理時間が５分と短かったにもかかわらず、ピール強度が５８Ｎ／１０ｍｍ幅となり、必要なピール強度（３０Ｎ／１０ｍｍ幅以上）が得られた。したがって、評価は良好（○）となった。 On the other hand, in the example of the present invention, although the shot blasting treatment time was as short as 5 minutes, the peel strength was 58 N / 10 mm width, and the required peel strength (30 N / 10 mm width or more) was obtained. Therefore, the evaluation was good (◯).
これによって、本発明の有効性が確認された。 This confirmed the effectiveness of the present invention.
１ 原鋼管
２ 不めっき塗料
３ 部分めっき鋼管
４ 研掃材（スチールグリット等）
５ ブロア
1 Raw steel pipe 2 Non-plated paint 3 Partially plated
5 blower
Claims (6)
原鋼管の両管端部の内面に不めっき塗料を塗布する不めっき塗料塗布工程と、
原鋼管の両管端部の内面に栓を嵌める栓打ち工程と、
原鋼管の外面の油脂およびスケールを除去する脱脂・酸洗工程と、
原鋼管の両管端部の内面に嵌めた栓を抜く栓抜き工程と、
原鋼管をめっき浴に浸漬し、鋼管の外面にめっき層を形成するめっき工程と
をその順に備えていることを特徴とする部分めっき鋼管の製造方法。 A method for manufacturing partially plated steel pipes with an outer surface plated.
The non-plating paint application process of applying non-plating paint to the inner surfaces of both pipe ends of the raw steel pipe,
The plugging process of fitting the plugs on the inner surfaces of both ends of the raw steel pipe,
A degreasing / pickling process that removes oil and scale from the outer surface of the raw steel pipe,
A bottle opener process to remove the stopper fitted on the inner surface of both pipe ends of the raw steel pipe,
A method for manufacturing a partially plated steel pipe, which comprises a plating step of immersing the raw steel pipe in a plating bath and forming a plating layer on the outer surface of the steel pipe in that order.
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| JPS53120638A (en) * | 1977-03-31 | 1978-10-21 | Sumitomo Metal Ind Ltd | Outside plating method for steel tube |
| JPS6049711B2 (en) * | 1977-09-08 | 1985-11-05 | 日新製鋼株式会社 | Manufacturing method of single-sided hot-dip galvanized steel pipe |
| JPS5511148A (en) * | 1978-07-11 | 1980-01-25 | Nippon Steel Corp | Partial fusion plating method for steel tube |
| JPS55164065A (en) * | 1979-06-07 | 1980-12-20 | Sumitomo Metal Ind Ltd | Method for plating on one side of steel pipe |
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