JP2020152991A - Method for manufacturing cast iron pipe and method for corrosively protecting surface of cast iron pipe - Google Patents
Method for manufacturing cast iron pipe and method for corrosively protecting surface of cast iron pipe Download PDFInfo
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- 229910001018 Cast iron Inorganic materials 0.000 title claims abstract description 97
- 238000000034 method Methods 0.000 title claims abstract description 40
- 238000004519 manufacturing process Methods 0.000 title claims abstract description 16
- 239000010410 layer Substances 0.000 claims abstract description 56
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims abstract description 48
- HCHKCACWOHOZIP-UHFFFAOYSA-N Zinc Chemical compound [Zn] HCHKCACWOHOZIP-UHFFFAOYSA-N 0.000 claims abstract description 35
- 238000000137 annealing Methods 0.000 claims abstract description 35
- 229910052725 zinc Inorganic materials 0.000 claims abstract description 34
- 239000011701 zinc Substances 0.000 claims abstract description 34
- 238000005507 spraying Methods 0.000 claims abstract description 31
- 229910052751 metal Inorganic materials 0.000 claims abstract description 30
- 239000002184 metal Substances 0.000 claims abstract description 30
- 238000000576 coating method Methods 0.000 claims abstract description 25
- 239000011248 coating agent Substances 0.000 claims abstract description 23
- 238000005260 corrosion Methods 0.000 claims abstract description 18
- 230000007797 corrosion Effects 0.000 claims abstract description 18
- 239000002344 surface layer Substances 0.000 claims abstract description 17
- 238000005266 casting Methods 0.000 claims abstract description 9
- 239000003973 paint Substances 0.000 claims description 26
- 239000011800 void material Substances 0.000 claims description 10
- 238000002347 injection Methods 0.000 claims description 4
- 239000007924 injection Substances 0.000 claims description 4
- 238000007751 thermal spraying Methods 0.000 abstract description 8
- 239000000463 material Substances 0.000 abstract description 5
- 238000010422 painting Methods 0.000 abstract description 4
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 12
- 229910001141 Ductile iron Inorganic materials 0.000 description 9
- 229910000859 α-Fe Inorganic materials 0.000 description 8
- UQSXHKLRYXJYBZ-UHFFFAOYSA-N Iron oxide Chemical compound [Fe]=O UQSXHKLRYXJYBZ-UHFFFAOYSA-N 0.000 description 6
- 229910000611 Zinc aluminium Inorganic materials 0.000 description 6
- HXFVOUUOTHJFPX-UHFFFAOYSA-N alumane;zinc Chemical compound [AlH3].[Zn] HXFVOUUOTHJFPX-UHFFFAOYSA-N 0.000 description 6
- 229910045601 alloy Inorganic materials 0.000 description 5
- 239000000956 alloy Substances 0.000 description 5
- 229910001567 cementite Inorganic materials 0.000 description 5
- KSOKAHYVTMZFBJ-UHFFFAOYSA-N iron;methane Chemical compound C.[Fe].[Fe].[Fe] KSOKAHYVTMZFBJ-UHFFFAOYSA-N 0.000 description 5
- 239000011159 matrix material Substances 0.000 description 5
- 239000007921 spray Substances 0.000 description 5
- 229920003002 synthetic resin Polymers 0.000 description 5
- 239000000057 synthetic resin Substances 0.000 description 5
- 229910052782 aluminium Inorganic materials 0.000 description 4
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 4
- 239000011247 coating layer Substances 0.000 description 4
- 238000001816 cooling Methods 0.000 description 4
- 238000010438 heat treatment Methods 0.000 description 4
- 229910052742 iron Inorganic materials 0.000 description 4
- 230000009466 transformation Effects 0.000 description 4
- 239000004925 Acrylic resin Substances 0.000 description 3
- 229920000178 Acrylic resin Polymers 0.000 description 3
- 238000010586 diagram Methods 0.000 description 3
- 230000000694 effects Effects 0.000 description 3
- 239000003822 epoxy resin Substances 0.000 description 3
- 229920000647 polyepoxide Polymers 0.000 description 3
- 229910004283 SiO 4 Inorganic materials 0.000 description 2
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 description 2
- REPKDCXRUILTRL-UHFFFAOYSA-N [Zn].[Mn].[Si] Chemical compound [Zn].[Mn].[Si] REPKDCXRUILTRL-UHFFFAOYSA-N 0.000 description 2
- 229910001566 austenite Inorganic materials 0.000 description 2
- 230000015572 biosynthetic process Effects 0.000 description 2
- 238000005422 blasting Methods 0.000 description 2
- 238000000354 decomposition reaction Methods 0.000 description 2
- 238000004453 electron probe microanalysis Methods 0.000 description 2
- 239000007789 gas Substances 0.000 description 2
- 238000013507 mapping Methods 0.000 description 2
- 239000000203 mixture Substances 0.000 description 2
- 230000003647 oxidation Effects 0.000 description 2
- 238000007254 oxidation reaction Methods 0.000 description 2
- 229910001562 pearlite Inorganic materials 0.000 description 2
- 238000001556 precipitation Methods 0.000 description 2
- 238000005096 rolling process Methods 0.000 description 2
- 238000001878 scanning electron micrograph Methods 0.000 description 2
- 229910052710 silicon Inorganic materials 0.000 description 2
- 239000010703 silicon Substances 0.000 description 2
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 description 1
- 229910001297 Zn alloy Inorganic materials 0.000 description 1
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 1
- 238000009750 centrifugal casting Methods 0.000 description 1
- 229910052802 copper Inorganic materials 0.000 description 1
- 239000010949 copper Substances 0.000 description 1
- LNEPOXFFQSENCJ-UHFFFAOYSA-N haloperidol Chemical compound C1CC(O)(C=2C=CC(Cl)=CC=2)CCN1CCCC(=O)C1=CC=C(F)C=C1 LNEPOXFFQSENCJ-UHFFFAOYSA-N 0.000 description 1
- 239000001301 oxygen Substances 0.000 description 1
- 229910052760 oxygen Inorganic materials 0.000 description 1
- 238000007591 painting process Methods 0.000 description 1
- 230000002093 peripheral effect Effects 0.000 description 1
- 239000010865 sewage Substances 0.000 description 1
- LGERWORIZMAZTA-UHFFFAOYSA-N silicon zinc Chemical compound [Si].[Zn] LGERWORIZMAZTA-UHFFFAOYSA-N 0.000 description 1
Landscapes
- Other Surface Treatments For Metallic Materials (AREA)
- Coating By Spraying Or Casting (AREA)
Abstract
Description
本発明は、鋳鉄管の製造方法および鋳鉄管の表面防食方法に関し、とりわけ、生産性の向上された外面耐食性を有する鋳鉄管の製造方法および鋳鉄管の外面防食方法に関する。 The present invention relates to a method for producing a cast iron pipe and a method for surface corrosion protection of a cast iron pipe, and more particularly to a method for producing a cast iron pipe having improved outer surface corrosion resistance and a method for external surface corrosion protection of a cast iron pipe.
従来から上下水道管などに用いられる鋳鉄管は、一般的には、金型遠心力鋳造などの方法で鋳造され、その後、組織改善のために約８００〜１０００℃の焼鈍炉に入れられて１〜２時間程度焼鈍処理が施される。焼鈍処理は酸素雰囲気下で行われるため、外周面が酸化されて空隙を有する厚い酸化皮膜（酸化スケールとも呼ばれる）が生成される。その後、生成した酸化鉄皮膜をショットブラスト処理などによりすべて除去し、耐食用の塗装が施されている。 Cast iron pipes that have been conventionally used for water and sewage pipes are generally cast by a method such as die centrifugal casting, and then placed in an annealing furnace at about 800 to 1000 ° C. for structural improvement. Annealing is performed for about 2 hours. Since the annealing treatment is performed in an oxygen atmosphere, the outer peripheral surface is oxidized to form a thick oxide film (also called an oxide scale) having voids. After that, all the iron oxide film formed is removed by shot blasting or the like, and a corrosion-resistant coating is applied.
例えば、一般的なダクタイル鋳鉄管の焼鈍は、一般的には連続焼鈍炉で行われる。この連続焼鈍炉において、ダクタイル鋳鉄管は、オーステナイト化温度域以上（８７０℃以上）に加熱される。これによりセメンタイトを完全に分解し、基地組織のオーステナイト化を行う。このセメンタイトの分解は、処理温度と処理時間に依存し、処理温度が高いほど処理時間を短くすることができる一方で、処理温度が低いほど長い処理時間を要する。この連続焼鈍炉は、炉内の均一な温度コントロールが困難であることが多い。このため、セメンタイトを確実にオーステナイト化するために、処理温度および処理時間を決定する必要がある。 For example, general annealing of ductile cast iron pipes is generally carried out in a continuous annealing furnace. In this continuous annealing furnace, the ductile cast iron pipe is heated above the austenitizing temperature range (870 ° C. or higher). This completely decomposes cementite and austenites the base tissue. The decomposition of cementite depends on the treatment temperature and the treatment time, and the higher the treatment temperature, the shorter the treatment time, while the lower the treatment temperature, the longer the treatment time. In this continuous annealing furnace, it is often difficult to control the temperature uniformly in the furnace. Therefore, it is necessary to determine the treatment temperature and the treatment time in order to surely austenite the cementite.
基地組織のオーステナイト化を完了したら、このオーステナイトからフェライトを析出させるため、共析変態点付近（６８０〜７５０℃程度）の温度域を一定時間保持するか、この共析変態点付近を徐冷する熱処理を行う。この際の保冷時間や冷却速度により、フェライト析出量が決定される。すなわち、保持時間が長いほど、または冷却速度が小さいほどフェライト析出量は増大する一方で、保持時間が短いほど、または冷却速度が大きいほどフェライト析出量は減少し、マトリックスの主体はパーライトとなる。 After the austeniticization of the matrix structure is completed, in order to precipitate ferrite from this austenite, the temperature range near the eutectoid transformation point (about 680 to 750 ° C.) is maintained for a certain period of time, or the vicinity of this eutectoid transformation point is slowly cooled. Perform heat treatment. The amount of ferrite deposited is determined by the cooling time and cooling rate at this time. That is, the longer the holding time or the lower the cooling rate, the larger the ferrite precipitation amount, while the shorter the holding time or the higher the cooling rate, the smaller the ferrite precipitation amount, and the matrix becomes pearlite.
この熱処理において連続焼鈍炉を用いる場合、厳密に温度コントロールを行ってフェライトとパーライトの量を細かくコントロールすることが困難なため、基本的にはフェライトが主体となる条件で焼鈍を実施して靱性の確保を図っている。 When a continuous annealing furnace is used in this heat treatment, it is difficult to finely control the amount of ferrite and pearlite by strictly controlling the temperature. Therefore, basically, annealing is performed under the condition that ferrite is the main component, and the toughness is increased. We are trying to secure it.
また、特許文献１には、ショットブラスト処理後に、亜鉛系金属を溶融して鋳鉄管の表面に吹き付け、続いて、ジンクリッチペイントを上塗りして鋳鉄管の表面に亜鉛系の防食層を形成する鋳鉄管の防食方法も開示されている。 Further, in Patent Document 1, after the shot blasting treatment, the zinc-based metal is melted and sprayed on the surface of the cast iron pipe, and then a zinc rich paint is overcoated to form a zinc-based anticorrosion layer on the surface of the cast iron pipe. Anticorrosion methods for cast iron pipes are also disclosed.
一方、特許文献２には、鋳造した金属鋳塊、具体的には銅の鋳塊を、連続圧延する前に、鋳塊の酸化皮膜を高圧水を噴射して除去することにより、圧延により酸化皮膜が鋳塊内部に押し込まれるのを防ぐことが記載されている。 On the other hand, Patent Document 2 states that a cast metal ingot, specifically a copper ingot, is oxidized by rolling by removing the oxide film of the ingot by injecting high-pressure water before continuous rolling. It is described to prevent the film from being pushed into the ingot.
しかしながら、特許文献１の方法では、酸化皮膜が全て除去されてしまうため、亜鉛系金属溶射膜や塗装膜などさらなる防食層が必要となりコスト高となるためさらに改善の余地がある。 However, in the method of Patent Document 1, since all the oxide film is removed, a further anticorrosion layer such as a zinc-based metal sprayed film or a coating film is required, which increases the cost, and there is room for further improvement.
また、特許文献２の方法は、鋳鉄やその該表面に生じる酸化皮膜の性状などは一切記載されておらず、一部の酸化皮膜を利用するという発想や具体例も全く記載されていない。 Further, the method of Patent Document 2 does not describe the properties of cast iron or the oxide film formed on the surface thereof, and does not describe the idea or specific example of using a part of the oxide film.
そこで、本発明は、一部の酸化皮膜を除去することなく耐食層として用いることによる、生産性の向上された外面耐食性を有する鋳鉄管の製造方法、ならびに鋳鉄管の外面防食方法を提供することを課題とする。 Therefore, the present invention provides a method for producing a cast iron pipe having improved outer surface corrosion resistance by using it as a corrosion resistant layer without removing a part of the oxide film, and a method for protecting the outer surface of the cast iron pipe. Is the subject.
本発明者らは、焼鈍処理後の鋳鉄管外面に高圧水を適用することにより、鉄地により近い緻密な酸化皮膜層を残したまま、表層の空隙率の高い酸化皮膜層を除去し、その後、緻密な酸化皮膜層上に亜鉛系金属溶射または塗装を行うことにより、生産性の向上された、外面耐食性を有する鋳鉄管を得ることができることを見出し、本発明を完成した。 By applying high-pressure water to the outer surface of the cast iron pipe after the annealing treatment, the present inventors remove the oxide film layer having a high void ratio on the surface layer while leaving a dense oxide film layer closer to the iron base, and then remove the oxide film layer. The present invention has been completed by finding that a cast iron pipe having improved productivity and outer surface corrosion resistance can be obtained by spraying or coating a zinc-based metal on a dense oxide film layer.
すなわち、本発明は、
［１］焼鈍処理後の鋳鉄管に高圧水処理を行い、高圧水処理を終えた鋳鉄管表面にそのまま亜鉛系金属を溶射し、亜鉛系金属溶射皮膜を形成する鋳鉄管の製造方法、
［２］鋳造後の鋳鉄管に焼鈍処理を行う工程、
焼鈍処理後の鋳鉄管外面に高圧水を噴射し、鋳鉄管外面表層の空隙率の高い酸化皮膜層を除去する工程、ならびに
残存した緻密な酸化皮膜層上に、亜鉛系金属を溶射する、または塗料を塗装する工程
を含む鋳鉄管の製造方法、
［３］高圧水の噴射開始時の鋳鉄管の管温度が４００〜６００℃である上記［２］記載の鋳鉄管の製造方法、
［４］鋳造後の鋳鉄管を焼鈍処理することにより鋳鉄管外面に形成された酸化皮膜の空隙率の高い表層を、高圧水を噴射することにより除去する工程、ならびに
残存した緻密な酸化皮膜層上に、亜鉛系金属を溶射する、または塗料を塗装する工程
を含む鋳鉄管外面の防食方法、ならびに
［５］高圧水の噴射開始時の鋳鉄管の管温度が４００〜６００℃である上記［４］記載の鋳鉄管外面の防食方法
に関する。
That is, the present invention
[1] A method for producing a cast iron pipe in which a cast iron pipe after annealing is subjected to high-pressure water treatment, and a zinc-based metal is directly sprayed onto the surface of the cast iron pipe after the high-pressure water treatment to form a zinc-based metal sprayed coating.
[2] A process of annealing a cast iron pipe after casting,
A step of spraying high-pressure water on the outer surface of the cast iron pipe after the annealing treatment to remove the oxide film layer having a high void ratio on the outer surface of the cast iron pipe, and spraying or spraying a zinc-based metal on the remaining dense oxide film layer. Manufacturing method of cast iron pipe including the process of applying paint,
[3] The method for manufacturing a cast iron pipe according to the above [2], wherein the pipe temperature of the cast iron pipe at the start of injection of high-pressure water is 400 to 600 ° C.
[4] A step of removing the surface layer having a high void ratio of the oxide film formed on the outer surface of the cast iron pipe by annealing the cast iron pipe after casting by injecting high-pressure water, and the remaining dense oxide film layer. A method for preventing corrosion of the outer surface of the cast iron pipe, which includes a step of spraying a zinc-based metal or applying a paint, and [5] the pipe temperature of the cast iron pipe at the start of injection of high-pressure water is 400 to 600 ° C. 4] The present invention relates to a method for preventing corrosion of the outer surface of a cast iron pipe.
本発明は、焼鈍処理後の鋳鉄管外面に高圧水を適用することにより、鉄地により近い緻密な酸化皮膜層を残したまま、表層の空隙率の高い酸化皮膜層を除去することができるため、これまで利用されていなかった緻密な酸化皮膜層を防食層の一部として利用することができ、生産性を向上させることができる。またそれにより、亜鉛系金属溶射皮膜や塗料による塗膜の厚さを削減することもできる。 According to the present invention, by applying high-pressure water to the outer surface of the cast iron pipe after the annealing treatment, it is possible to remove the oxide film layer having a high porosity on the surface layer while leaving a dense oxide film layer closer to the iron base. , A dense oxide film layer that has not been used so far can be used as a part of the anticorrosion layer, and the productivity can be improved. As a result, the thickness of the zinc-based metal sprayed coating or the coating film due to the paint can be reduced.
＜鋳鉄管の製造方法＞
本発明の一実施態様としては、鋳造後の鋳鉄管に焼鈍処理を行う工程、焼鈍処理後の鋳鉄管外面に高圧水を噴射し、鋳鉄管外面表層の空隙率の高い酸化皮膜層を除去する工程、ならびに、残存した緻密な酸化皮膜層上に、亜鉛系金属を溶射する、または塗料を塗装する工程を含む鋳鉄管の製造方法が提供される。
<Manufacturing method of cast iron pipe>
One embodiment of the present invention is a step of annealing a cast iron pipe after casting, spraying high-pressure water on the outer surface of the cast iron pipe after the annealing treatment, and removing an oxide film layer having a high void ratio on the outer surface of the cast iron pipe. A method for producing a cast iron pipe is provided, which comprises a step and a step of spraying a zinc-based metal or applying a paint on the remaining dense oxide film layer.
（焼鈍処理工程）
鋳造後の鋳鉄管の焼鈍処理は、基地組織のフェライト化のために行われ、加熱処理のため鋳鉄管表面に酸化皮膜が形成される。焼鈍処理の方法は、特に限定されるものではないが、電気炉、ガスバーナー炉などにより熱処理して行われ、連続焼鈍炉により行われるのが一般的である。焼鈍処理の条件は、８７０℃以上の温度でセメンタイトを完全に分解し、基地組織のオーステナイト化を行う。このセメンタイトの分解は、処理温度が高いほど処理時間を短縮できる。その後、基地組織のオーステナイト化が完了したら、フェライト化のために共析変態点付近（６８０〜７５０℃程度）の温度域を一定時間保持させるかまたは共析変態点付近にかけて徐冷する。その際、管温度が４００℃を下回らない間に、次工程の高圧水処理に付す必要がある。
(Annealing process)
The annealing treatment of the cast iron pipe after casting is performed for ferrite formation of the matrix structure, and an oxide film is formed on the surface of the cast iron pipe due to the heat treatment. The method of annealing treatment is not particularly limited, but it is generally performed by heat treatment in an electric furnace, a gas burner furnace, or the like, and is performed in a continuous annealing furnace. The conditions of the annealing treatment are that cementite is completely decomposed at a temperature of 870 ° C. or higher to austenitize the matrix structure. The higher the treatment temperature, the shorter the treatment time for this decomposition of cementite. After that, when the austeniticization of the matrix structure is completed, the temperature range near the eutectoid transformation point (about 680 to 750 ° C.) is maintained for a certain period of time for ferrite formation, or the mixture is slowly cooled toward the eutectoid transformation point. At that time, it is necessary to perform the next step of high-pressure water treatment while the pipe temperature does not fall below 400 ° C.
一般に、焼鈍により生成される酸化皮膜は、図３〜５に示すように、大きく分けて、酸化鉄（Ｆｅ3Ｏ4、Ｆｅ2Ｏ3など）を主成分とする表層の空隙率の高い酸化皮膜層１０３と、ケイ酸化鉄（Ｆｅ2ＳｉＯ4など）を主成分とする鋳鉄素地１０１により近いケイ素を含む緻密な酸化皮膜層１０２との二層構造を有する。ここで、表層の空隙率の高い酸化皮膜層１０３は、その空隙率の高さから、鋳鉄管外面から剥離しやすく、その上に形成され得る塗膜や金属溶射膜との密着性が低い。このため、この表層の空隙率の高い酸化皮膜層１０３を残したままであれば、金属溶射や塗料などの外面防食層との密着性が低下するため、本発明においては、この表層が次の高圧水処理により選択的に除去される。また残る鋳鉄素地１０１により近い緻密な酸化皮膜層１０２は、防食層として活用される。なお、図４および５は、それぞれ本発明とは異なり、空隙率の高い酸化皮膜層１０３の表層に溶射皮膜層が形成された鋳鉄管外面の断面のＳＥＭ画像およびＥＰＭＡの元素マッピングの画像であるが、酸化皮膜の二層構造を説明するために参考に示すものである。図４から酸化皮膜が、確かに表層の空隙率の高い酸化皮膜層１０３と、鋳鉄素地１０１により近い緻密な酸化皮膜層１０２との二層構造を有していることが分かり、また図５より、鋳鉄素地１０１により近い緻密な酸化皮膜層１０２がケイ酸化鉄（Ｆｅ2ＳｉＯ4など）を主成分とするケイ素を含む層であることが分かる。 In general, as shown in FIGS. 3 to 5, the oxide film formed by annealing is roughly divided into oxidation having a high void ratio in the surface layer containing iron oxide (Fe 3 O 4 , Fe 2 O 3, etc.) as a main component. It has a two-layer structure consisting of a film layer 103 and a dense oxide film layer 102 containing silicon, which is closer to a cast iron base 101 containing iron (Fe 2 SiO 4 or the like) as a main component. Here, the oxide film layer 103 having a high porosity on the surface layer is easily peeled off from the outer surface of the cast iron pipe due to its high porosity, and has low adhesion to a coating film or a metal sprayed film that can be formed on the oxide film layer 103. Therefore, if the oxide film layer 103 having a high porosity of the surface layer is left, the adhesion to the outer surface anticorrosion layer such as metal spraying or paint is lowered. Therefore, in the present invention, this surface layer has the next high pressure. It is selectively removed by water treatment. Further, the dense oxide film layer 102 closer to the remaining cast iron base 101 is utilized as an anticorrosion layer. Note that FIGS. 4 and 5 are SEM images and EPMA element mapping images of the cross section of the outer surface of the cast iron pipe in which the thermal spray coating layer is formed on the surface layer of the oxide film layer 103 having a high porosity, respectively, unlike the present invention. However, it is shown for reference in order to explain the two-layer structure of the oxide film. It can be seen from FIG. 4 that the oxide film certainly has a two-layer structure of an oxide film layer 103 having a high void ratio on the surface layer and a dense oxide film layer 102 closer to the cast iron base 101, and from FIG. It can be seen that the dense oxide film layer 102, which is closer to the cast iron base 101, is a layer containing silicon containing siliceous iron oxide (Fe 2 SiO 4 or the like) as a main component.
緻密な酸化皮膜層１０２の厚さは、約２５μｍ以上にすることにより、十分な防食層としての効果が得られる傾向がある。 By setting the thickness of the dense oxide film layer 102 to about 25 μm or more, a sufficient effect as an anticorrosion layer tends to be obtained.
（高圧水処理工程）
高圧水処理の一例を図１〜３を用いて説明する。鋳鉄管の焼鈍処理後、管温度があまり低下しないうちに、例えば管温度が好ましくは４００〜６００℃、より好ましくは５００〜６００℃である鋳鉄管Ｐを回転ローラ４上に載せ、回転させながら高圧水供給配管１に備えられた高圧水スプレーノズル２より高圧水３を噴射し、水冷を行う。これにより鋳鉄管の急激な収縮が起こり、多くの空隙１０４を有する表層の空隙率の高い酸化皮膜層１０３の剥離が促進され、鋳鉄素地１０１により近い緻密な酸化皮膜層１０２を残したまま、表層の空隙率の高い酸化皮膜層１０３を除去する。一般的に酸化皮膜は、緻密な状態で生成された場合、腐食の進行を抑制する効果があるため、本発明においては、緻密な酸化皮膜層１０２を耐食層として利用することが可能となる。
(High pressure water treatment process)
An example of high-pressure water treatment will be described with reference to FIGS. After the annealing treatment of the cast iron pipe, for example, the cast iron pipe P having a pipe temperature of preferably 400 to 600 ° C., more preferably 500 to 600 ° C. is placed on the rotary roller 4 and rotated while the pipe temperature does not drop so much. High-pressure water 3 is sprayed from the high-pressure water spray nozzle 2 provided in the high-pressure water supply pipe 1 to cool the water. As a result, the cast iron pipe is rapidly shrunk, the peeling of the oxide film layer 103 having a large porosity on the surface layer having many voids 104 is promoted, and the surface layer is left with the dense oxide film layer 102 closer to the cast iron base 101. The oxide film layer 103 having a high porosity is removed. Generally, when the oxide film is formed in a dense state, it has an effect of suppressing the progress of corrosion. Therefore, in the present invention, the dense oxide film layer 102 can be used as a corrosion resistant layer.
高圧水処理の条件としては、表層の空隙率の高い酸化皮膜層１０３を選択的に除去できる条件であれば特に限定されるものではないが、例えば、１０〜６０ＭＰａの水圧であれば、ケイ酸化鉄を主成分とする緻密な層を損傷させずに表層の空隙率の高い酸化皮膜層を選択的に除去できる傾向がある。 The conditions for the high-pressure water treatment are not particularly limited as long as the oxide film layer 103 having a high porosity on the surface layer can be selectively removed. For example, if the water pressure is 10 to 60 MPa, siliceous oxidation is performed. There is a tendency that the oxide film layer having a high porosity on the surface layer can be selectively removed without damaging the dense layer containing iron as a main component.
（亜鉛系金属溶射工程）
本発明の一実施態様としては、高圧水処理後に残存した緻密な酸化皮膜層上に、亜鉛系金属を溶射し、亜鉛系金属溶射皮膜を形成する。すなわち、焼鈍処理後の鋳鉄管に高圧水処理を行い、高圧水処理を終えた鋳鉄管表面にそのまま亜鉛系金属を溶射し、亜鉛系金属溶射皮膜を形成する。
(Zinc-based metal spraying process)
In one embodiment of the present invention, a zinc-based metal is sprayed onto a dense oxide film layer remaining after high-pressure water treatment to form a zinc-based metal sprayed film. That is, the cast iron pipe after the annealing treatment is subjected to high-pressure water treatment, and the zinc-based metal is directly sprayed on the surface of the cast iron pipe after the high-pressure water treatment to form a zinc-based metal sprayed film.
亜鉛系金属溶射皮膜としては、亜鉛溶射皮膜、亜鉛−アルミ合金溶射皮膜、亜鉛−アルミ擬合金溶射皮膜、亜鉛−ケイ素含有アルミ擬合金溶射皮膜、亜鉛−ケイ素マンガン含有アルミ擬合金溶射皮膜、亜鉛−スズ合金溶射皮膜などが挙げられる。なお、亜鉛−アルミニウム擬合金とは、溶射された亜鉛とアルミニウムとが不規則に重なり合い、外見的に亜鉛−アルミニウム合金を形成しているものをいう。 Zinc-based metal spray coatings include zinc spray coating, zinc-aluminum alloy spray coating, zinc-aluminum pseudoalloy spray coating, zinc-silicon-containing aluminum pseudoalloy spray coating, zinc-silicon manganese-containing aluminum pseudoalloy spray coating, and zinc-. Examples include a zinc alloy spray coating. The zinc-aluminum pseudo-alloy is an alloy in which the sprayed zinc and aluminum are irregularly overlapped to form a zinc-aluminum alloy in appearance.
溶射皮膜の膜厚は、溶射材料の種類、得られる鋳鉄管の用途によって適宜設定することができるが、水道管用の鋳鉄管の場合、例えば、亜鉛溶射皮膜では、日本ダクタイル鉄管協会規格のＪＤＰＡ Ｚ ２０１０−２００９「ダクタイル鋳鉄管合成樹脂塗装」に規定されている、１３０ｇ／ｍ2以上の溶射量で十分な効果を得ることができる。また、鋳鉄素地との密着性を考慮すれば、３００ｇ／ｍ2以下が好ましく、２６０ｇ／ｍ2以下がより好ましい。もちろん他の溶射材を用いた場合には、その防食性の観点から溶射量の好ましい上限は変動するものである。 The thickness of the sprayed coating can be appropriately set depending on the type of sprayed material and the intended use of the cast iron pipe obtained. However, in the case of cast iron pipes for water pipes, for example, for zinc sprayed coatings, JDPA Z of the Japan Ductile Iron Pipe Association standard. A sufficient effect can be obtained with a thermal spraying amount of 130 g / m 2 or more specified in 2010-2009 "Ductile cast iron pipe synthetic resin coating". Further, considering the adhesion to the cast iron base material, 300 g / m 2 or less is preferable, and 260 g / m 2 or less is more preferable. Of course, when another thermal spraying material is used, the preferable upper limit of the thermal spraying amount varies from the viewpoint of its anticorrosion property.
溶射方法は特に限定されるものではないが、たとえばガス溶射法やアーク溶射法、プラズマ溶射法があげられる。より具体的には、回転しながら管軸方向に移送される鋳鉄管に、固定した溶射ガンにより亜鉛、亜鉛−アルミニウム擬合金または亜鉛−アルミニウム合金、亜鉛−ケイ素マンガン含有アルミ擬合金を溶射する方法、回転させた鋳鉄管に、溶射ガンを移動させながら亜鉛を溶射する方法があげられる。 The thermal spraying method is not particularly limited, and examples thereof include a gas thermal spraying method, an arc thermal spraying method, and a plasma thermal spraying method. More specifically, a method of spraying zinc, zinc-aluminum pseudoalloy, zinc-aluminum alloy, or zinc-silicon manganese-containing aluminum pseudoalloy on a cast iron pipe that is transferred in the axial direction while rotating with a fixed spray gun. , A method of spraying zinc on a rotated cast iron pipe while moving a spraying gun can be mentioned.
（塗料の塗装工程）
本発明の一実施態様としては、高圧水処理後に残存した緻密な酸化皮膜層上に、塗料を塗装し、塗膜を形成した鋳鉄管とすることができる。塗料としては、特に限定されるものではなく、アクリル系樹脂、エポキシ系樹脂などを使用することができる。これらのアクリル系樹脂、エポキシ系樹脂は、鋳鉄管の上塗り塗料として流通しているものを用いればよく、特に限定されるものではない。水道管に使用する場合には、例えば、日本水道協会規格ＪＷＷＡ Ｋ １３９「水道用ダクタイル鋳鉄管合成樹脂塗料」に規定されている合成樹脂塗料を好適に用いることができる。
(Paint painting process)
As one embodiment of the present invention, a cast iron pipe can be obtained by coating a coating film on a dense oxide film layer remaining after high-pressure water treatment to form a coating film. The paint is not particularly limited, and an acrylic resin, an epoxy resin, or the like can be used. As these acrylic resins and epoxy resins, those currently distributed as topcoat paints for cast iron pipes may be used, and are not particularly limited. When used for water pipes, for example, synthetic resin paints specified in the Japan Water Works Association standard JWWA K 139 "Ductile cast iron pipe synthetic resin paint for water supply" can be preferably used.
具体的には、塗料として用いるアクリル系樹脂としては、例えば、大日本塗料（株）製のクリモトコートＷＲ、日本ペイント・インダストリアルコーティングス（株）製のクリモトコートＡＣ−１−ＳＲ、日本ペイント・インダストリアルコーティングス（株）製のクリモトコートＡＣ−１などを使用することができる。 Specifically, examples of the acrylic resin used as the paint include Kurimoto Coat WR manufactured by Dainippon Paint Co., Ltd., Kurimoto Coat AC-1-SR manufactured by Nippon Paint Industrial Coatings Co., Ltd., and Nippon Paint Co., Ltd. Kurimoto Coat AC-1 manufactured by Industrial Coatings Co., Ltd. can be used.
また、塗料として用いるエポキシ系樹脂としては、例えば、大日本塗料（株）製のクリモトコートＮＴ＃１００新Ｈ、関西ペイント（株）製のクリモトコートＮＴ＃１００新などを使用することができる。 As the epoxy resin used as the paint, for example, Kurimoto Coat NT # 100 New H manufactured by Dai Nippon Toryo Co., Ltd., Kurimoto Coat NT # 100 New H manufactured by Kansai Paint Co., Ltd., and the like can be used.
塗料を塗装する方法としては、管体を回転させながら、スプレーガンなどを用いてミスト状にした塗料を噴射して塗装する方法や、ローラーバケなどのハケを用いて塗装する方法などを使用することができる。 As a method of painting the paint, a method of spraying a mist-like paint using a spray gun or the like while rotating the tube body, or a method of painting with a brush such as a roller bucket is used. be able to.
塗料を塗装して得られる塗膜の膜厚は、鋳鉄管の用途や塗料の種類によって適宜設定することができるが、水道管用の鋳鉄管の場合、日本ダクタイル鉄管協会規格のＪＤＰＡ Ｚ ２０１０−２００９「ダクタイル鋳鉄管合成樹脂塗装」において、所定の耐腐食性と耐久性を得るために目標塗膜厚さ１００μｍ以上行うことが定められている。 The thickness of the coating film obtained by applying the paint can be appropriately set depending on the application of the cast iron pipe and the type of paint, but in the case of the cast iron pipe for water pipes, JDPA Z 2010-2009 of the Japan Ductile Iron Pipe Association standard. In "Ductile cast iron pipe synthetic resin coating", it is stipulated that a target coating thickness of 100 μm or more is applied in order to obtain predetermined corrosion resistance and durability.
また、高圧水処理後に残存した緻密な酸化皮膜上に、亜鉛系金属を溶射し、亜鉛系金属溶射皮膜を形成した場合、さらに亜鉛系金属溶射皮膜上に塗料を塗装することもできる。この場合の塗料やその塗装方法については、上述の高圧水処理後に残存した緻密な酸化皮膜層上への塗料の塗装について記載した内容が全て適用される。また、得られる塗膜の膜厚は、鋳鉄管の用途や塗料の種類によって適宜設定することができる。上述したように、水道管用の鋳鉄管の場合、外面塗膜層の厚さは、日本ダクタイル鉄管協会規格のＪＤＰＡ Ｚ ２０１０−２００９「ダクタイル鋳鉄管合成樹脂塗装」において規定される、目標塗膜厚さを１００μｍ以上とする基準を満たすものであれば特に限定されず、たとえば溶射皮膜層の厚さが２０μｍ（溶射量としては１３０ｇ／ｍ2）の場合、塗料の塗膜層の厚さは８０μｍ以上であり、防食性と付着性を考慮して好ましくは１００μｍ〜２００μｍである。 Further, when the zinc-based metal is sprayed on the dense oxide film remaining after the high-pressure water treatment to form the zinc-based metal sprayed film, the paint can be further applied on the zinc-based metal sprayed film. As for the paint and its coating method in this case, all the contents described about the coating of the paint on the dense oxide film layer remaining after the high-pressure water treatment are applied. Further, the film thickness of the obtained coating film can be appropriately set depending on the use of the cast iron pipe and the type of paint. As described above, in the case of cast iron pipes for water pipes, the thickness of the outer coating layer is the target coating thickness specified in JDPA Z 2010-2009 "Ductile cast iron pipe synthetic resin coating" of the Japan Ductile Iron Pipe Association standard. The thickness is not particularly limited as long as it satisfies the standard of 100 μm or more. For example, when the thickness of the thermal spray coating layer is 20 μm (the amount of thermal spray is 130 g / m 2 ), the thickness of the coating film layer of the paint is 80 μm. As described above, it is preferably 100 μm to 200 μm in consideration of anticorrosion and adhesiveness.
＜鋳鉄管の外面防食方法＞
本発明の別の一実施態様としては、鋳造後の鋳鉄管を焼鈍処理することにより鋳鉄管外面に形成された酸化皮膜の空隙率の高い表層を、高圧水を噴射することにより除去する工程、ならびに、残存した緻密な酸化皮膜層上に、亜鉛系金属を溶射する、または塗料を塗装する工程を含む鋳鉄管外面の防食方法が提供される。
<How to protect the outer surface of cast iron pipes>
Another embodiment of the present invention is a step of removing the surface layer having a high void ratio of the oxide film formed on the outer surface of the cast iron pipe by annealing the cast iron pipe after casting by injecting high-pressure water. Further, a method for preventing corrosion of the outer surface of the cast iron pipe is provided, which comprises a step of spraying a zinc-based metal or applying a paint on the remaining dense oxide film layer.
本発明の鋳鉄管外面の防食方法については、上述の鋳鉄管の製造方法について説明した内容がすべて適用される。 As for the method for preventing corrosion of the outer surface of the cast iron pipe of the present invention, all the contents described above for the method for manufacturing the cast iron pipe are applied.
Ｐ 鋳鉄管
１ 高圧水供給配管
２ 高圧水スプレーノズル
３ 水
４ 回転ローラ
１０１ 鋳鉄素地
１０２ 緻密な酸化皮膜層
１０３ 表層の空隙率の高い酸化皮膜層
１０４ 空隙
１０５ 溶射皮膜層
P Cast iron pipe 1 High-pressure water supply pipe 2 High-pressure water spray nozzle 3 Water 4 Rotating roller 101 Cast iron base 102 Dense oxide film layer 103 Oxide film layer with high porosity on the surface 104 Void 105 Thermal spray coating layer
Claims (5)
焼鈍処理後の鋳鉄管外面に高圧水を噴射し、鋳鉄管外面表層の空隙率の高い酸化皮膜層を除去する工程、ならびに
残存した緻密な酸化皮膜層上に、亜鉛系金属を溶射する、または塗料を塗装する工程
を含む鋳鉄管の製造方法。 The process of annealing cast iron pipes after casting,
A step of spraying high-pressure water on the outer surface of the cast iron pipe after the annealing treatment to remove the oxide film layer having a high void ratio on the outer surface of the cast iron pipe, and spraying or spraying a zinc-based metal on the remaining dense oxide film layer. A method for manufacturing a cast iron pipe, which includes a step of applying paint.
残存した緻密な酸化皮膜層上に、亜鉛系金属を溶射する、または塗料を塗装する工程
を含む鋳鉄管外面の防食方法。 A step of removing the surface layer having a high void ratio of the oxide film formed on the outer surface of the cast iron pipe by annealing the cast iron pipe after casting by injecting high-pressure water, and on the remaining dense oxide film layer. A method for preventing corrosion of the outer surface of a cast iron pipe, which includes a step of spraying a zinc-based metal or applying a paint.
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| KR102428527B1 (en) * | 2022-05-27 | 2022-08-03 | 주식회사 태성스틸 | Apparatus and method for improving low-temperature toughness of steel pipe expansion part |
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| KR102341540B1 (en) * | 2021-03-25 | 2021-12-21 | 주식회사 호룡 | Boom of the ladder unit and boom coating method |
| KR102428527B1 (en) * | 2022-05-27 | 2022-08-03 | 주식회사 태성스틸 | Apparatus and method for improving low-temperature toughness of steel pipe expansion part |
| WO2023229241A1 (en) * | 2022-05-27 | 2023-11-30 | 주식회사 태성스틸 | Device and method for improving low-temperature toughness of steel pipe expansion part |
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