JP3354818B2 - External Corrosion Protection Method for Ductile Cast Iron Pipe - Google Patents
External Corrosion Protection Method for Ductile Cast Iron PipeInfo
- Publication number
- JP3354818B2 JP3354818B2 JP34026896A JP34026896A JP3354818B2 JP 3354818 B2 JP3354818 B2 JP 3354818B2 JP 34026896 A JP34026896 A JP 34026896A JP 34026896 A JP34026896 A JP 34026896A JP 3354818 B2 JP3354818 B2 JP 3354818B2
- Authority
- JP
- Japan
- Prior art keywords
- cast iron
- iron pipe
- metal
- ductile cast
- coating
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Fee Related
Links
Classifications
-
- 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
- F16L58/08—Coatings characterised by the materials used by metal
Landscapes
- Engineering & Computer Science (AREA)
- General Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- Protection Of Pipes Against Damage, Friction, And Corrosion (AREA)
- Coating By Spraying Or Casting (AREA)
Description
【０００１】[0001]
【産業上の利用分野】この発明は、ダクタイル鋳鉄管の
外面防食方法に関する。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for protecting an outer surface of a ductile cast iron pipe from corrosion.
【０００２】[0002]
【従来の技術】鋳鉄管は、一般に地中埋設管とされるの
で表面防食塗装が不可欠となる。この表面防食塗装は、
耐薬品性を有することは勿論、埋戻土砂などの衝撃や摩
擦に耐える物理的強度を有している必要がある。2. Description of the Related Art Cast iron pipes are generally buried underground, so that surface corrosion protection coating is indispensable. This anti-corrosion coating
It is necessary to have not only chemical resistance but also physical strength to withstand impact and friction such as backfilled earth and sand.
【０００３】従って、これら要求を満足する防食塗膜を
ポリエチレン樹脂などの合成樹脂材料で得ようとした場
合、塗膜厚さを非常に厚くする必要があり、施工現場で
管を切断する際や穿孔時に厚い塗膜を剥がす必要が生
じ、施工性が極めて悪くなるなど種々の弊害を生ずる。Therefore, in order to obtain an anticorrosion coating film that satisfies these requirements by using a synthetic resin material such as polyethylene resin, it is necessary to make the coating film thickness very large. At the time of perforation, it is necessary to peel off the thick coating film, which causes various adverse effects such as extremely poor workability.
【０００４】このような問題を解消する防食皮膜とし
て、鋳鉄管外周に溶融金属を射出して溶着させる金属溶
射皮膜が知られている。そして、金属溶射皮膜の金属材
料として鋳鉄管よりも硬い金属を用いた場合、鋳鉄管外
周の物理的保護が薄い皮膜で達成されるので好都合であ
る。[0004] As a corrosion-resistant coating which solves such a problem, a metal spray coating which injects and welds a molten metal to the outer periphery of a cast iron pipe is known. When a metal that is harder than the cast iron pipe is used as the metal material of the metal sprayed coating, it is advantageous because physical protection of the outer periphery of the cast iron pipe can be achieved with a thin coating.
【０００５】即ち金属溶射皮膜の場合、塗膜厚さを0.1m
程度とするだけで上記合成樹脂皮膜とほぼ同様な強度が
得られ、しかも塗膜が薄いことから切断や穿孔にも支障
をきたさない利点を有する。That is, in the case of a metal spray coating, the coating thickness is 0.1 m.
The strength is almost the same as that of the above-mentioned synthetic resin film only by the degree, and the thin film is advantageous in that cutting and perforation are not hindered.
【０００６】[0006]
【発明が解決しようとする課題】しかしながら、上記の
金属溶射皮膜はピンホールができ易いといった欠点があ
り、しかも、鋳鉄よりもイオン化傾向低い金属で溶射皮
膜を形成した場合、ピンホール部分に露出する鋳鉄が積
極的に腐食され、鋳鉄管の保守上好ましくない状態とな
る。However, the above-mentioned metal spray coating has a drawback that pinholes are easily formed, and when the spray coating is formed of a metal having a lower ionization tendency than cast iron, the metal spray coating is exposed to the pinhole portion. The cast iron is actively corroded, which is unfavorable for maintenance of the cast iron pipe.
【０００７】そこで、この発明は、金属溶射皮膜の利点
と合成樹脂塗料の利点とを組合わせることにより、強
度、耐蝕性に優れた皮膜を得ることを目的としてなされ
たものである。Therefore, the present invention has been made to obtain a coating excellent in strength and corrosion resistance by combining the advantages of a metal spray coating and the advantages of a synthetic resin coating.
【０００８】[0008]
【課題を解決するための手段】すなわち、この発明のダ
クタイル鋳鉄管の外面防食方法は、ダクタイル鋳鉄管の
外面にダクタイル鋳鉄よりも硬いアルミ系合金の金属に
より溶射金属皮膜を形成し、該溶射金属皮膜上に封孔性
に優れた塗料で外面塗装することを特徴とするものであ
る。That is, according to the method for protecting the outer surface of a ductile cast iron pipe of the present invention, a sprayed metal film is formed on the outer surface of the ductile cast iron pipe by using a metal of an aluminum alloy harder than the ductile cast iron. It is characterized in that the outer surface of the film is coated with a paint having excellent sealing properties.
【０００９】[0009]
【作用】この発明において、ダクタイル鋳鉄管よりも硬
い金属により溶射金属皮膜を形成するのは、薄い膜厚で
十分な物理的強度を付与するためである。In the present invention, the reason why the sprayed metal film is formed of a metal harder than the ductile cast iron pipe is to provide a sufficient physical strength with a thin film thickness.
【００１０】従って、鋳鉄管はこの金属皮膜によって耐
衝撃強度が付与され外面が補強される。この、ダクタイ
ル鋳鉄管よりも硬い金属としては主としてアルミ系合金
が使用される。Therefore, the cast iron pipe is given an impact resistance by the metal film and the outer surface is reinforced. As a metal harder than the ductile cast iron pipe, an aluminum alloy is mainly used.
【００１１】この金属皮膜は、既述のようにピンホール
ができ易く、これを皆無にするのは困難である。そこ
で、この金属皮膜の上から封孔性に優れた塗料で外面塗
装をする。As described above, pinholes are easily formed in the metal film, and it is difficult to completely eliminate the pinholes. Therefore, the outer surface is coated on the metal film with a paint having excellent sealing properties.
【００１２】従って、金属皮膜に形成されたピンホール
はこの外面塗装皮膜で封印され、かつこのピンホールは
極めて微小面積であるので、十分に封孔され耐蝕性が確
保される。Therefore, the pinhole formed in the metal film is sealed with this outer coating film, and since this pinhole has an extremely small area, the pinhole is sufficiently sealed to ensure corrosion resistance.
【００１３】なお、上記封孔性に優れた塗料としてはシ
リコン系塗料、エポキシ系塗料、アクリル系塗料などが
好適に使用される。[0013] Silicone paints, epoxy paints, acrylic paints and the like are preferably used as the paints having excellent sealing properties.
【００１４】[0014]
【実施例】次にこの発明の実施例を説明する。 ［実施例］溶射金属皮膜の金属材料として、AL- 15％Fe
合金とAl- 4Si-15Mn合金を用い、それぞれダクタイル鋳
鉄管外周に0.1mの層厚の溶射皮膜を形成した。Next, an embodiment of the present invention will be described. [Example] AL-15% Fe as the metal material of the sprayed metal film
A sprayed coating having a thickness of 0.1 m was formed on the outer periphery of each ductile cast iron pipe using the alloy and the Al-4Si-15Mn alloy.
【００１５】次に、この溶射金属皮膜の外面に市販のシ
リコン系塗料、エポキシ系塗料、アクリル系塗料をスプ
レーにより塗装し、乾燥させた。次いで、図１に示すよ
うに、これらの塗装ダクタイル鋳鉄管１を電解槽２に浸
し、鋳鉄管１と水中電極３との間に電圧を印加して電食
を起こさせ、ピンホールの有無を判別した。なお、図中
１Ａ、１Ａは鋳鉄管１内部を水密に封じる栓、１Ｂは鋳
鉄管１に設けた端子、３Ａは定電圧電源装置を示す。Next, a commercially available silicon-based paint, epoxy-based paint, and acrylic-based paint were applied to the outer surface of the sprayed metal film by spraying and dried. Next, as shown in FIG. 1, these painted ductile cast iron tubes 1 are immersed in an electrolytic cell 2, a voltage is applied between the cast iron tubes 1 and the underwater electrodes 3 to cause electrolytic corrosion, and the presence or absence of pinholes is determined. Determined. In the drawings, 1A and 1A are plugs for sealing the inside of the cast iron tube 1 in a watertight manner, 1B is a terminal provided on the cast iron tube 1, and 3A is a constant voltage power supply device.
【００１６】実施例のものは流出電流による塗膜剥離や
発錆などは見られず、溶射金属皮膜のピンホールは完全
に封孔されていることが判明した。次に、上記塗装ダク
タイル鋳鉄管１外面をナイフの刃で切り込み傷を付け、
傷痕を観察したところ、金属溶射皮膜には人力程度の切
り込み力では殆ど傷が付かなかった。 ［比較例］次に、比較例として、外面を塗装しない溶射
金属皮膜のままのダクタイル鋳鉄管を上述と同様に電解
槽２に浸し、水中電極３との間に電圧を印加して電食を
起こさせピンホールの有無を判別した。No peeling or rusting of the coating film due to the outflow current was observed in the example, and it was found that the pinhole of the sprayed metal film was completely sealed. Next, a cut was made on the outer surface of the painted ductile cast iron pipe 1 with a knife blade,
When the scar was observed, the metal sprayed coating was scarcely scratched with a cutting force of about human power. [Comparative Example] Next, as a comparative example, a ductile cast iron pipe having a sprayed metal coating without coating the outer surface was immersed in the electrolytic cell 2 in the same manner as described above, and a voltage was applied between the pipe and the underwater electrode 3 to perform electrolytic corrosion. The presence or absence of a pinhole was determined.
【００１７】この結果、鋳鉄管表面に直径0.5 〜1.0mm
程度の腐食痕が所々に散見され、封孔による腐食が発生
していることが確認された。また、実施例と比較例につ
いて管を切断し、金属溶射皮膜を拡大観察したところ、
実施例のものは図２に示すように、厚さ0.1mm の金属溶
射皮膜４のピンホール４Ａにスプレー塗装した塗料５が
浸透しており、ピンホール４Ａが完全に封じられている
のが観察された。As a result, a diameter of 0.5 to 1.0 mm
Some corrosion marks were found in some places, and it was confirmed that corrosion due to sealing had occurred. In addition, the tube was cut for the example and the comparative example, and the metal spray coating was observed under magnification.
In the case of the embodiment, as shown in FIG. 2, it was observed that the sprayed paint 5 penetrated into the pinhole 4A of the metal sprayed coating 4 having a thickness of 0.1 mm, and the pinhole 4A was completely sealed. Was done.
【００１８】[0018]
【発明の効果】以上説明したように、この発明は、鋳鉄
管表面に防食皮膜を形成する場合、下地として鋳鉄より
硬い金属による金属溶射皮膜を形成するので、鋳鉄管外
周は薄い皮膜であっても外面に傷が付き難く、耐擦過強
度、耐衝撃強度を付与することができる。As described above, according to the present invention, when an anticorrosion film is formed on the surface of a cast iron tube, a metal sprayed film of a metal harder than cast iron is formed as a base, so that the outer periphery of the cast iron tube is a thin film. Also, the outer surface is hardly scratched, and can provide abrasion resistance and impact resistance.
【００１９】そして、金属溶射皮膜にでき易いピンホー
ルは、その外面に塗布された封孔性に優れる塗料により
封孔されるので、ピンホールに起因する電食などの弊害
も有効に防止される。Since the pinholes which are easily formed on the metal spray coating are sealed by the coating material having excellent sealing properties applied to the outer surface thereof, adverse effects such as electrolytic corrosion caused by the pinholes can be effectively prevented. .
【００２０】さらに、金属溶射皮膜上に塗布される塗料
はピンホールを封孔することを主目的とするから、この
塗膜も厚くする必要はなく、この結果、管切断の際の加
工性も良い。Furthermore, since the paint applied on the metal spray coating is mainly intended to seal the pinholes, it is not necessary to increase the thickness of the coating. good.
【００２１】かつ、封孔部分は非常に小面積であり、封
孔部分の有機塗料が集中応力を受けて破壊されることも
殆どあり得ないため、金属溶射皮膜の欠点であるピンホ
ールを有効に補いつつ、利点である強度性が十分に発揮
され、長期にわたり信頼性に富む防食皮膜とすることが
できる効果を有する。In addition, since the sealing portion has a very small area, and the organic paint in the sealing portion is hardly broken due to the concentrated stress, the pinhole which is a defect of the metal spray coating is effectively used. In addition, the strength, which is an advantage, is sufficiently exhibited, and a highly reliable anticorrosive film can be formed over a long period of time.
【図１】この発明の方法で得たダクタイル鋳鉄管の試験
装置の説明図である。FIG. 1 is an explanatory view of a test device for a ductile cast iron pipe obtained by the method of the present invention.
【図２】この発明の方法で得たダクタイル鋳鉄管の防食
皮膜の拡大断面図である。FIG. 2 is an enlarged sectional view of an anticorrosion film of a ductile cast iron pipe obtained by the method of the present invention.
１…塗装ダクタイル鋳鉄管 ２…電解槽 ３…水中電極 ４…金属溶射皮膜 ４Ａ…ピンホール ５…塗料 DESCRIPTION OF SYMBOLS 1 ... Painted ductile cast iron pipe 2 ... Electrolysis tank 3 ... Underwater electrode 4 ... Metal spray coating 4A ... Pinhole 5 ... Paint
───────────────────────────────────────────────────── フロントページの続き (56)参考文献 特開 平７−18324（ＪＰ，Ａ) 特開 平５−222511（ＪＰ，Ａ) 実開 昭54−182413（ＪＰ，Ｕ) 特公 平８−4895（ＪＰ，Ｂ２) 特表 平８−505929（ＪＰ，Ａ) (58)調査した分野(Int.Cl.7，ＤＢ名) F16L 58/08 C23C 4/08 ──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-7-18324 (JP, A) JP-A-5-222511 (JP, A) JP-A 54-182413 (JP, U) 4895 (JP, B2) Table 8-505929 (JP, A) (58) Field surveyed (Int. Cl. 7 , DB name) F16L 58/08 C23C 4/08
Claims (1)
鉄よりも硬いアルミ系合金の金属により溶射金属皮膜を
形成し、該溶射金属皮膜上に封孔性に優れた塗料で外面
塗装することを特徴とするダクタイル鋳鉄管の外面防食
方法。The present invention is characterized in that a sprayed metal film is formed on the outer surface of a ductile cast iron pipe by using a metal of an aluminum alloy harder than ductile cast iron, and the outer surface is coated on the sprayed metal film with a paint having excellent sealing properties. Corrosion protection method for ductile cast iron pipes.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP34026896A JP3354818B2 (en) | 1996-12-20 | 1996-12-20 | External Corrosion Protection Method for Ductile Cast Iron Pipe |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP34026896A JP3354818B2 (en) | 1996-12-20 | 1996-12-20 | External Corrosion Protection Method for Ductile Cast Iron Pipe |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH10185079A JPH10185079A (en) | 1998-07-14 |
| JP3354818B2 true JP3354818B2 (en) | 2002-12-09 |
Family
ID=18335321
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP34026896A Expired - Fee Related JP3354818B2 (en) | 1996-12-20 | 1996-12-20 | External Corrosion Protection Method for Ductile Cast Iron Pipe |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP3354818B2 (en) |
Families Citing this family (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| FR2895485B1 (en) * | 2005-12-23 | 2012-04-13 | Vallourec Mannesmann Oil & Gas | EXTERNAL PROTECTION OF TUBULAR THREADED JOINTS FOR EXPANDING |
| JP2010222664A (en) * | 2009-03-25 | 2010-10-07 | Kubota Corp | Surface treatment method of cast iron pipe |
| JP5653084B2 (en) * | 2010-06-25 | 2015-01-14 | 株式会社クボタ | Iron-based member subjected to surface treatment and surface treatment method of iron-based member |
Family Cites Families (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS54182413U (en) * | 1978-06-14 | 1979-12-24 | ||
| JPH084895B2 (en) * | 1991-05-08 | 1996-01-24 | 株式会社栗本鐵工所 | Method for manufacturing corrosion-resistant centrifugal cast iron pipe |
| JPH05222511A (en) * | 1992-02-17 | 1993-08-31 | Kubota Corp | Manufacture of outer surface thermal-sprayed tube |
| FR2701754B1 (en) * | 1993-02-18 | 1995-04-07 | Pont A Mousson | Pipe element for buried pipe, corresponding buried pipe, and method for protecting such a pipe element. |
| JPH0718324A (en) * | 1993-07-05 | 1995-01-20 | Kubota Corp | Corrosion resistant tough cast iron pipe and its production |
-
1996
- 1996-12-20 JP JP34026896A patent/JP3354818B2/en not_active Expired - Fee Related
Also Published As
| Publication number | Publication date |
|---|---|
| JPH10185079A (en) | 1998-07-14 |
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