JP2022168683A - Resin-coated steel pipe and method for manufacturing the same - Google Patents
Resin-coated steel pipe and method for manufacturing the same Download PDFInfo
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- 229910000831 Steel Inorganic materials 0.000 title claims abstract description 90
- 239000010959 steel Substances 0.000 title claims abstract description 90
- 229920005989 resin Polymers 0.000 title claims abstract description 65
- 239000011347 resin Substances 0.000 title claims abstract description 65
- 238000004519 manufacturing process Methods 0.000 title claims description 24
- 238000000034 method Methods 0.000 title claims description 15
- HCHKCACWOHOZIP-UHFFFAOYSA-N Zinc Chemical compound [Zn] HCHKCACWOHOZIP-UHFFFAOYSA-N 0.000 claims abstract description 65
- -1 alkyl silicate Chemical compound 0.000 claims abstract description 52
- 238000006068 polycondensation reaction Methods 0.000 claims abstract description 23
- 239000002245 particle Substances 0.000 claims abstract description 22
- 239000007795 chemical reaction product Substances 0.000 claims abstract description 19
- 238000000576 coating method Methods 0.000 claims description 243
- 239000011248 coating agent Substances 0.000 claims description 242
- 239000010410 layer Substances 0.000 claims description 56
- 239000003973 paint Substances 0.000 claims description 42
- 239000004698 Polyethylene Substances 0.000 claims description 27
- 229920000573 polyethylene Polymers 0.000 claims description 27
- 230000003746 surface roughness Effects 0.000 claims description 17
- 239000000843 powder Substances 0.000 claims description 12
- 239000011247 coating layer Substances 0.000 claims description 11
- 239000007787 solid Substances 0.000 claims description 9
- 150000002894 organic compounds Chemical class 0.000 claims description 7
- 239000000463 material Substances 0.000 claims description 2
- 239000003595 mist Substances 0.000 abstract description 31
- 239000011701 zinc Substances 0.000 abstract description 26
- 229910052725 zinc Inorganic materials 0.000 abstract description 26
- 239000003205 fragrance Substances 0.000 abstract description 20
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 abstract description 9
- 239000007789 gas Substances 0.000 description 40
- 238000003466 welding Methods 0.000 description 36
- 230000000694 effects Effects 0.000 description 18
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 11
- 230000007257 malfunction Effects 0.000 description 9
- 239000008119 colloidal silica Substances 0.000 description 7
- 239000000047 product Substances 0.000 description 7
- 238000005260 corrosion Methods 0.000 description 6
- 239000010419 fine particle Substances 0.000 description 6
- JEIPFZHSYJVQDO-UHFFFAOYSA-N iron(III) oxide Inorganic materials O=[Fe]O[Fe]=O JEIPFZHSYJVQDO-UHFFFAOYSA-N 0.000 description 6
- 239000000049 pigment Substances 0.000 description 5
- 238000001179 sorption measurement Methods 0.000 description 5
- 239000003822 epoxy resin Substances 0.000 description 4
- 229920000647 polyepoxide Polymers 0.000 description 4
- BOTDANWDWHJENH-UHFFFAOYSA-N Tetraethyl orthosilicate Chemical compound CCO[Si](OCC)(OCC)OCC BOTDANWDWHJENH-UHFFFAOYSA-N 0.000 description 3
- 239000011230 binding agent Substances 0.000 description 3
- 238000005422 blasting Methods 0.000 description 3
- 238000004140 cleaning Methods 0.000 description 3
- 238000010276 construction Methods 0.000 description 3
- 230000007797 corrosion Effects 0.000 description 3
- 238000001035 drying Methods 0.000 description 3
- 239000003517 fume Substances 0.000 description 3
- 230000035943 smell Effects 0.000 description 3
- 238000005979 thermal decomposition reaction Methods 0.000 description 3
- VTYYLEPIZMXCLO-UHFFFAOYSA-L Calcium carbonate Chemical compound [Ca+2].[O-]C([O-])=O VTYYLEPIZMXCLO-UHFFFAOYSA-L 0.000 description 2
- 239000004593 Epoxy Substances 0.000 description 2
- NBIIXXVUZAFLBC-UHFFFAOYSA-N Phosphoric acid Chemical compound OP(O)(O)=O NBIIXXVUZAFLBC-UHFFFAOYSA-N 0.000 description 2
- NINIDFKCEFEMDL-UHFFFAOYSA-N Sulfur Chemical compound [S] NINIDFKCEFEMDL-UHFFFAOYSA-N 0.000 description 2
- 239000000853 adhesive Substances 0.000 description 2
- 230000001070 adhesive effect Effects 0.000 description 2
- 125000000217 alkyl group Chemical group 0.000 description 2
- 239000000956 alloy Substances 0.000 description 2
- 229910045601 alloy Inorganic materials 0.000 description 2
- 239000010426 asphalt Substances 0.000 description 2
- ZCDOYSPFYFSLEW-UHFFFAOYSA-N chromate(2-) Chemical compound [O-][Cr]([O-])(=O)=O ZCDOYSPFYFSLEW-UHFFFAOYSA-N 0.000 description 2
- 230000000052 comparative effect Effects 0.000 description 2
- 150000001875 compounds Chemical class 0.000 description 2
- 230000007547 defect Effects 0.000 description 2
- 238000009826 distribution Methods 0.000 description 2
- 125000001495 ethyl group Chemical group [H]C([H])([H])C([H])([H])* 0.000 description 2
- 229910052751 metal Inorganic materials 0.000 description 2
- 239000002184 metal Substances 0.000 description 2
- 239000011241 protective layer Substances 0.000 description 2
- 239000000741 silica gel Substances 0.000 description 2
- 229910002027 silica gel Inorganic materials 0.000 description 2
- 239000002356 single layer Substances 0.000 description 2
- 239000002893 slag Substances 0.000 description 2
- 239000007921 spray Substances 0.000 description 2
- 238000005507 spraying Methods 0.000 description 2
- 239000000758 substrate Substances 0.000 description 2
- 239000011593 sulfur Substances 0.000 description 2
- 229910052717 sulfur Inorganic materials 0.000 description 2
- 230000001629 suppression Effects 0.000 description 2
- LFQCEHFDDXELDD-UHFFFAOYSA-N tetramethyl orthosilicate Chemical compound CO[Si](OC)(OC)OC LFQCEHFDDXELDD-UHFFFAOYSA-N 0.000 description 2
- 239000004606 Fillers/Extenders Substances 0.000 description 1
- FYYHWMGAXLPEAU-UHFFFAOYSA-N Magnesium Chemical compound [Mg] FYYHWMGAXLPEAU-UHFFFAOYSA-N 0.000 description 1
- 229910019142 PO4 Inorganic materials 0.000 description 1
- ATJFFYVFTNAWJD-UHFFFAOYSA-N Tin Chemical compound [Sn] ATJFFYVFTNAWJD-UHFFFAOYSA-N 0.000 description 1
- GWEVSGVZZGPLCZ-UHFFFAOYSA-N Titan oxide Chemical compound O=[Ti]=O GWEVSGVZZGPLCZ-UHFFFAOYSA-N 0.000 description 1
- BZHJMEDXRYGGRV-UHFFFAOYSA-N Vinyl chloride Chemical compound ClC=C BZHJMEDXRYGGRV-UHFFFAOYSA-N 0.000 description 1
- 238000010306 acid treatment Methods 0.000 description 1
- 239000000654 additive Substances 0.000 description 1
- 230000000996 additive effect Effects 0.000 description 1
- 229910052782 aluminium Inorganic materials 0.000 description 1
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 1
- PNEYBMLMFCGWSK-UHFFFAOYSA-N aluminium oxide Inorganic materials [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 description 1
- 229910000147 aluminium phosphate Inorganic materials 0.000 description 1
- 238000004458 analytical method Methods 0.000 description 1
- 229910000019 calcium carbonate Inorganic materials 0.000 description 1
- 238000006243 chemical reaction Methods 0.000 description 1
- 230000003750 conditioning effect Effects 0.000 description 1
- 238000012790 confirmation Methods 0.000 description 1
- 238000011109 contamination Methods 0.000 description 1
- 238000005336 cracking Methods 0.000 description 1
- 238000009499 grossing Methods 0.000 description 1
- 239000010954 inorganic particle Substances 0.000 description 1
- 238000005304 joining Methods 0.000 description 1
- 238000007561 laser diffraction method Methods 0.000 description 1
- 229910052749 magnesium Inorganic materials 0.000 description 1
- 239000011777 magnesium Substances 0.000 description 1
- ZLNQQNXFFQJAID-UHFFFAOYSA-L magnesium carbonate Chemical compound [Mg+2].[O-]C([O-])=O ZLNQQNXFFQJAID-UHFFFAOYSA-L 0.000 description 1
- 239000001095 magnesium carbonate Substances 0.000 description 1
- 229910000021 magnesium carbonate Inorganic materials 0.000 description 1
- 125000002496 methyl group Chemical group [H]C([H])([H])* 0.000 description 1
- 239000000203 mixture Substances 0.000 description 1
- 230000009965 odorless effect Effects 0.000 description 1
- 239000011146 organic particle Substances 0.000 description 1
- 238000010422 painting Methods 0.000 description 1
- NBIIXXVUZAFLBC-UHFFFAOYSA-K phosphate Chemical compound [O-]P([O-])([O-])=O NBIIXXVUZAFLBC-UHFFFAOYSA-K 0.000 description 1
- 239000010452 phosphate Substances 0.000 description 1
- 238000005554 pickling Methods 0.000 description 1
- 229920000642 polymer Polymers 0.000 description 1
- 230000002265 prevention Effects 0.000 description 1
- 125000001436 propyl group Chemical group [H]C([*])([H])C([H])([H])C([H])([H])[H] 0.000 description 1
- 238000000790 scattering method Methods 0.000 description 1
- 238000003860 storage Methods 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- 239000000454 talc Substances 0.000 description 1
- 229910052623 talc Inorganic materials 0.000 description 1
- OQTSOKXAWXRIAC-UHFFFAOYSA-N tetrabutan-2-yl silicate Chemical compound CCC(C)O[Si](OC(C)CC)(OC(C)CC)OC(C)CC OQTSOKXAWXRIAC-UHFFFAOYSA-N 0.000 description 1
- UQMOLLPKNHFRAC-UHFFFAOYSA-N tetrabutyl silicate Chemical compound CCCCO[Si](OCCCC)(OCCCC)OCCCC UQMOLLPKNHFRAC-UHFFFAOYSA-N 0.000 description 1
- ZQZCOBSUOFHDEE-UHFFFAOYSA-N tetrapropyl silicate Chemical compound CCCO[Si](OCCC)(OCCC)OCCC ZQZCOBSUOFHDEE-UHFFFAOYSA-N 0.000 description 1
- 229910052718 tin Inorganic materials 0.000 description 1
- OGIDPMRJRNCKJF-UHFFFAOYSA-N titanium oxide Inorganic materials [Ti]=O OGIDPMRJRNCKJF-UHFFFAOYSA-N 0.000 description 1
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Abstract
Description
本発明は、主にガス管として用いられる樹脂塗覆装鋼管とその製造方法に関するものである。 TECHNICAL FIELD The present invention relates to a resin-coated steel pipe mainly used as a gas pipe and a method for manufacturing the same.
鋼管の外面に酸洗やブラスト処理などの素地調整を行った後、粘着剤または接着剤を介してポリエチレン被覆層を押出被覆により形成したポリエチレン被覆鋼管は、都市ガスなどのガス導管用鋼管として広く使用されている。
このポリエチレン被覆鋼管は、内面が無塗装の場合と、エポキシ樹脂塗料や無機ジンクリッチ系塗料などによる内面塗装が施される場合がある。
Polyethylene-coated steel pipes are widely used as steel pipes for gas pipelines such as city gas. in use.
The polyethylene-coated steel pipe may be uncoated on the inner surface or coated on the inner surface with an epoxy resin paint, an inorganic zinc-rich paint, or the like.
内面塗装が施されたポリエチレン被覆鋼管をガス導管に適用する場合、溶接施工時の熱により内面塗膜の熱分解生成物（以下「ミスト」という。）が発生し、このミストが配管系の電磁弁やフィルターに付着し、電磁弁作動不良やフィルター詰りなどの不具合を生じさせるという問題がある。
このような問題に対して、特許文献１には、アルキルシリケートをバインダー成分とする無機ジンクリッチ系塗料でポリエチレン被覆鋼管の内面塗装をする技術が示されており、このような内面塗装を施したポリエチレン被覆鋼管は、ガス導管の溶接施工時の熱によるミストの発生が抑えられため、近年急速に採用が拡大している。
When a polyethylene-coated steel pipe with an inner surface coating is applied to a gas pipe, thermal decomposition products (hereinafter referred to as “mist”) of the inner coating film are generated by the heat during welding, and this mist is an electromagnetic wave in the piping system. There is a problem that it adheres to valves and filters, causing problems such as malfunction of solenoid valves and clogging of filters.
In response to such problems, Patent Document 1 discloses a technique of coating the inner surface of a polyethylene-coated steel pipe with an inorganic zinc-rich paint containing an alkylsilicate as a binder component. The use of polyethylene-coated steel pipes has been rapidly expanding in recent years because it suppresses the generation of mist due to the heat generated during welding of gas pipes.
アルキルシリケートをバインダー成分とする無機ジンクリッチ系塗料で内面塗装したポリエチレン被覆鋼管は、上述したように溶接施工時の熱によるミストの発生を抑えることができるが、本発明者らが検討したところによれば、以下のような課題があることが判った。すなわち、無機ジンクリッチ系塗装で内面塗装したガス導管は、塗膜に含まれる亜鉛粒（亜鉛末）に起因する表面凹凸によって塗膜の平滑性が低下し、また塗膜表面に亜鉛粒が露出した状態となり、これらによって幾つかの問題を生じることが判った。 A polyethylene-coated steel pipe whose inner surface is coated with an inorganic zinc-rich paint containing an alkylsilicate as a binder component can suppress the generation of mist due to heat during welding, as described above. According to the results, it was found that there are the following problems. In other words, gas pipes that are internally coated with an inorganic zinc-rich coating have surface irregularities caused by zinc particles (zinc dust) contained in the coating film, which reduces the smoothness of the coating film, and zinc particles are exposed on the coating film surface. It has been found that these create several problems.
まず、管内に流すガスに含まれている付臭剤が塗膜に吸着され、ガスの臭いが初期に低下するという問題がある。この原因としては、（i）塗膜に含まれる亜鉛粒（亜鉛末）に起因する表面凹凸により塗膜の表面積が大きくなり、付臭剤が塗膜面に吸着されやすいこと、（ii）塗膜面に存在（露出）する亜鉛粒が付臭剤の硫黄分と親和性が高く、付臭剤の吸着サイトとなること、などが挙げられる。このガスの臭いが低下する問題は、ガスを定常的に流せば解消するが、ガス導管施工後にガスを流して行う臭気確認作業時になかなか臭いがしないという事象が発生し、ガスを多量に流す必要があるため臭気確認作業の能率が低下し、また、施工者に不安を与えるなどの問題もある。
また、ガス導管の溶接施工によりスパッタや鉄粉などの汚れが発生するため、溶接施工後にピグなどを用いた清掃が行われるが、内面塗膜の平滑性が低く、加えて塗膜面に亜鉛粒が存在（露出）していると、その汚れが塗膜面に付着しやすいため、清掃性が劣るという問題がある。
First, there is the problem that the odorant contained in the gas flowing through the pipe is adsorbed on the coating film, and the odor of the gas is initially reduced. The reasons for this are (i) that the surface area of the coating film increases due to the surface unevenness caused by the zinc particles (zinc dust) contained in the coating film, and (ii) the odorant is easily adsorbed on the coating film surface. Zinc grains present (exposed) on the film surface have a high affinity for the sulfur content of the odorant and serve as adsorption sites for the odorant. This problem of gas odor reduction can be solved by constantly flowing the gas, but when the odor is confirmed by flowing the gas after the construction of the gas pipe, it is difficult to smell it, and it is necessary to flow a large amount of gas. Therefore, there is a problem that the efficiency of the odor confirmation work is lowered and the installer is worried.
In addition, welding of gas pipes generates contamination such as spatter and iron powder, so cleaning is performed using a pig after welding. If the particles are present (exposed), dirt tends to adhere to the surface of the coating film, resulting in poor cleanability.
したがって本発明の目的は、以上のような従来技術の課題を解決し、溶接施工時の熱によるミストの発生が抑えられるとともに、（i）ガス管に適用した場合に、管内に流すガスに含まれている付臭剤が塗膜に吸着されにくい、（ii）溶接施工により生じたスパッタや鉄粉などの汚れが付着しにくく、溶接施工後の清掃が容易である、などの効果が得られる樹脂塗覆装鋼管およびその製造方法を提供することにある。 Accordingly, an object of the present invention is to solve the problems of the prior art as described above, suppress the generation of mist due to heat during welding, and (i) when applied to a gas pipe, to prevent the mist contained in the gas flowing through the pipe. (ii) stains such as spatter and iron powder generated by welding are less likely to adhere to the paint film, making it easier to clean after welding. An object of the present invention is to provide a resin-coated steel pipe and a method for manufacturing the same.
本発明者らは、上記の課題を解決すべく鋭意検討を行った結果、管内面の塗膜について、アルキルシリケート重縮合反応物と亜鉛末を含有する下層塗膜（アルキルシリケートをバインダー成分とする無機ジンクリッチ系塗料による塗膜）の上に、アルキルシリケート重縮合反応物を主成分とする上層塗膜を形成し、平滑な塗膜面とするとともに、下層塗膜の亜鉛粒が塗膜面に露出しないようにすることより、上記の課題を解決できることを見出した。 As a result of intensive studies to solve the above problems, the inventors of the present invention have found that, for the coating film on the inner surface of the tube, an underlayer coating film containing an alkylsilicate polycondensation reaction product and zinc dust (an alkylsilicate is used as a binder component Inorganic zinc-rich paint) is coated with an upper layer coating mainly composed of an alkyl silicate polycondensation reaction product to form a smooth coating surface, and the zinc grains of the lower layer coating form a coating surface. It has been found that the above problem can be solved by avoiding exposure to .
本発明は、このような知見に基づきなされたもので、以下を要旨とするものである。
［1］管外面に樹脂被覆層または塗膜を有し、管内面に塗膜を有する樹脂塗覆装鋼管であって、
管内面の塗膜は、アルキルシリケート重縮合反応物を５質量％以上、亜鉛末を３０質量％以上含有する下層塗膜（A1）と、アルキルシリケート重縮合反応物を５０質量％以上含有し、且つ亜鉛末を含有しないか、若しくは亜鉛末を下層塗膜（A1）よりも少ない含有量で含有する上層塗膜（A2）を有することを特徴とする樹脂塗覆装鋼管。
［2］上記［1］の樹脂塗覆装鋼管において、管内面の塗膜の表面粗さＲｚが１８μｍ以下であることを特徴とする樹脂塗覆装鋼管。
The present invention was made based on such findings, and has the following gist.
[1] A resin-coated steel pipe having a resin coating layer or coating on the outer surface of the pipe and a coating on the inner surface of the pipe,
The coating film on the inner surface of the tube comprises an underlayer coating film (A1) containing 5% by mass or more of an alkylsilicate polycondensation reaction product and 30% by mass or more of zinc dust, and 50% by mass or more of an alkylsilicate polycondensation reaction product, and a resin-coated steel pipe characterized by having an upper coating film (A2) containing no zinc dust or containing zinc dust in a smaller content than the lower coating film (A1).
[2] The resin-coated steel pipe of [1] above, wherein the coating film on the inner surface of the pipe has a surface roughness Rz of 18 μm or less.
［3］上記［1］または［2］の樹脂塗覆装鋼管において、上層塗膜（A2）が、平均粒径が５μｍ以上の粉体を含有しないことを特徴とする樹脂塗覆装鋼管。
［4］上記［1］～［3］のいずれかの樹脂塗覆装鋼管において、下層塗膜（A1）と上層塗膜（A2）が、有機化合物を含有しない無機系塗膜であることを特徴とする樹脂塗覆装鋼管。
［5］上記［1］～［4］のいずれかの樹脂塗覆装鋼管において、下層塗膜（A1）の膜厚と上層塗膜（A2）の膜厚が、各々５～８０μｍであることを特徴とする樹脂塗覆装鋼管。
［6］上記［1］～［5］のいずれかの樹脂塗覆装鋼管において、管外面にポリエチレン被覆層を有することを特徴とする樹脂塗覆装鋼管。
[3] A resin-coated steel pipe according to [1] or [2] above, wherein the upper coating film (A2) does not contain powder having an average particle size of 5 μm or more.
[4] In the resin-coated steel pipe according to any one of [1] to [3] above, the lower coating film (A1) and the upper coating film (A2) are inorganic coatings that do not contain organic compounds. Characteristic resin-coated steel pipe.
[5] In the resin-coated steel pipe according to any one of [1] to [4] above, the film thickness of the lower coating film (A1) and the film thickness of the upper coating film (A2) are each 5 to 80 μm. A resin-coated steel pipe characterized by:
[6] A resin-coated steel pipe according to any one of [1] to [5] above, characterized by having a polyethylene coating layer on the outer surface of the pipe.
［7］管外面に樹脂被覆層または塗膜を有し、管内面に塗膜を有する樹脂塗覆装鋼管の製造方法であって、
管内面を塗装するに際し、管内面に、塗料固形分中の割合でアルキルシリケートおよび／またはアルキルシリケートオリゴマーを５質量％以上、亜鉛末を３０質量％以上含有する下層塗膜用の塗料（a1）を塗装し、次いで、塗料固形分中の割合でアルキルシリケートおよび／またはアルキルシリケートオリゴマーを５０質量％以上含有し、且つ亜鉛末を含有しないか、若しくは亜鉛末を下層塗膜用の塗料（a1）よりも少ない含有量で含有する上層塗膜用の塗料（a2）を塗装することにより、管内面に下層塗膜（A1）と上層塗膜（A2）を有する塗膜を形成することを特徴とする樹脂塗覆装鋼管の製造方法。
[7] A method for manufacturing a resin-coated steel pipe having a resin coating layer or coating on the outer surface of the pipe and a coating on the inner surface of the pipe, comprising:
A paint (a1) for a lower coating film containing, when coating the inner surface of a pipe, 5% by mass or more of an alkylsilicate and/or an alkylsilicate oligomer and 30% by mass or more of zinc dust in terms of the solid content of the paint. and then containing 50% by mass or more of alkyl silicate and/or alkyl silicate oligomer in the solid content of the paint and containing no zinc dust or zinc dust for the lower layer coating (a1) By applying a paint (a2) for the upper layer coating that contains a lower content than A method for manufacturing a resin-coated steel pipe.
［8］上記［7］の製造方法において、管内面に下層塗膜（A1）と上層塗膜（A2）を有する表面粗さＲｚが１８μｍ以下の塗膜を形成することを特徴とする樹脂塗覆装鋼管の製造方法。
［9］上記［7］または［8］の製造方法において、上層塗膜用の塗料（a2）が、平均粒径が５μｍ以上の粉体を含有しないことを特徴とする樹脂塗覆装鋼管の製造方法。
［10］上記［7］～［9］のいずれかの製造方法において、下層塗膜用の塗料（a1）と上層塗膜用の塗料（a2）が、塗膜となる塗料固形分として有機化合物を含有しない無機系塗料であることを特徴とする樹脂塗覆装鋼管の製造方法。
［11］上記［7］～［10］のいずれかの製造方法において、下層塗膜（A1）の乾燥膜厚と上層塗膜（A2）の乾燥膜厚を、各々５～８０μｍとすることを特徴とする樹脂塗覆装鋼管の製造方法。
［12］上記［7］～［11］のいずれかの製造方法において、管外面にポリエチレン被覆層を形成することを特徴とする樹脂塗覆装鋼管の製造方法。
[8] In the production method of [7] above, a resin coating characterized by forming a coating film having a lower coating film (A1) and an upper coating film (A2) on the inner surface of the pipe and having a surface roughness Rz of 18 μm or less. A method for manufacturing a sheathed steel pipe.
[9] In the manufacturing method of [7] or [8] above, the paint (a2) for the upper coating film does not contain powder with an average particle size of 5 μm or more. Production method.
[10] In the production method of any one of [7] to [9] above, the paint for the lower layer coating (a1) and the paint for the upper layer coating (a2) are organic compounds as the coating solid content that will be the coating film A method for producing a resin-coated steel pipe, characterized in that it is an inorganic paint that does not contain
[11] In the production method of any one of [7] to [10] above, the dry film thickness of the lower coating film (A1) and the dry film thickness of the upper coating film (A2) are each 5 to 80 μm. A method for manufacturing a resin-coated steel pipe characterized by:
[12] A method for manufacturing a resin-coated steel pipe according to any one of [7] to [11] above, characterized in that a polyethylene coating layer is formed on the outer surface of the pipe.
本発明の樹脂塗覆装鋼管は、溶接施工時の熱によるミストの発生が抑えられるとともに、（i）管内に流すガスに含まれている付臭剤が塗膜に吸着されにくい、（ii）溶接施工により生じたスパッタや鉄粉などの汚れが付着しにくい、という効果が得られる。このため、樹脂塗覆装鋼管をガス管として用いる場合、溶接施工時の熱により発生するミストが付着することよる電磁弁作動不良やフィルター詰りなどの不具合が改善されるとともに、上記（i）の効果により、ガス工事後のガス導入時に速やかに付臭剤の臭いが確認できるので、施工能率を改善することができ、また、上記（ii）の効果により、溶接施工後の管内面の清掃（ピグなどを用いた清掃）が容易になり、清掃作業性を改善することができる。 In the resin-coated steel pipe of the present invention, the generation of mist due to heat during welding is suppressed, and (i) the odorant contained in the gas flowing in the pipe is less likely to be adsorbed by the coating film, and (ii) It is possible to obtain the effect that stains such as spatter and iron powder generated by welding work are less likely to adhere. For this reason, when resin-coated steel pipes are used as gas pipes, problems such as solenoid valve malfunctions and filter clogging due to adhesion of mist generated by heat during welding work can be improved, and the above (i) As a result, the odor of the odorant can be immediately confirmed when the gas is introduced after the gas work is performed, so the work efficiency can be improved. (Cleaning using a pig or the like) is facilitated, and cleaning workability can be improved.
本発明の樹脂塗覆装鋼管は、管外面に樹脂被覆層または塗膜を有し、管内面に塗膜を有するものであり、種々の用途に使用することができるが、特にガス導管などのガス管に好適な樹脂塗覆装鋼管である。代表的には、管外面に樹脂被覆層を有するものとしてポリエチレン被覆鋼管、硬質塩化ビニル被覆鋼管などが挙げられ、管外面に塗膜を有するものとしてエポキシ塗装鋼管などが挙げられるが、これらに限定されるものではない。
管内面の塗膜（内面塗装）は、アルキルシリケート重縮合反応物を５質量％以上、亜鉛末を３０質量％以上含有する下層塗膜A1（第１層）と、アルキルシリケート重縮合反応物を５０質量％以上含有し、且つ亜鉛末を含有しないか、若しくは亜鉛末を下層塗膜A1よりも少ない含有量で含有する上層塗膜A2（第２層）を有する塗膜で構成される。
The resin-coated steel pipe of the present invention has a resin coating layer or a coating film on the outer surface of the pipe and a coating film on the inner surface of the pipe, and can be used for various purposes, particularly gas pipes and the like. It is a resin-coated steel pipe suitable for gas pipes. Typical examples of pipes having a resin coating layer on the outer surface thereof include polyethylene-coated steel pipes and hard vinyl chloride-coated steel pipes, and examples of pipes having a coating film on the outer surface thereof include epoxy-coated steel pipes, but are limited to these. not to be
The coating film on the inner surface of the tube (inner surface coating) is composed of a lower coating film A1 (first layer) containing 5% by mass or more of an alkyl silicate polycondensation reaction product and 30% by mass or more of zinc dust, and an alkyl silicate polycondensation reaction product. It is composed of a coating film having an upper coating film A2 (second layer) containing 50% by mass or more and not containing zinc dust or containing zinc dust in a smaller content than the lower coating film A1.
管内面の塗膜（下層塗膜A1および上層塗膜A2）に含まれるアルキルシリケート重縮合反応物（シロキサン結合を有する化合物）は、塗料に含まれるアルキルシリケート（オリゴマーである場合を含む。）に由来するものであり、管内面に塗装されたアルキルシリケートは、空気中の水分と反応して加水分解し、さらに重縮合してシロキサン結合を形成し、シロキサン結合を有する強固な高分子化合物、すなわちアルキルシリケート重縮合反応物となる。このアルキルシリケート重縮合反応物を含有する塗膜は、溶接施工時の熱によるミスト（塗膜の熱分解生成物）の発生が抑えられ、このミストによるガス導管の電磁弁の動作不良やフィルターの詰りなどの不具合を防止することができる。 The alkylsilicate polycondensation reaction products (compounds with siloxane bonds) contained in the paint films on the inner surface of the tube (undercoat A1 and upper coat A2) are The alkyl silicate coated on the inner surface of the tube reacts with moisture in the air, hydrolyzes, and further polycondenses to form siloxane bonds, resulting in a strong polymer compound having siloxane bonds, that is, It becomes an alkyl silicate polycondensation reaction product. The coating film containing this alkylsilicate polycondensation reaction product suppresses the generation of mist (thermal decomposition products of the coating film) due to the heat during welding, and the mist causes malfunction of electromagnetic valves in gas pipes and damage to filters. Problems such as clogging can be prevented.
下層塗膜A1中でのアルキルシリケート重縮合反応物の含有量が５質量％未満では、塗膜の造膜性に劣り、必要な塗膜強度を確保できない。亜鉛末の含有量との関係でアルキルシリケート重縮合反応物の含有量の実質的な上限は７０質量％であるが、アルキルシリケート重縮合反応物の含有量は３０～７０質量％の範囲が造膜性、耐食性、溶接時のミスト低減効果が優れるので好ましく、また、特に４０～６０質量％の範囲が造膜性、耐食性、溶接時のミストの低減効果が最も優れ、また亜鉛ヒュームの発生も抑えられるので特に好ましい。 If the content of the alkylsilicate polycondensation reaction product in the lower coating film A1 is less than 5% by mass, the coating film will be poor in film-forming properties and the required coating film strength cannot be ensured. The practical upper limit of the content of the polycondensation product of alkylsilicate is 70% by mass in relation to the content of zinc dust, but the content of the polycondensation product of alkylsilicate is in the range of 30 to 70% by mass. It is preferable because it has excellent film properties, corrosion resistance, and the effect of reducing mist during welding, and in particular, the range of 40 to 60% by mass is the most excellent in film-forming properties, corrosion resistance, and the effect of reducing mist during welding, and zinc fume generation is also suppressed. It is particularly preferable because it can be suppressed.
また、下層塗膜A1に含まれる亜鉛末は、内面塗装後、配管施工までの間の防錆性を確保するのに効果がある。すなわち、亜鉛末の犠牲防食作用により鋼管内面での錆の発生を抑え、仮に発生したとしてもガス導管の動作不良や詰りなどの不具合を発生させるような大きな錆を発生させない効果がある。
亜鉛末としては、金属亜鉛の粉末のほか、亜鉛を主成分とする合金（例えば、アルミニウム、マグネシウム、錫などの１種以上との合金）の粉末でもよい。
下層塗膜A1中での亜鉛末の含有量が３０質量％未満では、塗膜の犠牲防食作用が不足し、保管期間中にさびが発生し易くなる。アルキルシリケート重縮合反応物の含有量との関係で亜鉛末の含有量の実質的な上限は９５質量％であるが、亜鉛末の含有量は３０～７０質量％の範囲が造膜性、耐食性、溶接時のミスト低減効果が優れるので好ましく、また、特に４０～６０質量％の範囲が造膜性、耐食性、溶接時のミストの低減効果が最も優れ、また亜鉛ヒューム（溶接時に生じる亜鉛蒸気に起因して発生する亜鉛ヒューム）の発生も抑えられるので特に好ましい。
In addition, the zinc dust contained in the underlayer coating film A1 is effective in ensuring antirust properties during the period from the inner surface coating to piping construction. In other words, the sacrificial anti-corrosion action of zinc dust suppresses the generation of rust on the inner surface of the steel pipe, and even if it does occur, it has the effect of preventing the generation of large rust that may cause problems such as malfunction and clogging of gas pipes.
The zinc powder may be metallic zinc powder or powder of an alloy containing zinc as a main component (for example, an alloy with one or more of aluminum, magnesium, tin, etc.).
If the content of zinc dust in the underlayer coating film A1 is less than 30% by mass, the sacrificial anti-corrosion action of the coating film is insufficient, and rust tends to occur during storage. The substantial upper limit of the content of zinc dust is 95% by mass in relation to the content of the polycondensation product of alkylsilicate, but the content of zinc dust is in the range of 30 to 70% by mass. , It is preferable because the mist reduction effect during welding is excellent, and in particular, the range of 40 to 60% by mass is the most excellent in film-forming properties, corrosion resistance, and the effect of reducing mist during welding. It is particularly preferable because it also suppresses the generation of zinc fumes generated due to this.
下層塗膜A1は、アルキルシリケート重縮合反応物と亜鉛末以外の成分として、例えば、コロイダルシリカ（水分散コロイダルシリカなど）、非晶性シリカ、シリカゲル、タルク、炭酸カルシウム、酸化チタン、アルミナホワイト、塩基性炭酸マグネシウムなどの無機系微粒子（顔料）の１種以上を含有してもよい。これら無機系微粒子（顔料）は、塗膜強度を高める効果があるが、なかでも水分散コロイダルシリカが、特に塗膜強度を高める効果が高く且つ溶接欠陥を低減させる効果もあるので好ましい。このような効果を得るために、無機系微粒子の含有量は１質量％以上とするのが好ましい。ただし、このアルキルシリケート重縮合反応物と亜鉛末以外の成分の含有量は、合計で１０質量％程度を上限とすることが好ましい。
下層塗膜A1は、溶接時のミストの発生を抑えるため、有機樹脂などの有機化合物を含まない無機系塗膜とすることが好ましい。また、有機化合物を含む場合でも、５質量％程度を上限とすることが好ましい。
The underlayer coating film A1 contains, as components other than the alkylsilicate polycondensation reaction product and zinc dust, colloidal silica (water-dispersed colloidal silica, etc.), amorphous silica, silica gel, talc, calcium carbonate, titanium oxide, alumina white, It may contain one or more inorganic fine particles (pigments) such as basic magnesium carbonate. These inorganic fine particles (pigments) have the effect of increasing the strength of the coating film. Among them, water-dispersed colloidal silica is particularly preferable because it has a high effect of increasing the strength of the coating film and also has the effect of reducing weld defects. In order to obtain such effects, the content of the inorganic fine particles is preferably 1% by mass or more. However, the upper limit of the total content of components other than the alkylsilicate polycondensation product and zinc dust is preferably about 10% by mass.
In order to suppress generation of mist during welding, the lower coating film A1 is preferably an inorganic coating film that does not contain an organic compound such as an organic resin. Moreover, even when an organic compound is included, the upper limit is preferably about 5% by mass.
上層塗膜A2は、管内面の塗膜表面を平滑化するとともに、下層塗膜A1を覆うことで下層塗膜A1の亜鉛粒が管内面の塗膜面に露出しないようにするために形成するものであり、溶接時のミストの発生を抑えかつ必要な塗膜強度を確保するとともに、塗膜表面の平滑化を図るために、アルキルシリケート重縮合反応物の含有量を５０質量％以上とする。また、上記の観点から、上層塗膜A2中のアルキルシリケート重縮合反応物の好ましい含有量は７５質量％以上、より好ましい含有量は８５質量％以上である。さらに、上層塗膜A2は、管内面の塗膜面に亜鉛粒を露出させないか、若しくは塗膜面に亜鉛粒が露出したとしても、その量を少なく抑えるという観点から、亜鉛末を含有しないか、若しくは亜鉛末を含有する場合でも下層塗膜A1よりも少ない含有量とする。この場合において、使用できる亜鉛末の種類は、さきに下層塗膜A1に関して述べたものと同様である。
このような上層塗膜A2を形成することにより、亜鉛末を含有する単層塗膜を形成する場合（従来技術）に較べて管内面の塗膜面が平滑化されるとともに、下層塗膜A1の亜鉛粒が管内面の塗膜面に露出しないため、ガス管として使用した場合に、（i）管内に流すガスに含まれている付臭剤が塗膜に吸着されにくい、（ii）溶接施工により生じたスパッタや鉄粉などの汚れが付着しにくい、という効果が得られる。
The upper coating film A2 is formed to smooth the coating film surface of the inner surface of the pipe and to cover the lower coating film A1 so that the zinc grains of the lower coating film A1 are not exposed on the inner coating surface of the pipe. In order to suppress the generation of mist during welding, secure the required coating film strength, and smoothen the coating film surface, the content of the alkyl silicate polycondensation reaction product is set to 50% by mass or more. . From the above viewpoint, the content of the alkylsilicate polycondensation reaction product in the upper coating film A2 is preferably 75% by mass or more, more preferably 85% by mass or more. Furthermore, the top layer coating A2 does not expose zinc particles on the coating surface of the inner surface of the pipe, or even if zinc particles are exposed on the coating surface, the amount of zinc particles is suppressed. Or, even if zinc dust is contained, the content is less than that of the lower coating film A1. In this case, the types of zinc dust that can be used are the same as those described above for the undercoat layer A1.
By forming such an upper coating film A2, the coating film surface on the inner surface of the pipe is smoothed compared to the case of forming a single-layer coating film containing zinc dust (prior art), and the lower coating film A1 When used as a gas pipe, (i) the odorant contained in the gas flowing through the pipe is less likely to be adsorbed on the coating, and (ii) welding An effect is obtained in that dirt such as spatter and iron powder generated by construction is less likely to adhere.
また、上層塗膜A2は、管内面の塗膜表面を平滑化させるために、平均粒径が５μｍ以上の粉体（粉粒物なども含む。）を含まないことが好ましい。また、平均粒径が５μｍ以上の粉体を含む場合でも、５質量％程度を上限とすることが好ましい。この粉体としては、例えば、亜鉛末などの金属粉、金属粉以外の無機系粒子（例えば、体質顔料）、有機系粒子などが挙げられる。ここで、平均粒径とは、レーザー回折・散乱法による粒度分布の測定値から算出される体積基準のメディアン径であり、市販のレーザー解析・散乱式粒度分布測定装置を用いて得られる。
さらに、上層塗膜A2も、溶接時のミストの発生を抑えるため、有機樹脂などの有機化合物を含まない無機系塗膜とすることが好ましい。
In order to smooth the coating film surface of the inner surface of the tube, the upper coating film A2 preferably does not contain powder (including powder particles) having an average particle diameter of 5 μm or more. In addition, even when powder having an average particle size of 5 μm or more is included, the upper limit is preferably about 5% by mass. Examples of the powder include metal powder such as zinc powder, inorganic particles other than metal powder (for example, extender pigment), and organic particles. Here, the average particle diameter is a volume-based median diameter calculated from a particle size distribution measured by a laser diffraction/scattering method, and is obtained using a commercially available laser analysis/scattering particle size distribution analyzer.
Further, the upper coating film A2 is also preferably an inorganic coating film that does not contain organic compounds such as organic resins in order to suppress generation of mist during welding.
上層塗膜A2は、アルキルシリケート重縮合反応物以外の成分として、例えば、コロイダルシリカ（水分散コロイダルシリカなど）、非晶性シリカ、シリカゲルなどの無機系微粒子（顔料）の１種以上を含有してもよい。さきに述べたように、これら無機系微粒子（顔料）は、塗膜強度を高める効果があるが、なかでも水分散コロイダルシリカが、特に塗膜強度を高める効果が高く且つ溶接欠陥を低減させる効果もあるので好ましい。このような効果を得るために、無機系微粒子の含有量は１質量％以上とするのが好ましい。 The upper coating film A2 contains one or more inorganic fine particles (pigments) such as colloidal silica (water-dispersed colloidal silica, etc.), amorphous silica, silica gel, etc., as components other than the alkylsilicate polycondensation reaction product. may As mentioned earlier, these inorganic fine particles (pigments) have the effect of increasing the strength of the coating film. Among them, the water-dispersed colloidal silica has a particularly high effect of increasing the strength of the coating film and also has the effect of reducing welding defects. It is preferable because there is In order to obtain such effects, the content of the inorganic fine particles is preferably 1% by mass or more.
また、本発明では、管内面の塗膜（下層塗膜A1および上層塗膜A2を有する塗膜）の平滑性をさらに高めるために、管内面の塗膜の表面粗さＲｚ（最大高さＲｚ）を１８μｍ以下とすることが好ましく、このため上層塗膜A2は、この表面粗さＲｚが得られるように形成されることが好ましい。管内面の塗膜の表面粗さＲｚを１８μｍ以下とすることにより塗膜の平滑性がさらに高まるので、ガス管として使用した場合に、（i）管内に流すガスに含まれている付臭剤が塗膜に吸着されにくい、（ii）溶接施工により生じたスパッタや鉄粉などの汚れが付着しにくい、という効果がさらに高まる。 In addition, in the present invention, in order to further improve the smoothness of the coating film on the inner surface of the pipe (the coating film having the lower coating film A1 and the upper coating film A2), the coating film on the inner surface of the pipe has a surface roughness Rz (maximum height Rz ) is preferably 18 μm or less, and therefore the upper coating film A2 is preferably formed so as to obtain this surface roughness Rz. By setting the surface roughness Rz of the coating film on the inner surface of the pipe to 18 μm or less, the smoothness of the coating film is further improved, so when it is used as a gas pipe, (i) the odorant contained in the gas flowing through the pipe is less likely to be adsorbed by the coating film, and (ii) stains such as spatter and iron powder generated by welding work are less likely to adhere.
管内面の塗膜厚は、下層塗膜A1の膜厚を５～８０μｍ、上層塗膜A2の膜厚を５～８０μｍとすることが好ましい。
下層塗膜A1の膜厚が５μｍ未満では防錆効果が低下し、一方、膜厚が８０μｍを超えると塗膜の内部応力が大きくなって剥離し易くなり、また溶接時の亜鉛ヒューム発生の影響も大きくなる。また、特に好ましい膜厚は１０～３０μｍであり、防錆性、溶接時の亜鉛ヒュームの発生抑制、溶接時のミストの発生抑制の観点から最適である。
上層塗膜A2の膜厚が５μｍ未満では、下層塗膜A1の粗さをカバーする効果が低下する。一方、膜厚が８０μｍを超えると塗膜の内部応力が大きくなり、剥離しやすくなる。また、特に好ましい膜厚は１０～３０μｍであり、塗膜の平滑化と付臭剤の吸着抑制の観点から最適である。
また、管内面の塗膜（下層塗膜＋上層塗膜）の合計膜厚が１００μｍを超えると、塗膜の内部応力で割れやすい等の問題が発生する可能性があるので、合計膜厚は１００μｍ以下とすることが好ましい。
As for the coating thickness on the inner surface of the pipe, it is preferable that the thickness of the lower coating film A1 is 5 to 80 μm and the thickness of the upper coating film A2 is 5 to 80 μm.
If the film thickness of the lower coating film A1 is less than 5 µm, the anti-corrosion effect is reduced. will also grow. A particularly preferable film thickness is 10 to 30 μm, which is optimal from the viewpoint of rust prevention, suppression of zinc fume generation during welding, and suppression of mist generation during welding.
If the film thickness of the upper coating film A2 is less than 5 μm, the effect of covering the roughness of the lower coating film A1 is reduced. On the other hand, if the film thickness exceeds 80 μm, the internal stress of the coating film increases and the coating tends to peel off. A particularly preferable film thickness is 10 to 30 μm, which is optimal from the viewpoint of smoothing the coating film and suppressing adsorption of the odorant.
In addition, if the total thickness of the coating film on the inner surface of the pipe (lower layer coating + upper coating) exceeds 100 μm, problems such as susceptibility to cracking due to internal stress of the coating may occur. It is preferably 100 μm or less.
下層塗膜A1と上層塗膜A2に含まれるアルキルシリケート重縮合反応物のもとになるアルキルシリケート（オリゴマーである場合を含む。）としては、アルキル基がエチル基、メチル基、プロピル基などのものがあり、例えば、エチルシリケート、メチルシリケート、テトラエチルオルトシリケート、テトラメチルオルトシリケート、テトラ－ｎ－プロピルオルトシリケート、テトラ－ｉ－プロピルオルトシリケート、テトラ－ｎ－ブチルオルトシリケート、テトラ－sec－ブチルオルトシリケートなどが挙げられ、これらの１種以上を用いることができるが、なかでもアルキル基がエチル基のものが、造膜性の面で最適である。 The alkyl silicate (including the case where it is an oligomer), which is the source of the alkyl silicate polycondensation reaction product contained in the lower coating film A1 and the upper coating film A2, has an alkyl group such as an ethyl group, a methyl group, or a propyl group. such as ethyl silicate, methyl silicate, tetraethyl orthosilicate, tetramethyl orthosilicate, tetra-n-propyl orthosilicate, tetra-i-propyl orthosilicate, tetra-n-butyl orthosilicate, tetra-sec-butyl Orthosilicate and the like can be mentioned, and one or more of these can be used, but among them, those in which the alkyl group is an ethyl group are most suitable in terms of film-forming properties.
図１は、本発明の樹脂塗覆装鋼管の一実施形態において、内面塗膜の厚さ方向断面を模式に示す説明図であり、図１（ア）は下層塗膜A1のみが形成された状態を、図１（イ）は、その下層塗膜A1上に上層塗膜A２が形成された状態を、それぞれ示している。
図１（ア）に示す下層塗膜A1のみが形成された状態は、特許文献１に示されるような従来技術の樹脂塗覆装鋼管（ポリエチレン被覆鋼管）が有する内面塗膜と同じであり、塗膜に含まれる亜鉛粒（粉末）による表面凹凸により塗膜面の表面粗さＲｚが大きく、また亜鉛粒が塗膜面に露出した状態にある。この状態では、塗膜に含まれる亜鉛粒（亜鉛末）に起因する表面凹凸により塗膜の表面積が大きくなり、付臭剤が塗膜面に吸着されやすいこと、塗膜面に存在（露出）する亜鉛粒が付臭剤の硫黄分と親和性が高く、付臭剤の吸着サイトとなること、などにより管内に流すガスに含まれる付臭剤が塗膜に吸着されやすい。加えて、ガス管の溶接施工により発生するスパッタや鉄粉などの汚れが塗膜面に付着しやすいため、清掃性も劣る。
FIG. 1 is an explanatory view schematically showing a cross section in the thickness direction of the inner coating film in one embodiment of the resin-coated steel pipe of the present invention, and FIG. FIG. 1(a) shows the state in which the upper layer coating film A2 is formed on the lower layer coating film A1.
The state in which only the lower layer coating film A1 is formed as shown in FIG. The surface roughness Rz of the coating film surface is large due to surface irregularities due to the zinc particles (powder) contained in the coating film, and the zinc particles are exposed on the coating film surface. In this state, the surface area of the coating film increases due to the surface unevenness caused by the zinc particles (zinc dust) contained in the coating film, and the odorant is easily adsorbed on the coating film surface. The zinc grains have a high affinity with the sulfur content of the odorant and act as an adsorption site for the odorant, so the odorant contained in the gas flowing into the pipe is easily adsorbed by the coating film. In addition, dirt such as spatter and iron powder generated by welding of gas pipes easily adheres to the coated surface, resulting in poor cleanability.
また、仮に塗膜面の表面粗さＲｚが小さくても（例えば、表面粗さＲｚ：１８μｍ以下）、図１（ア）のように亜鉛粒が塗膜面に露出した状態にあると、塗膜面に存在（露出）する亜鉛粒が付臭剤の吸着サイトとなるため、付臭剤が塗膜に吸着されやすく、また、スパッタや鉄粉などの汚れが塗膜面に付着しやすい。
これに対して、図１（イ）に示すように下層塗膜A1の上に上層塗膜A2が形成されることにより、塗膜表面が平滑化されるとともに、下層塗膜A1が上層塗膜A2で覆われ、下層塗膜A1の亜鉛粒が塗膜面に露出しないようにすることができ、この結果、（i）管内に流すガスに含まれている付臭剤が塗膜に吸着されにくい、（ii）溶接施工により生じたスパッタや鉄粉などの汚れが付着しにくい、という効果が得られる。
Also, even if the surface roughness Rz of the coating surface is small (for example, surface roughness Rz: 18 μm or less), if the zinc particles are exposed on the coating surface as shown in FIG. Since the zinc grains present (exposed) on the film surface serve as adsorption sites for the odorant, the odorant is easily adsorbed on the coating film, and dirt such as spatter and iron powder easily adheres to the coating film surface.
On the other hand, as shown in FIG. 1 (a), by forming the upper layer coating A2 on the lower layer coating A1, the coating surface is smoothed and the lower layer coating A1 is the upper layer coating Covered with A2, it is possible to prevent the zinc grains of the lower coating film A1 from being exposed on the coating surface, and as a result, (i) the odorant contained in the gas flowing into the pipe is adsorbed on the coating film. and (ii) stains such as spatter and iron powder generated by welding are less likely to adhere.
さきに述べたように、本発明が対象とする樹脂塗覆装鋼管の代表例は、ポリエチレン被覆鋼管であり、このポリエチレン被覆鋼管としては、ＪＩＳ Ｇ３４６９、ＪＩＳ Ｇ３４７７－２、ＪＩＳ Ｇ３４７７－１に規定されるポリエチレン被覆鋼管などがあるが、特に溶接接合が主体となる中圧導管に多く使用されるＪＩＳ Ｇ３４７７－２のＰＥ２Ｓ、ＪＩＳ Ｇ３４６９のＰ２Ｓなどに好適である。ただし、これらに限定されるものではない。 As mentioned above, a representative example of the resin-coated steel pipes targeted by the present invention is polyethylene-coated steel pipes, and polyethylene-coated steel pipes are specified in JIS G3469, JIS G3477-2, and JIS G3477-1. PE2S of JIS G3477-2, P2S of JIS G3469, etc., which are often used for medium-pressure pipes that are mainly welded, are suitable. However, it is not limited to these.
本発明において、管内面の塗膜の膜厚及び表面粗さＲｚは、以下のようにして測定されたものとする。
まず、下層塗膜A1の膜厚については、下層塗膜A1を塗装した時点で、電磁膜厚計により管の両端近傍位置の周方向４点（周方向で等間隔の４点）で内面塗膜厚を測定し、それらの平均値を下層塗膜A1の膜厚とする。
上層塗膜A2の膜厚については、内面塗膜（下層塗膜A1と上層塗膜A2を有する塗膜）について、電磁膜厚計により管の両端近傍位置の周方向４点（周方向で等間隔の４点）で塗膜厚を測定し、それらの平均値を求め、この平均値から上記下層塗膜A1の膜厚を差し引いた値を上層塗膜A2の膜厚とする。
また、内面塗膜（下層塗膜A1と上層塗膜A2を有する塗膜）の表面粗さＲｚについては、小型表面粗さ計を用い、管の両端近傍位置の周方向４点（周方向で等間隔の４点）で内面塗膜の表面粗さＲｚ（最大高さＲｚ）を管軸方向に沿って約１０ｍｍの範囲で測定し、それらの平均値を塗膜の表面粗さＲｚとする。
In the present invention, the film thickness and surface roughness Rz of the coating film on the inner surface of the pipe shall be measured as follows.
First, regarding the film thickness of the lower layer coating film A1, when the lower layer coating film A1 was applied, the inner surface coating was measured at 4 points in the circumferential direction near both ends of the pipe (4 points at equal intervals in the circumferential direction) using an electromagnetic thickness meter. The film thickness is measured, and the average value thereof is taken as the film thickness of the lower coating film A1.
Regarding the film thickness of the upper layer coating A2, the internal coating (coating having the lower layer coating A1 and the upper layer coating A2) was measured at four points in the circumferential direction near both ends of the tube (equal in the circumferential direction) using an electromagnetic thickness meter. The thickness of the coating film is measured at 4 points in the interval), the average value is obtained, and the thickness of the upper coating film A2 is obtained by subtracting the thickness of the lower coating film A1 from this average value.
In addition, the surface roughness Rz of the inner coating film (coating film having the lower layer coating film A1 and the upper layer coating film A2) was measured using a small surface roughness meter at four points in the circumferential direction near both ends of the pipe ( The surface roughness Rz (maximum height Rz) of the inner coating film is measured in a range of about 10 mm along the tube axis direction at four points at equal intervals), and the average value thereof is taken as the surface roughness Rz of the coating film. .
次に、本発明の樹脂塗覆装鋼管の製造方法について、ガス管用のポリエチレン被覆鋼管を例に説明する。なお、他の樹脂塗覆装鋼管の製造においても、内面塗装については、以下の説明に準じた方法が採られる。
使用する鋼管（原管）は、ガス管用に用いられる鋼管であれば特に種類は問わない。一般的にはＪＩＳ Ｇ３４５２に規定されるＳＧＰ、ＪＩＳ Ｇ３４５４に規定されるＳＴＰＧが最もよく用いられる。溶接接合を行うため、予め両管端はベベル加工がなされていることが好ましい。
鋼管（原管）には、内面塗装と外面樹脂被覆を施す前に、素地調整を目的として、酸洗またはブラスト処理（ショットブラスト、グリットブラストなど）が施され、鋼管内外面のさびや汚れ、ミルスケールを除去する。
Next, the method for manufacturing the resin-coated steel pipe of the present invention will be described by taking a polyethylene-coated steel pipe for gas pipes as an example. In the manufacture of other resin-coated steel pipes as well, the inner surface coating is applied in accordance with the method described below.
The steel pipe (original pipe) to be used is not particularly limited as long as it is a steel pipe used for gas pipes. Generally, SGP defined in JIS G3452 and STPG defined in JIS G3454 are most often used. It is preferable that both pipe ends are preliminarily beveled for welding and joining.
Steel pipes (original pipes) are subjected to pickling or blasting (shot blasting, grit blasting, etc.) for the purpose of surface conditioning before the inner surface coating and outer surface resin coating are applied to remove rust, dirt, Remove mill scale.
鋼管の内面塗装では、管内面に、塗料固形分中の割合でアルキルシリケートおよび／またはアルキルシリケートオリゴマーを５質量％以上、亜鉛粉末を３０質量％以上含有する下層塗膜用の塗料a1を塗装（塗布）し、次いで、塗料固形分中の割合でアルキルシリケートおよび／またはアルキルシリケートオリゴマーを５０質量％以上含有し、且つ亜鉛末を含有しないか、若しくは亜鉛末を下層塗膜用の塗料a1よりも少ない含有量で含有する上層塗膜用の塗料a2を塗装（塗布）することにより、管内面に下層塗膜A1と上層塗膜A2を有する塗膜（好ましくは、表面粗さＲｚが１８μｍ以下の塗膜）を形成する。
塗料a1，a2中には、さきに説明した成分組成の塗膜となるように各成分（固形分）が配合される。また、塗料a1，a2中にはアルキルシリケートを単独で用いることもあるが、アルキルシリケートをある程度縮合させたオリゴマー状態で使用してもよい。いずれの形態でも効果は同様である。
In the coating of the inner surface of steel pipes, the inner surface of the pipe is coated with paint a1 for the lower layer coating containing 5% by mass or more of alkyl silicate and/or alkyl silicate oligomer and 30% by mass or more of zinc powder in terms of the solid content of the paint ( coating), and then containing 50% by mass or more of alkyl silicate and/or alkyl silicate oligomer in terms of the solid content of the paint, and containing no zinc dust or zinc dust than the paint a1 for the lower layer coating film By painting (applying) the paint a2 for the upper layer coating film that contains a small content, the coating film having the lower layer coating film A1 and the upper layer coating film A2 on the inner surface of the pipe (preferably, the surface roughness Rz is 18 μm or less form a coating film).
Each component (solid content) is blended in the paints a1 and a2 so as to form a coating film having the component composition described above. In some cases, the alkyl silicates are used alone in the paints a1 and a2, but they may be used in the form of oligomers in which the alkyl silicates are condensed to some extent. The effect is the same regardless of the form.
鋼管の内面塗装は、一般にエアレススプレーにより行われ、鋼管内面（素地）に下層塗膜用の塗料a1を塗装（塗布）し、一定程度乾燥させた後、上層塗膜用の塗料a2を塗装（塗布）し、乾燥させて内面塗膜を形成する。このエアレススプレーによる内面塗装では、先端にノズルのついたアームを管内部に挿入し、鋼管を回転させながらノズル先端から塗料を噴出させ、アームを徐々に引き抜きながら鋼管内面全長に塗装を施す。下層塗膜A1、上層塗膜A2ともに、アームの引き抜き速度を調整することで所望の膜厚となるようにする。アルキルシリケートおよび／またはアルキルシリケートオリゴマーを含有する塗料は塗装後、空気中の水分と接触することで硬化し造膜するが、この造膜後、乾燥炉で加熱してもよい。 The inner surface of steel pipes is generally painted by airless spraying. Paint a1 for the lower layer coating is applied to the inner surface of the steel pipe (substrate), and after drying to a certain extent, paint a2 for the upper layer coating is applied ( coating) and drying to form an inner coating film. In this airless spraying method, an arm with a nozzle at the tip is inserted into the inside of the pipe, and the paint is sprayed from the tip of the nozzle while rotating the steel pipe. Both the lower layer coating film A1 and the upper layer coating film A2 are made to have a desired film thickness by adjusting the drawing speed of the arm. A paint containing an alkyl silicate and/or an alkyl silicate oligomer cures and forms a film by contact with moisture in the air after being applied, and may be heated in a drying oven after the film is formed.
鋼管外面については、必要に応じて、クロメート処理やノンクロメート処理（例えば、リン酸塩処理、リン酸処理、）などの化成処理を行った後、アスファルト系粘着材などによるアンダーコートを施す。
その後、押出成形機のクロスヘッドダイ（丸ダイ）やＴダイを介して鋼管外面にポリエチレンを被覆する。また、Ｐ２Ｓ、ＰＥ２Ｓタイプなどは、防食用のポリエチレンを被覆した後、その上に更にもう一層保護層としてのポリエチレンを被覆する場合もある。
また、鋼管外面については、エポキシ樹脂塗装などの樹脂塗装を行う（すなわち、エポキシ塗装鋼管のような樹脂塗装鋼管とする）ことも可能であり、この場合には、鋼管をターニングローラーなどに乗せて回転させながら、エアレススプレーなどによって、エポキシ樹脂塗装などの樹脂塗装を鋼管外面の全面に行う。
以上述べたような製造方法により、本発明の樹脂塗覆装鋼管が製造される。
The outer surface of the steel pipe is subjected to a chemical conversion treatment such as chromate treatment or non-chromate treatment (for example, phosphate treatment, phosphoric acid treatment) as necessary, and then undercoated with an asphalt-based adhesive material or the like.
Thereafter, the outer surface of the steel pipe is coated with polyethylene through a crosshead die (round die) or a T-die of an extruder. In addition, P2S and PE2S types may be coated with anticorrosive polyethylene and then coated with another layer of polyethylene as a protective layer.
In addition, the outer surface of the steel pipe can be coated with a resin such as epoxy resin coating (i.e., a resin-coated steel pipe such as an epoxy-coated steel pipe). While being rotated, a resin coating such as epoxy resin coating is applied to the entire outer surface of the steel pipe by an airless spray or the like.
The resin-coated steel pipe of the present invention is manufactured by the manufacturing method described above.
ＪＩＳ Ｇ３４５２に規定するＳＧＰ（両管端をベベル加工した鋼管）を原管として、ＪＩＳ Ｇ３４６９に規定するポリエチレン被覆鋼管Ｐ２Ｓ（２００Ａ）を製造した。
鋼管の内外面にグリットブラスト処理（Ｓａ２．５）を施し、鋼管表面のさびや汚れ、ミルスケールを除去した。この鋼管に対して、以下のような方法で内面塗装と外面樹脂被覆を施し、ポリエチレン被覆鋼管とした。
また、比較例のポリエチレン被覆鋼管として、管内面に単層の塗膜（本発明の下層塗膜に相当する塗膜）を形成したもの、管内面をエポキシ樹脂塗装したもの、管内面を無塗装としたものを製造した。
A polyethylene-coated steel pipe P2S (200A) defined in JIS G3469 was manufactured using SGP (steel pipe with both pipe ends beveled) defined in JIS G3452 as a base pipe.
The inner and outer surfaces of the steel pipe were grit blasted (Sa 2.5) to remove rust, dirt, and mill scale from the surface of the steel pipe. The inner surface coating and the outer surface resin coating were applied to this steel pipe by the following method to obtain a polyethylene-coated steel pipe.
In addition, as polyethylene-coated steel pipes of comparative examples, those having a single-layer coating film (a coating film corresponding to the lower layer coating film of the present invention) formed on the inner surface of the pipe, those having the inner surface coated with an epoxy resin, and those having no coating on the inner surface of the pipe. I manufactured what I did.
（a）内面塗装
下層塗膜用の塗料、上層塗膜用の塗料ともに、アルキルシリケート（オリゴマーである場合を含む。）としては、エチルシリケートを用いた。また、下層塗膜用の塗料、上層塗膜用の塗料ともに、その他の添加物として水分散コロイダルシリカを添加した。
内面塗装は、下層塗膜、上層塗膜ともに、エアレススプレーにより行った。鋼管内面（素地）に下層塗膜用の塗料を塗装し、一定程度乾燥させた後、上層塗膜用の塗料を塗装し、自然乾燥させて内面塗膜を形成した。この内面塗装では、先端にノズルのついたアームを管内面に挿入し、鋼管を回転させながらノズル先端から塗料を噴出させ、アームを徐々に引き抜きながら鋼管内面全長に塗装を行った。下層塗膜・上層塗膜ともに、アームの引き抜き速度を調整することで所望の膜厚となるようにした。
(a) Inner Surface Coating Ethyl silicate was used as the alkyl silicate (including the case where it is an oligomer) for both the paint for the lower layer coating film and the paint for the upper layer coating film. In addition, water-dispersed colloidal silica was added as another additive to both the paint for the lower layer coating film and the paint for the upper layer coating film.
Both the lower layer coating film and the upper layer coating film were applied to the inner surface by an airless spray. The inner surface (substrate) of the steel pipe was coated with the paint for the lower layer coating, dried to a certain extent, then coated with the paint for the upper layer coating, and allowed to dry naturally to form an inner coating. In this inner surface coating, an arm with a nozzle at the tip was inserted into the inner surface of the pipe, the paint was sprayed from the tip of the nozzle while rotating the steel pipe, and the entire length of the inner surface of the steel pipe was coated while the arm was gradually pulled out. Both the lower layer coating film and the upper layer coating film were made to have desired film thickness by adjusting the drawing speed of the arm.
（b）外面樹脂被覆
管外面にアスファルト系粘着剤によるアンダーコート塗装を行った。このアンダーコートが塗装された管外面に、押出成形機のクロスヘッドダイ（丸ダイ）により、防食用ポリエチレンを被覆し、さらにその上層に、保護層樹脂としてのポリエチレンを被覆し、樹脂被覆層とした。
(b) Outer surface resin coating The outer surface of the pipe was coated with an asphalt adhesive undercoat. The outer surface of the pipe coated with this undercoat is coated with anticorrosion polyethylene using a crosshead die (round die) of an extruder, and further coated with polyethylene as a protective layer resin on the upper layer to form a resin coating layer. did.
ポリエチレン被覆鋼管の内面塗装の下層塗膜と上層塗膜の膜厚、塗膜の表面粗さＲｚは、先に述べた方法で測定した。
得られた本発明例及び比較例のポリエチレン被覆鋼管について、下記のような特性評価を行った。
（1）溶接接合性（溶接時のミスト発生の有無、ミストによる電磁弁固着の有無）
ガス導管を設置するためにポリエチレン被覆鋼管の端部をアーク溶接により円周溶接して接合し、その際のミスト（塗膜の熱分解生成物）発生の有無や程度を調べた。また、そのガス導管に電磁弁を取り付けて半年間使用し、電磁弁にミストが付着することによる動作不良の有無や程度を調べた。
◎：溶接時のミスト発生が全く無く、このためミスト付着による電磁弁の動作不良も無い。
〇：溶接時のミスト発生が殆ど無く、このためミスト付着による電磁弁の動作不良も無い。
△：溶接時に若干のミストが発生し、このためミスト付着による電磁弁の動作不良が若干発生した。
×：溶接時に大量のミストが発生し、このためミスト付着による電磁弁の動作不良が多発した。
The film thicknesses of the lower layer coating film and the upper layer coating film of the inner surface coating of the polyethylene-coated steel pipe and the surface roughness Rz of the coating film were measured by the method described above.
The obtained polyethylene-coated steel pipes of the present invention examples and comparative examples were evaluated for the following characteristics.
(1) Weldability (presence or absence of mist during welding, presence or absence of solenoid valve sticking due to mist)
In order to install a gas pipe, the ends of polyethylene-coated steel pipes were circumferentially welded by arc welding and jointed, and the presence or absence and degree of generation of mist (thermal decomposition products of the coating film) at that time was investigated. In addition, a solenoid valve was attached to the gas pipe and used for half a year, and the presence and degree of malfunction due to mist adhering to the solenoid valve was investigated.
⊚: No mist was generated during welding, and there was no malfunction of the solenoid valve due to adhesion of mist.
◯: Almost no mist was generated during welding, so there was no malfunction of the solenoid valve due to adhesion of mist.
Δ: A small amount of mist was generated during welding, and the adherence of the mist caused a slight malfunction of the solenoid valve.
x: A large amount of mist was generated during welding, and due to this, malfunctions of the solenoid valve frequently occurred due to adhesion of the mist.
（2）付臭剤の臭い（付臭剤の塗膜への非吸着性）
ポリエチレン被覆鋼管で構成した１２ｍの配管に都市ガスを３Ｎｍ３／ｈｒ流し、付臭剤の臭いを確認した。
◎：ガスを流し始めて直ぐに臭いがしてくる。
〇：ガスを流し始めてから１０秒以内の時間は無臭があるが、その後臭いがしてくる。
△：ガスを流し始めてから１０秒超１分以内の時間は無臭があるが、その後臭いがしてくる。
×：ガスを流し始めてから１分超の時間がたたないと、臭いがしてこない。
(2) Odor of odorant (non-adsorption of odorant to coating film)
3 Nm 3 /hr of town gas was flowed through a 12 m pipe made of a polyethylene-coated steel pipe, and the odor of the odorant was confirmed.
⊚: Immediately after starting to flow the gas, an odor is generated.
◯: There is no odor within 10 seconds after starting to flow the gas, but the odor starts afterward.
Δ: Odorless for more than 10 seconds and up to 1 minute from the start of gas flow, but smells afterward.
x: The smell does not come out until more than 1 minute has elapsed since the gas flow started.
（3）清掃作業性（溶接で生じたスラグやスパッタ等の清掃性）
ポリエチレン被覆鋼管の端部をアーク溶接により円周溶接して接合した後、その溶接部をスポンジピグで清掃し、溶接で生じたスラグやスパッタ等の清掃性（ピグの走行性を含む）を調べた。
◎：スポンジピグで全く支障なく清掃可能。
〇：スポンジピグで多少の引っ掛かりがある。
△：スポンジピグでは綺麗に汚れが取れない。
×：スポンジピグが引っ掛かり、ピグの走行に支障がある。
(3) Cleanability (Cleanability of slag, spatter, etc. generated during welding)
After the ends of polyethylene-coated steel pipes were circumferentially welded by arc welding and joined, the welded portion was cleaned with a sponge pig, and the cleanability of slag, spatter, etc. generated by welding (including pig runnability) was investigated. .
A: Can be cleaned with a sponge pig without any trouble.
◯: There is some catching on the sponge pig.
Δ: Dirt cannot be removed cleanly with a sponge pig.
x: The sponge pig is caught, and the traveling of the pig is hindered.
A1 下層塗膜
A2 上層塗膜
a1，a2 塗料
A1 Lower layer coating
A2 Top coat
a1, a2 Paint
Claims (12)
管内面の塗膜は、アルキルシリケート重縮合反応物を５質量％以上、亜鉛末を３０質量％以上含有する下層塗膜（A1）と、アルキルシリケート重縮合反応物を５０質量％以上含有し、且つ亜鉛末を含有しないか、若しくは亜鉛末を下層塗膜（A1）よりも少ない含有量で含有する上層塗膜（A2）を有することを特徴とする樹脂塗覆装鋼管。 A resin-coated steel pipe having a resin coating layer or coating on its outer surface and a coating on its inner surface,
The coating film on the inner surface of the tube comprises an underlayer coating film (A1) containing 5% by mass or more of an alkylsilicate polycondensation reaction product and 30% by mass or more of zinc dust, and 50% by mass or more of an alkylsilicate polycondensation reaction product, and a resin-coated steel pipe characterized by having an upper coating film (A2) containing no zinc dust or containing zinc dust in a smaller content than the lower coating film (A1).
管内面を塗装するに際し、管内面に、塗料固形分中の割合でアルキルシリケートおよび／またはアルキルシリケートオリゴマーを５質量％以上、亜鉛末を３０質量％以上含有する下層塗膜用の塗料（a1）を塗装し、次いで、塗料固形分中の割合でアルキルシリケートおよび／またはアルキルシリケートオリゴマーを５０質量％以上含有し、且つ亜鉛末を含有しないか、若しくは亜鉛末を下層塗膜用の塗料（a1）よりも少ない含有量で含有する上層塗膜用の塗料（a2）を塗装することにより、管内面に下層塗膜（A1）と上層塗膜（A2）を有する塗膜を形成することを特徴とする樹脂塗覆装鋼管の製造方法。 A method for producing a resin-coated steel pipe having a resin coating layer or coating on the outer surface of the pipe and a coating on the inner surface of the pipe, comprising:
A paint (a1) for a lower coating film containing, when coating the inner surface of a pipe, 5% by mass or more of an alkylsilicate and/or an alkylsilicate oligomer and 30% by mass or more of zinc dust in terms of the solid content of the paint. and then containing 50% by mass or more of alkyl silicate and/or alkyl silicate oligomer in the solid content of the paint and containing no zinc dust or zinc dust for the lower layer coating (a1) By applying a paint (a2) for the upper layer coating that contains a lower content than A method for manufacturing a resin-coated steel pipe.
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