JP2004132464A - Fluid pipe and preserving method for pipe connecting part - Google Patents

Fluid pipe and preserving method for pipe connecting part Download PDF

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Publication number
JP2004132464A
JP2004132464A JP2002297663A JP2002297663A JP2004132464A JP 2004132464 A JP2004132464 A JP 2004132464A JP 2002297663 A JP2002297663 A JP 2002297663A JP 2002297663 A JP2002297663 A JP 2002297663A JP 2004132464 A JP2004132464 A JP 2004132464A
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Prior art keywords
pipe
tubular body
alloy
fluid
welding
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Inventor
Yasuyuki Fujitani
藤谷　泰之
Takahiro Ota
太田　高裕
Seiji Asada
朝田　誠治
Toshizo Oya
大屋　寿三
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Mitsubishi Heavy Industries Ltd
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Mitsubishi Heavy Industries Ltd
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    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E30/00—Energy generation of nuclear origin

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  • Non-Disconnectible Joints And Screw-Threaded Joints (AREA)
  • Butt Welding And Welding Of Specific Article (AREA)

Abstract

<P>PROBLEM TO BE SOLVED: To provide a technique for environmentally cutting off a 600 alloy without developing a welding crack in a 690 alloy. <P>SOLUTION: This fluid pipe 1 connects an upstream side pipe 10 and a downstream side pipe 20 by a connecting part 30 including a welding part 32 composed of the 600 alloy, and is provided with a first tubular body 41 composed of the 600 alloy and arranged in the fluid pipe 1 so as to cover the connecting part 30 and a second tubular body 43 composed of the 690 alloy and arranged in the fluid pipe 1 so as to cover the first tubular body 41. A build-up welding part 42 is arranged in a shaft directional end part of the first tubular body 41. <P>COPYRIGHT: (C)2004,JPO

Description

【０００１】
【発明の属する技術分野】
本発明は、高温高圧流体が搬送される配管接続部の保全方法及び流体配管に関し、特に、６００合金を用いて溶接された配管接続部の保全方法及び流体配管に関する。
【０００２】
【従来の技術】
流体が流れる配管は、通常、予め規定された所定長さで作成される。従って、長尺の配管を得るにはこれら配管同士を接続する必要があり、例えばアーク溶接を用いて接続部を形成する接続手法が広く用いられてきた。
特に、流体として高温高圧流体が内部を流れる原子炉容器の配管では、接続部が高い耐熱性・耐食性を有していることが要求されており、従来より、ＪＩＳ　Ｇ４９０１−４に規定される６００合金を用いて、溶接による接続部の形成が行われてきた。
【０００３】
ところが、近年、６００合金にて溶接を行った上記接続部に亀裂が入り、内部の流体が漏れ出してしまうという問題が生じている。これは応力腐食割れと呼ばれる現象であり、配管内部を流れる高温高圧流体が、溶接によって残留応力が付与された６００合金に直接触れることにより生ずるものといわれている。特に、加圧水型軽水炉（ＰＷＲ）の１次冷却水が流れる配管で生ずる応力腐食割れは、ＰＷＳＣＣと呼ばれている。
そこで、配管内部に露出している６００合金（接続部）を、この６００合金に比べ湿潤腐食媒体及び高温雰囲気中での耐食性に優れる６９０合金（ＪＩＳ　Ｇ４９０１−４）で覆うことにより、高温高圧流体と６００合金とを環境遮断する対応策が考えられる。
【０００４】
例えば、特開２００２−９０４９４号公報には、原子炉容器に溶接により固着されるニッケル基合金（６００合金）で形成した小口径管である炉内計装筒の内周面に、その開口端からリング状の凹部を形成し、さらに炉内計装筒の材料よりも応力腐食割れに対してより大きな耐蝕性を有する他のニッケル基合金（６９０合金）で形成した円筒状のスリーブを、前記炉内計装筒の開口端から挿入して溶接による残留応力が発生している部分に嵌め込み、その後このスリーブの内部空間にレーザ溶接工具を挿入し、このレーザ溶接工具を炉内計装筒の中心軸回りに回転しつつレーザ光を前記スリーブの内周面側から照射することによりこのスリーブを炉内計装筒の内周面にクラッディングする管内周面の改質方法が開示されている。
【０００５】
【特許文献１】
特開２００２−９０４９４号公報（第１頁、要約）
【０００６】
【発明が解決しようとする課題】
本発明者等は特開２００２−９０４９４号公報に開示されている方法を含め、６９０合金を用いたＰＷＳＣＣの発生防止技術について検討を行った。その結果、６９０合金を管等の被溶接部材に溶接した際に、６９０合金に溶接割れが生ずることがあることが確認された。
そこで本発明は、６９０合金に溶接割れを生じさせることなく６００合金を環境遮断することのできる手法を提供することを課題とする。
【０００７】
【課題を解決するための手段】
本発明者は６９０合金に生ずる溶接割れの原因について検討した。被溶接部材を構成する材料、例えばステンレス鋼中に含まれるＰ（燐）およびＳ（硫黄）の量が多い場合（例えば、Ｐ：０．０３０ｗｔ％以上、Ｓ：０．０１０ｗｔ％以上）に溶接割れが生ずることを確認した。したがって、Ｐ、Ｓを低減した材料を被溶接母材として用いればＰ、Ｓを原因とする溶接割れを生じさせることはない。ところが、Ｐ、Ｓを多く含んだ被溶接部材を用いた既設のプラントを保全する場合は、Ｐ、Ｓを多く含むことを前提とした溶接割れ防止技術が必要となる。
かかる観点のもとに、本発明者等は、Ｐ、Ｓを多く含むステンレス鋼に６９０合金を直接溶接することを回避することによって６９０合金の溶接割れを防止することを提案する。したがって本発明は、第１配管と第２配管とが６００合金によって溶接された配管接続部を有し、内部を高温高圧流体が流れる流体配管であって、６００合金で構成されかつ前記配管接続部を覆うように前記流体配管内に配設された第１管状体と、６９０合金で構成されかつ前記第１管状体を覆うように前記流体配管内に配設される第２管状体と、を備えることを特徴とする流体配管である。
【０００８】
本発明による流体配管は、溶接割れの生じない６００合金から構成される第１管状体を前記配管接続部を覆うように配設し、６９０合金からなる第２管状体を第１管状体を覆うように配設するという構成を採用するため、６９０合金を第１配管、第２配管に直接溶接する必要がない。したがって、第１配管および／または第２配管がＰ、Ｓを多く含む材料から構成されていても、６９０合金に溶接割れが生じるのを防止することができる。
【０００９】
本発明の流体配管において、別途作製されたスリーブを挿入、溶接することにより第１管状体および第２管状体を構成することができる。また、肉盛溶接により、第１管状体および第２管状体を構成することもできる。前者の場合、第１管状体の一方端を第１配管に溶接し、かつ第１管状体の他方端を第２配管に溶接することにより接続配管を覆う構成とすることができる。この構成は、第１管状体を流体配管内の所定位置に挿入した後に、ＴＩＧ溶接またはレーザ溶接を施すことにより得ることができる。溶接は第１管状体の全長にわたって行なうこともできる。また、第１配管および／または第２配管は、単一の部材で構成される場合に限らず、複数の部材で構成されるものを包含する。第１配管および／または第２配管のうち、第１管状体と溶接される部位を構成する材料がＰ、Ｓを多く含んでいても、第１管状体が６００合金で構成されているために溶接割れは生じない。
【００１０】
本発明の流体配管において、第１管状体の一方端と第１配管との境界領域、および第１管状体の他方端と第２配管との境界領域にステンレス鋼から構成される封止部材を配設することが望ましい。そして、第２管状体の両端部をこの封止部材上に溶接することにより、第２管状体および封止部材が第１管状体を覆う構成とすることが望ましい。
以上の構成を採用することにより、第１管状体の径方向における流体配管内部への露出を第２管状体が、また第１管状体の軸方向における流体配管内部への露出を封止部材が防ぐことができる。加えて、封止部材として低Ｐ、Ｓのステンレス鋼を用いると、６９０合金から構成される第２管状体を溶接により接合したとしても、６９０合金に溶接割れが生ずるのを防止することができる。なお、封止部材を構成するステンレス鋼としては、Ｐ、Ｓの含有量がＰ：０．０１５ｗｔ％以下、Ｓ：０．００５ｗｔ％以下に規制されたＳＵＳ３０９鋼が望ましい。第２管状体を封止部材に溶接した際に、第２管状体を構成する６９０合金に割れを生じさせないためである。
【００１１】
以上の流体配管を得るための配管接続部の保全方法を本発明は提供する。この配管接続部の保全方法は、第１配管と第２配管とが６００合金によって溶接された配管接続部を有し、内部を高温高圧流体が流れる流体配管の配管接続部の保全方法であって、配管接続部を覆うように流体配管内部に６００合金から構成される第１管状体を接合する第１の接合工程と、６９０合金から構成される第２管状体を第１管状体を覆うように接合する第２の接合工程と、を備えることを特徴とする。
本発明の配管接続部の保全方法においては、第２の接合工程に先立って、第１管状体の軸方向両端部と第１配管の内周面とが形成する境界領域にステンレス鋼を用いた肉盛溶接部を形成する。しかる後に、６９０合金から構成される第２管状体を第１管状体を覆うように、かつその両端部が肉盛溶接部上に配設し、その状態で当該両端部を前記肉盛溶接部に溶接するという工程を採用することにより本発明による流体配管を得ることができる。
【００１２】
本発明において、６００合金及び６９０合金は、共にＪＩＳ　Ｇ４９０１−４に規定されるものであれば、その組成はその範囲内において適宜選定して差し支えない。また本発明において、ＳＵＳ３０９鋼も、同様にＪＩＳで規定される範囲内で適宜組成を選定することができる。
【００１３】
【発明の実施の形態】
以下、添付図面に示す実施の形態に基づいてこの発明を詳細に説明する。
図１は本発明が適用された流体配管１の実施の形態を示す部分断面図である。なお、流体配管１は、加圧水型軽水炉容器に接続され、その内部を１次冷却水が流れるものとする。
図１において、符号１０は図中矢印で示す高温高圧流体の流れる方向の上流側に配設される上流側配管、符号２０は搬送方向下流側に配設される下流側配管である。ここで、上流側配管１０は、図１に示すように、低合金鋼（ＳＱＶＡ２Ａ（Ｍｎ−Ｍｏ−Ｎｉ鋼）から構成される）から構成される基管１１と、この基管１１の内面すなわち水との接触領域に内張りされる保護管１２（ＳＵＳ３０９鋼から構成される）とを有している。これら上流側配管１０及び下流側配管２０の肉厚は５０−１００ｍｍの範囲で設定される。また、下流側配管２０は、ＳＵＳ３１６にて構成されている。そして、この流体配管１には、高温高圧流体として、３００℃程度かつ１５０気圧程度に加温加圧された水が流れる。
【００１４】
また、これら上流側配管１０及び下流側配管２０は、接続部３０によって接続されている。この接続部３０は、６００合金を用いたアーク溶接によって形成されるもので、図１に示すように、上流側配管１０に溶接させたバタリング部３１と、このバタリング部３１を介して上流側配管１０と下流側配管２０とをアーク溶接した溶接部３２とを有している。ここで、これらバタリング部３１及び溶接部３２は、共に６００合金によって構成される。
なお、保全前には、接続部３０が流体配管１内部に露出した状態、すなわち６００合金と高温高圧の水とが直接接触し得る状態で使用されている。
【００１５】
図１に示すように、流体配管１の接続部３０の内周面には、保全部４０が配設されている。保全部４０は、６００合金から構成される第１管状体４１と、ＳＵＳ３０９鋼から構成される肉盛溶接部４２と、６９０合金から構成される第２管状体４３を備えている。
次に、上述した流体配管１の保全方法を図２〜図５を参照しつつ説明する。
図２は、保全前の流体配管１の部分断面図を示している。
本発明にしたがった保全は、はじめに６００合金から構成される第１管状体４１を流体配管１内に挿入する。第１管状体４１は、図３に示すように、接続部３０を覆う所定位置に挿入される。第１管状体４１を所定位置に配設したならば溶接を行って第１管状体４１を流体配管１に接合する。第１管状体４１の一方端を上流側配管１０に、他方端を下流側配管２０に溶接しているので、接続部３０は第１管状体４１によって覆われる。この溶接は、例えばＴＩＧ溶接、レーザ溶接を適用することができる。また、溶接は第１管状体４１の全長にわたって行なうこともできる。
６００合金は、Ｐ、ＳをＰ：０．０３０ｗｔ％以上、Ｓ：０．０１０ｗｔ％以上程度と多く含むＳＵＳ３１６、低合金鋼に対して溶接を行っても、溶接割れが生じない。
【００１６】
第１管状体４１を溶接により接合した後に、図４に示すように、第１管状体４１の両端部に肉盛溶接部４２を形成する。この肉盛溶接部４２は、Ｐ、Ｓ含有量が各々Ｐ：０．０１５ｗｔ％以下、Ｓ：０．００５ｗｔ％以下に規制されたＳＵＳ３０９鋼を用いて形成される。
肉盛溶接部４２は、２つの目的のために配設される。１つは、後に配設される第２管状体４３と保護管１２、第２管状体４３と下流側配管２０とが直接接触することを阻止することである。他の１つは、第１管状体４１の流体配管１の軸方向端部を封止して環境遮断することである。なお、ＳＵＳ３０９鋼に代表されるステンレス鋼は、ＰＷＳＣＣを生ずることがなく、かつＰ、Ｓ含有量の多い低合金鋼、ＳＵＳ３１６に対して溶接を行っても溶接割れが生じない。
【００１７】
肉盛溶接部４２を形成した後に、図５に示すように、第１管状体４１および肉盛溶接部４２を覆うように第２管状体４３を挿入する。図５に示すように、６００合金で構成される第１管状体４１は第２管状体４３および肉盛溶接部４２とによって、流体配管１の内部への露出が防止される。したがって、ＰＷＳＣＣの発生を防止することができる。
次に、６９０合金によって構成される第２管状体４３は溶接によって流体配管１に接合される。より具体的には、その両端部を各々肉盛溶接部４２に対して例えばＴＩＧ溶接またはレーザ溶接によって溶接する。ここで、肉盛溶接部４２を構成するＳＵＳ３０９鋼はＰ、ＳがＰ：０．０１５ｗｔ％以下、Ｓ：０．００５ｗｔ％以下に規制されているために、第２管状体４３を接合したとても第２管状体４３を構成する６９０合金に溶接割れは生じない。なお、第２管状体４３の溶接は、その全体にわたって行なうことを許容する。
【００１８】
本実施の形態による流体配管１は、以上の構成を採用しているために、接続部３０を構成する６００合金、および第１管状体４１を構成する６００合金が、１次冷却水と接触することがないため、ＰＷＳＣＣの発生が防止される。また、第２管状体４３を構成する６９０合金が、Ｐ、Ｓを多く含む部材と接触することがないため、溶接割れを起すこともない。しかも、１次冷却水に接触するのは、６９０合金から構成される第２管状体４３の他に、ＰＷＳＣＣを招くことのないＳＵＳ３０９鋼から構成される肉盛溶接部４２のみであるから、流体配管１の接続部３０においてＰＷＳＣＣの発生を阻止することができる。
【００１９】
以上の実施の形態は、保護管１２のＰ、Ｓが多いことを前提としている。しかし、保護管１２のＰ、Ｓが各々Ｐ：０．０１５ｗｔ％以下、Ｓ：０．００５ｗｔ％以下と低い値である場合には、図６に示すように、保護管１２上に肉盛溶接部４２を設けることなく、第２管状体４３を保護管１２に直接溶接することもできる。
また、以上の実施の形態では、第１管状体４１、第２管状体４３を別途作製されたスリーブを挿入、溶接する例を示したが、本発明はこの形態に限定されない。例えば、第１管状体４１、第２管状体４３を肉盛溶接によって構成することもできる。
さらに、以上の実施の形態は、原子炉容器に接続された流体配管１を例にして説明したが、本発明の適用はこれに限定されず、応力腐食割れが生じ得る種々の環境に適用することができる。
【００２０】
【発明の効果】
以上説明したように、本発明の流体配管及び配管接続部の保全方法によれば、６００合金からなる配管接続部を６９０合金からなる管状体で覆うから、６００合金の応力腐食割れの発生を防止することができる。しかも、６９０合金とＰ、Ｓを多く含む部材との接触を回避しているため、溶接割れをも防止することができる。
【図面の簡単な説明】
【図１】本発明が適用された流体配管の実施の形態の部分断面図である。
【図２】配管接続部の保全を行う前の流体配管を示す部分断面図である。
【図３】流体配管の配管接続部に第１管状体を配設した状態を示す部分断面図である。
【図４】流体配管の配管接続部に肉盛溶接部を形成した状態を示す部分断面図である。
【図５】流体配管の配管接続部に第２管状体を配設した状態を示す部分断面図である。
【図６】本実施の形態の変形例を示す部分断面図である。
【符号の説明】
１…流体配管、１０…上流側配管、１１…基管、１２…保護管、２０…下流側配管、３０…接続部、３１…バタリング部、３２…溶接部、４０…保全部、４１…第１管状体、４２…肉盛溶接部、４３…第２管状体[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a method for maintaining a pipe connection through which a high-temperature and high-pressure fluid is conveyed, and more particularly to a method for maintaining a pipe connection welded using 600 alloy and a fluid pipe.
[0002]
[Prior art]
The pipe through which the fluid flows is usually formed with a predetermined length. Therefore, it is necessary to connect these pipes in order to obtain a long pipe. For example, a connection method of forming a connection portion using arc welding has been widely used.
Particularly, in piping of a nuclear reactor vessel in which a high-temperature and high-pressure fluid flows as a fluid, it is required that the connecting portion has high heat resistance and corrosion resistance. Conventionally, 600 parts specified in JIS G4901-4 are required. Connections have been formed by welding using alloys.
[0003]
However, in recent years, there has been a problem that a crack is formed in the connection portion welded with 600 alloy and the fluid inside leaks out. This is a phenomenon called stress corrosion cracking, and it is said that the high-temperature high-pressure fluid flowing inside the pipe comes into direct contact with the 600 alloy to which residual stress has been applied by welding. In particular, the stress corrosion cracking that occurs in the piping of the pressurized water reactor (PWR) through which the primary cooling water flows is called PWSCC.
Therefore, the 600 alloy (connection portion) exposed inside the pipe is covered with a 690 alloy (JIS G4901-4) which is superior to the 600 alloy in corrosion resistance in a wet corrosion medium and in a high-temperature atmosphere, thereby forming a high-temperature high-pressure fluid. A countermeasure for shielding the environment between the alloy and the alloy 600 is conceivable.
[0004]
For example, Japanese Unexamined Patent Application Publication No. 2002-90494 discloses that an inner end surface of an in-core instrumentation tube, which is a small-diameter tube formed of a nickel-based alloy (600 alloy) fixed to a reactor vessel by welding, has an open end. A cylindrical sleeve formed of another nickel-based alloy (690 alloy) having a greater corrosion resistance to stress corrosion cracking than the material of the in-core instrumentation tube. Insert from the open end of the in-furnace instrument tube to fit into the part where residual stress is generated by welding, then insert the laser welding tool into the inner space of this sleeve, and insert this laser welding tool into the in-furnace instrument tube. A method of reforming a pipe inner peripheral surface is disclosed in which a laser beam is irradiated from the inner peripheral surface side of the sleeve while rotating about a central axis, whereby the sleeve is clad on the inner peripheral surface of an in-core instrumentation tube. .
[0005]
[Patent Document 1]
JP-A-2002-90494 (page 1, abstract)
[0006]
[Problems to be solved by the invention]
The present inventors have studied a technique for preventing the occurrence of PWSCC using a 690 alloy, including the method disclosed in JP-A-2002-90494. As a result, it was confirmed that when the 690 alloy was welded to a member to be welded such as a pipe, welding cracks sometimes occurred in the 690 alloy.
Therefore, an object of the present invention is to provide a method capable of shielding the environment of the 600 alloy without causing welding cracks in the 690 alloy.
[0007]
[Means for Solving the Problems]
The present inventors have studied the causes of weld cracks occurring in the 690 alloy. When the amount of P (phosphorus) and S (sulfur) contained in the material constituting the member to be welded, for example, stainless steel is large (for example, P: 0.030 wt% or more, S: 0.010 wt% or more), welding is performed. It was confirmed that cracks occurred. Therefore, if a material with reduced P and S is used as the base material to be welded, welding cracks caused by P and S will not occur. However, in order to maintain an existing plant using a member to be welded containing a large amount of P and S, a technique for preventing welding cracks on the premise of containing a large amount of P and S is required.
From such a viewpoint, the present inventors propose to prevent welding crack of the 690 alloy by avoiding directly welding the 690 alloy to stainless steel containing a large amount of P and S. Therefore, the present invention is a fluid pipe having a pipe connection in which a first pipe and a second pipe are welded by a 600 alloy, and a fluid pipe through which a high-temperature and high-pressure fluid flows. A first tubular body disposed in the fluid pipe so as to cover the first tubular body, and a second tubular body made of 690 alloy and disposed in the fluid pipe so as to cover the first tubular body. It is a fluid pipe characterized by comprising.
[0008]
In the fluid pipe according to the present invention, a first tubular body made of 600 alloy that does not cause welding cracks is disposed so as to cover the pipe connection part, and a second tubular body made of 690 alloy covers the first tubular body. Therefore, it is not necessary to directly weld the 690 alloy to the first pipe and the second pipe. Therefore, even if the first pipe and / or the second pipe are made of a material containing a large amount of P and S, it is possible to prevent the occurrence of welding cracks in the 690 alloy.
[0009]
In the fluid pipe of the present invention, the first tubular body and the second tubular body can be formed by inserting and welding a separately manufactured sleeve. Further, the first tubular body and the second tubular body can be formed by overlay welding. In the former case, the connecting pipe can be covered by welding one end of the first tubular body to the first pipe and welding the other end of the first tubular body to the second pipe. This configuration can be obtained by performing TIG welding or laser welding after inserting the first tubular body into a predetermined position in the fluid pipe. The welding may be performed over the entire length of the first tubular body. Further, the first pipe and / or the second pipe is not limited to the case where the first pipe and / or the second pipe are formed of a single member, but includes a case where the first pipe and / or the second pipe are formed of a plurality of members. In the first pipe and / or the second pipe, even if the material constituting the portion to be welded to the first tubular body contains a large amount of P and S, the first tubular body is made of 600 alloy. No weld cracks occur.
[0010]
In the fluid pipe of the present invention, a sealing member made of stainless steel is provided in a boundary area between one end of the first tubular body and the first pipe and a boundary area between the other end of the first tubular body and the second pipe. It is desirable to arrange. Then, it is preferable that the second tubular body and the sealing member cover the first tubular body by welding both ends of the second tubular body onto the sealing member.
By employing the above configuration, the second tubular body exposes the first tubular body to the inside of the fluid pipe in the radial direction, and the sealing member exposes the first tubular body to the inside of the fluid pipe in the axial direction. Can be prevented. In addition, when low P and S stainless steel is used as the sealing member, even if the second tubular body made of the 690 alloy is joined by welding, it is possible to prevent the occurrence of weld cracks in the 690 alloy. . As the stainless steel constituting the sealing member, SUS309 steel in which the contents of P and S are regulated to P: 0.015 wt% or less and S: 0.005 wt% or less is desirable. This is because, when the second tubular body is welded to the sealing member, the 690 alloy constituting the second tubular body does not crack.
[0011]
The present invention provides a method for maintaining a pipe connection for obtaining the above fluid pipe. This method of maintaining a pipe connection has a pipe connection in which a first pipe and a second pipe are welded by a 600 alloy, and is a method of maintaining a pipe connection of a fluid pipe through which a high-temperature and high-pressure fluid flows. A first joining step of joining a first tubular body made of 600 alloy to the inside of the fluid piping so as to cover the pipe connection portion, and a second tubular body made of 690 alloy to cover the first tubular body. And a second joining step of joining the first and second members.
In the method for maintaining a pipe connection according to the present invention, prior to the second joining step, stainless steel is used in a boundary region formed by both ends in the axial direction of the first tubular body and the inner peripheral surface of the first pipe. Form build-up welds. Thereafter, the second tubular body made of the 690 alloy is disposed so as to cover the first tubular body, and both ends of the second tubular body are disposed on the overlay welding portion. By adopting the step of welding to the fluid pipe, the fluid pipe according to the present invention can be obtained.
[0012]
In the present invention, the composition of the 600 alloy and the 690 alloy may be appropriately selected within the range as long as both are specified in JIS G4901-4. In the present invention, the composition of SUS309 steel can also be appropriately selected within the range specified by JIS.
[0013]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, the present invention will be described in detail based on embodiments shown in the accompanying drawings.
FIG. 1 is a partial sectional view showing an embodiment of a fluid pipe 1 to which the present invention is applied. The fluid pipe 1 is connected to a pressurized water type light water reactor vessel, and primary cooling water flows inside the vessel.
In FIG. 1, reference numeral 10 denotes an upstream pipe provided on the upstream side in a direction in which the high-temperature and high-pressure fluid flows as indicated by an arrow in the figure, and reference numeral 20 denotes a downstream pipe provided on the downstream side in the transport direction. Here, as shown in FIG. 1, the upstream pipe 10 includes a base pipe 11 made of a low-alloy steel (composed of SQVA2A (Mn-Mo-Ni steel)), and an inner surface of the base pipe 11, And a protective tube 12 (made of SUS309 steel) lined in a contact area with water. The thickness of the upstream pipe 10 and the downstream pipe 20 is set in the range of 50-100 mm. The downstream pipe 20 is made of SUS316. Then, water heated and pressurized to about 300 ° C. and about 150 atm as a high-temperature and high-pressure fluid flows through the fluid pipe 1.
[0014]
The upstream pipe 10 and the downstream pipe 20 are connected by a connection portion 30. This connecting portion 30 is formed by arc welding using a 600 alloy, and as shown in FIG. 1, a buttering portion 31 welded to the upstream side pipe 10 and an upstream side pipe via this buttering portion 31. 10 and a welding portion 32 obtained by arc welding the downstream pipe 20. Here, the buttering portion 31 and the welding portion 32 are both made of 600 alloy.
Prior to maintenance, the connection portion 30 is used in a state where the connection portion 30 is exposed inside the fluid pipe 1, that is, in a state where the alloy 600 and high-temperature and high-pressure water can directly contact each other.
[0015]
As shown in FIG. 1, a maintenance part 40 is provided on the inner peripheral surface of the connection part 30 of the fluid pipe 1. The maintenance unit 40 includes a first tubular body 41 made of 600 alloy, a build-up welded part 42 made of SUS309 steel, and a second tubular body 43 made of 690 alloy.
Next, a method for maintaining the fluid pipe 1 will be described with reference to FIGS.
FIG. 2 shows a partial cross-sectional view of the fluid pipe 1 before maintenance.
In the maintenance according to the present invention, first, the first tubular body 41 made of 600 alloy is inserted into the fluid pipe 1. As shown in FIG. 3, the first tubular body 41 is inserted at a predetermined position covering the connection part 30. When the first tubular body 41 is disposed at a predetermined position, welding is performed to join the first tubular body 41 to the fluid pipe 1. Since one end of the first tubular body 41 is welded to the upstream pipe 10 and the other end of the first tubular body 41 is welded to the downstream pipe 20, the connection portion 30 is covered by the first tubular body 41. For this welding, for example, TIG welding or laser welding can be applied. Further, welding can be performed over the entire length of the first tubular body 41.
The 600 alloy does not cause weld cracking even when it is welded to SUS316 or a low-alloy steel containing P and S in an amount of about 0.030 wt% or more and S: about 0.010 wt% or more.
[0016]
After joining the first tubular body 41 by welding, as shown in FIG. 4, overlay welding portions 42 are formed at both ends of the first tubular body 41. The overlay welding portion 42 is formed using SUS309 steel in which the contents of P and S are regulated to P: 0.015 wt% or less and S: 0.005 wt% or less, respectively.
Overlay welds 42 are provided for two purposes. One is to prevent direct contact between the second tubular body 43 and the protective tube 12, and the second tubular body 43 and the downstream pipe 20, which are provided later. The other is to seal the axial end of the fluid pipe 1 of the first tubular body 41 to shield the environment. It should be noted that stainless steel typified by SUS309 steel does not cause PWSCC, and does not cause weld cracking even when welding is performed on SUS316, a low-alloy steel having a high P and S content.
[0017]
After forming the overlay weld 42, the second tubular body 43 is inserted so as to cover the first tubular body 41 and the overlay weld 42 as shown in FIG. As shown in FIG. 5, the first tubular body 41 made of the 600 alloy is prevented from being exposed to the inside of the fluid pipe 1 by the second tubular body 43 and the overlay welding portion 42. Therefore, occurrence of PWSCC can be prevented.
Next, the second tubular body 43 made of the 690 alloy is joined to the fluid pipe 1 by welding. More specifically, both end portions are welded to the overlay welding portion 42 by, for example, TIG welding or laser welding. Here, since the SUS309 steel constituting the weld overlay 42 is restricted to P and S of P: 0.015 wt% or less and S: 0.005 wt% or less, the second tubular body 43 joined very much. No welding crack occurs in the 690 alloy constituting the second tubular body 43. The welding of the second tubular body 43 is allowed to be performed over the entirety.
[0018]
Since the fluid pipe 1 according to the present embodiment adopts the above configuration, the 600 alloy forming the connecting portion 30 and the 600 alloy forming the first tubular body 41 come into contact with the primary cooling water. Therefore, the occurrence of PWSCC is prevented. In addition, the 690 alloy constituting the second tubular body 43 does not come into contact with a member containing a large amount of P and S, so that welding cracks do not occur. Moreover, since only the second tubular body 43 made of 690 alloy and the overlay welding portion 42 made of SUS309 steel that does not cause PWSCC are in contact with the primary cooling water, The occurrence of PWSCC can be prevented at the connection portion 30 of the pipe 1.
[0019]
The above embodiment is based on the premise that the protection tube 12 has many P and S. However, when P and S of the protection tube 12 are low values of P: 0.015 wt% or less and S: 0.005 wt% or less, respectively, as shown in FIG. The second tubular body 43 can be directly welded to the protective tube 12 without providing the portion 42.
Further, in the above embodiment, the example in which the first tubular body 41 and the second tubular body 43 are inserted and welded with the separately manufactured sleeve has been described, but the present invention is not limited to this embodiment. For example, the first tubular body 41 and the second tubular body 43 may be formed by overlay welding.
Furthermore, in the above embodiment, the fluid pipe 1 connected to the reactor vessel has been described as an example, but the application of the present invention is not limited to this, and is applied to various environments where stress corrosion cracking may occur. be able to.
[0020]
【The invention's effect】
As described above, according to the method for maintaining a fluid pipe and a pipe connection of the present invention, the pipe connection made of the 600 alloy is covered with the tubular body made of the 690 alloy, so that the occurrence of stress corrosion cracking of the 600 alloy is prevented. can do. In addition, since contact between the 690 alloy and a member containing a large amount of P and S is avoided, welding cracks can also be prevented.
[Brief description of the drawings]
FIG. 1 is a partial sectional view of an embodiment of a fluid pipe to which the present invention is applied.
FIG. 2 is a partial cross-sectional view showing a fluid pipe before maintenance of a pipe connection part is performed.
FIG. 3 is a partial cross-sectional view showing a state where a first tubular body is provided at a pipe connection part of a fluid pipe.
FIG. 4 is a partial cross-sectional view showing a state where a build-up weld is formed at a pipe connection part of a fluid pipe.
FIG. 5 is a partial cross-sectional view showing a state where a second tubular body is provided at a pipe connection part of a fluid pipe.
FIG. 6 is a partial cross-sectional view showing a modification of the present embodiment.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Fluid piping, 10 ... Upstream piping, 11 ... Base pipe, 12 ... Protection pipe, 20 ... Downstream piping, 30 ... Connection part, 31 ... Buttering part, 32 ... Welding part, 40 ... Maintenance part, 41 ... No. 1 tubular body, 42: overlay welding portion, 43: second tubular body

Claims (8)

第１配管と第２配管とが６００合金によって溶接された配管接続部を有し、内部を高温高圧流体が流れる流体配管であって、
前記６００合金で構成されかつ前記配管接続部を覆うように前記流体配管内に配設された第１管状体と、
６９０合金で構成されかつ前記第１管状体を覆うように前記流体配管内に配設される第２管状体と、
を備えることを特徴とする流体配管。A fluid pipe having a pipe connection part in which a first pipe and a second pipe are welded by a 600 alloy, and through which a high-temperature and high-pressure fluid flows,
A first tubular body made of the 600 alloy and disposed in the fluid pipe so as to cover the pipe connection portion;
A second tubular body made of 690 alloy and disposed in the fluid pipe so as to cover the first tubular body;
A fluid pipe comprising: 前記第１管状体および前記第２管状体が別途作製されたスリーブから構成され、前記第１管状体の一方端が前記第１の配管に溶接され、かつ前記第１管状体の他方端が前記第２配管に溶接されることにより前記第１管状体が前記配管接続部を覆うことを特徴とする請求項１に記載の流体配管。The first tubular body and the second tubular body are composed of separately manufactured sleeves, one end of the first tubular body is welded to the first pipe, and the other end of the first tubular body is The fluid pipe according to claim 1, wherein the first tubular body covers the pipe connection part by being welded to a second pipe. 前記第１管状体および前記第２管状体が肉盛溶接により形成されることを特徴とする請求項１に記載の流体配管。The fluid pipe according to claim 1, wherein the first tubular body and the second tubular body are formed by overlay welding. 前記第１管状体の一方端と前記第１配管との境界領域、および前記第１管状体の他方端と前記第２配管との境界領域にステンレス鋼から構成される封止部材が配設され、
前記第２管状体の両端部が前記封止部材に溶接されることにより前記第２管状体および前記封止部材が前記第１管状体を覆うことを特徴とする請求項１または２に記載の流体配管。A sealing member made of stainless steel is disposed in a boundary area between one end of the first tubular body and the first pipe and a boundary area between the other end of the first tubular body and the second pipe. ,
The said 2nd tubular body and the said sealing member cover the said 1st tubular body by welding both ends of the said 2nd tubular body to the said sealing member, The Claim 1 or 2 characterized by the above-mentioned. Fluid piping. 前記ステンレス鋼は、Ｐ、Ｓの含有量がＰ：０．０１５ｗｔ％以下、Ｓ：０．００５ｗｔ％以下に規制されたＳＵＳ３０９鋼であることを特徴とする請求項４に記載の流体配管。The fluid pipe according to claim 4, wherein the stainless steel is SUS309 steel in which the contents of P and S are restricted to P: 0.015 wt% or less and S: 0.005 wt% or less. 第１配管と第２配管とが６００合金によって溶接された配管接続部を有し、内部を高温高圧流体が流れる流体配管の配管接続部の保全方法であって、
前記６００合金から構成される第１管状体を前記配管接続部を覆うように前記流体配管内部に配設する第１の接合工程と、
６９０合金から構成される第２管状体を前記第１管状体を覆うように配設する第２の接合工程と、
を備えることを特徴とする配管接続部の保全方法。A method for maintaining a pipe connection of a fluid pipe in which a first pipe and a second pipe have a pipe connection portion welded with an alloy 600, and through which a high-temperature and high-pressure fluid flows,
A first joining step of disposing a first tubular body made of the 600 alloy inside the fluid pipe so as to cover the pipe connection part;
A second joining step of disposing a second tubular body made of 690 alloy so as to cover the first tubular body;
A method for maintaining a pipe connection, comprising the steps of: 前記第２の接合工程に先立って、
前記第１管状体の軸方向両端部と前記第１配管の内周面とが形成する境界領域にステンレス鋼を用いた肉盛溶接部を形成する請求項６に記載の配管接続部の保全方法。Prior to the second bonding step,
7. The method for preserving a pipe connection according to claim 6, wherein a build-up weld using stainless steel is formed in a boundary region formed by both ends in the axial direction of the first tubular body and an inner peripheral surface of the first pipe. . 前記第２管状体は、その両端部が前記肉盛溶接部上に配設されることを特徴とする請求項７に記載の配管接続部の保全方法。The method according to claim 7, wherein both ends of the second tubular body are disposed on the overlay welding portion.
JP2002297663A 2002-10-10 2002-10-10 Fluid pipe and preserving method for pipe connecting part Withdrawn JP2004132464A (en)

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2010234419A (en) * 2009-03-31 2010-10-21 Ihi Corp Structure of different material joint, and method for manufacturing the same

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2010234419A (en) * 2009-03-31 2010-10-21 Ihi Corp Structure of different material joint, and method for manufacturing the same

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