JP5979665B2 - Method for welding tube body to header and welded structure in which tube body is welded to header - Google Patents

Method for welding tube body to header and welded structure in which tube body is welded to header Download PDF

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JP5979665B2
JP5979665B2 JP2012179411A JP2012179411A JP5979665B2 JP 5979665 B2 JP5979665 B2 JP 5979665B2 JP 2012179411 A JP2012179411 A JP 2012179411A JP 2012179411 A JP2012179411 A JP 2012179411A JP 5979665 B2 JP5979665 B2 JP 5979665B2
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header
tube
welding
heat transfer
welded
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JP2014036971A (en
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英政 原田
英政 原田
誠治 菊原
誠治 菊原
久典 重森
久典 重森
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Mitsubishi Power Ltd
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Mitsubishi Hitachi Power Systems Ltd
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Description

本発明は、ボイラ装置などにおいて内部の水や水蒸気などの被加熱媒体に外部の高温ガスなどの加熱媒体からの熱を吸収させて流動させる伝熱管などの管体が、該管体の管寄せに溶接された溶接構造体に係り、特に高温高圧で高強度を有する管体と管寄せからなる溶接構造体とその溶接方法に関する。   The present invention provides a tubular body such as a heat transfer tube that causes a heated medium such as internal water or water vapor to absorb heat from a heated medium such as an external high-temperature gas in a boiler apparatus. In particular, the present invention relates to a welded structure including a tubular body and a header having high strength at high temperature and pressure, and a welding method thereof.

石炭、ガス、重原油などを燃料とする火力発電用など大出力のボイラ装置は、高温、高圧化することで効率が向上することから、近年、蒸気温度が600℃以上のボイラ装置が増加している。   High-power boiler devices such as those for thermal power generation using coal, gas, heavy crude oil, etc. as fuel improve efficiency by increasing the temperature and pressure. In recent years, boiler devices with a steam temperature of 600 ° C or higher have increased. ing.

こうした高温のボイラ装置においては、ボイラ火炉周壁にはバーナが設けられ、石炭、ガス、重原油などを燃料として、燃焼用空気と共に火炉内に供給して前記燃料の燃焼が行われる。ボイラ火炉内の上部や該上部に続くボイラ火炉からの燃焼排ガスの流路内には過熱器や再熱器などの熱交換器が配置されており、該熱交換器は運転中には内部を水蒸気などの被加熱媒体が流れる複数の伝熱管(管体と称することがある。)からなる伝熱管群(複数の伝熱管を伝熱管群と称することがある。)とその伝熱管群の管寄せから構成されており、燃焼排ガスなどの加熱媒体の熱を吸収して伝熱管内を流通する被加熱媒体である水蒸気を加熱して所定の蒸気条件にしている。   In such a high-temperature boiler device, a burner is provided on the peripheral wall of the boiler furnace, and the fuel is burned by supplying coal, gas, heavy crude oil or the like into the furnace together with combustion air. Heat exchangers such as a superheater and a reheater are arranged in the upper part of the boiler furnace and in the flow path of the combustion exhaust gas from the boiler furnace that follows the upper part of the boiler furnace. A heat transfer tube group (a plurality of heat transfer tubes may be referred to as a heat transfer tube group) composed of a plurality of heat transfer tubes (sometimes referred to as tube bodies) through which a heated medium such as steam flows, and a tube of the heat transfer tube group It is composed of a pool and absorbs the heat of a heating medium such as combustion exhaust gas to heat the steam, which is a heated medium that circulates in the heat transfer tube, to a predetermined steam condition.

図5は一般的な火力発電用ボイラの側断面構造の簡略図であり、ボイラ火炉(以下、単に火炉と称することがある。)7の内部(炉内と称することがある。)およびそれに続く燃焼排ガスの流路内との上方に設けられた伝熱管と平鋼などからなる天井壁16のさらに上方、すなわち前記炉内などとは天井壁16を境界とする炉外に設置された管寄せ1と、前記炉内の上部に設置された過熱器や再熱器などの熱交換器5を構成する前記伝熱管4群の位置関係を示すものである。 FIG. 5 is a simplified diagram of a side sectional structure of a general thermal power generation boiler, inside a boiler furnace (hereinafter sometimes simply referred to as a furnace) 7 (sometimes referred to as the inside of a furnace) and subsequent to that. A heat exchanger tube provided above the flow path of the combustion exhaust gas and a ceiling wall 16 made of flat steel or the like, that is, a header installed outside the furnace with the ceiling wall 16 as a boundary from the inside of the furnace. 1 and the positional relationship of the heat transfer tube 4 group constituting the heat exchanger 5 such as a superheater or a reheater installed in the upper part of the furnace.

前記ボイラの側断面構造では、炉内には伝熱管4群が複数のパネルまたはコイル形状で吊下げて設けてあり、燃焼排ガスの熱を高効率に吸収できるようになっており、該複数のパネルまたはコイルはその上部から複数の伝熱管4が天井壁を貫通して天井壁16の上方、すなわち炉外に設けた大径の管寄せ1方向に延伸して溶接により該管寄せ1に接続されている。すなわち管寄せ1には小径の伝熱管4が数本から多数本接続している。該管寄せ1は前記伝熱管4群と共にボイラの天井梁17に吊下げられている。 In the side cross-sectional structure of the boiler, the heat transfer tube 4 group is suspended in a plurality of panels or coils in the furnace, and can absorb the heat of combustion exhaust gas with high efficiency. From the top of the panel or coil, a plurality of heat transfer tubes 4 pass through the ceiling wall and extend above the ceiling wall 16, that is, in the direction of the large diameter header 1 provided outside the furnace and connected to the header 1 by welding. Has been. That is, several to many small-diameter heat transfer tubes 4 are connected to the header 1. Tube jogger 1 is hung on the ceiling beams 17 of the boiler with pre Kiden exchanger tube 4 groups.

図6(a)は管寄せ1に伝熱管4が多数本接続した状態を示す管寄せ側面図の一例を、図6(b)はその管寄せ1の底面から見た図、図6(c)は図6(a)のA−A線矢視図を示す。また図7に1本の伝熱管4と管寄せ1との従来技術の溶接構造を説明するための断面図を示す。図7に示す伝熱管4はスタッブ管2と中間ピース3を介して溶接により管寄せ1に接合される。   FIG. 6A is an example of a side view of the header showing a state in which a large number of heat transfer tubes 4 are connected to the header 1, FIG. 6B is a view seen from the bottom of the header 1, FIG. ) Shows an AA arrow view of FIG. FIG. 7 is a cross-sectional view for explaining a conventional welding structure between one heat transfer tube 4 and the header 1. The heat transfer tube 4 shown in FIG. 7 is joined to the header 1 by welding via the stub tube 2 and the intermediate piece 3.

図8は従来技術の管寄せ1の一部横断面とそれに接続されたスタッブ管2と中間ピース3と伝熱管4を示す模式図であり、スタッブ管2と中間ピース3と伝熱管4をそれらの管軸である中心線を実線にして示す。また、実線で示すスタッブ管2と中間ピース3、中間ピース3と伝熱管4との間に記載した前記実線に垂直な2本の短線はそれぞれスタッブ管2と中間ピース3、中間ピース3と伝熱管4との溶接部を示す。
なお後で説明するが、図7と図8とはスタッブ管2と伝熱管4とが異種材料および/または異なる外径で、中間ピース3を介して接続する例である。
FIG. 8 is a schematic diagram showing a partial cross section of a conventional header 1, a stub tube 2, an intermediate piece 3, and a heat transfer tube 4 connected thereto, and the stub tube 2, the intermediate piece 3 and the heat transfer tube 4 are shown in FIG. The center line that is the tube axis is shown as a solid line. Also, two short lines perpendicular to the solid line described between the stub tube 2 and the intermediate piece 3 and between the intermediate piece 3 and the heat transfer tube 4 indicated by the solid line are the stub tube 2 and the intermediate piece 3 and the intermediate piece 3 and the heat transfer, respectively. The welding part with the heat pipe 4 is shown.
As will be described later, FIG. 7 and FIG. 8 are examples in which the stub tube 2 and the heat transfer tube 4 are connected via the intermediate piece 3 with different materials and / or different outer diameters.

ここで、過熱器や再熱器のボイラ装置での設置位置に基づいて各部品に使用される材料について説明する。
過熱器や再熱器を構成する伝熱管4は、伝熱管群のパネルまたはコイルがその主要部であり、ボイラ火炉7内に設置されるため、火炉7内に流れる燃焼排ガスに晒されている。これに対して過熱器や再熱器を構成する管寄せ1は炉外に設置されるため燃焼排ガスに晒されていない。このため伝熱管4にはより高温強度の高い材料が使用され、管寄せ1には経済性も考慮して伝熱管4に使用する材料よりも高温強度の低いものが使用されている。
Here, the material used for each component is demonstrated based on the installation position in the boiler apparatus of a superheater or a reheater.
The heat transfer tubes 4 constituting the superheater and the reheater are exposed to the combustion exhaust gas flowing in the furnace 7 because the panel or coil of the heat transfer tube group is the main part and installed in the boiler furnace 7. . On the other hand, the header 1 constituting the superheater and the reheater is not exposed to the combustion exhaust gas because it is installed outside the furnace. For this reason, a material having higher high-temperature strength is used for the heat transfer tube 4, and a material having a lower high-temperature strength than the material used for the heat transfer tube 4 is used for the header 1 in consideration of economy.

次に、従来技術において管寄せ1に接続されるスタッブ管2について説明する。そもそもスタッブ管2は管寄せ1と共に炉外設置であり、炉内に設置される伝熱管4と同じ材料を使用する必要がないことから、スタッブ管2は管寄せ1と同材質の材料が使用される。具体的には、伝熱管4に使用する材料は、伝熱管4の内部を流れる被加熱媒体である水蒸気の過熱温度条件が560℃程度以下と低い場合にはSTBA24、STBA26、火STBA27、火STBA28、火STBA29などの2.25〜11%クロム(Cr)含有フェライト系耐熱鋼が使用され、管寄せ1及びスタッブ管2にはSTPA24等の2.25%クロム(Cr)含有フェライト系耐熱鋼が使用される。   Next, the stub tube 2 connected to the header 1 in the prior art will be described. In the first place, the stub tube 2 is installed outside the furnace together with the header 1, and since it is not necessary to use the same material as the heat transfer tube 4 installed in the furnace, the stub tube 2 is made of the same material as the header 1. Is done. Specifically, the material used for the heat transfer tube 4 is STBA24, STBA26, fire STBA27, fire STBA28 when the superheat temperature condition of water vapor, which is a heated medium flowing inside the heat transfer tube 4, is as low as about 560 ° C. or less. 2.25-11% chromium (Cr) containing ferritic heat resistant steel such as STBA29 is used, and 2.25% chromium (Cr) containing ferritic heat resistant steel such as STPA24 is used for the header 1 and the stub tube 2. used.

また、前記蒸気温度条件が560℃を超えると、伝熱管4にはSUS304、SUS309、SUS310、SUS316、SUS321、SUS347などのオーステナイト系ステンレス鋼が使用され、管寄せ1およびスタッブ管2にはSTPA24、STPA26、火STPA27、火STPA28、火STPA29などの2.25〜11%クロム(Cr)含有フェライト系耐熱鋼が使用される。さらに650℃程度になると管寄せ1およびスタッブ管2にはインコネル617(インコネルはニッケル基の超合金の商標、以下同じ)などのNi基合金が使用され、伝熱管にもインコネル617などのNi基合金が使用されることになる。   When the steam temperature condition exceeds 560 ° C., austenitic stainless steel such as SUS304, SUS309, SUS310, SUS316, SUS321, and SUS347 is used for the heat transfer tube 4, and STPA 24, for the header 1 and the stub tube 2, 2.25-11% chromium (Cr) containing ferritic heat resistant steels such as STPA26, fire STPA27, fire STPA28, fire STPA29, etc. are used. Further, when the temperature reaches about 650 ° C., Ni-base alloys such as Inconel 617 (Inconel is a trademark of a nickel-based superalloy, the same shall apply hereinafter) are used for the header 1 and the stub tube 2, and Ni-based alloys such as Inconel 617 are also used for the heat transfer tubes. An alloy will be used.

次に、前記スタッブ管2と伝熱管4とが異種材料および/または外径が異なる場合には中間ピース3がスタッブ管2と伝熱管4との間に挿入される。中間ピース3が挿入される例を図7と図8に示している。図7において、スタッブ管2の内径、管寄せ側の管孔径、中間ピース3の内径、および伝熱管4の内径は、伝熱管4からの内部流体の流動状態に悪影響を与えないようにするためほぼ同寸法の径とする。一方でスタッブ管2と伝熱管4とは使用する材料が異種材料である場合は、高温強度は伝熱管4側が大となるため、伝熱管4の肉厚に対してスタッブ管2の肉厚が大になり、スタッブ管2の外径が伝熱管より大となる。このため、中間ピース3はスタッブ管2と伝熱管4との肉厚および外径寸法調整の役目も担っている。   Next, when the stub tube 2 and the heat transfer tube 4 have different materials and / or different outer diameters, the intermediate piece 3 is inserted between the stub tube 2 and the heat transfer tube 4. An example in which the intermediate piece 3 is inserted is shown in FIGS. In FIG. 7, the inner diameter of the stub tube 2, the diameter of the hole on the header side, the inner diameter of the intermediate piece 3, and the inner diameter of the heat transfer tube 4 do not adversely affect the flow state of the internal fluid from the heat transfer tube 4. The diameter is approximately the same. On the other hand, when the materials used for the stub tube 2 and the heat transfer tube 4 are different materials, the thickness of the stub tube 2 is larger than the thickness of the heat transfer tube 4 because the high temperature strength is larger on the heat transfer tube 4 side. The outer diameter of the stub tube 2 becomes larger than that of the heat transfer tube. For this reason, the intermediate piece 3 also plays a role of adjusting the thickness and outer diameter of the stub tube 2 and the heat transfer tube 4.

また、前記中間ピース3を使用することにより、ボイラ装置の組み立て工程において、次のような理由から過熱器、再熱器を効率的に設置することができ、経済的効果が大となる。   In addition, by using the intermediate piece 3, in the boiler device assembly process, the superheater and the reheater can be efficiently installed for the following reason, and the economic effect is increased.

過熱器や再熱器を構成する伝熱管4の主要部はパネル又はコイル状に形成されており、炉内に設置される。これに対して過熱器や再熱器を構成する管寄せ1は炉外に設置される。ボイラ装置はボイラ鉄骨に吊下げられており、管寄せ1もボイラ鉄骨の最上部にある天井梁17から吊下げられる。ボイラ装置の組み立て時には、梁や柱からなる主なボイラ鉄骨を組み立ててボイラ建屋を建てた後、まずボイラ上部の部位から組み立てるのが基本手順であり、管寄せ1は据付工程の早い段階で吊上げられる。これに対して伝熱管4の主要部は炉内に設置するため、前記管寄せ1と一体化しての吊上げは行われない場合が多い。このため伝熱管4群は、管寄せ1とは別工程で、炉内と炉外との境界部に設置される天井壁16を挟んで既に炉外に設置された管寄せ1に対して炉内側に吊上げられ、該伝熱管4群から複数の伝熱管4を、天井壁16を構成する複数の天井壁管の間から貫通させて炉外に延伸させ、管寄せ1に接続して、過熱器や再熱器の組み立てが完了する。 The main part of the heat transfer tube 4 constituting the superheater or the reheater is formed in a panel or coil shape, and is installed in the furnace. On the other hand, the header 1 constituting the superheater and the reheater is installed outside the furnace. The boiler device is suspended from the boiler steel frame, and the header 1 is also suspended from the ceiling beam 17 at the top of the boiler steel frame. At the time of assembly of the boiler apparatus, after it built a boiler building to assemble the main boiler steel Ru Rana or beams and columns, first is the basic procedure to assemble from the site of the boiler top, early in the tube pulling 1 installation process It is lifted by. On the other hand, since the main part of the heat transfer tube 4 is installed in the furnace, it is often not lifted integrally with the header 1. For this reason, the heat transfer tube 4 group is a separate process from the header 1, and the furnace tube with respect to the header 1 already installed outside the furnace with the ceiling wall 16 installed at the boundary between the inside and outside of the furnace interposed therebetween. A plurality of heat transfer tubes 4 suspended from the inside of the heat transfer tube 4 group are penetrated from between the plurality of ceiling wall tubes constituting the ceiling wall 16 and extended outside the furnace, connected to the header 1, and heated. Assembling of the heater and reheater is completed.

ここで管寄せ1とスタッブ管2との溶接部は、管寄せ1一つに対して複数個所のスタッブ管2の溶接終了時に管寄せ1とスタッブ管2とが一体化しての全体での応力除去焼鈍などの溶接後熱処理を行うことで作業効率が向上すること、厚肉の管寄せ1に対してスタッブ管2の肉厚は薄く、管寄せ1とスタッブ管2との溶接時に溶接入熱の熱伝導において偏りが生じ、溶け込み深さや異種材料の合金元素の希釈量の調整が難しいなど溶接の難易度が高いことから熱処理設備、溶接および検査装置の設備が整った工場での施工が望ましく、予め工場において溶接により接続される。従って、図7、図8などに示す従来技術においては工場において前記管寄せ1にスタッブ管2が溶接されて一体となり、全体を焼鈍炉に入れて必要な後熱処理が施されたものが吊上げられる。 Here, the welded portion between the header 1 and the stub tube 2 is the total stress when the header 1 and the stub tube 2 are integrated with each other at the end of the welding of the stub tube 2 at a plurality of locations. Work efficiency is improved by performing post-weld heat treatment such as removal annealing, and the thickness of the stub tube 2 is thinner than that of the thick-walled header 1, and the welding heat input during welding of the header 1 and the stub tube 2 It is desirable to perform in a factory equipped with heat treatment equipment, welding and inspection equipment because of the high degree of difficulty in welding, such as the occurrence of bias in heat conduction and the difficulty of adjusting the penetration depth and the dilution amount of alloy elements of different materials. , And connected in advance at the factory by welding. Accordingly, FIG. 7, come together are welded stub pipe 2 to the tube pulling 1 in a factory in the prior art shown in FIG. 8 or the like, those Netsusho management required post placed across the annealing furnace has been subjected Can be lifted.

また、中間ピース3は、図7、図8などに示す従来技術において伝熱管4とスタッブ管2とが異種材料および/または外径が異なる場合に使用される。中間ピース3では前記肉厚および外径寸法調整の役目も課していることもあるが、より重要なことは、中間ピース3と伝熱管4との溶接が据付け現地での過熱器や再熱器を組み立てるための最終溶接部となることから、この溶接部が溶接後熱処理を必要とする場合には、溶接後熱処理時の保持範囲、上昇時や下降時の温度勾配、温度保持時間等の管理が必要となるため、これを避けることが望ましい。そのため、中間ピース3には伝熱管4との溶接後の後熱処理が不要となるような材料を選択し、中間ピース3は予め工場において前記スタッブ管2と溶接しておき、工場において管寄せ1、スタッブ管2および中間ピース3とが一体化されて全体で焼鈍炉に入れ必要な後熱処理を施すようにしている。 Further, the intermediate piece 3 is used when the heat transfer tube 4 and the stub tube 2 have different materials and / or different outer diameters in the prior art shown in FIGS. The intermediate piece 3 may also have the role of adjusting the thickness and the outer diameter, but more importantly, the welding of the intermediate piece 3 and the heat transfer tube 4 is performed by a superheater or reheater at the installation site. When this weld requires heat treatment after welding, the holding range during heat treatment after welding, temperature gradient during rising and falling, temperature holding time, etc. It is desirable to avoid this because it requires management. Therefore, a material is selected for the intermediate piece 3 so that post-heat treatment after welding with the heat transfer tube 4 is not required. The intermediate piece 3 is previously welded to the stub tube 2 at the factory, and the header 1 at the factory. , so that applying Netsusho management required post placed in the annealing furnace in whole integrated and stub tube 2 and the intermediate piece 3.

例えば、管寄せ1とスタッブ管2とが9%クロム含有フェライト系耐熱鋼であり、伝熱管4がSUS310などのオーステナイト系ステンレス鋼である場合、中間ピース3には伝熱管4と同材質の材料が使用される。前記管寄せ1は工場においてスタッブ管2と中間ピース3とが順番に溶接されて一体となり、全体を焼鈍炉に入れて必要な応力除去焼鈍などの溶接後熱処理が施されたものが吊上げられ、現地において中間ピース3と伝熱管4との最終溶接部が溶接され、この場合溶接後熱処理は不要である。 For example, when the header 1 and the stub tube 2 are 9% chromium-containing ferritic heat resistant steel and the heat transfer tube 4 is austenitic stainless steel such as SUS310, the intermediate piece 3 is made of the same material as the heat transfer tube 4. Is used. The tube pulling 1 and stub tube 2 and the intermediate piece 3 is integrally welded to the order in the factory, lifting the entire which after welding Netsusho management such as annealing furnace put the necessary stress relief annealing is performed In this case, the final welded portion between the intermediate piece 3 and the heat transfer tube 4 is welded. In this case, post-weld heat treatment is unnecessary.

また過熱器や再熱器では管寄せ1に数十本のスタッブ管2が溶接により接続される構造のものが多いため、前記のように、管寄せ1、スタッブ管2、中間ピース3および伝熱管4といった部品が多く、管寄せ1とスタッブ管2、スタッブ管2と中間ピース3、中間ピース3と伝熱管4との全溶接箇所数が膨大な数になる。従って、これらの溶接部は品質管理されており効率よく溶接作業が行える工場においてできるだけ多くの箇所を溶接しておき、また溶接後熱処理が必要なものは全体での溶接後熱処理を実施しておき、作業環境が劣るボイラ据付け現地では中間ピース3と伝熱管4との最終溶接部のみ溶接するようにして未然に溶接不良や事故の発生を防止している。   In addition, since many superheaters and reheaters have a structure in which dozens of stub tubes 2 are connected to the header 1 by welding, as described above, the header 1, the stub tube 2, the intermediate piece 3, and the transmission piece. There are many parts such as the heat pipe 4, and the total number of welded places between the header 1 and the stub pipe 2, the stub pipe 2 and the intermediate piece 3, and the intermediate piece 3 and the heat transfer pipe 4 is enormous. Therefore, these welds are quality-controlled and welded as many points as possible in a factory where efficient welding work can be performed, and those that require post-weld heat treatment should be subjected to post-weld heat treatment as a whole. In the boiler installation site where the working environment is inferior, only the final welded portion between the intermediate piece 3 and the heat transfer tube 4 is welded to prevent welding defects and accidents.

ここで、従来例である図7を用いて1本の伝熱管4と管寄せ1との従来の溶接構造を説明する。図7において、スタッブ管2は管寄せ1の外径面に溶接により接続するが、その前段階として、図9に図7に示すスタッブ管2を管寄せ1の外径面に接続した溶接部断面図示すように、管寄せ1へのスタッブ管2の取付位置に対して、管寄せ1の外部からドリル等により管孔1aを加工する。前記管孔1aの径とスタッブ管2との内径とは同寸法である。次に管寄せ1の外径面内側に前記管孔1aの中心と同軸でスタッブ管2の外径に合わせた寸法で数ミリ深さにエンドミル等で機械加工してスタッブ管2を差込んで設定する孔(以下、セットオン孔と称する。)1bを形成する。 Here, a conventional welding structure of one heat transfer tube 4 and the header 1 will be described with reference to FIG. In FIG. 7, the stub tube 2 is connected to the outer diameter surface of the header 1 by welding. As a previous stage, a welded portion in which the stub tube 2 shown in FIG. 9 is connected to the outer diameter surface of the header 1. As shown in the cross-sectional view, the tube hole 1 a is processed from the outside of the header 1 by a drill or the like with respect to the attachment position of the stub tube 2 to the header 1. The diameter of the tube hole 1a and the inner diameter of the stub tube 2 are the same. Next, the stub tube 2 is inserted into the outer diameter surface of the header 1 by machining with an end mill or the like to a depth of several millimeters in the dimension that is coaxial with the center of the tube hole 1a and matched to the outer diameter of the stub tube 2. A hole to be set (hereinafter referred to as a set-on hole) 1b is formed.

次に、前記セットオン孔1bに管体を差し込み後はスタッブ管2と管寄せ1とを溶接により接続する。溶接部の強度は溶接脚長L1およびのど厚L2の寸法により確保するが、その必要脚長L1およびのど厚L2が得られる外径寸法および深さの孔(以下、座繰り孔と称する。)1cを前記セットオン孔1bの外径方向にエンドミル等で機械加工しておく。セットオン孔1bと座繰り孔1cの加工後は、端面を面取りしたスタッブ管2を前記セットオン孔1bに差し込み、仮止め等によりスタッブ管2と管寄せ1とを仮設定する。座繰り孔1cとスタッブ管2の端部とは外部よりTIGやMIGなどによる隅肉溶接方法により溶接脚長を確保して接続する。 Next, after inserting the tube body 4 into the set-on hole 1b, the stub tube 2 and the header 1 are connected by welding. The strength of the welded portion is ensured by the dimensions of the weld leg length L1 and the throat thickness L2, and a hole (hereinafter referred to as a countersink hole) 1c having an outer diameter and a depth from which the required leg length L1 and throat thickness L2 can be obtained. Machined with an end mill or the like in the outer diameter direction of the set-on hole 1b. After processing the set-on hole 1b and the counterbore 1c, the stub tube 2 whose end face is chamfered is inserted into the set-on hole 1b, and the stub tube 2 and the header 1 are temporarily set by temporary fixing or the like. The countersunk hole 1c and the end of the stub tube 2 are connected from the outside by securing a weld leg length by a fillet welding method such as TIG or MIG.

図9に示すように、隅肉溶接により、スタッブ管2側と管寄せ1側の溶接金属層10の外側にそれぞれ溶接熱影響部8が形成される。この溶接熱影響部8は金属組織が溶接時の高熱による急速加熱および熱伝達による急速冷却によりスタッブ管2及び管寄せ1の母材組織から変化しており、材料によっては硬化するため、溶接後の組織を改善するための熱処理や残留応力を除去するための熱処理を行う必要がある。従来の溶接構造ではセットオン孔1bの底部および底部近傍とスタッブ管2の端面および端面近傍の側面側には隙間が残っており、該隙間と座繰り孔1cの底部とスタッブ管の端面近傍とを溶融した溶接金属層10ののど厚方向の最奥部との間において切り欠き構造となっていることから運転中に割れ8aが生じる起点になる可能性がある。また、管寄せ1の外径面と溶接金属10との境界部の溶接熱影響部8の一部は、管寄せ1に働く内圧18による応力の方向に対して垂直方向に位置していることから、この部分で応力が大きくなった場合には運転中に割れ8bが生じる起点になる可能性がある。 As shown in FIG. 9, the weld heat affected zone 8 is formed outside the weld metal layer 10 on the stub tube 2 side and the header 1 side by fillet welding. The weld heat-affected zone 8 changes from the base metal structure of the stub tube 2 and the header 1 due to rapid heating due to high heat during welding and rapid cooling due to heat transfer. Therefore, it is necessary to perform a heat treatment for improving the structure and a heat treatment for removing residual stress. In the conventional welded structure, gaps remain on the bottom of the set-on hole 1b and in the vicinity of the bottom and on the end face of the stub tube 2 and the side surface near the end face, and the gap, the bottom of the countersink hole 1c, and the vicinity of the end face of the stub tube 2 Since it has a notch structure between the weld metal layer 10 and the innermost part in the throat thickness direction, the crack 8a may occur during operation. In addition, a part of the weld heat affected zone 8 at the boundary between the outer diameter surface of the header 1 and the weld metal 10 is located in a direction perpendicular to the direction of stress due to the internal pressure 18 acting on the header 1. Therefore, when the stress increases in this portion, there is a possibility that the crack 8b is generated during operation.

次に、スタッブ管2と中間ピース3とは予めそれぞれの接続側の端部を機械加工により、突合せ溶接用の開先に加工しておき、スタッブ管2と中間ピース3とを仮止め溶接等により仮設定した後に完全溶け込み突合せ溶接により接続する。このスタッブ管2と中間ピース3の溶接部は管寄せ1およびスタッブ管2の材料と伝熱管4の材料の組み合せにより異種材料溶接継手となることがある。この場合、現地据付での品質管理や作業性を考慮し最終溶接後に高温および長時間の後熱処理が必要とならないように中間ピース3に使用する材料を選択する。例えば、管寄せ1およびスタッブ管2が2.25〜11%クロム(Cr)含有フェライト系耐熱鋼で、伝熱管4がオーステナイト系ステンレス鋼、またはNi基合金鋼の場合には、中間ピース3として伝熱管4と同種材料が使用される。この場合、スタッブ管2と中間ピース3とは異種材料溶接継手となる。   Next, the stub tube 2 and the intermediate piece 3 are previously machined into end portions for butt welding by machining, and the stub tube 2 and the intermediate piece 3 are temporarily welded. After the temporary setting, the connection is made by full penetration butt welding. The welded portion between the stub tube 2 and the intermediate piece 3 may become a dissimilar material weld joint by combining the material of the header 1 and the stub tube 2 and the material of the heat transfer tube 4. In this case, considering the quality control and workability in the field installation, the material used for the intermediate piece 3 is selected so that high-temperature and long-time post heat treatment is not required after final welding. For example, when the header 1 and the stub tube 2 are 2.25 to 11% chromium (Cr) -containing ferritic heat resistant steel and the heat transfer tube 4 is austenitic stainless steel or Ni-base alloy steel, the intermediate piece 3 is used. The same kind of material as the heat transfer tube 4 is used. In this case, the stub tube 2 and the intermediate piece 3 are dissimilar material weld joints.

管寄せ1およびスタッブ管2がNi基合金鋼で、伝熱管4が前記オーステナイト系ステンレス鋼の場合は、中間ピース3として伝熱管4と同種材料が使用され、スタッブ管2と中間ピース3とは異種材料溶接継手となる。一方、伝熱管4がNi基合金の場合は、中間ピース3を使用する必要は無い。前記スタッブ管2と中間ピース3とが異種材料溶接継手で、中間ピース3にNi基合金を使用した場合には、スタッブ管2と中間ピース3との溶接においては、中間ピース3の成分と同一な共金系溶接材料が使用される。   When the header 1 and the stub tube 2 are Ni-base alloy steel and the heat transfer tube 4 is the austenitic stainless steel, the same kind of material as the heat transfer tube 4 is used as the intermediate piece 3, and the stub tube 2 and the intermediate piece 3 are It becomes a dissimilar material welded joint. On the other hand, when the heat transfer tube 4 is a Ni-based alloy, it is not necessary to use the intermediate piece 3. When the stub tube 2 and the intermediate piece 3 are dissimilar material weld joints and a Ni-based alloy is used for the intermediate piece 3, the components of the intermediate piece 3 are the same in the welding of the stub tube 2 and the intermediate piece 3. A common metal welding material is used.

発電プラント用の大型ボイラにおいては、高温部の管寄せ1や主蒸気管等の厚肉大径の配管には、従来STPA24等の2.25%クロム(Cr)含有フェライト系耐熱鋼が長年用いられてきた。近年、二酸化炭素の排出抑制を背景として、特に石炭焚火力発電プラントではプラント効率向上のため蒸気温度が向上しつつあり、現在では主蒸気温度600℃のプラントも稼動している。   In large boilers for power plants, 2.25% chromium (Cr) -containing ferritic heat-resistant steel such as STPA24 has been used for many years for thick-walled large-diameter pipes such as headers 1 and main steam pipes in high-temperature parts. Has been. In recent years, against the backdrop of carbon dioxide emission suppression, particularly in a coal-fired thermal power plant, the steam temperature is being improved to improve the plant efficiency. Currently, a plant with a main steam temperature of 600 ° C. is also operating.

一方、更なるプラント効率の向上を目指して主蒸気温度650℃、700℃の発電プラント開発も進められている。600℃のような高温域では、高温強度及び耐食性に問題があるため、もはや従来の2.25%クロム(Cr)含有フェライト系耐熱鋼の適用は不可能となる。このため高温部の管寄せ1や主蒸気管等の厚肉大径の配管に高クロムフェライト系の耐熱鋼である火STPA28に代表される9Cr−1Mo−V−Nb鋼、火STPA29に代表される9Cr−0.5Mo−W−V−Nb鋼(%を記載省略。これらの鋼材を以下、9%Crフェライト系耐熱鋼ということがある。)や火SUS410J3に代表される11Cr−0.5Mo−W−Cu−Nb−V鋼(%を記載省略。以下、12%Crフェライト系耐熱鋼ということがある。)等が用いられるようになった。   On the other hand, development of a power plant with main steam temperatures of 650 ° C. and 700 ° C. is being promoted with the aim of further improving plant efficiency. In a high temperature region such as 600 ° C., there is a problem in high temperature strength and corrosion resistance, so that the conventional 2.25% chromium (Cr) containing ferritic heat resistant steel can no longer be applied. For this reason, it is represented by 9Cr-1Mo-V-Nb steel represented by fire STPA28, which is a high-chromium ferritic heat-resistant steel, and fire STPA29, for thick-walled and large-diameter pipes such as the header 1 of the high temperature part and the main steam pipe. 9Cr-0.5Mo-W-V-Nb steel (% not shown. These steel materials may be hereinafter referred to as 9% Cr ferritic heat resistant steel) and 11Cr-0.5Mo represented by fire SUS410J3. -W-Cu-Nb-V steel (% omitted). Hereinafter, 12% Cr ferritic heat-resistant steel may be used.

図7、図9に示す溶接構造を形成する方法は、主として蒸気温度が560℃以下である従来のボイラ火炉に用いられていたものであり、代表的な材料としては管寄せ1がSTPA24に代表される2.25%Cr−1%Moのフェライト系耐熱鋼であり、従来は問題なく適用されてきたが、蒸気温度がより高温で使用される前記9%Crフェライト系耐熱鋼、12%Crフェライト系耐熱鋼では、高温下での長時間使用により溶接熱影響部(HAZ部)8でクリープ損傷による割れが発生しやすくなることが予見され、構造的に問題となる可能性があった。   The method for forming the welded structure shown in FIG. 7 and FIG. 9 is mainly used in a conventional boiler furnace having a steam temperature of 560 ° C. or less. As a typical material, the header 1 is represented by the STPA 24. 2.25% Cr-1% Mo ferritic heat resistant steel, which has been applied without any problem in the past, but the 9% Cr ferritic heat resistant steel used at higher steam temperature, 12% Cr In the ferritic heat resistant steel, it is predicted that cracks due to creep damage are likely to occur in the weld heat-affected zone (HAZ portion) 8 due to long-term use at high temperatures, which may cause structural problems.

特開2008−80347号公報JP 2008-80347 A

本出願人は、フェライト系耐熱鋼の管寄せ1に開先部を設け、前記管寄せ1にNi基合金から成るスタッブ管2をNi基合金からなる溶接金属材料で溶接により接続する場合において管寄せ1側に割れが発生し易いことを低減するために、管寄せ1に設けた開先内に予めリンと硫黄の合計含有率が0.02重量%以下に規制されたNi基合金からなる溶接金属材料で肉盛溶接によるバタリング層(以下、バタリング層と称することがある。)を設け、該バタリング層をさらに開先加工し、管寄せに直接溶接するのではなく、前記バタリング層に伝熱管を溶接する溶接構造体を提案した(特許文献)。 The present applicant provides a groove portion in a header 1 of ferritic heat-resistant steel, and connects the stub tube 2 made of Ni-base alloy to the header 1 by welding metal material made of Ni-base alloy. In order to reduce the possibility of cracking on the side of the header 1, it is made of a Ni-based alloy in which the total content of phosphorus and sulfur is regulated in advance to 0.02% by weight or less in the groove provided in the header 1. A weld metal layer is provided with a buttering layer (hereinafter also referred to as a buttering layer) by overlay welding, and the buttering layer is further grooved and welded directly to the header, instead of being transferred to the buttering layer. A welded structure that welds heat pipes was proposed (Patent Document 1 ).

前記特許文献記載の溶接構造体は、第1ステップとして図10の断面図に示す9%クロム(Cr)フェライト系耐熱鋼の管寄せ1の外径面内に設けた開先部に、リンと硫黄の合計含有率が0.02重量%以下に規制されたNi基合金を予め肉盛溶接してバタリング層14を設け、第2ステップとして図10に示すようにバタリング層14を開先加工した後にNi%:44.5−Cr%:20.0〜24.0−Co%:10.0〜溶接部11.0−Mo%:8.0〜10.0(いずれも重量%)からなるNi基合金(インコネル617(商標、以下同じ)やインコネル625)から成るスタッブ管2を同じくNi基合金(インコネル617(商標)やインコネル625)からなる共金系溶接金属材料で溶接して、図11に示すNi基合金(インコネル617(商標)やインコネル625)からなる溶接金属層15を形成したものである。 As a first step, the welded structure described in Patent Document 1 is provided with a groove portion provided in the outer diameter surface of the header 1 of 9% chromium (Cr) ferritic heat resistant steel shown in the cross-sectional view of FIG. A Ni-based alloy whose total content of sulfur and sulfur is regulated to 0.02% by weight or less is preliminarily welded to provide a buttering layer 14, and as a second step, the buttering layer 14 is grooved as shown in FIG. After Ni%: 44.5-Cr%: 20.0 to 24.0-Co%: 10.0 to welded portion 11.0-Mo%: 8.0 to 10.0 (both wt%) A stub tube 2 made of a Ni-based alloy (Inconel 617 (trademark; the same applies hereinafter) and Inconel 625) is welded with a metal alloy weld metal material also made of a Ni-based alloy (Inconel 617 (trademark) or Inconel 625), The Ni-based alloy shown in FIG. Connell 617 is obtained by forming a weld metal layer 15 made of (R) or Inconel 625).

すなわち特許文献記載の溶接構造体は、工場において管寄せ1とスタッブ管2、あるいは必要に応じて管寄せ1とスタッブ管2と中間ピース3とを一体化し必要に応じて溶接後熱処理を行った後に据付け現地に搬送することを前提としており、溶接構造体の構成としては従来技術の図7、図8と同様の構成になっている。 That is, the welded structure described in Patent Document 1 is manufactured by integrating the header 1 and the stub tube 2 or, if necessary, the header 1, the stub tube 2 and the intermediate piece 3 at the factory, and performing post-weld heat treatment as necessary. After that, it is assumed that it will be transported to the installation site, and the structure of the welded structure is the same as that of FIGS. 7 and 8 of the prior art.

また、特許文献記載の溶接構造体によれば、図10に示すようにスタッブ管2を接続する前に管寄せ1のスタッブ管2の取り付け部に対して、肉盛溶接前と肉盛溶接後との2回、開先加工を行う必要がある。また前記開先加工前には通常は、管寄せ1に管孔を空けておくが、前記管孔を避けての肉盛は容易でなく、管孔側に肉盛部分が張り出すように積層し張り出した部分は管孔径に仕上げるために切削する必要がある。このときNi基合金からなる溶接金属の加工は容易ではない。 Moreover, according to the welded structure described in Patent Document 1, before connecting the stub tube 2 as shown in FIG. It is necessary to perform groove processing twice later. In addition, a pipe hole is usually made in the header 1 before the groove processing, but it is not easy to build up avoiding the pipe hole, so that the built-up portion projects over the pipe hole side. and overhanging portion should be cut cutting to finish the tube bore diameter. At this time, it is not easy to process a weld metal made of a Ni-based alloy.

本発明の課題は、ボイラ装置等において伝熱管などの管体を該管体の管寄せに溶接する方法と溶接構造体において、主蒸気温度が560℃以上といった高い温度である場合においても、長時間使用による溶接熱影響部(HAZ部)でのクリープ損傷による割れが発生しにくい品質信頼性の高い構造を有しており、また管寄せと伝熱管(管体)との溶接構造体の構成が最小単位であり、開先加工などの機械加工が最小限であり、工場および据付現地での溶接および熱処理の管理が容易な溶接方法と溶接構造体を提供することにある。   The subject of the present invention is a method and welding structure for welding a tubular body such as a heat transfer tube to a header of a tubular body in a boiler apparatus or the like, even when the main steam temperature is as high as 560 ° C. or higher. It has a highly reliable structure in which cracks due to creep damage at the heat affected zone (HAZ) due to time use are unlikely to occur, and the structure of the welded structure between the header and the heat transfer tube (tube) Is a minimum unit, and machining such as groove processing is minimal, and it is an object to provide a welding method and a welded structure that can easily manage welding and heat treatment at a factory and an installation site.

本発明の上記課題は次の解決手段で解決される。
請求項1記載の発明は、管体4を管寄せ1に溶接する方法において、前記管寄せ1の外径面上の管体取り付け位置に所定の肉盛高さの溶接金属層10を積層して設けて管寄せ1の円周方向と平行な外径面上領域に溶接熱影響部8を形成させた後、該溶接金属層10を含む前記外径面上の管体取り付け位置に管孔1aを加工すると共に、前記溶接金属層10の高さ方向の端面に一方の突合せ溶接開先の片側を形成し、これに端面に他方の突合せ溶接開先の片側を形成した管体4を突き合わせて完全溶け込み突き合せ溶接により前記管寄せ1に管体4を接続することを特徴とする管体を管寄せに溶接する方法である。
The above-mentioned problem of the present invention is solved by the following means.
According to the first aspect of the present invention, in the method for welding the tubular body 4 to the header 1, a weld metal layer 10 having a predetermined build-up height is laminated at a tubular body mounting position on the outer diameter surface of the header 1. The weld heat-affected zone 8 is formed in a region on the outer diameter surface parallel to the circumferential direction of the header 1 , and then a pipe hole is formed at the tube attachment position on the outer diameter surface including the weld metal layer 10. While processing 1a, the pipe body 4 which formed one side of one butt welding groove on the end surface of the welding metal layer 10 in the height direction, and formed one side of the other butt welding groove on this end surface is butt-matched Te is a full penetration butt method of welding to thereby KanYadoriki the tubular body, characterized in that connecting pipe 4 to the pipe shifting 1 by welding.

請求項2記載の発明は、管寄せ1、該管寄せ1に接続する管体4、溶接金属層10の積層に使用する溶接材料および突合せ溶接に使用する溶接材料の材質がそれぞれ、フェライト系耐熱鋼、オーステナイト系ステンレス鋼またはNi基合金、Ni基合金およびNi基合金であることを特徴とする請求項1記載の管体4を管寄せ1に溶接する方法である。   According to the second aspect of the present invention, the material of the header 1, the pipe 4 connected to the header 1, the welding material used for laminating the weld metal layer 10 and the welding material used for the butt welding are respectively ferritic heat resistant. The method according to claim 1, wherein the pipe body 4 is welded to the header 1, which is steel, austenitic stainless steel, Ni-base alloy, Ni-base alloy, or Ni-base alloy.

例えば、管寄せ1は火STPA28に代表される9重量%Cr−1重量%Mo−VNb鋼または火STPA29に代表される9重量%Cr−0.5重量%Mo−1.8重量%W−VNb鋼からなるフェライト系鋼であり、管寄せ1に接続する管体4がSUS304、SUS309、SUS310、SUS316、SUS321、SUS347などのオーステナイト系ステンレス鋼または、Ni基合金(インコネル617(商標))やインコネル625などであり、溶接金属層10の積層に使用する溶接材料はNi重量%44.5−Cr重量%20.0〜24.0−Co重量%10.0〜15.0−Mo重量%8.0〜10.0からなるNi基合金(インコネル617(商標))やインコネル625およびSFA―5.14、ERNiCr−3相当の溶接材料であり、突合せ溶接に使用する溶接材料は前記と同じくNi基合金(インコネル617(商標)、インコネル625およびSFA―5.14、ERNiCr−3相当等の溶接材料などを用いる。   For example, the header 1 is composed of 9 wt% Cr-1 wt% Mo-VNb steel represented by fire STPA28 or 9 wt% Cr-0.5 wt% Mo-1.8 wt% W- represented by fire STPA29. Ferritic steel made of VNb steel, and the tube 4 connected to the header 1 is austenitic stainless steel such as SUS304, SUS309, SUS310, SUS316, SUS321, SUS347, or Ni-based alloy (Inconel 617 (trademark)), The welding material used for laminating the weld metal layer 10 such as Inconel 625 is Ni weight% 44.5-Cr weight% 20.0 to 24.0-Co weight% 10.0 to 15.0-Mo weight%. Ni-based alloy (Inconel 617 (trademark)) composed of 8.0 to 10.0, Inconel 625, SFA-5.14, ERNiCr-3 phase The welding material used for the butt welding is a Ni-based alloy (such as a welding material such as Inconel 617 (trademark), Inconel 625, SFA-5.14, ERNiCr-3, or the like).

請求項3記載の発明は、ボイラ火炉7内に設けられた伝熱管群から火炉7外に伸延した管体4が、該火炉7外に設けられた管寄せ1に溶接された溶接構造体であって、前記溶接構造体は、管寄せ1と、該管寄せ1の外径面上の管体取付け位置に積層して設けられた所定の肉盛高さを有し、略中心部に管孔1aが加工されて管寄せ1の円周方向と平行な外径面上領域に溶接熱影響部8が形成されるようにした溶接金属層10と、一方の突合せ溶接開先の片側を加工形成した前記溶接金属層10の端面、他方の突合せ溶接開先の片側を加工形成した前記管体4の端面とを完全突合せ溶接した突き合わせ溶接部11と前記伝熱管群から火炉7外に伸延した管体4からなることを特徴とする管体が管寄せに溶接された溶接構造体である。 The invention according to claim 3 is a welded structure in which a tubular body 4 extending from a heat transfer tube group provided in a boiler furnace 7 to the outside of the furnace 7 is welded to a header 1 provided outside the furnace 7. The welded structure has a header 1, and a predetermined build-up height provided at a tube attachment position on the outer diameter surface of the header 1, and substantially at the center. a weld metal layer 10 lumen 1a is as weld heat affected zone 8 is formed in the circumferential direction and parallel to the radially outer surface region of the process tube jogger 1, one side of the hand of the butt weld groove and an end face of the weld metal layer 10 which is processed and formed, the furnace and where the tube 4 of the end surface and fully butt welded butt weld 11 on one side was processed and formed of butt weld groove other hand from the heat transfer tube group 7 is a welded structure in which a tubular body characterized by comprising a tubular body 4 extending outward is welded to a header.

請求項4記載の発明は、請求項3記載の管寄せ1の代わりにマニホールドを用いることを特徴とする溶接構造体である。
請求項5記載の発明は、請求項3記載の溶接構造体を過熱器及び再熱器の少なくともいずれかの熱交換器とすることを特徴とするボイラ装置である。
The invention of claim 4, wherein is a welding structure you comprises using the manifold in place of claim 3, wherein the tube pulling 1.
The invention of claim 5, wherein is a boiler apparatus which is characterized in that at least one of the heat exchanger of the superheater and reheater of the welding structure according to claim 3, wherein.

請求項1〜5記載の発明によれば、管体4を該管体4の管寄せ1に溶接する方法と溶接構造体において、管寄せ1の外径面上に所定の高さを有するように積層による溶接金属層10を形成して管寄せ1の円周方向と平行な外径面上領域に溶接熱影響部8を形成させるようにして、該溶接金属層10を開先加工するようにしたので、管体4を管寄せ1に完全溶け込み突合せ溶接を行うのに必要な空間を確保することができ、同時に、前記のように完全溶け込み突合せ溶接時の作業姿勢も溶接部の品質確保面で信頼性の高い作業姿勢が可能となる。また、管寄せ1の外径面内への開先加工が不要となり機械加工が最小限で済む。
According to the first to fifth aspects of the present invention, in the method and welding structure for welding the tubular body 4 to the header 1 of the tubular body 4, the outer diameter surface of the header 1 has a predetermined height. The weld metal layer 10 is formed by laminating, and the weld heat affected zone 8 is formed in the region on the outer diameter surface parallel to the circumferential direction of the header 1 so that the weld metal layer 10 is grooved. As a result, it is possible to secure the space necessary for complete penetration butt welding of the tubular body 4 to the header 1, and at the same time, the working posture during the complete penetration butt welding as described above ensures the quality of the welded portion. A highly reliable work posture is possible. In addition, groove processing in the outer diameter surface of the header 1 is not required, and machining is minimized.

特に請求項2記載の発明によれば、スタッブ管2、中間ピース3を使用しないため溶接箇所数の低減が行え、スタッブ管2、中間ピース3を使用する場合に比べて大幅な作業改善が可能となる。   In particular, according to the second aspect of the present invention, since the stub tube 2 and the intermediate piece 3 are not used, the number of welding points can be reduced, and the work can be greatly improved as compared with the case where the stub tube 2 and the intermediate piece 3 are used. It becomes.

また、請求項1〜5記載の発明によれば、ボイラ装置等において主蒸気温度が560℃以上といった高い温度である場合においても、長時間使用による溶接熱影響部(HAZ部)8でのクリープ損傷による割れが発生しにくい品質信頼性の高い溶接方法と溶接構造体を提供できる。   Further, according to the first to fifth aspects of the present invention, even when the main steam temperature is a high temperature of 560 ° C. or higher in a boiler apparatus or the like, the creep in the welding heat affected zone (HAZ portion) 8 due to long-term use is achieved. It is possible to provide a welding method and a welded structure with high quality and reliability in which cracking due to damage is unlikely to occur.

本発明の管寄せの外径面上に積層により溶接金属層を設け(図1(a))、溶接金属層の中央部に管孔および突合せ溶接開先部を形成する(図1(b))手順を示す管寄せ断面図である。A weld metal layer is provided by lamination on the outer diameter surface of the header of the present invention (FIG. 1 (a)), and a tube hole and a butt weld groove are formed at the center of the weld metal layer (FIG. 1 (b)). ) It is a sectional view of the header showing the procedure. 図1の溶接金属層の中央部に形成した管孔および突合せ溶接開先部とを設けて管寄せの外径面上から所定の高さに突合せ溶接開先部を形成し、先端に溶接開先部を形成した管体を前記溶接金属層の開先部に突き合わせて(図2(a))、完全溶け込み突合せ溶接部を形成する(図2(b))手順を説明する溶接構造体の断面図である。A tube hole and a butt weld groove formed at the center of the weld metal layer in FIG. 1 are provided to form a butt weld groove at a predetermined height from the outer diameter surface of the header, and a weld is opened at the tip. was to form a front portion tubular body against the groove portion of the weld metal layer (FIG. 2 (a)), full penetration butt forming the weld (FIG. 2 (b)) the procedure is described welded structure It is sectional drawing. 本発明の管寄せの外径面上に伝熱管を接続した溶接構造体の外観図(図3(a))と図3(a)の管寄せ外径面内に伝熱管を溶接する時の溶接部の拡大断面図((図3(b))である。FIG. 3A is an external view of a welded structure in which a heat transfer tube is connected to the outer diameter surface of the header of the present invention (FIG. 3A), and the heat transfer tube is welded to the outer diameter surface of the header of FIG. It is an expanded sectional view ((Drawing 3 (b)) of a welding part. 管寄せ外径面上にスタッブ管を接続する従来の図10、図11に示す溶接技術を適用した場合の溶接構造体の外観図(図4(a))と図4(a)の管寄せ外径面内にスタッブ管を溶接する時の溶接部の拡大断面図(図4(b))である。Appearance of welded structure (FIG. 4 (a)) and the header shown in FIG. 4 (a) when the conventional welding technique shown in FIGS. 10 and 11 in which a stub pipe is connected to the outer diameter surface of the header is applied. It is an expanded sectional view (Drawing 4 (b)) of a welding part when welding a stub pipe in an outside diameter surface. 発電プラントで用いられる大型ボイラの火炉とその後流側の燃焼ガス流路の側断面構造の簡略図である。It is a simplified diagram of a side cross-sectional structure of a furnace for a large boiler used in a power plant and a combustion gas passage on the downstream side. 発電プラントで用いられる大型ボイラの過熱器や再熱器などの管寄せに多数の伝熱管が接続した状態を示す管寄せ側面図(図6(a))、管寄せ底面図(図6(b))、図6(a)のA−A線矢視図(図6(c))である。A side view of the header (FIG. 6 (a)) and a bottom view of the header (FIG. 6 (b)) showing a state in which a large number of heat transfer tubes are connected to a header such as a superheater or reheater of a large boiler used in a power plant. )), And a view taken along the line AA in FIG. 6A (FIG. 6C). 従来の伝熱管を接続した管寄せ断面図である。It is a header cross-sectional view to which a conventional heat transfer tube is connected. 従来の伝熱管を接続した管寄せ断面図であり、管軸に対して垂直の断面図を簡略化した図である。It is a cross-sectional view of a header connected with a conventional heat transfer tube, and is a simplified view of a cross-sectional view perpendicular to the tube axis. 図7の管寄せとスタッブ管の溶接部断面の拡大図である。FIG. 8 is an enlarged view of a cross section of a welded portion of the header and the stub tube of FIG. 7. 従来技術の管寄せの外径面内に設けた開先部に予めバタリング溶接層を設けた後に再び開先部を設けてスタッブ管を溶接する準備中の構造体の断面図である。It is sectional drawing of the structure in preparation for welding a stub pipe by providing a groove part again after providing a buttering weld layer beforehand in a groove part provided in the outside diameter surface of a conventional header. 図10に示す管寄せとスタッブ管とを溶接して溶接金属層を形成した溶接構造体の断面図である。It is sectional drawing of the welded structure which welded the header shown in FIG. 10, and the stub pipe, and formed the weld metal layer.

本発明の実施例を図面と共に説明する。
図5は一般的な火力発電用ボイラの側断面構造の簡略図であり、ボイラ火炉(以下、単に火炉と称することがある)7の内部(炉内と称することがある)と外部およびそれに続く燃焼排ガスの流路の外部(炉外と称することがある)との境界に設けた伝熱管と平鋼などからなる天井壁16の上方、すなわち炉外に設置された管寄せ1と、火炉7内の上部に設置された過熱器や再熱器などの熱交換器5を構成する前記伝熱管群の位置関係を示すものである。前記ボイラの側断面構造では、火炉7内には伝熱管群が複数のパネルまたはコイル形状で吊下げて設けてあり、燃焼排ガスの熱を高効率に吸収できるようになっており、該複数のパネルまたはコイルの上部方向に複数の伝熱管4が天井壁16を貫通して天井壁16の上方、すなわち炉外に設けた大径の管寄せ1に溶接により接続されている。すなわち管寄せ1には小径の伝熱管が数本から多数本接続している。
Embodiments of the present invention will be described with reference to the drawings.
FIG. 5 is a simplified diagram of a side sectional structure of a general boiler for thermal power generation, inside (sometimes referred to simply as a furnace) 7 of a boiler furnace (hereinafter sometimes referred to simply as a furnace), outside, and subsequent thereto. Above the ceiling wall 16 made of a heat transfer tube and flat steel or the like provided at the boundary with the outside of the combustion exhaust gas flow path (sometimes referred to as the outside of the furnace), that is, the header 1 installed outside the furnace, and the furnace 7 The positional relationship of the said heat exchanger tube group which comprises the heat exchangers 5, such as a superheater and a reheater installed in the upper part is shown. In the side cross-sectional structure of the boiler, the heat transfer tube group is provided in the furnace 7 so as to be suspended in a plurality of panels or coils, so that the heat of the combustion exhaust gas can be absorbed with high efficiency. A plurality of heat transfer tubes 4 penetrates the ceiling wall 16 in the upper direction of the panel or coil and is connected to the large-diameter header 1 provided above the ceiling wall 16, that is, outside the furnace, by welding. That is, several to many small-diameter heat transfer tubes are connected to the header 1.

図6(a)は管寄せ1に伝熱管4(従来技術では伝熱管4の代わりにスタッブ管2を使用)が多数本接続した状態を示す管寄せ側面図の一例、図6(b)はその管寄せ1の底面図、図6(c)は図6(a)のA−A線矢視図を示しており、図6において従来技術では管寄せ1に接続しているのはスタッブ管2であるが、本発明の場合には伝熱管4が管寄せ1の外径面上に積層して設けた溶接金属層10(図3参照)に接続されている。ここでは伝熱管4は作図の都合上、煩雑になるのを防止するために先端部のみ図示している。   FIG. 6A is an example of a side view of a header showing a state in which a large number of heat transfer tubes 4 (in the conventional technology, stub tubes 2 are used instead of the heat transfer tubes 4) are connected to the header 1, and FIG. The bottom view of the header 1, FIG. 6 (c) shows an AA arrow view of FIG. 6 (a). In FIG. 6, the stub tube is connected to the header 1 in the prior art. However, in the case of the present invention, the heat transfer tube 4 is connected to a weld metal layer 10 (see FIG. 3) provided by being laminated on the outer diameter surface of the header 1. Here, only the tip of the heat transfer tube 4 is shown in order to prevent the heat transfer tube 4 from becoming complicated for the sake of drawing.

なお、図5において熱交換器5の主部である矩形部を斜線で示しているが、これは1枚のパネルまたはコイルを示しており、前記パネルまたはコイルが紙面奥行き方向に十数枚〜数十枚が隣接して設けられており、それらの複数のパネルまたはコイルから複数の伝熱管4が図6に示す管寄せ1に伸延して組み立て時に接続される。   In addition, in FIG. 5, although the rectangular part which is the main part of the heat exchanger 5 is shown with the oblique line, this has shown one panel or coil, and the said panel or coil is ten or more sheets in a paper surface depth direction. Several tens of sheets are provided adjacent to each other, and a plurality of heat transfer tubes 4 are extended from the plurality of panels or coils to the header 1 shown in FIG. 6 and connected at the time of assembly.

図5に示す発電プラントで用いられるボイラ火炉7の過熱器や再熱器の熱交換器5に用いられる管寄せ1に多数の伝熱管4を溶接により接続するに当たり、本実施例の図6(a)と図6(b)に示す例では管寄せ1の同一横断面のうち図示右側から第1列など奇数列に2本の伝熱管4の管軸が管寄せ1の管軸中心に対してなす角度を90度として溶接し、第2列など偶数列に2本の伝熱管4の管軸が管寄せ1の管軸中心に対してなす角度を45度として溶接し、これら合計4本の伝熱管4が順次管寄せ1の管軸方向に整列配置している。このため、管寄せ1に溶接する伝熱管4,4同士は、隣接する奇数列と数列では互いに図6(b)に示すように、管寄せ1の管軸中心に対してなす角度は22.5度しかない。そのため、管寄せ1の外径面上に伝熱管4を溶接接続するための作業空間は狭隘部となっている。 In connecting a large number of heat transfer tubes 4 to the header 1 used for the superheater of the boiler furnace 7 and the heat exchanger 5 of the reheater used in the power plant shown in FIG. 5 by welding, FIG. In the example shown in a) and FIG. 6 (b), the tube axes of the two heat transfer tubes 4 in the odd row such as the first row from the right side of the drawing in the same cross section of the header 1 are in relation to the tube axis center of the header 1. Welding is performed at 90 degrees, and welding is performed at an even number such as the second row, where the angle between the tube axes of the two heat transfer tubes 4 with respect to the tube axis center of the header 1 is 45 degrees. The heat transfer tubes 4 are sequentially arranged in the tube axis direction of the header 1. Therefore, heat transfer tubes 4, 4 to each other to be welded to the tube pulling 1, as shown in FIG. 6 to each other in odd columns and even number sequence adjacent (b), the angle formed with respect to the tube axis center of the tube pulling 1 22 Only 5 degrees. Therefore, the work space for welding and connecting the heat transfer tube 4 on the outer diameter surface of the header 1 is a narrow portion.

このような溶接作業空間で、熱交換器5の組み立て工程で能率良く溶接するためには従来は図8に示すように管寄せ1と予め製作したスタッブ管2とを溶接し、該スタッブ管2と中間ピース3とを溶接した後、さらに主に溶接時の応力除去を目的とした熱処理を施工しておくことによりボイラ据付け現地での伝熱管4との最終溶接時の作業空間を比較的広くなるようにしていた。すなわち、前記スタッブ管2または中間ピース3により管寄せ外径面上から所定の高さの位置に伝熱管4との完全溶け込み突合せ溶接位置を確保して伝熱管4を突合せ溶接により接続していた。 In order to weld efficiently in the assembly process of the heat exchanger 5 in such a welding work space, conventionally, as shown in FIG. 8, the header 1 and the stub tube 2 manufactured in advance are welded, and the stub tube 2 Compare working space during the final welding of the heat transfer tubes 4 in the boiler installation site by a after welding the intermediate piece 3, keep applying a heat treatment after the purpose of further mainly during welding stress removal removed by It was trying to be wide. That is, the stub tube 2 or the intermediate piece 3 secures a completely melted butt welding position with the heat transfer tube 4 at a predetermined height from the outside surface of the header, and the heat transfer tube 4 is connected by butt welding. .

伝熱管4の内部を流れる被加熱媒体である水蒸気の加熱温度条件、すなわち主蒸気温度が560℃程度以下と低い場合には管寄せ1とスタッブ管2との接続構造は図7、図9で示す構造を採用することも可能であるが、主蒸気温度が高温度になってくると、管寄せ1とスタッブ管2との接続構造において溶接部の健全性を向上させるために完全突合せ溶接を行うことが検討され、例えば、図10、図11に示すような管寄せ1の外径面内に一方の突合せ開先部を設け、これをスタッブ管2の端面に設けた他方の突合せ開先部との間で完全突合せ溶接を行い、管寄せ1の外径面を挟んで面内と面上間とに積層による溶接金属層15を形成している。   7 and FIG. 9 show the connection structure between the header 1 and the stub tube 2 when the heating temperature condition of the water vapor that is the medium to be heated flowing inside the heat transfer tube 4, that is, when the main steam temperature is as low as about 560 ° C. or less. It is possible to adopt the structure shown, but when the main steam temperature becomes high, complete butt welding is performed to improve the soundness of the welded portion in the connection structure between the header 1 and the stub tube 2. For example, one butt groove portion is provided in the outer diameter surface of the header 1 as shown in FIGS. 10 and 11, and the other butt groove is provided on the end surface of the stub tube 2. The weld metal layer 15 is formed by lamination between the in-plane and the surface with the outer diameter surface of the header 1 sandwiched between them.

これに対して本実施例では図1と図2に管寄せ1の横断面図に示すように管寄せ1の溶接部分の外径面上の溶接位置に、所定の高さに溶接金属材料を積層して所定の高さの溶接金属層10を形成しておき、該溶接金属層10を形成した後は一方の突合せ開先を形成するように機械加工し、これに他方の突合せ溶接開先となる開先加工を端面に施工した伝熱管4を前記と同じNi基合金と共金系の溶接金属材料を用いて完全突合せ溶接部11を形成するようにした。   In contrast, in this embodiment, as shown in the cross-sectional view of the header 1 in FIGS. 1 and 2, the weld metal material is placed at a predetermined height at the welding position on the outer diameter surface of the welded portion of the header 1. A weld metal layer 10 having a predetermined height is formed by laminating, and after the weld metal layer 10 is formed, it is machined to form one butt groove, and the other butt weld groove is formed thereon. A complete butt weld 11 is formed by using the same Ni-based alloy and the same metal welding metal material as those described above for the heat transfer tube 4 in which the groove processing is applied to the end face.

例えば伝熱管4が前述したNi重量%44.5−Cr重量%20.0〜24.0−Co重量%10.0〜15.0−Mo重量%8.0〜10.0からなるNi基合金(インコネル617(商標)である場合には前記Ni基合金と共金系の溶接金属材料を積層して所定の高さの溶接金属層10を形成する。   For example, the heat transfer tube 4 is made of the above-described Ni-based material comprising Ni weight% 44.5-Cr weight% 20.0-24.0-Co weight% 10.0-15.0-Mo weight% 8.0-10.0. In the case of an alloy (Inconel 617 (trademark)), a weld metal layer 10 having a predetermined height is formed by laminating the Ni-base alloy and a metal alloy weld metal material.

本実施例によれば、管寄せ1と伝熱管4との溶接作業に必要な作業空間を確保するのに、具体的には、図3(b)に示すように、管寄せ1の外径面上に所定の高さの位置での完全突合せ溶接可能とするための空間部を確保するのに、図4(b)の従来技術のように予めスタッブ管2や中間ピース3を接続しておくことなく比較的容易に施工できる積層による溶接金属層10を形成しておけばよい。図1と図2に本実施例の管寄せ1の外表面への積層による溶接金属層10の形成から伝熱管4との完全突合せ溶接までのステップを示している。 According to the present embodiment, in order to secure a work space necessary for welding work between the header 1 and the heat transfer tube 4, specifically, as shown in FIG. to ensure the space for allowing a complete butt weld at the position of a predetermined height on the surface, it connects the pre-stub tube 2 and the intermediate piece 3, as in the prior art shown in FIG. 4 (b) What is necessary is just to form the welding metal layer 10 by the lamination | stacking which can be constructed comparatively easily without leaving. FIG. 1 and FIG. 2 show steps from the formation of the weld metal layer 10 by lamination on the outer surface of the header 1 of this embodiment to the complete butt welding with the heat transfer tube 4.

本実施例では溶接金属層10の積層を7パスで5層とした。積層は管孔軸(管寄せ1の外径面上に形成した管孔1aの軸)の周りに溶接装置を回転させながら行うが、全積層を連続的に行っても良く、管寄せ1への入熱を制限する場合や積層の形状など積層の状態を確認しながら行う場合は断続的に行っても良い。図1と図2には、管寄せ1に形成した溶接金属層10を形成した後、溶接金属層10に伝熱管4の内径と等しい径の管孔1aを形成して伝熱管4を溶接する手順を示す。   In this example, the weld metal layer 10 was laminated in 5 layers in 7 passes. Lamination is performed while rotating the welding apparatus around the tube hole axis (the axis of the tube hole 1a formed on the outer diameter surface of the tube header 1). When the heat input is limited or when the state of lamination such as the shape of the lamination is confirmed, it may be performed intermittently. 1 and 2, after forming the weld metal layer 10 formed on the header 1, the tube 1 a having the same diameter as the inner diameter of the heat transfer tube 4 is formed in the weld metal layer 10 to weld the heat transfer tube 4. Show the procedure.

図1(a)には管寄せ1の外径面上に7パスで5層からなる積層により溶接金属層10を形成したものを示す。本実施例ではその第1層を2パスで重なり部分に大きな段差が生じないように行い、その上の第2層を2パスでそれぞれ第3パスが第1パスと第2パス上に重なり、第4パスが第2パスと第3パス上に重なるように積層し、第5パスを第3パスと第4パス上に重なるように積層し、第6パスから第7パスをそれぞれ1層で順次重なるように積層した。なお、図1、図2に示した積層、パス数は一例であり、積層の高さおよび幅は仕上げ寸法および作業効率などを考慮して適宜設定すればよい。   FIG. 1A shows the weld metal layer 10 formed on the outer diameter surface of the header 1 by laminating five layers in seven passes. In this embodiment, the first layer is overlapped by two passes so as not to cause a large step in the overlapping portion, the second layer above the second pass is overlapped by two passes, and the third pass overlaps the first pass and the second pass, The fourth path is stacked so as to overlap the second path and the third path, the fifth path is stacked so as to overlap the third path and the fourth path, and the sixth to seventh paths are each in one layer. The layers were stacked so as to overlap one another. Note that the stacking and the number of passes shown in FIGS. 1 and 2 are examples, and the height and width of the stacking may be appropriately set in consideration of finishing dimensions and work efficiency.

こうして管寄せ1の外径面上に多層を積層することにより所定の幅と高さ以上の溶接金属層10を得た後は、図1(b)に示すように管寄せ1の外径面上の所定の高さの位置に完全溶け込み突合せ溶接開先を加工する。従って、前記溶接金属層10の幅と高さは開先加工代を含んだ寸法以上の大きさで形成しておかなければならないことは云うまでもない。また伝熱管4に使用した材料と溶接金属層10の材料との強度が同じ場合には前記溶接金属層10の高さ方向の開先部の厚さは前記伝熱管4の肉厚と同じでよい。   After the weld metal layer 10 having a predetermined width and height is obtained by laminating multiple layers on the outer diameter surface of the header 1 in this way, the outer diameter surface of the header 1 as shown in FIG. A fully-penetrating butt weld groove is processed at a predetermined height above. Accordingly, it goes without saying that the width and height of the weld metal layer 10 must be formed with a size larger than the dimension including the groove machining allowance. When the material used for the heat transfer tube 4 and the material of the weld metal layer 10 have the same strength, the thickness of the groove portion in the height direction of the weld metal layer 10 is the same as the thickness of the heat transfer tube 4. Good.

図1(a)には管寄せ1の外径面上に溶接金属層10をドーナツ状に形成した実施例を示している。この図1(a)に示す例以外は図示していないが、積層を前記のようなドーナツ状ではなく管孔軸から伝熱管4の外径より大径を有する溶接金属層10を全体に積層してしてもよい。この場合は溶接金属層10のほぼ中心部に伝熱管4の内径に相当する寸法の孔1aをドリル加工等で形成する必要がある。   FIG. 1A shows an embodiment in which a weld metal layer 10 is formed in a donut shape on the outer diameter surface of the header 1. Although not shown except for the example shown in FIG. 1A, the weld metal layer 10 having a larger diameter than the outer diameter of the heat transfer tube 4 from the tube hole axis is laminated instead of the donut shape as described above. You may do it. In this case, it is necessary to form a hole 1a having a size corresponding to the inner diameter of the heat transfer tube 4 at a substantially central portion of the weld metal layer 10 by drilling or the like.

図1(b)に示すように、管寄せ1に溶接する伝熱管4の内径に相当する寸法の孔1aを溶接金属層10の中央部と管寄せ1を貫通させて設け、次に溶接金属層10の管寄せ外径面上の所定の高さにおいて、管寄せ1側の完全溶け込み突合せ開先部のルート面になるように加工を行うと共に、U字状の開先面とし、完全溶け込み突合せ溶接金属の深さDが伝熱管4の肉厚と同じになるように前記ルートを含む開先寸法を加工する。   As shown in FIG. 1 (b), a hole 1a having a size corresponding to the inner diameter of the heat transfer tube 4 to be welded to the header 1 is provided through the central portion of the weld metal layer 10 and the header 1, and then weld metal At the predetermined height on the outer diameter surface of the header of the layer 10, processing is performed so that it becomes the root surface of the completely welded butt groove portion on the header 1 side, and a U-shaped groove surface is used to completely dissolve the layer 10. The groove dimension including the route is processed so that the depth D of the butt weld metal is the same as the thickness of the heat transfer tube 4.

これに、図2(a)に示すように端部に開先加工を施した伝熱管4側開先部を溶接金属10に施した溶接開先に付き合わせて、管寄せ1の溶接金属10と伝熱管4の開先端部同士の突合せ部にできる開先部10aに、TIG溶接などにより前記Ni基合金と共金系の溶接金属からなるワイヤを補給しながら完全溶け込み突合せ溶接を行い、図2(b)に示すように、溶接金属10上に突合せ溶接部11を形成して管寄せ1と伝熱管4とを溶接により接続する。図1と図2に示したように、本実施例によれば、管寄せ1の外径面上に所定の高さと幅を有するように積層による溶接金属層10を形成しているので、熱交換器5の組み立て工程において完全溶け込み突合せ溶接を行うのに必要な空間を確保することができる。   As shown in FIG. 2 (a), the welded metal 10 of the header 1 is attached to the welded groove formed on the welded metal 10 with the grooved portion on the side of the heat transfer tube 4 that has been grooved at the end. And the groove portion 10a which can be a butt portion between the open tips of the heat transfer tube 4 is subjected to complete penetration butt welding while supplying a wire made of the Ni-base alloy and a selenium weld metal by TIG welding or the like. 2 (b), a butt weld 11 is formed on the weld metal 10 to connect the header 1 and the heat transfer tube 4 by welding. As shown in FIGS. 1 and 2, according to the present embodiment, the weld metal layer 10 is formed on the outer diameter surface of the header 1 so as to have a predetermined height and width. A space necessary for performing complete penetration butt welding in the assembly process of the exchanger 5 can be secured.

同時に、前記のように管寄せ1の外径面上に所定の高さ以上に溶接金属層10を形成することにより、完全溶け込み突合せ溶接時の作業姿勢も図3(b)に示したように溶接部の品質確保面で信頼性の高い作業姿勢が可能となる。また、管寄せ1の外径面内への開先加工が不要となり機械加工が最小限で済むので、溶接および熱処理の管理が容易な溶接方法と溶接構造体を提供できる。   At the same time, by forming the weld metal layer 10 to a predetermined height or more on the outer diameter surface of the header 1 as described above, the working posture at the time of complete penetration butt welding is also as shown in FIG. A highly reliable work posture is possible in terms of ensuring the quality of the weld. Further, since the groove working in the outer diameter surface of the header 1 is not required and machining is minimized, it is possible to provide a welding method and a welded structure that can easily manage welding and heat treatment.

また、管寄せ1へは肉盛溶接により溶接金属を積層するだけであり、溶接および熱処理の管理が容易な溶接方法と溶接構造体を提供できる。
次に、従来技術と本発明での管寄せ1の外径面に形成される溶接熱影響部(HAZ部)8における溶接割れ8bに対しての影響について説明する。
Moreover, only the weld metal is laminated on the header 1 by overlay welding, and a welding method and a welded structure that can easily manage welding and heat treatment can be provided.
Next, the influence on the weld crack 8b in the welding heat affected zone (HAZ portion) 8 formed on the outer diameter surface of the header 1 in the prior art and the present invention will be described.

図3に本発明の実施例となる管寄せ外径面上に伝熱管を接続した例(図3(a)、図3(b))を示し、図4に従来技術となる管寄せ外径面内にスタッブ管を接続した図(図4(a)、図4(b))を示す。 FIG. 3 shows an example (FIGS. 3 (a) and 3 (b)) in which a heat transfer tube is connected on the outer diameter surface of the header according to the embodiment of the present invention , and FIG. 4 shows the outer diameter of the header according to the prior art . The figure (FIG. 4 (a), FIG.4 (b)) which connected the stub pipe | tube in the surface is shown.

図3(a)には管寄せ1と管寄せ1の外径面上に形成した溶接金属層10を加工して形成した溶接開先部と伝熱管4の端部に設けた突合せ溶接部とを完全溶け込み突合せ溶接により接続した後の外観図を示し、図3(b)は図3(a)に示す溶接構造体を得るための一工程を示す一部断面図であって、前記両方の開先部の断面図と前記開先部を完全溶け込み突合せ溶接するための溶接前の開先と溶接装置のタングステン電極12aが装着された溶接ヘッド12の一部を示し、開先と溶接装置との位置関係を示す。 FIG. 3A shows the header 1, a weld groove formed by processing the weld metal layer 10 formed on the outer diameter surface of the header 1, and a butt weld provided at the end of the heat transfer tube 4. FIG. 3 (b) is a partial cross-sectional view showing one process for obtaining the welded structure shown in FIG. 3 (a). A sectional view of the groove portion, a groove before welding for completely melting and butt welding the groove portion, and a part of the welding head 12 to which the tungsten electrode 12a of the welding apparatus is mounted are shown. The positional relationship of is shown.

図4(a)には従来技術の図10、図11に示す溶接技術を適用した場合であり、管寄せ1と管寄せ1の外径面内に形成した溶接金属層10を加工した完全溶け込みを目的とした突合せ溶接開先部と伝熱管4の端部に設けた突合せ溶接開先部と溶接ヘッド12の外観図を示し、図4(b)には図4(a)に示す溶接構造を得るための管寄せ1の外径面内を切削して形成した座繰り孔に溶接金属層10を加工した突合せ溶接開先部とスタッブ管2の端部に設けた突合せ溶接開先部の断面図と前記両方の開先部を突合せ溶接するための溶接装置のタングステン電極12aが装着された溶接ヘッド12の一部を示し、開先と溶接装置との位置関係を示す。   FIG. 4 (a) shows a case where the welding technique shown in FIGS. 10 and 11 of the prior art is applied. The weld metal layer 10 formed in the outer diameter surface of the header 1 and the header 1 is completely melted. FIG. 4 (b) shows an external view of a butt welding groove part for the purpose of the above, a butt welding groove part provided at the end of the heat transfer tube 4 and the welding head 12, and FIG. 4 (b) shows a welding structure shown in FIG. 4 (a). A butt weld groove portion formed by machining the weld metal layer 10 into a countersink hole formed by cutting the inside surface of the header 1 to obtain the butt weld groove portion provided at the end of the stub tube 2. A cross-sectional view and a part of the welding head 12 to which the tungsten electrode 12a of a welding apparatus for butt-welding both the groove portions are mounted are shown, and the positional relationship between the groove and the welding apparatus is shown.

さらに図4(b)には溶接金属層10による管寄せ1の外径面内にそれぞれ形成される溶接熱影響部(HAZ)8を示している。
従来技術の図4(b)では、管寄せ1の外径面内に積層により溶接金属層10を形成するが、前記溶接金属層10の管寄せ1側に沿って溶接熱影響部8が形成される。熱影響部8の形状は管孔1a側から管孔円周方向に平行であるが、管寄せ1の外径面の終端では管寄せ1の半径方向に転じている。すなわち、管寄せ1の厚さ方向に数ミリ長さの熱影響部8が形成されている。溶接熱影響部8は母材(管寄せ1と伝熱管4)と比較して高温強度が低い。管寄せ1には運転中に内圧による応力18が管寄せ1の円周方向にかかっており、前記応力は管寄せ1の厚さ方向の熱影響部8と垂直となるため割れが発生する可能性が高い。
Further, FIG. 4B shows the weld heat affected zone (HAZ) 8 formed in the outer diameter surface of the header 1 by the weld metal layer 10.
In FIG. 4B of the prior art, the weld metal layer 10 is formed by lamination within the outer diameter surface of the header 1, but the weld heat affected zone 8 is formed along the header 1 side of the weld metal layer 10. Is done. The shape of the heat affected zone 8 is parallel to the circumferential direction of the pipe hole from the side of the pipe hole 1 a, but turns to the radial direction of the pipe head 1 at the end of the outer diameter surface of the pipe head 1. That is, a heat affected zone 8 having a length of several millimeters is formed in the thickness direction of the header 1. The welding heat affected zone 8 has a low high temperature strength compared to the base material (the header 1 and the heat transfer tube 4). A stress 18 due to internal pressure is applied to the header 1 in the circumferential direction of the header 1 during operation, and the stress is perpendicular to the heat-affected zone 8 in the thickness direction of the header 1, so that cracks may occur. High nature.

これに対して本発明の実施例である図3(b)に示すように、溶接金属層10の管寄せ1側に形成される溶接熱影響部8はほぼ全ての範囲で管寄せ1の円周方向と平行な領域にあり、割れが発生する可能性が低い。   On the other hand, as shown in FIG. 3B which is an embodiment of the present invention, the weld heat affected zone 8 formed on the header 1 side of the weld metal layer 10 has a circle of the header 1 in almost the entire range. In the region parallel to the circumferential direction, the possibility of cracking is low.

本実施例によれば、強度的に母材(本実施例では管寄せ1と伝熱管4)の金属組織より弱く、ボイラ運転中に割れが発生し易い部位となる溶接熱影響部8を内圧による影響の小さい範囲で形成することができるので割れが発生し難い溶接構造を実現することができる。   According to the present embodiment, the welding heat-affected zone 8 that is weaker than the metal structure of the base material (in this embodiment, the header 1 and the heat transfer tube 4) and easily cracks during boiler operation is applied to the internal pressure. Therefore, it is possible to realize a welded structure in which cracking hardly occurs.

次に、本実施例では溶接金属層10を管寄せ1の外径面上の所定の高さに形成しているので、図3(b)に示すように溶接ヘッド12から伝熱管4の管軸に対して直角に向けたタングステン電極12aを有する溶接ヘッド12による伝熱管4の軸周りの完全溶け込み突合せ溶接が可能となる。   Next, in this embodiment, since the weld metal layer 10 is formed at a predetermined height on the outer diameter surface of the header 1, the tube of the heat transfer tube 4 from the welding head 12 as shown in FIG. Complete penetration butt welding around the axis of the heat transfer tube 4 by the welding head 12 having the tungsten electrode 12a oriented perpendicular to the axis becomes possible.

前記溶接ヘッド12は伝熱管4の軸方向および該軸の垂直方向に移動可能であり、完全突合せ溶接における電極12aの角度、開先部からの距離、開先位置からの上下方向の距離を調整するための調整代を確保できる。例えば、図3(b)の溶接ヘッド12によればタングステン電極12aの方向を伝熱管4の管軸に対して真横となる90度からやや下向きの80度(管軸から時計回り方向に、以下同じ)、やや上向きの100度などの角度での溶接が可能である。   The welding head 12 is movable in the axial direction of the heat transfer tube 4 and in the vertical direction of the axis, and adjusts the angle of the electrode 12a, the distance from the groove, and the vertical distance from the groove position in complete butt welding. Can be secured for adjustment. For example, according to the welding head 12 of FIG. 3B, the direction of the tungsten electrode 12a is slightly downward from 90 degrees, which is right next to the tube axis of the heat transfer tube 4, slightly downward 80 degrees (in the clockwise direction from the tube axis) The same), welding at an angle such as 100 degrees slightly upward is possible.

これに対して、図4(b)に示すような従来技術(特許文献1)で管寄せ1の外径面内に開先部を形成する場合、溶接ヘッド12は伝熱管4の軸に沿って管寄せ1から離れる方向には移動可能であるが、近づく方向には管寄せ1の外径面に接触しない範囲までしか行えず、前記図3(b)に示すような溶接ヘッド12が使用できないため、例えば、図4(a)、図4(b)に示すような溶接ヘッド12の軸と同軸のタングステン電極12aを用いる溶接ヘッド12か、本体の溶接ヘッド12は図3(b)に示す場合と同じ方向に配置するが、溶接ヘッド12の先端部の電極12aの向きを溶接ヘッド12の軸に対して45度等に傾斜させた溶接ヘッド12を用いて、開先部の最奥部での完全溶け込みを図る必要がある。このため、電極12aの傾斜角度や溶接位置からの距離の調整に制限があり、目視での溶接状況の確認が困難となるため、完全溶け込み突合せ溶接を行うには難易度が高い。   On the other hand, when the groove portion is formed in the outer diameter surface of the header 1 by the conventional technique (Patent Document 1) as shown in FIG. 4 (b), the welding head 12 follows the axis of the heat transfer tube 4. Although it can move in the direction away from the header 1, it can only be moved to a range not contacting the outer diameter surface of the header 1 in the approaching direction, and the welding head 12 as shown in FIG. 3B is used. For example, the welding head 12 using the tungsten electrode 12a coaxial with the axis of the welding head 12 as shown in FIGS. 4 (a) and 4 (b) or the welding head 12 of the main body is shown in FIG. 3 (b). The welding head 12 is disposed in the same direction as that shown, but the electrode 12a at the tip of the welding head 12 is inclined at 45 degrees or the like with respect to the axis of the welding head 12, and the innermost portion of the groove is It is necessary to achieve complete penetration at the part. For this reason, there is a limit to the adjustment of the inclination angle of the electrode 12a and the distance from the welding position, and it is difficult to visually confirm the welding state. Therefore, it is difficult to perform complete penetration butt welding.

本実施例によれば、管寄せ1の外径面上から所定の高さに形成した溶接金属層10の開先部10aの位置に対して、伝熱管4の軸方向に沿って上下方向に移動可能であり、さらに伝熱管4の軸と垂直方向に移動可能な溶接ヘッド12が使用可能であるため、従来技術と比較して高品質な完全溶け込み溶接部11を得るための作業性が著しく向上する。   According to the present embodiment, with respect to the position of the groove portion 10 a of the weld metal layer 10 formed at a predetermined height from the outer diameter surface of the header 1, in the vertical direction along the axial direction of the heat transfer tube 4. Since it is possible to use a welding head 12 that is movable and movable in a direction perpendicular to the axis of the heat transfer tube 4, the workability for obtaining a high-quality fully-penetrating weld 11 as compared with the prior art is remarkably high. improves.

次に、溶接部の検査について述べる。
溶接部の品質を保証するために溶接部の検査は不可欠であり、耐圧部の非破壊検査として放射線透過検査が行われる。該放射線透過検査はX線やγ線を用いて被検部に照射して通過した放射線の強さの変化から欠陥や傷や割れの有無、状態を検査するもので、放射線に感光するフィルムを被検部の裏側に置いて放射線を照射し、放射線が被検部を透過してフィルムに到達し、フィルムを感光させる性能を利用する。透過放射線の強さは被検部の厚さが大きいほど弱くなるため、仮に割れなどの空隙があると、その部分の透過放射線強度は周囲より増大するためフィルムでは強く感光し、黒く出ることから被検部内での割れを検出できる。
Next, the inspection of the weld will be described.
Inspection of the welded part is indispensable for assuring the quality of the welded part, and a radiographic inspection is performed as a nondestructive inspection of the pressure resistant part. The radiation transmission inspection is to inspect the presence or absence of defects, scratches and cracks from the change in the intensity of the radiation that has passed through the X-ray or γ-rays and passed through it. It is placed on the back side of the part to be examined and irradiated with radiation, and the radiation passes through the part to be examined and reaches the film to utilize the performance of exposing the film. Since the intensity of the transmitted radiation becomes weaker as the thickness of the test part increases, if there is a gap such as a crack, the transmitted radiation intensity of that part will increase from the surroundings, so the film will be strongly exposed and appear black. It is possible to detect cracks in the test area.

しかしながら従来技術の場合は、突合せ溶接部は管寄せ1の外径面内とスタッブ管2との間に形成され、フィルムを貼付する位置としては管寄せ1の内径側か管孔1a側になるが、管寄せ1の肉厚は十数ミリ〜数十ミリと厚く、これに対してスタッブ管2は数ミリ程度と薄いことから、管寄せ1側の溶接部とスタッブ管2側の溶接部とを同時に放射線透過検査を行うことは困難であった。   However, in the case of the prior art, the butt weld is formed between the outer diameter surface of the header 1 and the stub tube 2, and the position where the film is applied is on the inner diameter side of the header 1 or the tube hole 1a side. However, since the wall thickness of the header 1 is as thick as several tens to several tens of millimeters, whereas the stub tube 2 is as thin as several millimeters, the welded portion on the header 1 side and the welded portion on the stub tube 2 side are thin. At the same time, it was difficult to perform a radiographic inspection.

これに対して本発明の実施例では突合せ溶接部11(図3)は伝熱管4と伝熱管4と同じ肉厚の溶接金属層10側の開先部の間に形成されるため、伝熱管4側についてのみ同時に放射線透過検査を行うことで検査が済むことになる。本発明の実施例によれば完全溶け込み突合せ溶接部11を形成する溶接部の溶接後の非破壊検査を確実に行うことができ健全な溶接部であることを確認することが可能となる。   In contrast, in the embodiment of the present invention, the butt weld 11 (FIG. 3) is formed between the heat transfer tube 4 and the groove portion on the side of the weld metal layer 10 having the same thickness as the heat transfer tube 4. The inspection can be completed by performing the radiographic inspection on only the four sides at the same time. According to the embodiment of the present invention, the non-destructive inspection after welding of the weld part forming the complete penetration butt weld part 11 can be surely performed, and it is possible to confirm that the weld part is sound.

その他、従来技術の管寄せ1とスタッブ管2との完全溶け込み突合せによる溶接部が管寄せ1の外径面上かまたはその近傍に有るため、前記突合せ溶接部にはボイラ運転中に伝熱管4と管寄せ1との線膨張係数の差による応力が作用するのに対して、本発明の実施例では完全溶け込み突合せ溶接部11を管寄せ1の外径面上の所定の高さ位置に設け、さらに管寄せ1と突合せ溶接部11の間には溶接金属層10が介在するため、前記突合せ溶接部11にかかる応力の作用を低減することができる。   In addition, since the welded portion by the full penetration butt between the header 1 and the stub tube 2 of the prior art is on or near the outer diameter surface of the header 1, the butt welded portion includes a heat transfer tube 4 during boiler operation. Whereas the stress due to the difference in the coefficient of linear expansion between the pipe header 1 and the header 1 acts, in the embodiment of the present invention, a completely penetration butt weld 11 is provided at a predetermined height position on the outer diameter surface of the header 1. Furthermore, since the weld metal layer 10 is interposed between the header 1 and the butt weld 11, the stress applied to the butt weld 11 can be reduced.

また、本発明では管寄せ1に溶接金属層10を介して伝熱管4を溶接により接続しているので、溶接金属層10が管寄せ1の外径面上の所定の高さ位置にあるため、経年使用により伝熱管4を交換する作業が発生した場合、完全溶け込み突合せ溶接部11での交換が、従来技術に比較して容易に行えるという特徴もある。   Further, in the present invention, since the heat transfer tube 4 is connected to the header 1 via the weld metal layer 10 by welding, the weld metal layer 10 is at a predetermined height position on the outer diameter surface of the header 1. Further, when the work for replacing the heat transfer tube 4 occurs due to the use over time, the replacement at the complete penetration butt weld 11 can be easily performed as compared with the prior art.

また、本発明の実施例では、600℃のような高温域での使用を想定しており、管寄せ1、該管寄せ1に接続する伝熱管4、溶接金属層10の積層に使用する溶接材料および突合せ溶接に使用する溶接材料の材質がそれぞれ、高クロム鋼、オーステナイト系ステンレス鋼またはNi基合金、Ni基合金およびNi基合金である。例えば、管寄せ1は火STPA28に代表される9重量%Cr−1重量%Mo−VNb鋼または火STPA29に代表される9重量%Cr−0.5重量%Mo−1.8重量%W−VNbなどのフェライト系鋼を用いる。また、管寄せ1に接続する伝熱管4としてはSUS304、SUS309、SUS310、SUS316、SUS321、SUS347などのオーステナイト系ステンレス鋼または、Ni重量%44.5−Cr重量%20.0〜24.0−Co重量%10.0〜15.0−Mo重量%8.0〜10.0%からなるNi基合金(インコネル617(商標))等を用いる。 Moreover, in the Example of this invention, the use in the high temperature region like 600 degreeC is assumed, and welding used for lamination | stacking of the header 1, the heat exchanger tube 4 connected to this header 1, and the weld metal layer 10 is used. The material and the material of the welding material used for butt welding are high chromium steel, austenitic stainless steel or Ni-base alloy , Ni-base alloy and Ni-base alloy, respectively. For example, the header 1 is composed of 9 wt% Cr-1 wt% Mo-VNb steel represented by fire STPA28 or 9 wt% Cr-0.5 wt% Mo-1.8 wt% W- represented by fire STPA29. Ferritic steel such as VNb is used. Moreover, as the heat exchanger tube 4 connected to the header 1, austenitic stainless steel such as SUS304, SUS309, SUS310, SUS316, SUS321, SUS347, or Ni weight% 44.5-Cr weight% 20.0 to 24.0- A Ni-based alloy (Inconel 617 (trademark)) made of Co wt% 10.0 to 15.0-Mo wt% 8.0 to 10.0% is used.

さらに、溶接金属層10の積層に使用する溶接材料はNi重量%44.5−Cr重量%20.0〜24.0−Co重量%10.0〜15.0−Mo重量%8.0〜10.0からなるNi基合金(インコネル617(商標))等の共金系溶接材料(SFA―5.14、ERNiCr−3等)を積層して設けた溶接金属層を用い、突合せ溶接に使用する溶接材料は前記と同じくNi基合金(インコネル617(商標)等の共金系溶接材料(SFA―5.14、ERNiCr−3等)などを用いる。   Furthermore, the welding material used for lamination | stacking of the weld metal layer 10 is Ni weight% 44.5-Cr weight% 20.0-24.0-Co weight% 10.0-15.0-Mo weight% 8.0. Used for butt welding, using a weld metal layer that is made by laminating co-welded welding materials (SFA-5.14, ERNiCr-3, etc.) such as 10.0 Ni-based alloy (Inconel 617 (trademark)) The welding material to be used is a Ni-based alloy (such as Inconel 617 (trademark)) or the like, as described above.

1 管寄せ
2 スタッブ管
3 中間ピース
4 伝熱管
5 熱交換器
7 火炉
8 溶接熱影響部
10 溶接金属層
11 完全溶け込み突合せ溶接部
12 溶接ヘッド
14 バタリング溶接層
15 溶接金属層
16 天井壁
17 ボイラ鉄骨(天井梁)
18 内圧
DESCRIPTION OF SYMBOLS 1 Pipe header 2 Stub tube 3 Intermediate piece 4 Heat transfer tube 5 Heat exchanger 7 Furnace 8 Welding heat affected zone 10 Weld metal layer 11 Complete penetration butt weld 12 Weld head 14 Buttering weld layer 15 Weld metal layer 16 Ceiling wall 17 Boiler steel frame (Ceiling beam)
18 Internal pressure

Claims (5)

管体を管寄せに溶接する方法において、
前記管寄せの外径面上の管体取り付け位置に所定の肉盛高さの溶接金属層を積層して設けて管寄せの円周方向と平行な外径面上領域に溶接熱影響部を形成させた後、該溶接金属層を含む前記外径面上の管体取り付け位置に管孔を加工すると共に、前記溶接金属層の高さ方向の端面に一方の突合せ溶接開先の片側を形成し、これに端面に他方の突合せ溶接開先の片側を形成した管体を突き合わせて完全溶け込み突合せ溶接により前記管寄せに管体を接続することを特徴とする管体を管寄せに溶接する方法。
In the method of welding the pipe body to the header,
A welding heat affected zone is provided in a region on the outer diameter surface parallel to the circumferential direction of the header by stacking a weld metal layer having a predetermined build-up height on the tube attachment position on the outer diameter surface of the header. After forming , the tube hole is processed at the tube attachment position on the outer diameter surface including the weld metal layer, and one side of one butt weld groove is formed on the end surface in the height direction of the weld metal layer. And joining the pipe body to the header by full penetration butt welding by butting the pipe body having one end of the other butt weld groove formed on the end face thereof. .
管寄せ、該管寄せに接続する管体、溶接金属層の積層に使用する溶接材料および突合せ溶接に使用する溶接材料の材質がそれぞれ、フェライト系耐熱鋼、オーステナイト系ステンレス鋼またはNi基合金、Ni基合金およびNi基合金であることを特徴とする請求項1記載の管体を管寄せに溶接する方法。   The materials of the header, the pipe connected to the header, the welding material used for laminating the weld metal layer and the welding material used for the butt welding are ferritic heat resistant steel, austenitic stainless steel or Ni-base alloy, Ni The method according to claim 1, wherein the tubular body is welded to a header. ボイラ火炉内に設けられた伝熱管群から火炉外に伸延した管体が、該火炉外に設けられた管寄せに溶接された溶接構造体であって、前記溶接構造体は、管寄せと、該管寄せの外径面上の管体取付け位置に積層して設けられた所定の肉盛高さを有し、略中心部に管孔が加工されて管寄せの円周方向と平行な外径面上領域に溶接熱影響部が形成されるようにした溶接金属層と、一方の突合せ溶接開先の片側を加工形成した前記溶接金属層の端面、他方の突合せ溶接開先の片側を加工形成した前記管体の端面とを完全突合せ溶接した突き合わせ溶接部と前記伝熱管群から火炉外に伸延した管体からなることを特徴とする管体が管寄せに溶接された溶接構造体。 The tube extended from the heat transfer tube group provided in the boiler furnace to the outside of the furnace is a welded structure welded to the header provided outside the furnace, and the welded structure includes a header, It has a predetermined build-up height provided at the tube mounting position on the outer diameter surface of the header, and a pipe hole is machined in a substantially central portion so that it is parallel to the circumferential direction of the header. and weld metal layer so as to weld heat affected zone is formed radial surface region, wherein the end face of the weld metal layer, a butt weld groove other hand obtained by processing forming one side of the hand of the butt weld groove welded structure tube body characterized by comprising a distraction the tube outside the furnace to the end face of the tube body on one side was processed and formed a complete butt welded butt welds from the heat transfer tube group is welded to the tube pulling body. 請求項3記載の管寄せの代わりにマニホールドを用いることを特徴とする溶接構造体。   A welded structure using a manifold instead of the header according to claim 3. 請求項3記載の溶接構造体を過熱器及び再熱器の少なくともいずれかの熱交換器とすることを特徴とするボイラ装置。   A boiler device, wherein the welded structure according to claim 3 is a heat exchanger of at least one of a superheater and a reheater.
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