JP2006083440A - Method for restraining generation or progression of stress corrosion crack - Google Patents
Method for restraining generation or progression of stress corrosion crack Download PDFInfo
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- JP2006083440A JP2006083440A JP2004270644A JP2004270644A JP2006083440A JP 2006083440 A JP2006083440 A JP 2006083440A JP 2004270644 A JP2004270644 A JP 2004270644A JP 2004270644 A JP2004270644 A JP 2004270644A JP 2006083440 A JP2006083440 A JP 2006083440A
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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
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- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
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Abstract
Description
本発明は、発電プラント、化学プラント等で重大な問題となっている応力腐食割れの発生或いは既に発生した応力腐食割れの進展を抑制する応力腐食割れの発生或いは進展抑制方法に関する。 The present invention relates to a method for suppressing or preventing the occurrence of stress corrosion cracking, which is a serious problem in power plants, chemical plants, etc., or suppressing the development of stress corrosion cracks that have already occurred.
近年、原子力発電所等に代表されるように、発電プラント、化学プラント等における応力腐食割れの発生や発生した応力腐食割れの進展による事故の発生が大きな問題となっている。 In recent years, as represented by nuclear power plants and the like, the occurrence of stress corrosion cracks in power plants, chemical plants, etc. and the occurrence of accidents due to the progress of the generated stress corrosion cracks have become a major problem.
これらの問題に対応するために、応力腐食割れの発生或いは進展する対象部位となる例えば溶接部を、該溶接部から離れた位置に押圧部材を配置し、該押圧部材の押圧によって圧縮応力を生じさせる方法が提案されている（例えば、特許文献１参照）。 In order to deal with these problems, for example, a welded portion that is a target site where stress corrosion cracking occurs or propagates is disposed at a position away from the welded portion, and a compressive stress is generated by pressing the pressed member. The method of making it propose is proposed (for example, refer patent document 1).
しかしながら、特許文献１の方法は、圧縮応力を生じさせるために押圧部材を用いるので、これら押圧部材を配置できない部分には、これらの方法を適用できない場合があるという問題があった。 However, since the method of Patent Document 1 uses a pressing member to generate a compressive stress, there is a problem in that these methods may not be applied to portions where these pressing members cannot be arranged.
本発明は、このような問題点に着目してなされたもので、押圧部材を用いることなく、応力腐食割れの発生或いは進展を抑制することのできる応力腐食割れの発生或いは進展抑制方法を提供することを目的としている。 The present invention has been made paying attention to such a problem, and provides a method for suppressing the occurrence or progress of stress corrosion cracking that can suppress the occurrence or progress of stress corrosion cracking without using a pressing member. The purpose is that.
上記課題を解決するために、本発明の請求項１に記載の応力腐食割れの発生或いは進展抑制方法は、
熱により収縮せしめられる部位と、該収縮せしめられる部位に連結した部位の組合せにおいて、該収縮せしめられる部位に連結した部位の拘束により、前記収縮せしめられる部位の収縮を起こりずらくして、該収縮せしめられる部位に連結した部位に圧縮応力を発生させて応力腐食割れの発生或いは進展を抑制することを特徴とする。
この特徴によれば、応力腐食割れによる亀裂が発生し難くなるとともに、仮に応力腐食割れによる亀裂が発生しても、該発生した応力腐食割れ（亀裂）の進展をし難くできる。尚、本発明における収縮せしめられる部位と、収縮せしめられる部位に連結した部位の関係は、より収縮せしめられる部位と、より収縮せしめられる部位に連結したそれより少なく収縮せしめられる部位の関係に置き換えても同様である。
In order to solve the above-mentioned problem, the method for suppressing or preventing the occurrence of stress corrosion cracking according to claim 1 of the present invention,
In a combination of a part that is contracted by heat and a part that is connected to the part that is contracted, the contraction of the part that is contracted is less likely to occur due to the restraint of the part that is connected to the part that is contracted. Compressive stress is generated in a portion connected to a portion to be suppressed to suppress occurrence or progress of stress corrosion cracking.
According to this feature, cracks due to stress corrosion cracking are difficult to occur, and even if cracks due to stress corrosion cracking occur, the stress corrosion cracks (cracks) that have occurred can hardly progress. In the present invention, the relationship between the contracted portion and the portion connected to the contracted portion is replaced with the relationship between the more contracted portion and the less contracted portion connected to the more contracted portion. Is the same.
本発明の請求項２に記載の応力腐食割れの発生或いは進展抑制方法は、
熱により膨張せしめられる部位と、該膨張せしめられる部位に連結する部位の組合せにおいて、該膨張せしめられる部位に連結する部位の拘束により、前記膨張せしめられる部位の膨張を起こりずらくして、該膨張せしめられる部位に圧縮応力を発生させて応力腐食割れの発生或いは進展を抑制することを特徴とする。
この特徴によれば、応力腐食割れによる亀裂が発生し難くなるとともに、仮に応力腐食割れによる亀裂が発生しても、該発生した応力腐食割れ（亀裂）の進展をし難くできる。尚、本発明における膨張せしめられる部位と、膨張せしめられる部位に連結した部位の関係は、より膨張せしめられる部位と、より膨張せしめられる部位に連結したそれより少なく膨張せしめられる部位の関係に置き換えても同様である。
The method for suppressing the occurrence or development of stress corrosion cracking according to claim 2 of the present invention is as follows.
In the combination of the part that is inflated by heat and the part that is connected to the part that is inflated, the restriction of the part that is connected to the part that is inflated makes the expansion of the part that is inflated difficult to occur, and It is characterized in that compressive stress is generated at a certain portion to suppress the occurrence or development of stress corrosion cracking.
According to this feature, cracks due to stress corrosion cracking are difficult to occur, and even if cracks due to stress corrosion cracking occur, the stress corrosion cracks (cracks) that have occurred can hardly progress. In the present invention, the relationship between the inflated portion and the portion connected to the inflated portion is replaced with the relationship between the more inflated portion and the less inflated portion connected to the more inflated portion. Is the same.
本発明の実施形態を図１（ａ）〜（ｃ）に示す。 An embodiment of the present invention is shown in FIGS.
まず、図１（ａ）に示すように、応力腐食割れの発生或いは進展を抑制する対象部位となる溶接部から離れた部位を冷却する。ここに上記部位の位置は、配管軸方向にみたときに溶接部に外側を凸とする変形が生じるように定める。冷却部は、高温部材にあっては、周上に放熱用のフィンを取り付けることにより設けてもよいし、水等による冷却でもよいし、その部分だけ配管表面の熱伝達率を他に比べ大きくし、熱が逃げやすくすることにより設けてもよい。同部分以外の配管表面から熱が逃げにくくしてもよい。 First, as shown to Fig.1 (a), the site | part away from the welding part used as the object site | part which suppresses generation | occurrence | production or progress of stress corrosion cracking is cooled. Here, the position of the above-mentioned part is determined so that the welded portion is deformed so that the outer side is convex when viewed in the pipe axis direction. In the case of a high temperature member, the cooling part may be provided by attaching a fin for heat dissipation on the circumference, or it may be cooled by water or the like, and only that part has a larger heat transfer coefficient on the pipe surface than others. However, it may be provided by making it easy for heat to escape. Heat may be difficult to escape from the pipe surface other than the same part.
そして、図１（ｂ）に示すように、図１（ａ）の処理を溶接部の左右両側で行う。ここに溶接部から冷却部位までの距離は左右で同じでも、異なってもよい。 And as shown in FIG.1 (b), the process of Fig.1 (a) is performed by the right-and-left both sides of a welding part. Here, the distance from the welded portion to the cooling site may be the same or different on the left and right.
また、内外壁の温度が同じか、それに近い状態の場合には、図１（ｃ）に示すように、加熱帯で溶接部を加熱し、配管軸方向にみたときに溶接部に外側を凸とする変形が生じるようにし、配管溶接部の内壁上に圧縮応力が生じるようにする。 If the inner and outer walls are at or near the same temperature, as shown in FIG. 1 (c), the welded portion is heated in a heating zone, and the outer side protrudes from the welded portion when viewed in the pipe axis direction. And a compressive stress is generated on the inner wall of the pipe weld.
また、配管内壁が高温の流体に触れる場合には、図７に示すように、溶接部あるいはそれを含む領域の外表面上の熱伝達率を同領域以外の配管表面の熱伝達率に比べ大きくし、熱が逃げやすくすることにより、同領域の肉厚内での温度勾配（内壁上で高く、外壁上で低い）が、同領域以外の肉厚内での温度勾配より大きくなり、配管溶接部の内壁上に他に比べより大きな圧縮応力を作ることができる。同領域の周上に放熱用のフィンを取り付けることによってもよいし、水等による冷却によってもよい。 When the inner wall of the pipe is in contact with a high-temperature fluid, as shown in FIG. 7, the heat transfer coefficient on the outer surface of the welded part or the area including the weld is larger than the heat transfer coefficient of the pipe surface other than the same area. However, by making it easier for heat to escape, the temperature gradient within the wall thickness in the same region (high on the inner wall and low on the outer wall) becomes larger than the temperature gradient in the wall thickness outside the same region, and pipe welding A larger compressive stress can be created on the inner wall of the portion than the others. A heat radiating fin may be attached on the circumference of the region, or may be cooled by water or the like.
以下、本発明の実施例を説明する。 Examples of the present invention will be described below.
前述の図１（ｂ）の一例を図２に示す。外径500mm, 肉厚35mmなるステンレス鋼配管溶接部を一例として想定し、内壁の温度を300℃とし、図のように溶接部の両側で配管外壁上において幅bにわたり熱伝達率を大きくした場合に、溶接部の配管内壁上に生じる軸方向応力σと周方向応力σθ の計算値を図３に示す。なお幅bなる部分以外の配管外壁の熱伝達率は10W/(m2・℃)とした。また図３はb＝50mmとした例である。幅bなる部分の外壁上の熱伝達率も10W/(m2・℃) の場合に、σとσθが負の符号（圧縮）をとるのは、配管内壁の温度が300℃であり、配管外壁の温度（280℃）に比べ高いことによるものである。図３より、幅bなる部分の外壁上の熱伝達率が大きくなると、同部の外壁上の温度Tは同部以外の外壁上の温度280℃に比べ低下し、σ、σθ共に圧縮が大きくなることがわかる。 An example of the aforementioned FIG. 1B is shown in FIG. Assuming a stainless steel pipe weld with an outer diameter of 500 mm and a wall thickness of 35 mm as an example, the inner wall temperature is 300 ° C, and the heat transfer coefficient is increased over the width b on the pipe outer wall on both sides of the weld as shown in the figure FIG. 3 shows calculated values of the axial stress σ and the circumferential stress σ θ generated on the pipe inner wall of the weld. Note that the heat transfer coefficient of the pipe outer wall other than the portion having the width b was 10 W / (m 2 · ° C.). FIG. 3 shows an example in which b = 50 mm. When the heat transfer coefficient on the outer wall of the part of width b is also 10W / (m 2 · ° C), the negative sign (compression) of σ and σ θ is that the temperature of the inner wall of the pipe is 300 ° C, This is because it is higher than the temperature of the outer wall of the pipe (280 ℃). As shown in FIG. 3, when the heat transfer coefficient on the outer wall of the portion having the width b increases, the temperature T on the outer wall of the same portion decreases compared to the temperature 280 ° C. on the outer wall other than the same portion, and both σ and σ θ are compressed. You can see it grows.
次に、図７の一例を図４に示す。配管寸法、内壁の温度、外気温は図２の場合と同じとした場合である。溶接部の配管外壁上において軸方向にBなる幅で熱伝達率を大きくした場合に、溶接部の配管内壁上に生じる軸方向応力σと周方向応力σθの計算値を図５に示す。なお幅Bなる部分以外の配管外壁の熱伝達率は10W/(m2・℃) とし、またB＝50mmとした例である。図５より幅Bなる部分の外壁上の熱伝達率が大きくなると、同部の外壁上の温度tは減少し、したがって内壁上の温度300℃との温度差が大きくなり、温度が高い内壁側においてσ、σθ共に圧縮が大きくなることがわかる。 Next, an example of FIG. 7 is shown in FIG. The pipe dimensions, inner wall temperature, and outside air temperature are the same as in FIG. FIG. 5 shows calculated values of the axial stress σ and the circumferential stress σ θ generated on the pipe inner wall of the welded portion when the heat transfer coefficient is increased with a width B in the axial direction on the pipe outer wall of the welded portion. In this example, the heat transfer coefficient of the pipe outer wall other than the width B portion is 10 W / (m 2 · ° C.), and B = 50 mm. When the heat transfer coefficient on the outer wall of the portion having a width B from FIG. 5 is increased, the temperature t on the outer wall of the portion is reduced, and thus the temperature difference from the temperature of 300 ° C. on the inner wall is increased. in sigma, sigma theta together it can be seen that the compression is increased.
尚、 図２に示す実施例１の形態と図４に示す実施例２の形態を組み合わせてもよい。一例として幅bなる部分と幅Bなる部分の熱伝達率を同じにして図３の場合と図５の場合を組み合わせた場合に生じるσ、σθは図６のようになり、溶接部の配管内壁上に大きな圧縮応力を生じさせることができる。 In addition, you may combine the form of Example 1 shown in FIG. 2, and the form of Example 2 shown in FIG. As an example, σ and σ θ generated when the heat transfer coefficient of the width b portion and the width B portion are the same and the case of FIG. 3 and the case of FIG. 5 are combined are as shown in FIG. A large compressive stress can be generated on the inner wall.
以上に示した実施例は一例であり、種々の寸法、内壁の温度、外気温、熱伝達率等の値はここに示した値に限られるものではない。また幅bなる部分、幅Bなる部分に対する処理は放熱用のフィン、水等による冷却によってもよい。 The embodiment described above is an example, and values of various dimensions, inner wall temperature, outside air temperature, heat transfer coefficient, etc. are not limited to the values shown here. Further, the treatment for the width b portion and the width B portion may be performed by cooling with a heat radiating fin, water, or the like.
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2009096004A1 (en) * | 2008-01-30 | 2009-08-06 | Mitsubishi Heavy Industries, Ltd. | Deteriorated portion reproducing method and deteriorated portion reproducing device |
| EP1927668A3 (en) * | 2006-11-28 | 2009-11-25 | Mitsubishi Heavy Industries, Ltd. | Restoration method for deteriorated part and restoration apparatus for deteriorated part |
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2004
- 2004-09-17 JP JP2004270644A patent/JP2006083440A/en active Pending
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP1927668A3 (en) * | 2006-11-28 | 2009-11-25 | Mitsubishi Heavy Industries, Ltd. | Restoration method for deteriorated part and restoration apparatus for deteriorated part |
| WO2009096004A1 (en) * | 2008-01-30 | 2009-08-06 | Mitsubishi Heavy Industries, Ltd. | Deteriorated portion reproducing method and deteriorated portion reproducing device |
| CN101784682A (en) * | 2008-01-30 | 2010-07-21 | 三菱重工业株式会社 | Deteriorated portion reproducing method and deteriorated portion reproducing device |
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