JPS62235539A - Maintenance and management of bolt - Google Patents
Maintenance and management of boltInfo
- Publication number
- JPS62235539A JPS62235539A JP7830186A JP7830186A JPS62235539A JP S62235539 A JPS62235539 A JP S62235539A JP 7830186 A JP7830186 A JP 7830186A JP 7830186 A JP7830186 A JP 7830186A JP S62235539 A JPS62235539 A JP S62235539A
- Authority
- JP
- Japan
- Prior art keywords
- bolt
- damage
- test
- amount
- destructive
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Pending
Links
- 238000012423 maintenance Methods 0.000 title claims abstract description 17
- 238000012360 testing method Methods 0.000 claims abstract description 36
- 230000001066 destructive effect Effects 0.000 claims abstract description 28
- 239000000463 material Substances 0.000 claims abstract description 21
- 238000004364 calculation method Methods 0.000 claims abstract description 7
- 230000006866 deterioration Effects 0.000 claims abstract description 6
- 230000005856 abnormality Effects 0.000 claims abstract description 5
- 238000007689 inspection Methods 0.000 claims description 18
- 238000000034 method Methods 0.000 claims description 17
- 238000007726 management method Methods 0.000 claims description 12
- 238000001514 detection method Methods 0.000 claims description 4
- 238000007542 hardness measurement Methods 0.000 claims description 4
- 238000009863 impact test Methods 0.000 claims description 3
- 238000009864 tensile test Methods 0.000 claims description 3
- 230000003247 decreasing effect Effects 0.000 claims 3
- 230000035882 stress Effects 0.000 description 20
- 230000000737 periodic effect Effects 0.000 description 9
- 238000010586 diagram Methods 0.000 description 8
- 230000007423 decrease Effects 0.000 description 6
- 238000009659 non-destructive testing Methods 0.000 description 6
- 150000001247 metal acetylides Chemical class 0.000 description 3
- 230000001052 transient effect Effects 0.000 description 3
- 229910000831 Steel Inorganic materials 0.000 description 2
- 230000015572 biosynthetic process Effects 0.000 description 2
- 238000009658 destructive testing Methods 0.000 description 2
- 238000011156 evaluation Methods 0.000 description 2
- 239000012535 impurity Substances 0.000 description 2
- 229910052750 molybdenum Inorganic materials 0.000 description 2
- 239000010959 steel Substances 0.000 description 2
- TVZRAEYQIKYCPH-UHFFFAOYSA-N 3-(trimethylsilyl)propane-1-sulfonic acid Chemical compound C[Si](C)(C)CCCS(O)(=O)=O TVZRAEYQIKYCPH-UHFFFAOYSA-N 0.000 description 1
- 230000002159 abnormal effect Effects 0.000 description 1
- 230000004913 activation Effects 0.000 description 1
- 238000001994 activation Methods 0.000 description 1
- 230000032683 aging Effects 0.000 description 1
- 229910052804 chromium Inorganic materials 0.000 description 1
- 238000005336 cracking Methods 0.000 description 1
- 239000013078 crystal Substances 0.000 description 1
- 238000013461 design Methods 0.000 description 1
- 238000009826 distribution Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 230000005489 elastic deformation Effects 0.000 description 1
- 230000005611 electricity Effects 0.000 description 1
- 238000005265 energy consumption Methods 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 230000007774 longterm Effects 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 230000003647 oxidation Effects 0.000 description 1
- 238000007254 oxidation reaction Methods 0.000 description 1
- 239000011148 porous material Substances 0.000 description 1
- 239000002244 precipitate Substances 0.000 description 1
- 238000001556 precipitation Methods 0.000 description 1
- 230000003449 preventive effect Effects 0.000 description 1
- 230000007425 progressive decline Effects 0.000 description 1
- 238000005070 sampling Methods 0.000 description 1
- 239000006104 solid solution Substances 0.000 description 1
- 238000005496 tempering Methods 0.000 description 1
- 238000010998 test method Methods 0.000 description 1
- 230000008646 thermal stress Effects 0.000 description 1
- 229910052721 tungsten Inorganic materials 0.000 description 1
- 229910052720 vanadium Inorganic materials 0.000 description 1
Landscapes
- Testing Of Devices, Machine Parts, Or Other Structures Thereof (AREA)
Abstract
Description
【発明の詳細な説明】
〔発明の目的〕
（産業上の利用分野）
本発明は、クリープ領域で使用される高温ボルトの寿命
管理方法に関する。DETAILED DESCRIPTION OF THE INVENTION OBJECTS OF THE INVENTION (Industrial Field of Application) The present invention relates to a method for managing the life of high temperature bolts used in creep areas.
（従来の技術）
石油化学プラント、火力発電プラント等の高温で使用さ
れる材料には、耐酸化性、高温クリープ性に優れ、長時
間にわたり組織が安定で脆化の発生しにくい事が要求さ
れる。(Conventional technology) Materials used at high temperatures in petrochemical plants, thermal power plants, etc. are required to have excellent oxidation resistance and high temperature creep resistance, and to have a stable structure over a long period of time and to be resistant to embrittlement. Ru.
蒸気タービンを例にとると、代表的な高温ボルトは、高
圧、中圧ケーシングの水平継手の締付あるいは主要蒸χ
弁の上蓋の締付けに用いられるものであり、大きいもの
ではネジ径が１７８φ、長さ１６５０ｍｍにも達するも
のがある。これらのボルトは高温下で長時間使用される
ため、経年的な劣化現象が不可避的に進行するが、ター
ビンの運転中に所要の締付力が維持できなくなると高温
・高圧の蒸気が外部に漏洩するためユニットの安定運用
に重大な支障をきたすことになる。また定期点検時に割
れなどが発見されたとき、多くの場合、同一使用箇所の
ボルト全数を交換することが多いが、この場合製作納期
の関係から定期点検工程を圧迫し給電計画の変更に至る
ことも考えられる。Taking steam turbines as an example, typical high-temperature bolts are used to tighten horizontal joints of high-pressure and intermediate-pressure casings, or to tighten the main steam
It is used to tighten the upper cover of a valve, and some large ones have a thread diameter of 178φ and a length of 1650 mm. Since these bolts are used for long periods of time under high temperatures, they inevitably deteriorate over time, but if the required tightening force cannot be maintained during turbine operation, high temperature and high pressure steam will leak outside. This leakage will seriously impede the stable operation of the unit. In addition, when cracks are discovered during periodic inspections, in many cases all bolts in the same location are replaced, but in this case, due to production deadlines, this puts pressure on the periodic inspection process and leads to changes in the power supply plan. can also be considered.
蒸気タービンに使用される高温ボルトには、捌付時ある
いは定期点検組立時の初期締付力の他に、フランジなど
の被締付体との熱膨張差やケーシングの熱変形力によっ
て生ずる応力と、内圧によって生ずる応力が加わる。こ
れらの応力によって高温ボルトにはりリープリラクゼー
シミンにもとづく締付力の低下と寿命の消費が同時に進
行する。High-temperature bolts used in steam turbines are subject to stress caused by the initial tightening force during removal or periodic inspection and assembly, as well as the difference in thermal expansion with the body to be tightened such as a flange, and the thermal deformation force of the casing. , stress caused by internal pressure is applied. Due to these stresses, the tightening force of the high-temperature bolt due to leakage and relaxation progresses, and the service life of the bolt is reduced at the same time.
また、タービンの起動・停止過程のような熱的な過渡状
態下では、ケーシングなどの大きな熱変形力が付加され
るので、低サイクル疲労が生じて寿命消費が促進される
。In addition, under thermal transient conditions such as the startup and shutdown processes of a turbine, a large thermal deformation force is applied to the casing, etc., resulting in low cycle fatigue and accelerated life consumption.
１２ＣｒＭｏＶＷ鋼やＣｒＭｏＶ鋼の高温ボルト材は炭
化物生成元素であるＣｒ、Ｍｏ、Ｖ 、 Ｗの添加によ
り過度のＣｒ２３ Ｃｌｌ形化化物生成を抑制し材料を
安定化するとともに、Ｍｏ、Ｗなどは固溶体強化の役目
をも有し、さらにＶを含めてＭ２ｘ相を生成し、焼もど
しによる二次硬化によって常温や高温強度を高くしてお
り、いずれもすぐれた強度を靭性を有している。このボ
ルト材は、高温・高応力下で長時間使用されると緻密に
析出していた炭化物が結晶粒界に凝集粗大化したり、Ｐ
などの極微量含まれている不純物元素が析出して、強度
と靭性の低下が進行する。この現象を結晶粒内でみると
当初高密度で存在していた極微細炭化物の数が経年的に
減少して、粒子間距離と粒経が増大し、転位密度が減少
する。このためボルト材に軟化現象が認められる。High-temperature bolt materials such as 12CrMoVW steel and CrMoV steel are stabilized by adding carbide-forming elements Cr, Mo, V, and W to suppress excessive Cr23 Cl formation and stabilize the material, and Mo, W, etc. are solid solution strengthened. In addition, it also contains V to form an M2x phase, and has high strength at room temperature and high temperature through secondary hardening through tempering, both of which have excellent strength and toughness. When this bolt material is used for a long time under high temperature and high stress, the densely precipitated carbides aggregate at the grain boundaries and become coarse.
Impurity elements contained in extremely small amounts, such as, precipitate, leading to a progressive decline in strength and toughness. Looking at this phenomenon within crystal grains, the number of ultrafine carbides that initially existed at high density decreases over time, the interparticle distance and grain size increase, and the dislocation density decreases. For this reason, a softening phenomenon is observed in the bolt material.
粗大化した炭化物や不純物元素の析出は、高温ボルト材
の結晶粒界の強度と靭性の低下をもたらすため、経年劣
化による割れは、先ず粒界に滑りが生じたりあるいは極
微細な空孔が生じ、これらが成長伝播することにより生
ずる。この破壊形態では破面附近に殆ど伸びや絞りを伴
わず、脆化した粒界破断が生じる。Precipitation of coarse carbides and impurity elements reduces the strength and toughness of the grain boundaries of high-temperature bolt materials, so cracks caused by aged deterioration are first caused by slipping at the grain boundaries or by the formation of microscopic pores. , are caused by the growth and propagation of these. In this fracture mode, embrittled intergranular fracture occurs near the fracture surface with almost no elongation or narrowing.
一方、以上のように結晶粒界に割れが発生しなくても転
位密度の減少によって軟化が著しく進行することにより
、クリープ変形に対する抵抗力が低下するため、定期点
検毎にボルトの伸びが生じていることがある。著しい場
合にはタービンの運転中に締付力が不足して蒸気漏洩に
至ることもある。On the other hand, as described above, even if no cracks occur at grain boundaries, softening progresses significantly due to a decrease in dislocation density, and the resistance to creep deformation decreases, resulting in bolt elongation at each periodic inspection. Sometimes there are. In severe cases, the tightening force may be insufficient during turbine operation, leading to steam leakage.
このようなボルトの経年劣化の特徴をよく理解、して、
余寿命評価を行ない、適切な保守管理を行なうことが必
要となってきている。Understand and understand the characteristics of bolt deterioration over time.
It has become necessary to evaluate the remaining life and perform appropriate maintenance management.
特に、長時間使用タービンの増加とＤＳＳ（Ｄａｉｎｙ
Ｓｔａｒｔ Ｓｔｏρ）運用の変化が急激に進行してい
る現在、従来にも増して高温ボルトの定期的な保守点検
と寿命評価の必要性が増してきている。In particular, the increase in the number of long-term use turbines and the
Start Stoρ) At present, with rapid changes in operation, the need for periodic maintenance inspection and life evaluation of high-temperature bolts is increasing more than ever before.
この高温ボルトの保守管理は、従来は非破壊試験をベー
スとした管理が行なわれていた。この非破壊試験の内容
は音響試験、硬度測定、超音波探傷試験、寸法試験がベ
ースとなっており、音響試験はボルトを組立てた状態で
ハンマー等を使用してナツトの頭を叩き、異音が認めら
れるかどうか確認する方法、硬度測定はボルトの代表部
を硬度測定し、経年的な軟化量を把握し、硬さ基準値を
満足しているかどうかの確認を行う方法、超音波探傷試
験はボルトの頭部の探接触子を当ててボルトネジ部にき
裂の発生が認められるかどうかの確認を行なう方法１寸
法試験はボルトのネジ形状、ボルトの径等の寸法が設計
最小寸法を満足しているかどうかを確認するものである
。Conventionally, maintenance management of these high-temperature bolts has been based on non-destructive testing. The content of this non-destructive test is based on an acoustic test, hardness measurement, ultrasonic flaw detection test, and dimensional test.The acoustic test involves hitting the head of a nut with a hammer or the like while the bolt is assembled, and detecting abnormal noises. A method to check whether or not the hardness is recognized, a method to measure the hardness of a representative part of the bolt, understand the amount of softening over time, and confirm whether the hardness standard value is satisfied, an ultrasonic flaw detection test Method 1: Dimension test: The bolt thread shape, bolt diameter, and other dimensions satisfy the minimum design dimensions. This is to check whether it is.
（発明が解決しようとする問題点）
しかし、前述した高温使用状態での材質の経年劣化を考
えてみると、上記の非破壊検査では靭性の低下、すなわ
ち脆化という重要な項目が抜けており、これをどう扱う
かが重要な問題として残っていた。確かに強度の低下は
強度に密接に関係した硬度測定で把握することはできる
が、脆化程度は従来の非破壊検査では管理できないとい
う問題が残っている。また強度低下について考えてみた
場合、硬度測定という点では確かに実施しているが、ボ
ルトで最も損傷が著しいネジ底の硬度測定が現実には実
施できないという問題があり代表部の硬度測定でどこま
でカバーできているかの問題もある。(Problem to be solved by the invention) However, when considering the aging of materials under high-temperature usage conditions, the non-destructive tests mentioned above omit the important item of decrease in toughness, that is, embrittlement. , how to deal with this remained an important issue. It is true that the decrease in strength can be detected by measuring hardness, which is closely related to strength, but the problem remains that the degree of embrittlement cannot be controlled by conventional non-destructive testing. Also, when thinking about strength reduction, although hardness measurements are certainly being carried out, there is a problem in that it is not actually possible to measure the hardness of the thread bottom, where the damage is most severe in bolts. There is also the issue of whether it is being covered.
本発明の目的はこのような点に鑑み、高温部で使用され
るボルトの保守管理法として、従来の非破壊検査のみに
頼っていた材質劣化と損傷の蓄積量の把握を、ボルトの
損傷を受ける部位の中で最もその損傷の程度が大きいボ
ルトネジ底の寿命計算と結びつけた新しい保守管理法を
得ることを目的としている。In view of these points, the purpose of the present invention is to improve the maintenance and management method for bolts used in high-temperature parts by improving the ability to grasp the amount of material deterioration and damage accumulated, which previously relied only on non-destructive testing, and to improve the ability to detect damage to bolts. The purpose of this study is to obtain a new maintenance management method that combines the lifespan calculation of the bolt thread bottom, which is the most severely damaged part of the system.
（問題点を解決するための手段）
本発明は、ボルトの交換を決定するにあたって、ボルト
の使用状態に応じたクリープ損傷量φｃおよび疲労損傷
量φｆを求め、これらクリープ損傷量φＣおよび疲労損
傷量φｆの総和であるトータル損傷量φを指標とするボ
ルトの保守管理方法であって、特にボルトネジ底部分の
損傷量の計算結果に基づいてボルトの非破壊検査、破壊
検査又は交換を判断し、この判断には従来通り実施され
る非破壊検査結果が反映されるようになったことを特徴
とし、ボルトにき裂等の損傷が発生し重大な事態に至る
前に適切な交換時期を求める方法である。(Means for Solving the Problems) When deciding whether to replace a bolt, the present invention calculates the amount of creep damage φc and the amount of fatigue damage φf depending on the usage condition of the bolt, and calculates the amount of creep damage φc and the amount of fatigue damage. A bolt maintenance management method that uses the total amount of damage φ, which is the sum of φf, as an index, and in particular, determines whether to conduct a non-destructive inspection, destructive inspection, or replacement of the bolt based on the calculation result of the amount of damage at the bottom of the bolt thread. It is characterized by the fact that the results of non-destructive tests, which are carried out in the past, are now reflected in the judgment, and it is a method to determine the appropriate time to replace bolts before cracks or other damage occurs and a serious situation develops. be.
（作用）
本発明においては、計算によって求められたボルトの損
傷量に応じて非破壊検査、破壊検査を行なったうえでボ
ルトの交換が決定されるがら１本発明によればボルト切
損等に至る前に計画的にボルトの交換を行なうことがで
きる。(Function) In the present invention, bolt replacement is determined after performing non-destructive inspection and destructive inspection according to the amount of damage to the bolt determined by calculation. Bolts can be replaced in a planned manner before reaching the end.
（実施例）
第１図は本発明の一実施例を説明するもので、基本的に
この手法は計算によって損傷を求めるルート（Ａ）と非
破壊検査によって異常を検出するルート（Ｂ）の二つの
根幹から成る。(Example) Fig. 1 explains an example of the present invention. Basically, this method consists of two routes: finding damage by calculation (A) and detecting abnormalities by non-destructive testing (B). Consisting of two roots.
ルートＡにおいては、まずタービン運転実績データ１に
基づいてボルトの特にネジ底部分のクリープ損傷量φｃ
および疲労損傷量φｆを計算しくステップ２）、その結
果を合算したトータル損傷量φについて、φの大きさに
応じて次に行なうべき事項を決定する（ステップ３）、
いま、トータル損傷量をＯ≦φ≦１で決めるようにすれ
ば、φく０．８のときには特に支障なしとして（ステッ
プ４）、あらためて損傷量の計算を行なうことを決定す
る。In route A, first, based on the turbine operation performance data 1, the amount of creep damage φc of the bolt, especially the threaded bottom part, is calculated.
and the fatigue damage amount φf (Step 2), and the total damage amount φ that is the sum of the results, determines what to do next depending on the size of φ (Step 3).
Now, if the total amount of damage is determined as O≦φ≦1, there will be no problem when φ is 0.8 (step 4), and it is decided to calculate the amount of damage again.
０．８≦φ≦０．９のときには、なるべく早い時期に、
通常は次回の定検時に非破壊検査を行なうことを決定し
くステップ５）、また０、９〈φ のときには同様に破
壊試験を行うことを決定しくステップ６）、ボルトを１
本抜取って行なう破壊試験の結果、材料が劣化していれ
ばボルトを交換することを決定°し、劣化していなけれ
ば今度は非破壊検査を行うことを決定する（ステップ７
）。When 0.8≦φ≦0.9, as soon as possible,
Normally, it is decided to conduct a non-destructive test at the next periodic inspection (Step 5), and when 0 or 9〈φ, it is decided to conduct a similar destructive test (Step 6).
If the material has deteriorated as a result of the destructive test carried out by sampling, it is decided to replace the bolt, and if it has not deteriorated, it is decided to conduct a non-destructive test (Step 7).
).
上記破壊試験は具体的には引張試験および衝・撃試験で
あり、これら試験によって強度および靭性を評価するこ
とができる。材料が劣化しているが否かを判断する基準
としては、引張強さ、耐力がその材料規格値より夫々１
０％低下、衝撃値が５０％低下等の各項目を採用するこ
とができる。Specifically, the above-mentioned destructive test is a tensile test and an impact/impact test, and strength and toughness can be evaluated by these tests. The criteria for determining whether a material has deteriorated is that the tensile strength and yield strength are each 1 or less than the standard value of the material.
Items such as 0% reduction, 50% reduction in impact value, etc. can be adopted.
他方、ルートＢにおいては、タービン運転実績データ１
を踏まえて、音響試験、硬度測定、超音波探傷検査、お
よび寸法試験のうちいずれか１種以上の検査からなる非
破壊検査を行ない（ステップ８）、き裂発生等に基づく
異常が認められればボルトの交換（ステップ１０）を決
定し、特に異常がなければあらためて損傷量φを計算す
ることを決定する（ステップ９）。On the other hand, in route B, turbine operation performance data 1
Based on this, a non-destructive test consisting of one or more of acoustic tests, hardness measurements, ultrasonic flaw detection tests, and dimensional tests is performed (Step 8), and if abnormalities due to cracking etc. are found, It is decided to replace the bolt (step 10), and if there is no particular abnormality, it is decided to calculate the damage amount φ again (step 9).
上記破壊試験および非破壊検査は定期検査時等のタービ
ン停止時に行ない、また損傷量の計算は同様に定検時ま
たはその他の機会に行なう。The above-mentioned destructive tests and non-destructive tests are performed when the turbine is stopped, such as during periodic inspections, and the amount of damage is similarly calculated during periodic inspections or other occasions.
次にボルト損傷量の計算手法について第２図を参照して
説明する。ボルトの損傷量はクリープ損傷量φＣと疲労
損傷量φｆをボルトの使用状況に応じて求め、線形損傷
総和側に基づいて両者を合算したトータル損傷量がφ＝
１．０（１００％）になった時点で余寿命が零であると
判定することとしている。Next, a method for calculating the amount of bolt damage will be explained with reference to FIG. 2. The amount of damage to the bolt is obtained by calculating the amount of creep damage φC and the amount of fatigue damage φf according to the usage status of the bolt, and the total amount of damage obtained by adding both based on the linear damage summation side is φ =
When it reaches 1.0 (100%), it is determined that the remaining life is zero.
すなわち、次の２種類の損傷量を対象とする。That is, the following two types of damage amounts are targeted.
（ａ）クリープリラクゼーションによる経時的応力変化
を考慮したボルト締付応力に基づくクリープ損傷、ｔ：
φＣ
（ｂ）起動・停止により発生するケーシング等の熱変形
力に基づく過渡的応力による疲労損傷量：φｆ
しかして、クリープ損傷量φｃと疲労損傷量φ、は線形
損傷総和側によるトータル損傷量φで評価する。(a) Creep damage based on bolt tightening stress considering stress change over time due to creep relaxation, t:
φC (b) Amount of fatigue damage due to transient stress based on thermal deformation force of the casing, etc. caused by starting and stopping: φf Therefore, the amount of creep damage φc and the amount of fatigue damage φ are the total amount of damage φ due to the linear damage summation side Evaluate with.
φ＝φＣ＋φ、≦１．０ ・・・ ■ここでク
リープ損傷量φＣは以下の手法によって算出される。ク
リープ損傷は、ボルト締付応力による応力状態が高温下
でクリープリラクゼーションにより変化することを考慮
し、第２図および第３図に示す曲線に基づいて計算され
る。ボルトは繰返し使用されるため、分解の時に完全に
ゆるめ、その再度締直すという繰返しのクリープ損傷を
受けることになり、クリープ損傷量φＧの計算を行なう
にあたってはタービンの定期点検インターバルを考慮す
ることが必要となる。第２図の曲線はボルトを高温で使
用した場合の応力緩和特性を示すクリープリラクゼーシ
ョン曲線であり、第３図の曲線はそのボルト材のクリー
プ破断強度を示すもので、付与される応力と温度および
破断時間の関係を次式で示すラーソン・ミラー・パラメ
ータ（ＬＭＰ）で整理したものである。φ=φC+φ, ≦1.0... ■Here, the amount of creep damage φC is calculated by the following method. Creep damage is calculated based on the curves shown in FIGS. 2 and 3, taking into account that the stress state due to bolt tightening stress changes due to creep relaxation at high temperatures. Since bolts are used repeatedly, they are subject to creep damage due to repeated loosening and re-tightening during disassembly, so when calculating the amount of creep damage φG, it is necessary to take into account the periodic inspection interval of the turbine. It becomes necessary. The curve in Figure 2 is a creep relaxation curve that shows the stress relaxation characteristics when a bolt is used at high temperatures, and the curve in Figure 3 shows the creep rupture strength of the bolt material. The relationship between the rupture time is organized using the Larson-Miller parameter (LMP) shown by the following equation.
ＬＭＰ ＝Ｔ （Ｃ＋１ｏｃｔ） −０４）ただし
Ｔ：絶対温度（” Ｋ）、 ｔ ：破断時間（ｈｒ、）
Ｃ：材料定数
クリープ損傷量φｃを求めるには、まず第２図の曲線の
時間に対する応力変化の少ない箇所をΔを時間分とり、
このときの応力σ１に相当するＬ Ｍ Ｐを第３図から
求め、次式により算出する。LMP = T (C+1oct) -04) where T: absolute temperature (K), t: rupture time (hr, )
C: Material constant To find the amount of creep damage φc, first take the portion of the curve in Figure 2 where the stress changes with respect to time is small, and take Δ for the time.
L M P corresponding to the stress σ1 at this time is determined from FIG. 3 and calculated using the following formula.
上式により全ての時間の各Δ乞時間につき計算を行ない
それらを加算すれば、クリープ損傷量φＣを求めること
ができる。The amount of creep damage φC can be obtained by calculating each Δ time for all times using the above formula and adding them.
しかして（イ）式の計算をボルトの取外し・再締付回数
に応じて行ない、それらを加算すれば蓄積されたクリー
プ損傷量を知ることができる。Therefore, by calculating the formula (a) according to the number of times the bolt is removed and retightened, and adding them together, the amount of accumulated creep damage can be determined.
次に疲労損傷量の計算手法について説明する。Next, a method for calculating the amount of fatigue damage will be explained.
これは各運転パターン（コールド、ウオーム、ホット）
毎にタービンケーシング等に発生する熱変形力により、
ボルトに作用する過渡的応力の繰返しによる疲労損傷を
求めるものである。すなわち。This is for each driving pattern (cold, warm, hot)
Due to the thermal deformation force generated in the turbine casing etc.
This method determines fatigue damage caused by repeated transient stress acting on bolts. Namely.
ボルトのネジ底部分に発生する熱荷重による繰返し応力
を求めるのであるが、このときクリープリラクゼーショ
ンによるネジ山の荷重集中率の変化を考慮する。一般に
通常のメートルネジではネジ山の荷重分担率が一様でな
く、第４図に示すようにかかりの初めのところに荷重が
集中するようになっている。このためタービンに使用す
るボルトではめねじ有効径とおねじ有効径の間に呼び応
じて一定のすきまをもたせ、かつ公差を厳格にし、さら
にある一定のテーパ（通常は１／２００）を付すことに
よりネジ山の荷重分担を一様にするよう設計されている
。しかし、この荷重分担の均一化はネジ山の弾性変形に
よって与えられるため、ボルトの締付荷重が変化すれば
それに応じて変化することとなり、第２図に示したよう
にクリープリラクゼーションにより応力緩和があると第
５図のように荷重集中率が徐々に大きくなり、疲労損傷
量を計算するにはこのネジ山の荷重集中率の変化を考慮
しなければ的確な評価を行うことができない。The repeated stress due to the thermal load generated at the thread bottom of the bolt is determined, and at this time, changes in the load concentration rate of the thread due to creep relaxation are taken into account. In general, in a normal metric screw, the load sharing ratio on the screw thread is not uniform, and the load is concentrated at the beginning of the hook, as shown in Figure 4. For this reason, bolts used in turbines have a certain clearance between the effective diameter of the female thread and the effective diameter of the male thread, strict tolerances, and a certain taper (usually 1/200). Designed to evenly distribute load on threads. However, this equalization of load distribution is given by the elastic deformation of the screw thread, so if the tightening load of the bolt changes, it will change accordingly, and as shown in Figure 2, the stress will be relaxed by creep relaxation. If this occurs, the load concentration rate gradually increases as shown in Fig. 5, and in order to calculate the amount of fatigue damage, accurate evaluation cannot be performed unless this change in the load concentration rate of the screw thread is taken into account.
本実施例においては、疲労損傷量を求めるにあたってボ
ルトに作用する熱応力として次のようにネジ山荷重集中
率を考慮したピーク応力振幅Δσｔを用いる。In this embodiment, when determining the amount of fatigue damage, the peak stress amplitude Δσt is used as the thermal stress acting on the bolt in consideration of the thread load concentration ratio as follows.
Δσｔ＝σＸＫ、ＸＫ、 ・・・■ここでσ：熱
応力、に、：ネジ山荷重集中率に、：応力集中係数
第６図はボルト材の疲労強度を示す線図であり。Δσt=σXK,
この線図から、上記ピーク応力振幅Δσ、が作用した場
合、そのΔσ、に対する許容繰返し数Ｎを求めることが
できる。そしてこの許容繰返し数Ｎの逆数１／Ｎが、Δ
σｔなる応力振幅が１回作用した時の疲労損傷量となる
。つまり、
Δφｆ ＝ １／Ｎ ・・・０しかして、各
運転パターン毎にΔφ、を求め。From this diagram, when the peak stress amplitude Δσ acts, the permissible number of repetitions N for that Δσ can be determined. Then, the reciprocal number 1/N of this allowable repetition number N is Δ
This is the amount of fatigue damage when the stress amplitude σt acts once. In other words, Δφf = 1/N...0 Then, calculate Δφ for each driving pattern.
それぞれ起動回数に応じた和を求め、それらを合算する
ことにより全ての運転パターンを含めた疲労損傷量φず
を算出することができる。By calculating the sum according to the number of activations and summing them, it is possible to calculate the fatigue damage amount φZ including all driving patterns.
φ、＝ΣΔφｆ＝Σ（Δφｆ）ｃ＋Σ（Δφｆ）ｖ＋Σ
（Δφｆ）ｏ・・・■ここで（Δφｆ）ｃｅＷｍ、４：
Ｃ・・・コールド、Ｗ・・・ウオーム、Ｈ・・・ホッ
ト、各ス
タート時の１回当りの疲
労回数
ｎｃｓｎＶｙｎＨ：それぞれの運転パターンの起動回数
以上のようにして疲労損傷量φｆを求め、これ損傷量φ
を求める。φ,=ΣΔφf=Σ(Δφf)c+Σ(Δφf)v+Σ
(Δφf)o...■Here (Δφf)ceWm, 4:
C...Cold, W...Warm, H...Hot, Number of fatigue per start ncsnVynH: Calculate the amount of fatigue damage φf from the number of starts of each operation pattern or more, and calculate this. Damage amountφ
seek.
φ；φＣ＋φｆ ・・・■このトータル損
傷量φを用いて第１図に示した判断を行なう、第７図は
以上の手順を示した流れ図である。上記計算に基づいて
ボルトネジ底部分にクリープ或いは疲労によるき裂が発
生するか否かを判断することが可能となり、この判断に
より第１図に示した非破壊検査さらに破壊試験を行なっ
て予防保全を目的としたボルトの保守管理が行なえるよ
うになる。φ; φC+φf . . . The judgment shown in FIG. 1 is made using this total damage amount φ. FIG. 7 is a flowchart showing the above procedure. Based on the above calculation, it is possible to judge whether or not cracks due to creep or fatigue will occur at the bottom of the bolt thread. Based on this judgment, preventive maintenance can be carried out by performing the non-destructive inspection shown in Figure 1 and further destructive testing. You will be able to perform targeted maintenance and management of bolts.
このように本実施例によれば、従来の非破壊検査では推
測することしかできなかったボルトネジ底部分の損傷量
を定量的に把握でき、この損傷量を基本としてその後の
非破壊検査又は破壊試験を行なうことにより、ボルトの
交換についてより的確な判断をすること□ができる。In this way, according to this embodiment, it is possible to quantitatively understand the amount of damage to the bottom part of the bolt thread, which could only be estimated in conventional non-destructive testing, and based on this amount of damage, subsequent non-destructive testing or destructive testing can be carried out. By doing this, you can make a more accurate decision about replacing the bolt.
以上説明したように１本発明は高温ボルトの保守管理を
行なうにあたって、ボルトネジ底部分の損傷量を計算に
よって求め、この計算による損傷量に応じてその後に行
なうべき処置を決定するものであるから１本発明によれ
ば切損等の重大事態に至る前に計画的にボルトの交換を
行なうことができ、したがってタービンの定期点検を常
に予定通り行なうことができることとなり、長時間ター
ビンの増加とＤＳＳ運用の増加に十分対応できることと
併せ、電力の安定供給に大いに寄与することができる。As explained above, (1) the present invention calculates the amount of damage to the bottom portion of the bolt thread when performing maintenance and management of high-temperature bolts, and determines the subsequent measures to be taken in accordance with the calculated amount of damage; (1) According to the present invention, it is possible to systematically replace bolts before a serious situation such as breakage occurs, and therefore regular inspections of the turbine can always be carried out as scheduled, which reduces the need for an increase in the number of turbines and DSS operation. In addition to being able to adequately cope with the increase in energy consumption, it can also greatly contribute to the stable supply of electricity.
第１図は本発明の一実施例に係るボルトの保守管理方法
の全体を示す概念図、第２図はボルトのクリープリラク
ゼーション曲線、第３図はボルト材の応力とラーソンミ
ラーパラメータ（ＬＭＰ）の関係を示す線図、第４図は
ボルトの荷重分担率を説明する図、第５図は時間に対す
るネジ山荷重集中率の関係を示す線図、第６図はボルト
材の応力振幅と許容繰返し回数の関係を示す線図、第１
図はクリープ損傷量および疲労損傷量の計算方法の概略
を示す流れ図である。
代理人 弁理士 則 近 憲 佑
同 三俣弘文
第２図 第３図
第５図
き１迭傘Ｆ主セｔ−６皇返し■ト瑠くＮ第６図
第７図Fig. 1 is a conceptual diagram showing the entire bolt maintenance management method according to an embodiment of the present invention, Fig. 2 is a creep relaxation curve of the bolt, and Fig. 3 is a diagram showing the stress of the bolt material and the Larson Miller parameter (LMP). A diagram showing the relationship. Figure 4 is a diagram explaining the load sharing ratio of the bolt. Figure 5 is a diagram showing the relationship between the thread load concentration rate and time. Figure 6 is a diagram showing the stress amplitude of the bolt material and the allowable repetition. Diagram showing the relationship between numbers, 1st
The figure is a flowchart showing an outline of a method for calculating the amount of creep damage and the amount of fatigue damage. Agent Patent Attorney Nori Chika Ken Yudo Hirofumi MitsumataFigure 2Figure 3Figure 5K1 迭UmbrellaFSet-6Kōgaeshi■ToRukuNFigure 6Figure 7
Claims (6)
用状態に応じたクリープ損傷量φ＿ｃおよび疲労損傷量
φ＿ｆを求め、これらクリープ損傷量φ＿ｃおよび疲労
損傷量φ＿ｆの総和であるトータル損傷量φを指標とす
るボルトの保守管理方法。(1) When deciding to replace a bolt, calculate the amount of creep damage φ_c and the amount of fatigue damage φ_f depending on the usage condition of the bolt, and use the total amount of damage φ, which is the sum of the amount of creep damage φ_c and the amount of fatigue damage φ_f, as an index. How to maintain and manage bolts.
検査あるいは破壊検査を行ないボルトの交換を決定する
特許請求の範囲第１項記載のボルトの保守管理方法。(2) The method for maintenance and management of bolts according to claim 1, in which bolt replacement is determined by performing a non-destructive inspection or a destructive inspection of the bolts depending on the value of the total damage amount φ.
、ｂ（ａ＜ｂ）によって異なる三つの範囲に分類すると
き、 ・φ＜ａのときにはトータル損傷量φをその後あらため
て算出することを決定し、 ・ａ≦φ≦ｂのときには当該ボルトについて非破壊検査
を行なうことを決定し、 ・ｂ＜φのときには当該ボルトについて破壊試験を行な
うことを決定し、 さらに、 ・破壊試験を行なった結果材料の劣化が認められたとき
にはボルトの交換を決定し、そうでないときには残余の
ボルトについて非破壊検査を行なうことを決定し、 ・非破壊検査を行なった結果異常が認められたときには
少なくとも当該ボルトを交換することを決定し、そうで
ないときにはトータル損傷量φをあらためて算出するこ
とを決定する ことを含む特許請求の範囲第２項記載のボルトの保守管
理方法。(3) Two constants a depending on the total damage amount φ
When classifying into three different ranges depending on , b (a<b), ・When φ<a, it is decided to calculate the total amount of damage φ again, ・When a≦φ≦b, it is determined that the bolt in question is non-destructive. Decided to conduct an inspection, ・If b<φ, decided to conduct a destructive test on the bolt in question; Furthermore, ・If deterioration of the material was found as a result of the destructive test, decided to replace the bolt, If this is not the case, it will be decided to conduct a non-destructive test on the remaining bolts, and if an abnormality is found as a result of the non-destructive test, it will be decided to at least replace the bolt, and if not, the total amount of damage φ will be calculated. 3. The method for maintenance and management of bolts according to claim 2, which includes determining to perform the calculation again.
検査、寸法検査のうち少なくともいずれか１つを含む特
許請求の範囲第３項記載のボルトの保守管理方法。(4) The method for maintenance and management of bolts according to claim 3, wherein the nondestructive test includes at least one of acoustic testing, hardness measurement, ultrasonic flaw detection, and dimensional testing.
もいずれか１つを含む特許請求の範囲第３項記載のボル
トの保守管理方法。(5) The bolt maintenance method according to claim 3, wherein the destructive test includes at least one of a tensile test and an impact test.
張強さ耐力のいずれもがその材料の規格値の１０％低下
、衝撃試験にあっては衝撃値がその材料規格値の５０％
低下したことをもって材料の劣化が認められたと判断す
る特許請求の範囲第５項記載のボルトの保守管理方法。(6) As a result of the destructive test, the tensile strength and yield strength in the tensile test decreased by 10% of the standard value of the material, and in the impact test, the impact value decreased by 50% of the material standard value.
6. The bolt maintenance and management method according to claim 5, wherein it is determined that material deterioration has been recognized when the material has decreased.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP7830186A JPS62235539A (en) | 1986-04-07 | 1986-04-07 | Maintenance and management of bolt |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP7830186A JPS62235539A (en) | 1986-04-07 | 1986-04-07 | Maintenance and management of bolt |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JPS62235539A true JPS62235539A (en) | 1987-10-15 |
Family
ID=13658098
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP7830186A Pending JPS62235539A (en) | 1986-04-07 | 1986-04-07 | Maintenance and management of bolt |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPS62235539A (en) |
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2008180735A (en) * | 2000-04-14 | 2008-08-07 | Toshiba Corp | Method apparatus for diagnosing life of component |
| JP2010223624A (en) * | 2009-03-19 | 2010-10-07 | Hitachi Ltd | Method for assessing remaining lifespan of bolt used at high temperatures |
| JP2011154048A (en) * | 2011-05-19 | 2011-08-11 | Hitachi Ltd | Method for diagnosing remaining life of bolt used under high temperature |
| JP2013057611A (en) * | 2011-09-09 | 2013-03-28 | Shimadzu Corp | Material testing machine |
-
1986
- 1986-04-07 JP JP7830186A patent/JPS62235539A/en active Pending
Cited By (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2008180735A (en) * | 2000-04-14 | 2008-08-07 | Toshiba Corp | Method apparatus for diagnosing life of component |
| JP2008249732A (en) * | 2000-04-14 | 2008-10-16 | Toshiba Corp | Method and device for diagnosing life of member |
| JP4649497B2 (en) * | 2000-04-14 | 2011-03-09 | 株式会社東芝 | Method for diagnosing lifetime of member and method and apparatus for diagnosing the lifetime |
| JP4745366B2 (en) * | 2000-04-14 | 2011-08-10 | 株式会社東芝 | Method for diagnosing lifetime of member and apparatus for diagnosing the lifetime |
| JP2010223624A (en) * | 2009-03-19 | 2010-10-07 | Hitachi Ltd | Method for assessing remaining lifespan of bolt used at high temperatures |
| JP2011154048A (en) * | 2011-05-19 | 2011-08-11 | Hitachi Ltd | Method for diagnosing remaining life of bolt used under high temperature |
| JP2013057611A (en) * | 2011-09-09 | 2013-03-28 | Shimadzu Corp | Material testing machine |
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