JPS6183962A - Ultrasonic flaw detection of centrifugally cast pipe - Google Patents

Ultrasonic flaw detection of centrifugally cast pipe

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Publication number
JPS6183962A
JPS6183962A JP59206858A JP20685884A JPS6183962A JP S6183962 A JPS6183962 A JP S6183962A JP 59206858 A JP59206858 A JP 59206858A JP 20685884 A JP20685884 A JP 20685884A JP S6183962 A JPS6183962 A JP S6183962A
Authority
JP
Japan
Prior art keywords
flaw detection
wave
divided
centrifugally cast
ultrasonic
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
Application number
JP59206858A
Other languages
Japanese (ja)
Inventor
Masanaga Iwasaki
岩崎　全長
Sadao Kawashima
貞夫 河島
Yoshiichi Mori
森　芳一
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Kobe Steel Ltd
Original Assignee
Kobe Steel Ltd
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by Kobe Steel Ltd filed Critical Kobe Steel Ltd
Priority to JP59206858A priority Critical patent/JPS6183962A/en
Publication of JPS6183962A publication Critical patent/JPS6183962A/en
Pending legal-status Critical Current

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Classifications

    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N29/00—Investigating or analysing materials by the use of ultrasonic, sonic or infrasonic waves; Visualisation of the interior of objects by transmitting ultrasonic or sonic waves through the object
    • G01N29/44—Processing the detected response signal, e.g. electronic circuits specially adapted therefor
    • G01N29/46—Processing the detected response signal, e.g. electronic circuits specially adapted therefor by spectral analysis, e.g. Fourier analysis or wavelet analysis
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N29/00—Investigating or analysing materials by the use of ultrasonic, sonic or infrasonic waves; Visualisation of the interior of objects by transmitting ultrasonic or sonic waves through the object
    • G01N29/04—Analysing solids
    • G01N29/06—Visualisation of the interior, e.g. acoustic microscopy
    • G01N29/0609—Display arrangements, e.g. colour displays
    • G01N29/0618—Display arrangements, e.g. colour displays synchronised with scanning, e.g. in real-time
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N29/00—Investigating or analysing materials by the use of ultrasonic, sonic or infrasonic waves; Visualisation of the interior of objects by transmitting ultrasonic or sonic waves through the object
    • G01N29/34—Generating the ultrasonic, sonic or infrasonic waves, e.g. electronic circuits specially adapted therefor
    • G01N29/348—Generating the ultrasonic, sonic or infrasonic waves, e.g. electronic circuits specially adapted therefor with frequency characteristics, e.g. single frequency signals, chirp signals
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N29/00—Investigating or analysing materials by the use of ultrasonic, sonic or infrasonic waves; Visualisation of the interior of objects by transmitting ultrasonic or sonic waves through the object
    • G01N29/36—Detecting the response signal, e.g. electronic circuits specially adapted therefor
    • G01N29/38—Detecting the response signal, e.g. electronic circuits specially adapted therefor by time filtering, e.g. using time gates
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N2291/00—Indexing codes associated with group G01N29/00
    • G01N2291/02—Indexing codes associated with the analysed material
    • G01N2291/025—Change of phase or condition
    • G01N2291/0258—Structural degradation, e.g. fatigue of composites, ageing of oils
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N2291/00—Indexing codes associated with group G01N29/00
    • G01N2291/04—Wave modes and trajectories
    • G01N2291/042—Wave modes
    • G01N2291/0421—Longitudinal waves
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N2291/00—Indexing codes associated with group G01N29/00
    • G01N2291/04—Wave modes and trajectories
    • G01N2291/042—Wave modes
    • G01N2291/0428—Mode conversion
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N2291/00—Indexing codes associated with group G01N29/00
    • G01N2291/04—Wave modes and trajectories
    • G01N2291/044—Internal reflections (echoes), e.g. on walls or defects
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N2291/00—Indexing codes associated with group G01N29/00
    • G01N2291/26—Scanned objects
    • G01N2291/263—Surfaces
    • G01N2291/2634—Surfaces cylindrical from outside

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  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Immunology (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Chemical & Material Sciences (AREA)
  • Analytical Chemistry (AREA)
  • Biochemistry (AREA)
  • Health & Medical Sciences (AREA)
  • Pathology (AREA)
  • General Health & Medical Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Signal Processing (AREA)
  • Acoustics & Sound (AREA)
  • Mathematical Physics (AREA)
  • Spectroscopy & Molecular Physics (AREA)
  • Investigating Or Analyzing Materials By The Use Of Ultrasonic Waves (AREA)

Abstract

PURPOSE:To enable the flaw detection of an internal flaw, by using a probe having a wide band frequency characteristic and subjecting the entire periphery of a centrifugally cast pipe to ultrasonic flaw detection by a longitudinal wave regular reflection method. CONSTITUTION:By using a longitudinal wave in the flaw detection of a centrifugally cast pipe 3A, an ultrasonic wave id regularly reflected at a flaw part 5 and received by a receiving probes 1a or 1B. However, because the longitudinal wave is used, the reflected wave 2 or 2' having flaw information is transmitted to the receiving probe 1a or 1B at first and forest like beam due to the scattered wave of a crystal grain boundary or traverse wave receiving mode conversion at the time of reflection reaches the receiving probe 1A or 1B so as to be delayed from the reflected wave 2 or 2'. Hereupon, a gate is provided in the vicinity of the time, which is calculated by dividing an ultrasonic beam distance by the speed of the longitudinal wave, to easily obtain flaw information.

Description

【発明の詳細な説明】 （産業上の利用分野） 本発明は、水蒸気接触改質用加熱管等の遠心鋳造管の経
年変化により発生する内部欠陥、生として周方向の欠陥
の検出に有効となり得る超音＃Ｒ傷による非破壊検査方
法に関する。Detailed Description of the Invention (Field of Industrial Application) The present invention is effective in detecting internal defects, such as defects in the circumferential direction, that occur due to aging in centrifugally cast tubes such as heating tubes for steam catalytic reforming. This invention relates to a non-destructive inspection method using ultrasonic #R scratches.

この種水蒸気接触改質用加熱管は主に遠心鋳造によＶ製
作されたａｘ　−４０（０，４０９６Ｃ１２５９６Ｏｒ
。This type of heating tube for steam catalytic reforming is mainly manufactured by centrifugal casting.
.

２０％Ｎｉ系）材等のオーステナイト系耐熱鋳鋼管を複
数本溶接接続して組立てられている。この加熱管は使用
状態では触媒が充填さｔ′Ｌ友管内管内部タン等のガス
と高圧水蒸気が圧送さルるとともに管外部からの加熱に
より管内部は高温高圧下にさらされる。この丸め加熱管
は使用期間の経過につれフーグ応力によるクリープフィ
ッシャーが管内部より外面に向って数対状に進展する傾
向がめり、また管内外の温度差（外熱内冷）に起因して
管内面の円周方向に欠陥を発生する怖れがるる。従って
上記加熱管の経年変化を把握し茂存痔命を推定すること
＃ｉｎ業安定上不可欠の事柄でるる。It is assembled by welding and connecting multiple austenitic heat-resistant cast steel pipes such as 20% Ni based material. When this heating tube is in use, it is filled with a catalyst, and gas and high-pressure steam are fed under pressure from the inside of the tube, and the inside of the tube is exposed to high temperature and high pressure due to heating from the outside of the tube. As this rounded heating tube is used, creep fissures due to Hoog stress tend to develop in pairs from the inside of the tube toward the outside surface. There is a fear that defects may occur in the circumferential direction of the surface. Therefore, it is essential to understand the aging of the heating tube and estimate the risk of hemorrhoids existing in order to stabilize the industry.

（従来の技術〕 遠心鋳造管からなるこの種加熱管の非破壊検査として＃
：を放射線透過検査と超音波探傷とがある。しかし放射
線透過検査は、放射線の進行方向にある程度以上の厚さ
、一般的には板厚の１％程度以上のｗＬさと放射線の進
行方向に対して直角方向の拡がりを持つ几欠陥でないと
検出さｆＬｍ＜、それ以外の欠陥、例えばワレ状欠陥の
ような場合は検出できず、検出精度が悪い＠超音波探傷
は一般に鉄鋼材料の内部欠陥に対する非破壊検査方法と
して有効であり、広く釣用されている。探傷法として、
パルス反射法、透過法、共振法などがあり、また探触子
を１個便用するもの、２個使用するもの、さらに超音波
を被検体に投入する方向Ｔｈ垂直あるい＃：ｔｆＩ４−
角とする方法などが知られており、各種被検体の形状、
欠陥の極類その他により適宜選択便用される＠ しかし本発明対象の遠心鋳造管は一般鍛圧鋼材や炭素鋼
鋳鏑材に比し超音波の減衰が大きいこと、ｉｋ結晶心大
で粒界反射による林状エフ゛−が出やすい丸め波形が複
雑となることなどに起因して、通常の超音波探傷法を遠
心鋳造管に適用することは非常に困難で６つ丸。例えば
、１探触子のパルス反射法による探傷法は結晶粒界等に
より林状エコーが生じ欠陥エコーと林状エフ−との区別
がつき難く、ま几送信パルス幅をるる程度より狭くする
ことが困難であり、従つて探傷面に近い欠陥を検出で１
！ない欠点がある。(Prior art) As a non-destructive inspection of this type of heating tube made of centrifugally cast tube, #
:There are radiographic inspection and ultrasonic flaw detection. However, radiographic inspection can detect defects only if they have a wL of more than a certain thickness in the direction of radiation propagation, generally about 1% or more of the plate thickness, and extend perpendicular to the direction of radiation propagation. fLm<, other defects, such as crack-like defects, cannot be detected and the detection accuracy is poor.@Ultrasonic flaw detection is generally effective as a non-destructive inspection method for internal defects in steel materials, and is widely used. ing. As a flaw detection method,
There are pulse reflection methods, transmission methods, resonance methods, etc., and methods that use one or two probes, and the direction in which the ultrasound is applied to the subject: vertical or #:tfI4-
Methods such as making corners are known, and the shape of various objects,
Selection can be made as appropriate depending on the polarity of defects, etc.@ However, the centrifugally cast pipes targeted by the present invention have greater attenuation of ultrasonic waves than general forged pressed steel materials or carbon steel cast iron materials, and grain boundary reflection due to the large size of the ik crystal core. It is extremely difficult to apply the normal ultrasonic flaw detection method to centrifugally cast pipes due to the complex rounded waveforms that tend to produce forest-like effects. For example, in flaw detection using the pulse reflection method using a single probe, forest-like echoes occur due to grain boundaries, etc., making it difficult to distinguish between defective echoes and forest-like F-. Therefore, it is difficult to detect defects close to the detection surface.
! There are no drawbacks.

ｔ７２．透過法は、直接欠陥エコー’ｅＭ象とせず、減
衰の状態から欠陥の状ｌｌＡｔ−推定する方法であり、
欠陥による超音波の減衰１を測定する。ただし、この場
合その位置での母材の減衰Ｉを知っておく必要があり、
母材の結晶粒が粗大で超音波の減衰が大きい遠心鋳造管
では確実性に欠ける方法である。t72. The transmission method is a method of estimating the state of the defect from the state of attenuation, without directly considering the defect echo'eM.
Measure the ultrasonic attenuation 1 due to the defect. However, in this case, it is necessary to know the attenuation I of the base material at that position.
This is an unreliable method for centrifugally cast tubes, where the crystal grains of the base material are coarse and the ultrasonic waves are attenuated greatly.

（発明が解決しようとする時題点） 本発明は、前記性状の遠心鋳造管に対する非破壊検査に
ついての従来技術の諸問題を克服し、その内部欠陥の探
傷、主に周方向の欠陥に有効となり得る超音波探傷法を
提唱することを目的とする。(Problems to be Solved by the Invention) The present invention overcomes the problems of the prior art regarding non-destructive testing of centrifugally cast pipes with the above properties, and is effective for detecting internal defects, mainly defects in the circumferential direction. The purpose of this study is to propose a possible ultrasonic flaw detection method.

（問題点を解決するための手段、作用および実施例〕 本発明は、超音波探傷の測定段階とその測定信号に対す
る特定の信号処理段階との関連により成立つ。(Means for Solving the Problems, Effects, and Embodiments) The present invention is realized by the relationship between the measurement step of ultrasonic flaw detection and a specific signal processing step for the measurement signal.

すなわち（１）測定段階では、広帯域のｊ！ｉ波故波性
特性つ探触子を使用し縦波正反射法により遠心鋳造管の
全周にわｔり超音波探傷を行い探傷エコーを得る。帯域
幅は後述１段階の分割を可能とする充分な幅とする。That is, (1) in the measurement stage, wideband j! Ultrasonic flaw detection is performed around the entire circumference of the centrifugally cast tube using a longitudinal wave specular reflection method using a probe with i-wave decay characteristics to obtain flaw detection echoes. The bandwidth is set to be sufficient to enable one stage of division as described below.

そして（ＩＪ信号処理段階では次の手法を採用するＯ （〜　前記探傷エコーｔ−Ａ／Ｄ変換素子でディジタル
値に変換する。Then, in the IJ signal processing stage, the following method is adopted.

（ｂ）　　次に、この信号ｔ−フーリエ変換し、周波数
ｗ４坂に変換する。例えば信号の周ｉ＆帯域が中心円Ｉ
Ｅ＆ｆ・、帯域Ｂとし、周波数軸上で一定の帯域幅でｍ
個に分割するとし、分割範囲は（１−ａ）　ｆ　＊　＜
　ｆ　＜　（１＋ａ）　ｆ＊　（ここにａ＝０．７〜０
．８）で分割した個々の中心周技致の差ムｆが０．０１
　ｆ・くムｆ’（Ｑ、ｉｆ・、個々の帯域幅す轡が５ム
ｆりｂ・り２０Δｆの間にとるとよい。(b) Next, this signal is subjected to t-Fourier transform and converted to a frequency w4 slope. For example, the signal circumference i & band is the center circle I
E&f・, band B, m with a constant bandwidth on the frequency axis
The division range is (1-a) f * <
f < (1+a) f* (here a=0.7~0
．． 8) The difference f between the individual center circumferential techniques divided by 0.01
f.times.f' (Q, if..). It is preferable that the individual bandwidths be between 5 mm and b.times.20 Δf.

ＣＯ）　　分割した個々の周波数帯域で逆変換し、時間
軸に戻す。これらによって得らｆ’Ｌ　７’ｌ−ｍ個の
波形を各々２乗する。そして時間軸の各時間毎に麗個の
波形を比較し、最も小さい出力をその時間での出力とす
る。CO) Inversely transform each divided frequency band and return to the time axis. The f'L 7'l-m waveforms obtained by these are each squared. Then, the multiple waveforms are compared for each time on the time axis, and the smallest output is taken as the output at that time.

（由　上記出力のうち、しきい値を越えているものを欠
陥とみなす。(Reason) Among the above outputs, those exceeding the threshold are considered defects.

以下２本発明を具体例を伴わせて詳細に説明する。The following two aspects of the present invention will be described in detail with reference to specific examples.

一般に、超音波の縦波を用いて欠陥Ｓｔ−探傷する場合
、第９図け）のように、探触子（１）からの超音＆　（
２）を被検体（３）の底Ｉｆｉ部（４）で一度反射させ
欠陥部（５）でさらに反射させ返ってくる超音ｍを探触
子（１）に受信するのが普通である。Generally, when detecting defects St using longitudinal waves of ultrasonic waves, ultrasonic waves from the probe (1) & (
2) is reflected once at the bottom Ifi portion (4) of the object (3), further reflected at the defective portion (5), and the returned ultrasonic sound m is normally received by the probe (1).

第９図−）のように超ｆｉの方向を逆にしても同じであ
る。第９図ｅ→は縦波についての入射角（ロ）に対する
２回の音圧反射率との関係を示し、第９図に）は横波に
ついての同様関係を示す。この場合、底面部と欠陥部と
の２回の反射でエネルギー損失が大きく、−！上底面で
の反射の際モード変換して縦波の一部が横波になりエネ
ルギーの損失を生ずることが起り、九だでさえ減衰の大
きい遠心鋳造管では欠陥を検出することは困難でるる。The same result can be obtained even if the direction of the super fi is reversed as shown in Fig. 9-). FIG. 9e→ shows the relationship between the two sound pressure reflectances and the incident angle (b) for longitudinal waves, and FIG. 9) shows the same relationship for transverse waves. In this case, energy loss is large due to two reflections at the bottom and the defect, and -! When reflected at the top surface, a part of the longitudinal wave becomes a transverse wave due to mode conversion, resulting in loss of energy, making it difficult to detect defects in centrifugally cast tubes with large attenuation.

これに対し、本発明では、第１図ば）および（ロ）に示
すように、被検体（５Ａ）が管であることを利用し、１
つの探触子（１Ａ）で欠陥（５）に超音＃ｌ　（りを当
てその正反射（２）ｔ−もう１つの探触子（１Ｂ）で受
信する配置構成とする。・このことでエネルギーの損失
を少くすることができる。On the other hand, in the present invention, as shown in FIGS.
One probe (1A) emits ultrasonic sound #1 to the defect (5), and its specular reflection (2) is received by the other probe (1B). Energy loss can be reduced.

次に、本発明では、縦ｆＩＬ″ｆ：使用することから次
の事が可能となる。Next, in the present invention, by using the vertical fIL″f:, the following becomes possible.

ナなわら、欠陥（５）がある場合、超音波は欠陥部で正
反射し受信探触子（ＩＢ）で受信されるが、縦波を使用
している丸め、欠陥着報１に持つ九反射波（２）が一番
最初に受信探触子（１Ｂ）に伝わり、結晶粒界等の飲乱
波あるいは反射時モード変換しＺａｔ技等による林状エ
コーはそれより遅れることになる。そこで超音波ビーム
路程を縦波の速度で別って哀めｍ時間の近傍のダートを
かけてお、くと、欠陥清報ｔ−持つｔ出力を得ることが
可能となる。However, when there is a defect (5), the ultrasonic wave is specularly reflected at the defect and received by the receiving probe (IB). The reflected wave (2) is transmitted to the receiving probe (1B) first, and the forest-like echoes due to disturbance waves such as grain boundaries or mode conversion at the time of reflection, such as the Zat technique, are delayed. Therefore, by dividing the ultrasonic beam path by the velocity of the longitudinal wave and applying darts in the vicinity of m time, it becomes possible to obtain an output of t with defect information t-.

探触子ＣＩＡ）（ＩＢ）の配置は想定する欠陥ｆｆ　（
５）に対し、超音波ビーム路程が可能な限り短かいこと
が減衰の点から有利であることは言うまでもない。しか
し現実には、管の溶接部周辺に機械加工の段付部（テー
バＳ）があるという幾何学的制約がるり、まｔ第２図に
示すように２つの探触子ＣＩＡ）（１Ｂ）を想定した欠
陥（５）位置に対しあまり近すけ過ぎると、超音波ビー
ム（２）が円周方向に近づくため、送信探触子（１Ａ）
からの送信波の−ｆＥＪ　（２）が欠陥で正反射せずと
も直接受信探触子（１Ｂ）に入射しＳ／ＩＮ　ｔ？低下
させることから、探触子配置に限界がある。実検による
と、第１図（４）１７）図中記号テ、Ｌｔ　＝　１５−
４０ｇ　、　　Ｌｘ　＝　１５−４０　”　％Ｌ＝Ｌ　
Ｉ＋　Ｌ　ｘ　＝　５０〜８０　”　％Ｗ　＝　５０−
１００曙の範囲で艮好なＳ／Ｎが得ら九る。The arrangement of the probe CIA) (IB) is based on the expected defect ff (
5), it goes without saying that it is advantageous in terms of attenuation for the ultrasonic beam path to be as short as possible. However, in reality, there is a geometrical constraint that there is a machined stepped part (Taber S) around the welded part of the tube, and two probes (CIA) (1B) are used as shown in Figure 2. If the position is too close to the assumed defect (5) position, the ultrasonic beam (2) will approach in the circumferential direction, causing the transmitting probe (1A)
-fEJ (2) of the transmitted wave from S/IN t? directly enters the receiving probe (1B) without being specularly reflected due to a defect. There are limits to probe placement because of the According to the actual inspection, Fig. 1 (4) 17) Symbol Te in the figure, Lt = 15-
40g, Lx = 15-40”%L=L
I+Lx=50~80''%W=50-
Excellent S/N can be obtained within a range of 100 degrees.

またビームの太さｔ−、音響レンズで絞ることにより管
壁等で反射される正体不明のエコーの発生を少なくする
。Furthermore, by adjusting the beam thickness t- and narrowing it down with an acoustic lens, the generation of unidentified echoes reflected from tube walls, etc., is reduced.

身上の探触子配置および関連配備によって遠心鋳造管を
探傷して得ｍ探傷波形の一例を第６図に示す。こｔｌ−
は、仮検体として管周１８０の位置に肉ｊＪ　（ｔ）の
１／２の深さの人工欠陥を設けｔ遠心鋳造管の試験片を
使用し、単−周波数で゛探傷し丸もので横軸には管の円
周方向の角度をと９縦軸には反射波のダートをかけた範
囲内のピーク値の電圧を反射強度としてプロットし几も
ので、ある。この探傷波形でも欠陥らしきものが得らｎ
ているが、欠陥信号、パッククランドノイズともに場所
により振幅が大きくＢｌＭ　ｔｉ略々１の程度である。FIG. 6 shows an example of a flaw detection waveform obtained by flaw detection of a centrifugally cast tube using the probe arrangement on the body and related arrangements. Kotl-
As a temporary specimen, an artificial defect with a depth of 1/2 of the wall jJ (t) was created at a position of 180 mm around the tube circumference, and a specimen of a centrifugally cast tube was used. The angle in the circumferential direction of the tube is plotted on the axis, and the voltage at the peak value within the range multiplied by the reflected wave dart is plotted on the vertical axis as the reflected intensity. Even with this flaw detection waveform, something that looks like a defect was obtained.
However, both the defect signal and the packed noise have large amplitudes depending on the location, and are approximately equal to BlM ti of 1.

従ってこのままでは前記性状の遠心鋳造管の欠陥検出法
としては充分に確実なものとするに足りない。Therefore, as it stands, it is insufficient to be a sufficiently reliable method for detecting defects in centrifugally cast tubes having the above properties.

第４図は、本発明方法ｔ−測定段階、信号処理段階を通
じてグロック図的に示すものである。FIG. 4 is a block diagram showing the t-measurement step and signal processing step of the method of the present invention.

第４図において、（１〕では広帯域の同波数帯域を持つ
探触子を採用し、上記正反射法により遠心鋳造管からな
る被検体を探傷する。In FIG. 4, in (1), a probe with a broadband same wave number band is employed, and a test object made of a centrifugally cast tube is flaw-detected by the specular reflection method described above.

（１−ａ）では、探傷エコー　ｔ−Ａ／Ｄ　９ｆ、　換
Ｒ子テデイジタル値に変換する。In (1-a), the flaw detection echo t-A/D 9f is converted into a digital value.

第５図は横軸の測定範囲と縦軸の振幅との関係で示す探
傷エコー信号ディジタル値のＷ、波形である。FIG. 5 shows the waveform of the flaw detection echo signal digital value W shown in the relationship between the measurement range on the horizontal axis and the amplitude on the vertical axis.

ＣＭ−ｂ）では、この信号をフーリエ変換し、周波敗饋
域に変換する。この場合、第６図全参照して、信号の周
波数帯域が中心周波＆　ｆ　ｓ、帯域幅Ｂであるとする
。そしてこｆ′Ｌヲ図示のように周波数柵上で一定の帯
＃、幅でｍ個に分割するにつき、例えば１分割範囲は（
１−ａ）　ｆ　ｏ　（ｆ＜　（１＋ａ　）　ｆ＋　（こ
こにａ　＝　０．７　”　０．８　）で公印Ｊした個々
の中心周波数の差Δｆが肌０１ｆ・くムｆ＜０−１ｆｓ
、個々の分割帯域ｂ＠が５Δｆ　（、ｂｅ　ｒ　２０ａ
ｆの間にと９、広帯域受信信号がｍ個の分割スペクトラ
ムの個別の信号にすらさ九るようにする。In CM-b), this signal is Fourier transformed and converted into a frequency loss region. In this case, with full reference to FIG. 6, it is assumed that the frequency band of the signal is the center frequency &fs and the bandwidth B. When f'L is divided into m pieces with a certain band # and width on the frequency fence as shown in the figure, for example, one division range is (
1-a) f o (f < (1+a) f+ (here a = 0.7 ” 0.8) The difference Δf of the individual center frequencies marked with the official seal is skin 01f・kum f<0-1fs
, each subband b@ is 5Δf (, be r 20a
Between f and 9, the broadband received signal is evenly divided into m separate signals of the spectrum.

第７図「）は分割帯域の中−心向波数ｆｋ　ｚ　４．６
４ＭＨｚ分割帯域幅ｂｅ　＝５００ＫＨｚの波形を例示
し、第７図（ロ）は中心ＩＮ！ｉｌ技＆　ｆｋ　＝　５
．８６　ＭＨｚ　、同分割帯域幅の波形を例示し几もの
であるが、人工欠陥エコーに較べて粒界エコーが著しく
変化していることが知られる。Figure 7 ") is the center-directed wave number fk z 4.6 of the divided band.
A waveform with a 4 MHz divided bandwidth be = 500 KHz is illustrated, and FIG. 7 (b) shows the center IN! il technique & fk = 5
．． Although the waveform of 86 MHz and the same division bandwidth is shown as an example, it is known that the grain boundary echo is significantly changed compared to the artificial defect echo.

（１−Ｃ）ではｍ分割した個々の周波数帯域で各波形を
逆変換しそ几らを時１１（＋＠に戻す〇（１−Ｃ’）で
これらによって得らｎたｍ個の波形を各々２乗する。そ
して（１−ｃ）で時間軸の各時間毎にｍ個の波形を比較
し、最も小さ１ミ”出力をその時間での出力とする。第
４図は以上のデータ信号の変換処理および算法処理を経
て得几各時間区間の最小値を重ね合せて得几最終出力波
形を示す。In (1-C), each waveform is inversely transformed in each frequency band divided into m, and then returned to 11 (+@).In (1-C'), each of the n and m waveforms obtained by Then, in (1-c), m waveforms are compared for each time on the time axis, and the smallest 1" output is taken as the output at that time. Figure 4 shows the above data signal. The minimum value of each time interval obtained through the conversion process and algorithm process is superimposed to show the final output waveform.

こうして（１−ｄ）で上記出力のうち、しきい値を越え
ているものを欠陥とみなす。In this way, in (1-d), among the above outputs, those exceeding the threshold are regarded as defects.

本発明方法は上記（υ（１）の過程にさらに付加的処理
（りを加えて実施することができ゛る。すなわち欠陥＋
ｉろる拡がＤｆｃ持つことから、探傷位置を連続ｔ！１
１＊は離散的に数位置に変更して超音技探傷（υを行い
、上記（１）過程の処理を行いながらその孜ケ分の出力
を加え合わせそれらがあるしきい値を越えｔ場合を欠陥
とやＪ定する。The method of the present invention can be carried out by adding additional processing to the process (υ(1)) above.
Since iRorukou has Dfc, the flaw detection position is continuous! 1
1*: Perform ultrasonic flaw detection (υ) by discretely changing several positions, and adding up the outputs of the above while processing the process (1) above, and if the output exceeds a certain threshold value. is determined to be a defect.

（発明の効果） 以上のように本発明方法によると、水蒸気接触改質用加
熱管等の結晶粒が粗大で超音波の減衰が大きい遠心鋳造
管に対し、経年変化により発生する内部欠陥を超音技探
傷により非破壊横五する場合に、超音波の減衰および散
乱によるノイズの影響′ｔ−減じて欠陥信号七億実に検
出することが可能となり、ｔ７′ｃその変換、算法の過
程はコンピュータ処理により容易に行うことができ、送
信波と反射波とで相開をとる必要もないので、格別の手
数、負担が加わらず、そして探傷の員実性により使用中
の管の信頼性、伐存痔命を的確に把握してその保守文換
を合理的最小限にすることができる等の効果がある。(Effects of the Invention) As described above, according to the method of the present invention, it is possible to eliminate internal defects that occur due to aging in centrifugally cast tubes with coarse crystal grains and large attenuation of ultrasonic waves, such as heating tubes for steam catalytic reforming. When performing non-destructive horizontal flaw detection using acoustic flaw detection, it is possible to detect 700 million defect signals by subtracting the effects of noise due to ultrasonic attenuation and scattering, and the process of conversion and calculation is performed by a computer. It can be easily carried out through processing, and there is no need to take a phase difference between the transmitted wave and the reflected wave, so there is no extra effort or burden, and the practicality of flaw detection improves the reliability of the pipe in use. There are effects such as being able to accurately grasp existing hemorrhoids and minimizing the need for maintenance and translation to a reasonable minimum.

【図面の簡単な説明】[Brief explanation of the drawing]

第１図り）は本発明方法の実施に使用する探傷子配置を
示す側面図、第１図（ロ）はその端面図、第２７Ｆｉそ
の不適当配置を示す側面図、第６図（ｃ４）ｉｌｔ横軸
に管周角度位置、縦軸に反射強度をとって示す単一周波
数の探傷波形図、第４図は本発明方法の段階過程を示す
グロ７り図、第５図は４ｉｉ軸に測定範囲、縦軸に振幅
をとって示す本発明のディジタル変換を経た原技形図、
第６図は本始明における広帯域周波数帯域の分割思様を
示す図、第７図ば）は分割帯域に番目の波形図第７図（
句は分割帯域に＋５番目の波形図、第８図は本発明方法
による最終出力波形図、第９図は）は従来の探触子配置
の１例を示す図、第９図（ｍはその超音波ビームが反対
の図、第９図←→は横軸の角度に対する縦軸の縦波反射
ｔＬｇ１度を示す図、第９図に）は同じく横波反射波ｇ
ｉ度を示す図である。 （１）（１ムＸＩＢ）・・探触子、（２）　（２）　（
２）・・超音波ビーム、（３）（５Ａ）・・被検体、（
４）・・底面部。 （５）・・欠陥部ｓ　　Ｃｒ・）・・中心局ｉ＆、（躇
・・帯域幅％　　（ｊ：ｈｆ）・・分割帯域中心周波数
差ｈ　　（ｂｅ）・・分割帯域幅、（θ］・・入射角、
（１）・・肉厚。 蕗５１２１ 篤８１図 に１１Figure 1) is a side view showing the flaw detector arrangement used in carrying out the method of the present invention, Figure 1 (b) is its end view, Figure 27 is a side view showing its inappropriate placement, Figure 6 (c4) ilt A single-frequency flaw detection waveform diagram with the horizontal axis representing the circumferential angular position and the vertical axis representing the reflection intensity, Figure 4 is a diagram showing the step process of the method of the present invention, and Figure 5 is the measurement along the 4ii axis. An original technical shape diagram that has undergone digital conversion of the present invention, showing the range and amplitude on the vertical axis,
Fig. 6 is a diagram showing how the wide frequency band is divided in the present invention, and Fig. 7 (b) is a diagram showing the waveform diagram of the divided band.
Figure 8 is the final output waveform diagram according to the method of the present invention, Figure 9 is a diagram showing an example of the conventional probe arrangement, Figure 9 (m is The diagram in which the ultrasonic beam is opposite, Figure 9 ← → is a diagram showing the longitudinal wave reflection tLg 1 degree on the vertical axis against the angle on the horizontal axis, and the figure (in Figure 9) also shows the shear wave reflected wave g
It is a figure which shows i degrees. (1) (1μXIB)... Probe, (2) (2) (
2)... Ultrasonic beam, (3) (5A)... Subject, (
4)...Bottom part. (5)...Defective part s Cr)...Center station i&, (hesitation...Bandwidth % (j:hf)...Divided band center frequency difference h (be)...Divided bandwidth, (θ]... ·Angle of incidence,
(1) Thickness. Fuki 5121 Atsushi 81 figure 11

Claims (3)

【特許請求の範囲】[Claims] （１）広帯域の周波数帯域をもつ探触子を使用して縦波
正反射法により遠心鋳造管の全周にわたり超音波探傷を
行い、探傷エコーをＡ／Ｄ変換素子でディジタル値に変
換し、次にこのディジタル値信号をフーリエ変換し複数
の等分帯域幅の中心周波数差のある分割周波数帯域に変
換し、次に分割した個々の周波数帯域で逆変換して時間
軸に戻し、これらによつて得られた個々の波形を各々２
乗し、そして時間軸の各時間毎に周波数分割波形を比較
し最も小さい出力をその時間での出力とし、この出力の
うちしきい値を越えているものを欠陥と判定する遠心鋳
造管の超音波探傷法。(1) Using a probe with a wide frequency band, perform ultrasonic flaw detection over the entire circumference of the centrifugally cast tube using the longitudinal wave specular reflection method, and convert the flaw detection echoes into digital values with an A/D conversion element. Next, this digital value signal is Fourier-transformed into divided frequency bands with center frequency differences of multiple equally divided bandwidths, and then inversely transformed in each divided frequency band and returned to the time axis. Each waveform obtained by
Then, the frequency-divided waveforms are compared for each time on the time axis, the smallest output is taken as the output at that time, and any output that exceeds the threshold is determined to be defective. Sonic flaw detection method. （２）探傷信号の周波数帯域を中心周波数ｆｏ．帯域幅
Ｂとし、前記フーリエ変換の周波数軸上での変換を一定
の帯域幅で分割し、分割範囲は（１−ａ）ｆｏ＜ｆ＜（
１＋ａ）ｆｏ（ここにａ＝０．７〜０．８）で、分割し
た個々の中心周波数の差Δｆが０．０１ｆｏ≦Δｆ≦０
．１ｆｏ、個々の帯域幅ｂｏが５Δｆ≦ｂｏ≦２０Δｆ
の間にとる特許請求の範囲第１項記載の遠心鋳造管の超
音波探傷法。(2) Set the frequency band of the flaw detection signal to the center frequency fo. Assuming that the bandwidth is B, the Fourier transform on the frequency axis is divided by a constant bandwidth, and the division range is (1-a)fo<f<(
1+a)fo (here a=0.7 to 0.8), the difference Δf between the divided individual center frequencies is 0.01fo≦Δf≦0
．． 1fo, individual bandwidth bo is 5Δf≦bo≦20Δf
An ultrasonic flaw detection method for centrifugally cast tubes according to claim 1, taken between （３）測定段階での超音波探傷を、位置を離散的を含め
連続的にずらせて行い、判定過程前でその数ケ分の出力
を加え合わせ、それがあるしきい値を越える場合を欠陥
と判定する特許請求の範囲第１項記載の遠心鋳造管の超
音波探傷法。(3) At the measurement stage, ultrasonic flaw detection is performed by continuously shifting the position, including discrete positions, and before the judgment process, the outputs of several are added together, and if the output exceeds a certain threshold, it is detected as a defect. The ultrasonic flaw detection method for centrifugally cast pipes according to claim 1, which determines that.
JP59206858A 1984-10-01 1984-10-01 Ultrasonic flaw detection of centrifugally cast pipe Pending JPS6183962A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
JP59206858A JPS6183962A (en) 1984-10-01 1984-10-01 Ultrasonic flaw detection of centrifugally cast pipe

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
JP59206858A JPS6183962A (en) 1984-10-01 1984-10-01 Ultrasonic flaw detection of centrifugally cast pipe

Publications (1)

Publication Number Publication Date
JPS6183962A true JPS6183962A (en) 1986-04-28

Family

ID=16530208

Family Applications (1)

Application Number Title Priority Date Filing Date
JP59206858A Pending JPS6183962A (en) 1984-10-01 1984-10-01 Ultrasonic flaw detection of centrifugally cast pipe

Country Status (1)

Country Link
JP (1) JPS6183962A (en)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2001318085A (en) * 2000-05-08 2001-11-16 Daido Steel Co Ltd Padding pipe inspecting method

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2001318085A (en) * 2000-05-08 2001-11-16 Daido Steel Co Ltd Padding pipe inspecting method

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