CA1211832A - Method of ultrasonic flaw detection of pipe - Google Patents
Method of ultrasonic flaw detection of pipeInfo
- Publication number
- CA1211832A CA1211832A CA000439026A CA439026A CA1211832A CA 1211832 A CA1211832 A CA 1211832A CA 000439026 A CA000439026 A CA 000439026A CA 439026 A CA439026 A CA 439026A CA 1211832 A CA1211832 A CA 1211832A
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- Prior art keywords
- pipe
- test piece
- piece part
- flaw detection
- ultrasonic flaw
- Prior art date
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- Investigating Or Analyzing Materials By The Use Of Ultrasonic Waves (AREA)
Abstract
Abstract of the Disclosure A method of ultrasonic flaw detection of a pipe applicable, for example, to an austenic heat resisting cast steel pipe used as a hydrogen manufacturing reformer tube. This method is free from adverse influence of macrostructures unevenly distributed in the peripheral direction of the pipe, and enables a quantitative grasp of flaws in a base material and a weld of the pipe.
Description
12~3~
This invention relates to a method of ultrasonic flaw detection of a pipe to detect flaws in a base material and a weld of the pipe by transmitting ultrasonic waves therethrough. The method is applicable to reactor pipes at a chemical plant such as a hydrogen manufacturing reformer tube, and to other pipes used for varied functions.
The present invention will he illustrated with reference to the accompanying drawings in which:
Figs. 1-3 are schematic sectional views showing flaw detection modes wherein the test piece part comprises a weld, Fig. 4 is a graph showing detection data and how the data are processed, and Figs. 5 and 6 are schematic front and vertically sec-tional views, respectively, showing a flaw detection mode wherein the test piece part comprises a base material portion of a pipe.
The method of ultrasonic flaw detection of a pipe according to the prior art, generally, is explained with refer-ence to Fig. 1. As seen, an incident sound from a transmitting probe 3a mounted on a pipe adjacent a test piece part 2A (which is a weld 2 in this example) is received by a receiving probe 3b mounted on the pipe adjacent and across the test piece part 2A, and whether there is a flaw in the test piece part 2A or not is determined by attenuation of the sound occurring as it traverses the test piece part 2A. With such a flaw detection method, how-ever, the attenuation of the sound is affected by macrostructures, surface roughness and the like of the pipe, and is received in an affected state by the receiving probe 3b to measure its deci-bel value, which results in a very low degree of detecting pre-cision.
In order to eliminate the above disadvantage, a method ~" I' `~
1211~332 as explained with reference to Fig.s 2 and 3 has been proposed, in which the decibel values of through-transmission sounds as received are measured using the transrnitting probe 3a and the receiving probe 3b at two pipe positions opposite to each other relative to the test piece part 2A, and an arithmetic mean of these decibel values is compared with a decibel value of a through-transmission sound obtained at the test piece part 2A, a difference therebetween providing a basis for determining pre-sence of a flaw. This method is effective to offset the adverse influence of macrostructures, surface roughness and the like of the pipe and to detect flaws with a relatively high precision.
However, according to this method, the arithmetic mean of the decibel values of the received sounds measured at two positions adjacent the test piece part 2A (i.e. only one position at each side of the test piece part 2A) is regarded as the mean value throughout an entire periphery of the pipe. Therefore, this method after all lacks in detecting precision when applied to pipes whose macrostructures and surface roughness are uneven in the peripheral direction.
To be particular, an austenic heat resisting cast steel pipe to be used as a steam catalytic reforming heater pipe, for example, which is usually made by centrifugal casting has macrostructures distributed quite unevenly not only in the axial direction but in the peripheral direction also. Since the foregoing method carries out flaw de-tection without regard to such a peripheral distribution of mac-rostructures, it is impossible to detect flaws with a truly good precision or to provide a quantitative indication of tendencies of the flaws.
The present invention eliminates the foregoing disadvan-tages of the prior art methods and provides a useful flaw detect-ing method capable of high precision flaw detection even for austenic heat resisting cast steel pipes and the like and of pro-viding a quantitative indication of tendencies of the flaws.
According to the present invention there is provideda method of ultrasonic flaw detection of a pipe wherein a test piece part of the pipe is searched by transmitting ultrasonic waves, said method comprising the steps of measuring decibel values T(dB) and B(dB) of the ultrasonic waves received after being transmitted through the pipe continuously or intermit-tently over entire peripheries of the pipe adjacent both sides of the test piece part; measuring a decibel value W(dB) of the ultrasonic wave received after being transmitted through the pipe continuously or intermittently over an entire periphery of the pipe at the test piece part; establishing an evaluation line X by determining a number of evaluation points Xn at equal in-tervals peripherally of the pipes by means of the following equa-tion (1):
X Tn(dB) + Bn(dB) _ K ............. (1) where n is a detecting position, and K is a constant; drawing a further line W by plotting the decibel values W(dB) so as to show a variation thereof around.the test piece part; and deriving differences between the decibel values W(dB) on the further line W and the evaluation points Xn located on said 1211~332 evaluation line X and each corresponding to one of said decibel values W(dB) over the entire periphery of the pipe, to determine flaw developing tendencies in the test piece part on the basis of variations of the difference in the peripheral direction of the pipe.
A method of ultrasonic flaw detection of a pipe accord-ing to this invention comprises the steps of measuring decibel values T(dB) and B(dB) of the ultrasonic waves received after being transmitted through the pipe continuously or intermittently over entire peripheries of the pipe adjacent both sides of the test piece part, measuring a decibel value W(dB) of the ultra-sonic wave received after being transmitted through the pipe con-tinuously or intermittently over an entire periphery of the pipe at the test piece part, and deriving a diference between an arithmetic mean of the decibel values T(dB) and B(dB) of the ultrasonic waves adjacent both sides of the test piece part and the _ 3a i decibel value W(dB~ of the ultrasonic wave at *he test piece part at a particular~phase in the peripheral direction of the pipe, continuously or intermittently over~the .entire periphery of the pipe., to determine flaw developing S tendencies in the test piece part on the basis of variations of the differenc`e in the peripheral direction of the pipe.
..According ~ thi~ m~thod a de~cribe.d ah~e, ultrasonic waves-are transmitted though the pipe a~ two positions across and adjacent-the test piece part to calculate an lO arithmetic mean of decibel values T(dB) and B(dB) of the ..received.ultrasonic waves, and to obtain a difference between this arithmetic mean and.the decibel value W(dB) of the ultrasonic wave received after ll~ing pa~ed throu~h the test piece part. Whether there is a flaw in the 15 test piece part or not is determined with high precision : snd ~ithout ad~erse influence o~ the.macrostructures and surface roughness of the pipe, on the basis of ~hether ; the difference exceeds a predetermined ~al~e or not.
Particularly since the difference is obtained continuously ' 20 ~ or intermittchtly at very slight intervals over the-entire periphery o~ the pipe, ~laws in ~ pipe such a~ an austenic heat resisting cast steel pipe that has ~uite an unevcn peripheral di~trib~tion of macrostructures aré detected with high precision and free from the i~l~lucnce of thc ~uneven distribution of the macrostructures.. ~urthermore, the tendency of the flawls development in the test piece 1211~ Z
part is determined on the basis of how the above difference varies in the peripheral direction of the pipe according to, for example, a peripheral width of each flaw and a peripheral distribution of the flaws. As a result, lives of base material and weld of the pipe are predicted very accurately, whereby trouble such as leakage is now effectively prevented.
Referring once more to the accompanying drawings and embodiment of the invention in which a weld 2 is a test piece part 2A, is described with reference to Figs. 1-4.
As shown in Fig. 1, a transmitting probe 3a and a ;
lZ~1l 332 receiv~ng probe 3b are ~et acros~ a weld 2 c'onnecting:pipe~ .
la and l.b end to end.\ The two probes 3a and 3b are moved at the.same rate perlpherally of the pipes while cau~ing . an ultras'onic'wave~to tr~verse the weld 2 at an angle .: to a pipe axis P. A correlation bet~een variation~ in .flaw detecting positions in the peripheral.direc~ion o~ithe pipe and variations in saturatea decibel value~W(dB) of the ,. ultra60nic wave received byithe'receiving probe 3b i~
automatically and,continuou~ly r,ecorded in a solid line on a graph as shown in Fig.' 4.
As shown in ~ig. 2, the tran6~i~ting probe 3a and .~the recei~ing probe 3b are set on .the upper pipe la adjacent the weld,2,;and.the t~o probe~ 3a and 3~ are moved at the same rate periphe'rally of tke pipe while ,.tran6mitting an ultrasonic wave through the pipe at an angle to the pipe axi~ P. A correlstion between variations .
in flaw detecting position~ in the peripheral direction :of the pipe and vàriation~.in saturated decibel value '.T~d~)'of the ultrasonic wave received by the receiv,ing 20. probe 3b i~ autom3tically and continnn~l61y reçorded in a,dotted line on the graph:as shown in Fig. 4.
As shown in Fig. 3,' the transmitting probe 3a ~nd I the receiving probe 3b are set on.the lower pipe lb adjacent the weld 2, and the two probes 3a and 3b are,moved , Z5 ~ at the same rate per-ipherally of the.pipe while transmitting an ultrasonic wave through the,pipe st an angle to the _ 6 --121~332 pipe~axis P. A correlation between~var`iation~ ~n flaw.
~etecting po6ition~ in~the peri~hera} direction of the' plpe and variations in ~aturated decibel value.B~dB) of the l~lt.rasonic wav~-- received ~y the receiving probe'~
. 5 3b i~ automatically and continuously recorded in a dot and dash line on the graph as shown in Fig. 4.
~ The.abové three;flaw detecting operations may be :
~carried out~in any or~er or ~imultaneously..
Subseque~tly, an evaluation line x as represented 10 . by a double dot and dash line in.Fig. 4 is drawn by ..deriv.ing an evaluation point for each one of a great .l~any. positions at equal lnter.~als peripherally of the .
pipes, from the following equation (1) which is based on the decibel values~T(d~)`and B(dB) tak~n from ~ particular position~ in the same direction of the pipes la and lb:
: Tn(dB) ~ Bn(dB) Xn - _ ~ ......................... (1) where~n n is a detecting position~ and K is a constant (generally about .7.5).
20 . Then, the line (i.e. ~he ~vlid line in Fig. 4) showing .
~ariation~ in the decibel value W(dB) is compared with the:
evaluation line x, and pr.e6ence of a fla~ i~ d~termined where the decibel value W(dB) is lower than the evaluation line x. At the ~a~e ti~e,!flaw developing tendencies are gra5ped quantitatively on the basis of each flaw width e _.7 _ .
lZ11832 and the flaw di6tribution in the periphe~ direction o~ the ~pipes, .whereby theilife of~ the weld;2 is predicted.
~ A f~rther embod;ment in.~hich the base materi~lfof a.pipe 1 is.t~e test:piece part 2AI~ is hereinafte~
de~cribod with reference t~ Figs~ S and 6.
. First:, thc transmitting probe 3a and the recei~ing probe-3b are set to tll~ obj!ect pipe 1 ~. an angle:to the axis;P thereof, and the two probes 3a and 3b are moved.i~ the above p~sitional relationship at .the same rate along the axis:P of the pipe li, in.search o~ ~laws~ ;
If the decibel ~alue of the;received ultrasonic wa~e drops at a certain part o~ the base material of the pipe, 1, thi~ part.makes the test piece part 2A.' Then, as in .
. the foregoing exa~ple,- the two probes 3a and 3b are divided across the-test piece part 2A and at an angle to the axis ;
.P, and moved to~ether at the same rate peripherally of ~the pipe 1. A correlatiDn between flaw detecting positions in the.peripheral direction of the pipe l and var;ation~
. in 6aturated decibel value W(dB) of the ultrasonic wave 20 .~received by the reeeiving probe 3~ is a~tomatically and : continuously recorded on a graph. F~rther, as in the . ~ore~oin~ e~bodiment, the tran~mitting probe 3a and the receiving ~robe 3b are set adjacent each side of the test ;
piece!part 2A and at an an~le ~o the axis ~, and moved together at the sa~e rate peripherally of the pipe 1 Gorrelations between~flaw detectin~ positions in the ~Z11~332 peripheral direction' o~ the pipe l and variations in saturated decibel values~T(dB~ and B(dB) of the ultrasonic wave received by the receiving pnobé 3b are automati'c`ally and continuously recorded on the graph. A~ luation line x is drawn on the basis'of the equatiori (l) and is comp~red with the line showing v~riations in the decibel ' value W(dB). Thus, ~la~ de'veloping tendencies are grasped quantitati~ely on the ~a~i~ of each flaw width e and flaw distribution in the per'ipheral direction of the pipe !: 10 ~ 1, whereby the life of the base material is predicted.
' For moving the'transmitting probe 3a and the receivin~
probe 3b peripherall~ or axially of ~he pi peis tog~ther, ' it is a common practice to provide a holder having a ~ rotational drive means in order to set the probe~ 3a and 3b lsS1 to the pipes la,' lb and 1 ard automaticall~ move the prove8 3a and 3b at the ~ame rate. The specific construction therefor i~ variable as desired.' The probes 3a and 3b may be movcd manually at,the fiam~ rate. Further, the probes 3a and 3b may be moved automatically or manulally 'at very sli~ht intervals, taking'flaw detection data at stops.
The flaw detection'data may be pr~ ssed, for ex~mple, by der'ivin~ evaluation points Xn from the equation (2) set out below, and deciding that there are flaw~ where ' the evaluation pointsiXn are minus. Any other equation may be ~lsed from which the difference ~etwec'n the arithmetic _ 9 _ lZ~183Z
.mean.of the mea~ured d~cibel.values T(dBl) and ~(d~) of -the pipes,la~ lb and l~and the measured decibel value ~
W(dB) o~-the te~t piece~part~A such a~ ~eld 2 i8 derived.
Further,:it will be of-pract~cal advantage to process the detection data on a computer.and to record data necessa~y for determining flaws.
iXn - W - ~(Tn,~ Bn)j2;- K ~ ....~. (2) , liThe described method of ultrasonic fla~ detection aocording to this,invention i8 applicable.to any types o~ pipe and ultrasonic'fla~ ~etecting apparatus to be used therefor iB variable in it~ specific construction.
This invention relates to a method of ultrasonic flaw detection of a pipe to detect flaws in a base material and a weld of the pipe by transmitting ultrasonic waves therethrough. The method is applicable to reactor pipes at a chemical plant such as a hydrogen manufacturing reformer tube, and to other pipes used for varied functions.
The present invention will he illustrated with reference to the accompanying drawings in which:
Figs. 1-3 are schematic sectional views showing flaw detection modes wherein the test piece part comprises a weld, Fig. 4 is a graph showing detection data and how the data are processed, and Figs. 5 and 6 are schematic front and vertically sec-tional views, respectively, showing a flaw detection mode wherein the test piece part comprises a base material portion of a pipe.
The method of ultrasonic flaw detection of a pipe according to the prior art, generally, is explained with refer-ence to Fig. 1. As seen, an incident sound from a transmitting probe 3a mounted on a pipe adjacent a test piece part 2A (which is a weld 2 in this example) is received by a receiving probe 3b mounted on the pipe adjacent and across the test piece part 2A, and whether there is a flaw in the test piece part 2A or not is determined by attenuation of the sound occurring as it traverses the test piece part 2A. With such a flaw detection method, how-ever, the attenuation of the sound is affected by macrostructures, surface roughness and the like of the pipe, and is received in an affected state by the receiving probe 3b to measure its deci-bel value, which results in a very low degree of detecting pre-cision.
In order to eliminate the above disadvantage, a method ~" I' `~
1211~332 as explained with reference to Fig.s 2 and 3 has been proposed, in which the decibel values of through-transmission sounds as received are measured using the transrnitting probe 3a and the receiving probe 3b at two pipe positions opposite to each other relative to the test piece part 2A, and an arithmetic mean of these decibel values is compared with a decibel value of a through-transmission sound obtained at the test piece part 2A, a difference therebetween providing a basis for determining pre-sence of a flaw. This method is effective to offset the adverse influence of macrostructures, surface roughness and the like of the pipe and to detect flaws with a relatively high precision.
However, according to this method, the arithmetic mean of the decibel values of the received sounds measured at two positions adjacent the test piece part 2A (i.e. only one position at each side of the test piece part 2A) is regarded as the mean value throughout an entire periphery of the pipe. Therefore, this method after all lacks in detecting precision when applied to pipes whose macrostructures and surface roughness are uneven in the peripheral direction.
To be particular, an austenic heat resisting cast steel pipe to be used as a steam catalytic reforming heater pipe, for example, which is usually made by centrifugal casting has macrostructures distributed quite unevenly not only in the axial direction but in the peripheral direction also. Since the foregoing method carries out flaw de-tection without regard to such a peripheral distribution of mac-rostructures, it is impossible to detect flaws with a truly good precision or to provide a quantitative indication of tendencies of the flaws.
The present invention eliminates the foregoing disadvan-tages of the prior art methods and provides a useful flaw detect-ing method capable of high precision flaw detection even for austenic heat resisting cast steel pipes and the like and of pro-viding a quantitative indication of tendencies of the flaws.
According to the present invention there is provideda method of ultrasonic flaw detection of a pipe wherein a test piece part of the pipe is searched by transmitting ultrasonic waves, said method comprising the steps of measuring decibel values T(dB) and B(dB) of the ultrasonic waves received after being transmitted through the pipe continuously or intermit-tently over entire peripheries of the pipe adjacent both sides of the test piece part; measuring a decibel value W(dB) of the ultrasonic wave received after being transmitted through the pipe continuously or intermittently over an entire periphery of the pipe at the test piece part; establishing an evaluation line X by determining a number of evaluation points Xn at equal in-tervals peripherally of the pipes by means of the following equa-tion (1):
X Tn(dB) + Bn(dB) _ K ............. (1) where n is a detecting position, and K is a constant; drawing a further line W by plotting the decibel values W(dB) so as to show a variation thereof around.the test piece part; and deriving differences between the decibel values W(dB) on the further line W and the evaluation points Xn located on said 1211~332 evaluation line X and each corresponding to one of said decibel values W(dB) over the entire periphery of the pipe, to determine flaw developing tendencies in the test piece part on the basis of variations of the difference in the peripheral direction of the pipe.
A method of ultrasonic flaw detection of a pipe accord-ing to this invention comprises the steps of measuring decibel values T(dB) and B(dB) of the ultrasonic waves received after being transmitted through the pipe continuously or intermittently over entire peripheries of the pipe adjacent both sides of the test piece part, measuring a decibel value W(dB) of the ultra-sonic wave received after being transmitted through the pipe con-tinuously or intermittently over an entire periphery of the pipe at the test piece part, and deriving a diference between an arithmetic mean of the decibel values T(dB) and B(dB) of the ultrasonic waves adjacent both sides of the test piece part and the _ 3a i decibel value W(dB~ of the ultrasonic wave at *he test piece part at a particular~phase in the peripheral direction of the pipe, continuously or intermittently over~the .entire periphery of the pipe., to determine flaw developing S tendencies in the test piece part on the basis of variations of the differenc`e in the peripheral direction of the pipe.
..According ~ thi~ m~thod a de~cribe.d ah~e, ultrasonic waves-are transmitted though the pipe a~ two positions across and adjacent-the test piece part to calculate an lO arithmetic mean of decibel values T(dB) and B(dB) of the ..received.ultrasonic waves, and to obtain a difference between this arithmetic mean and.the decibel value W(dB) of the ultrasonic wave received after ll~ing pa~ed throu~h the test piece part. Whether there is a flaw in the 15 test piece part or not is determined with high precision : snd ~ithout ad~erse influence o~ the.macrostructures and surface roughness of the pipe, on the basis of ~hether ; the difference exceeds a predetermined ~al~e or not.
Particularly since the difference is obtained continuously ' 20 ~ or intermittchtly at very slight intervals over the-entire periphery o~ the pipe, ~laws in ~ pipe such a~ an austenic heat resisting cast steel pipe that has ~uite an unevcn peripheral di~trib~tion of macrostructures aré detected with high precision and free from the i~l~lucnce of thc ~uneven distribution of the macrostructures.. ~urthermore, the tendency of the flawls development in the test piece 1211~ Z
part is determined on the basis of how the above difference varies in the peripheral direction of the pipe according to, for example, a peripheral width of each flaw and a peripheral distribution of the flaws. As a result, lives of base material and weld of the pipe are predicted very accurately, whereby trouble such as leakage is now effectively prevented.
Referring once more to the accompanying drawings and embodiment of the invention in which a weld 2 is a test piece part 2A, is described with reference to Figs. 1-4.
As shown in Fig. 1, a transmitting probe 3a and a ;
lZ~1l 332 receiv~ng probe 3b are ~et acros~ a weld 2 c'onnecting:pipe~ .
la and l.b end to end.\ The two probes 3a and 3b are moved at the.same rate perlpherally of the pipes while cau~ing . an ultras'onic'wave~to tr~verse the weld 2 at an angle .: to a pipe axis P. A correlation bet~een variation~ in .flaw detecting positions in the peripheral.direc~ion o~ithe pipe and variations in saturatea decibel value~W(dB) of the ,. ultra60nic wave received byithe'receiving probe 3b i~
automatically and,continuou~ly r,ecorded in a solid line on a graph as shown in Fig.' 4.
As shown in ~ig. 2, the tran6~i~ting probe 3a and .~the recei~ing probe 3b are set on .the upper pipe la adjacent the weld,2,;and.the t~o probe~ 3a and 3~ are moved at the same rate periphe'rally of tke pipe while ,.tran6mitting an ultrasonic wave through the pipe at an angle to the pipe axi~ P. A correlstion between variations .
in flaw detecting position~ in the peripheral direction :of the pipe and vàriation~.in saturated decibel value '.T~d~)'of the ultrasonic wave received by the receiv,ing 20. probe 3b i~ autom3tically and continnn~l61y reçorded in a,dotted line on the graph:as shown in Fig. 4.
As shown in Fig. 3,' the transmitting probe 3a ~nd I the receiving probe 3b are set on.the lower pipe lb adjacent the weld 2, and the two probes 3a and 3b are,moved , Z5 ~ at the same rate per-ipherally of the.pipe while transmitting an ultrasonic wave through the,pipe st an angle to the _ 6 --121~332 pipe~axis P. A correlation between~var`iation~ ~n flaw.
~etecting po6ition~ in~the peri~hera} direction of the' plpe and variations in ~aturated decibel value.B~dB) of the l~lt.rasonic wav~-- received ~y the receiving probe'~
. 5 3b i~ automatically and continuously recorded in a dot and dash line on the graph as shown in Fig. 4.
~ The.abové three;flaw detecting operations may be :
~carried out~in any or~er or ~imultaneously..
Subseque~tly, an evaluation line x as represented 10 . by a double dot and dash line in.Fig. 4 is drawn by ..deriv.ing an evaluation point for each one of a great .l~any. positions at equal lnter.~als peripherally of the .
pipes, from the following equation (1) which is based on the decibel values~T(d~)`and B(dB) tak~n from ~ particular position~ in the same direction of the pipes la and lb:
: Tn(dB) ~ Bn(dB) Xn - _ ~ ......................... (1) where~n n is a detecting position~ and K is a constant (generally about .7.5).
20 . Then, the line (i.e. ~he ~vlid line in Fig. 4) showing .
~ariation~ in the decibel value W(dB) is compared with the:
evaluation line x, and pr.e6ence of a fla~ i~ d~termined where the decibel value W(dB) is lower than the evaluation line x. At the ~a~e ti~e,!flaw developing tendencies are gra5ped quantitatively on the basis of each flaw width e _.7 _ .
lZ11832 and the flaw di6tribution in the periphe~ direction o~ the ~pipes, .whereby theilife of~ the weld;2 is predicted.
~ A f~rther embod;ment in.~hich the base materi~lfof a.pipe 1 is.t~e test:piece part 2AI~ is hereinafte~
de~cribod with reference t~ Figs~ S and 6.
. First:, thc transmitting probe 3a and the recei~ing probe-3b are set to tll~ obj!ect pipe 1 ~. an angle:to the axis;P thereof, and the two probes 3a and 3b are moved.i~ the above p~sitional relationship at .the same rate along the axis:P of the pipe li, in.search o~ ~laws~ ;
If the decibel ~alue of the;received ultrasonic wa~e drops at a certain part o~ the base material of the pipe, 1, thi~ part.makes the test piece part 2A.' Then, as in .
. the foregoing exa~ple,- the two probes 3a and 3b are divided across the-test piece part 2A and at an angle to the axis ;
.P, and moved to~ether at the same rate peripherally of ~the pipe 1. A correlatiDn between flaw detecting positions in the.peripheral direction of the pipe l and var;ation~
. in 6aturated decibel value W(dB) of the ultrasonic wave 20 .~received by the reeeiving probe 3~ is a~tomatically and : continuously recorded on a graph. F~rther, as in the . ~ore~oin~ e~bodiment, the tran~mitting probe 3a and the receiving ~robe 3b are set adjacent each side of the test ;
piece!part 2A and at an an~le ~o the axis ~, and moved together at the sa~e rate peripherally of the pipe 1 Gorrelations between~flaw detectin~ positions in the ~Z11~332 peripheral direction' o~ the pipe l and variations in saturated decibel values~T(dB~ and B(dB) of the ultrasonic wave received by the receiving pnobé 3b are automati'c`ally and continuously recorded on the graph. A~ luation line x is drawn on the basis'of the equatiori (l) and is comp~red with the line showing v~riations in the decibel ' value W(dB). Thus, ~la~ de'veloping tendencies are grasped quantitati~ely on the ~a~i~ of each flaw width e and flaw distribution in the per'ipheral direction of the pipe !: 10 ~ 1, whereby the life of the base material is predicted.
' For moving the'transmitting probe 3a and the receivin~
probe 3b peripherall~ or axially of ~he pi peis tog~ther, ' it is a common practice to provide a holder having a ~ rotational drive means in order to set the probe~ 3a and 3b lsS1 to the pipes la,' lb and 1 ard automaticall~ move the prove8 3a and 3b at the ~ame rate. The specific construction therefor i~ variable as desired.' The probes 3a and 3b may be movcd manually at,the fiam~ rate. Further, the probes 3a and 3b may be moved automatically or manulally 'at very sli~ht intervals, taking'flaw detection data at stops.
The flaw detection'data may be pr~ ssed, for ex~mple, by der'ivin~ evaluation points Xn from the equation (2) set out below, and deciding that there are flaw~ where ' the evaluation pointsiXn are minus. Any other equation may be ~lsed from which the difference ~etwec'n the arithmetic _ 9 _ lZ~183Z
.mean.of the mea~ured d~cibel.values T(dBl) and ~(d~) of -the pipes,la~ lb and l~and the measured decibel value ~
W(dB) o~-the te~t piece~part~A such a~ ~eld 2 i8 derived.
Further,:it will be of-pract~cal advantage to process the detection data on a computer.and to record data necessa~y for determining flaws.
iXn - W - ~(Tn,~ Bn)j2;- K ~ ....~. (2) , liThe described method of ultrasonic fla~ detection aocording to this,invention i8 applicable.to any types o~ pipe and ultrasonic'fla~ ~etecting apparatus to be used therefor iB variable in it~ specific construction.
Claims (5)
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. A method of ultrasonic flaw detection of a pipe wherein a test piece part of the pipe is searched by trans-mitting ultrasonic waves, said method comprising the steps of measuring decibel values T(dB) and B(dB) of the ultrasonic waves received after being transmitted through the pipe con-tinuously or intermittently over entire peripheries of the pipe adjacent both sides of the test piece part; measuring a decibel value W(dB) of the ultrasonic wave received after being transmitted through the pipe continuously or intermittently over an entire periphery of the pipe at the test piece part; estab-lishing an evaluation line ? by determining a number of evalua-tion points Xn at equal intervals peripherally of the pipes by means of the following equation (1):
(1) where n is a detecting position, and K is a constant; drawing a further line W by plotting the decibel values W(dB) so as to show a variation thereof around the test piece part; and deriving differences between the decibel values W(dB) on the further line W and the evaluation points Xn located on said evaluation line ? and each corresponding to one of said decibel values W(dB) over the entire periphery of the pipe, to deter-mine flaw developing tendencies in the test piece part on the basis of variations of the difference in the peripheral direc-tion of the pipe.
(1) where n is a detecting position, and K is a constant; drawing a further line W by plotting the decibel values W(dB) so as to show a variation thereof around the test piece part; and deriving differences between the decibel values W(dB) on the further line W and the evaluation points Xn located on said evaluation line ? and each corresponding to one of said decibel values W(dB) over the entire periphery of the pipe, to deter-mine flaw developing tendencies in the test piece part on the basis of variations of the difference in the peripheral direc-tion of the pipe.
2. A method of ultrasonic flaw detection as defined in claim 1, wherein the pipe comprises an austenic heat resisting cast steel pipe.
3. A method of ultrasonic flaw detection as defined in claim 2, wherein the test piece part comprises a weld inter-connecting pipes end to end.
4. A method of ultrasonic flaw detection as defined in claim 2, wherein the test piece part comprises a base material of the pipe.
5. A method of ultrasonic flaw detection as defined in claim 4, further comprising a step of searching flaws in the axial direction of the pipe beforehand in order to determine the test piece part.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000439026A CA1211832A (en) | 1983-10-14 | 1983-10-14 | Method of ultrasonic flaw detection of pipe |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000439026A CA1211832A (en) | 1983-10-14 | 1983-10-14 | Method of ultrasonic flaw detection of pipe |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1211832A true CA1211832A (en) | 1986-09-23 |
Family
ID=4126276
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000439026A Expired CA1211832A (en) | 1983-10-14 | 1983-10-14 | Method of ultrasonic flaw detection of pipe |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1211832A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN115905961A (en) * | 2023-03-09 | 2023-04-04 | 广东广宇科技发展有限公司 | Pipeline defect analysis method based on multi-source data |
-
1983
- 1983-10-14 CA CA000439026A patent/CA1211832A/en not_active Expired
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN115905961A (en) * | 2023-03-09 | 2023-04-04 | 广东广宇科技发展有限公司 | Pipeline defect analysis method based on multi-source data |
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