US 8,027,796 B2Granted

S/N ratio measuring method in eddy current testing on internal surface of pipe or tube

AssigneeSumitomo Metal Industries, Ltd.

InventorsShoji Kinomura, Yoshiyuki Nakao, Toshiya Kodai, Shugo Nishiyama

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Abstract

A method in accordance with the present invention includes the steps of: separating an eddy current signal into an X-axis component and a Y-axis component to obtain signal waveform data of the respective components; excluding predetermined low-frequency components respectively from the respective signal waveform data thus obtained; calculating a noise voltage value V1 defined by the following Equation (1) based upon voltage values X(i) and Y(i) of the signal waveform data of the X-axis component and the Y-axis component from which the low-frequency components have been excluded; and calculating an S/N ratio by dividing a voltage value D of an eddy current signal corresponding to a predetermined artificial flaw by the noise voltage value V1: V ⁢ ⁢ 1 = π / n · ∑ i = 1 n ⁢ ( X ⁡ ( i ) 2 + Y ⁡ ( i ) 2 ) 1 / 2 ( 1 ) where n represents the number of samplings of the signal waveform data.

Claims6

Dependent claims

A method for measuring an S/N ratio in an eddy current testing on an internal surface of a pipe or tube comprising the steps of:

using a microprocessor for;
separating an eddy current signal obtained by executing an eddy current testing on the internal surface of a pipe or tube in an axis direction into an X-axis component and a Y-axis component that are different from each other by 90° in the phases thereof to obtain signal waveform data of the X-axis component and signal waveform data of the Y-axis component;
excluding predetermined low-frequency components respectively from the signal waveform data of the X-axis component and the signal waveform data of the Y-axis component thus obtained;
calculating a noise voltage value V1 defined by the following Equation (1) based upon a voltage value X(i) of the signal waveform data of the X-axis component with the low-frequency component excluded therefrom and a voltage value Y(i) of the signal waveform data of the Y-axis component with the low-frequency component excluded therefrom;
and
calculating an S/N ratio defined by the following Equation (2) based upon a voltage value D of an eddy current signal corresponding to a predetermined artificial flaw, obtained by executing an eddy current testing on an internal surface of a pipe or tube with the artificial flaw formed therein, and the noise voltage value V1:
V
⁢
⁢
1
=
π
/
n
·
∑
i
=
1
n
⁢
(
X
⁡
(
i
)
2
+
Y
⁡
(
i
)
2
)
1
/
2
(
1
)
where n represents the number of samplings of the signal waveform data,
S/N ratio=D/V1 (2).

41 more elements

A method for measuring an S/N ratio in an eddy current testing on an internal surface of a pipe or tube comprising the steps of:

using a microprocessor for;
separating an eddy current signal obtained by executing an eddy current testing on the internal surface of a pipe or tube in an axis direction into an X-axis component and a Y-axis component that are different from each other by 90° in the phases thereof to obtain signal waveform data of the X-axis component and signal waveform data of the Y-axis component;
excluding predetermined low-frequency components respectively from the signal waveform data of the X-axis component and the signal waveform data of the Y-axis component thus obtained;
dividing the signal waveform data of the X-axis component with the low-frequency component excluded therefrom and the signal waveform data of the Y-axis component with the low-frequency component excluded therefrom respectively into signal waveform data for each of a plurality of sections j (j=1 to N, N:
an integer of 2 or more) in the axis direction of the pipe or tube;
calculating a noise voltage value V2(j) defined by the following Equation (3) for each of the divided sections j based upon a voltage value X(i, j) of the signal waveform data of the X-axis component with the low-frequency component excluded therefrom and a voltage value Y(i, j) of the signal waveform data of the Y-axis component with the low-frequency component excluded therefrom;
and
calculating an S/N ratio defined by the following Equation (4) based upon a voltage value D of an eddy current signal corresponding to a predetermined artificial flaw, obtained by executing an eddy current testing on an internal surface of a pipe or tube with the artificial flaw formed therein, as well as based upon a maximum value V2 over the entire sections of the noise voltage value V2(j) calculated for each of the sections j:
V
⁢
⁢
2
⁢
(
j
)
=
π
/
m
·
∑
i
=
1
m
⁢
(
X
⁡
(
i
,
j
)
2
+
Y
⁡
(
i
,
j
)
2
)
1
/
2
(
3
)
where m represents the number of samplings of the signal waveform data in each section,
S/N ratio=D/V2 (4).

51 more elements

A method for measuring an S/N ratio in an eddy current testing on an internal surface of a pipe or tube comprising the steps of:

using a microprocessor for;
separating an eddy current signal obtained by executing an eddy current testing on the internal surface of a pipe or tube in an axis direction into an X-axis component and a Y-axis component that are different from each other by 90° in the phases thereof to obtain signal waveform data of the X-axis component and signal waveform data of the Y-axis component;
dividing the signal waveform data of the X-axis component and the signal waveform data of the Y-axis component thus obtained respectively into signal waveform data for each of a plurality of sections j (j=1 to N, N:
an integer of 2 or more) in the axis direction of the pipe or tube;
excluding predetermined low-frequency components respectively from the signal waveform data of the X-axis component and the signal waveform data of the Y-axis component for each of the divided sections j;
calculating a noise voltage value V2(j) defined by the following Equation (3) for each of the divided sections j based upon a voltage value X(i, j) of the signal waveform data of the X-axis component with the low-frequency component excluded therefrom and a voltage value Y(i, j) of the signal waveform data of the Y-axis component with the low-frequency component excluded therefrom;
and
calculating an S/N ratio defined by the following Equation (4) based upon a voltage value D of an eddy current signal corresponding to a predetermined artificial flaw, obtained by executing an eddy current testing on an internal surface of a pipe or tube with the artificial flaw formed therein, as well as based upon a maximum value V2 over the entire sections of the noise voltage value V2(j) calculated for each of the sections j:
V
⁢
⁢
2
⁢
(
j
)
=
π
/
m
·
∑
i
=
1
m
⁢
(
X
⁡
(
i
,
j
)
2
+
Y
⁡
(
i
,
j
)
2
)
1
/
2
(
3
)
where m represents the number of samplings of the signal waveform data in each section,
S/N ratio=D/V2 (4).

51 more elements

Dependencies are inferred from the claim text.