Pipe Crack Recognition Based on Eddy Current NDT and 2D Impedance Characteristics
Round 1
Reviewer 1 Report
The paper shows a combination of method based on signal processing and neural network to detect wedging defect on pipes.
English is good and this is a good starting point, also the paper is quite-well organised.
However, I have some minor/major comments:
MINOR:
- Avoid the use of abbreviation in the abstract, and if use abbreviation please be consistent to use them in the manuscript whenever is needed.
-Abstract: EMAT is not a method is a type of transducer. So correct with "the use of ultrasonic testing by EMATs".
Keywords: inner surface - I have never seen such a keyword. Please use a different one.
- line 117 : "we first achieve" is "we first retrieve"
MAJOR:
- Eddy-current testing is very sensitive to the lift-off. I don't see any information about this in the manuscript, neither if the Authors tried with different lift-off. Also extend the description of the experimental setup because what has been reported it is not enough. Type of probe? frequency of the signal? dimension? Please provide them and explain how you dealt with lift-off.
- Extend the literature. There is a plethora of studies in eddy-current. The reference list is not satisfactory for me. Have a look also in EU and US research.
Author Response
R: The paper shows a combination of method based on signal processing and neural network to detect wedging defect on pipes. English is good and this is a good starting point, also the paper is quite-well organized.
A: We thank the reviewer a lot for the encouragement.
R: However, I have some minor/major comments:
A: We sincerely thank the reviewer for providing us the following comments and suggestions. We have carefully read each item and made corresponding revisions. We believe the paper is somehow improved with the efforts.
R: MINOR:
R: - Avoid the use of abbreviation in the abstract, and if use abbreviation please be consistent to use them in the manuscript whenever is needed.
A: As commented by the reviewer, we have deleted each and every abbreviations in the abstract. And for the convenience of description, abbreviations are still used in the main body of the paper. The full name of each abbreviation is given at its first appearance.
R: -Abstract: EMAT is not a method is a type of transducer. So correct with "the use of ultrasonic testing by EMATs".
A: As commented by the reviewer, we have corrected the old expression with "the use of ultrasonic testing by electromagnetic acoustic transducers".
R: Keywords: inner surface - I have never seen such a keyword. Please use a different one.
A: After careful consideration, we deleted the keyword ‘inner surface’ since ‘inner surface’ is not a key feature of our method.
R: - line 117 : "we first achieve" is "we first retrieve"
A: As commented by the reviewer, we have used the word “retrieve” to substitute the word “achieve”. We thank the reviewer for this kind suggestion.
R: MAJOR:
R: - Eddy-current testing is very sensitive to the lift-off. I don't see any information about this in the manuscript, neither if the Authors tried with different lift-off. Also extend the description of the experimental setup because what has been reported it is not enough. Type of probe? frequency of the signal? dimension? Please provide them and explain how you dealt with lift-off.
A: We agree with the reviewer’s comment. Eddy-current testing is very sensitive to the lift-off. Therefore its influence on the impedance diagram in our proposed ECT method should be investigated. As a response, we have added a new sub-section 3.5 to the revised manuscript to provide our investigation results in terms of lift-off. In this section, 3 types of cracks, respectively weld crack, body crack and weld toe crack are all tested under 4 different lift-off values, 0mm, 1mm, 2mm and 5mm. Similar characteristics are observed among the three type of cracks. As the lift-off increases, the size of the impedance diagram pattern accordingly decreases, but the pattern structure and shape remain unchanged. When the lift-off value is over 2mm, the pattern size become too small that the crack type can no longer be identified. As a result, the lift-off should be limited within 2mm, and the smaller the better.
A: On the other hand, as suggested by the reviewer, we extended the description of the experimental setup. The stimulating frequency of the probe is 100kHz, the type of the probe is “external absolute eddy current probe” which is a product of ZHIMIN technology in Xiamen, China. The photograph of the probe is given in Figure 2c.
R: - Extend the literature. There is a plethora of studies in eddy-current. The reference list is not satisfactory for me. Have a look also in EU and US research.
A: As suggested by the reviewer, we have added 5 references to the reference list in the field of eddy-current testing, which are important researches in EU and US.
A: We again appreciate the reviewer for the helpful comments.
Author Response File: 
Author Response.pdf
Reviewer 2 Report
Presented paper refers to important issue in engineering – the need of easy and reliable method of NDT of welded pipelines.
There are several used methods, still their reliability and accuracy are being discussed. This is why engineers seek for new solutions; among them the embedded eddy current based method seems to be most attractive proposal.
Presented work is well planned and structured, proposed methodology is correct, presentation of results and their discussion is excellent, English language and style is fine.
In opinion of the reviewer there is no need for any corrections and it is postulated to accept the paper in present form.
Reviewer congratulates the team for flawless work and will look forward for further developments of its work.
Author Response
We sincerely and deeply appreciate the reviewer for your acceptance of our work and for your kindly encouragement.
Round 2
Reviewer 1 Report
Thanks - the manuscript is now fine.
