Mechanical Characterization of Resistance-Welded and Seamless API 5L X52 Pipes: A Comparative Study
, Daniel Angeles-Herrera 3, Noé Eliseo González-Arévalo 4, Esther Torres-Santillan 2 and Arturo Cervantes-Tobón 4Round 1
Reviewer 1 Report
Comments and Suggestions for Authors
The authors conducted a series of Charpy V-notch tests on coupons taken from X52 steel pipes. Charpy energy values, hardness, and microstructures were shown to be dependent on the specimen direction. The following points should be considered by the authors:
• "The main threats to the pipelines’ integrity in North America are material and weld failure and corrosion, while in Europe the main threats are corrosion, external interference and material and weld failure" → Please clarify what can be classified as "external interference" and why it is not a threat in North America. Otherwise, this sentence should be revised.
• The nomenclature provided in Table 1 could be extended. There are some abbreviations in the main text such as HIC and SCC which weren't mentioned in Table 1.
• "To reach all the mechanical requirements, factors such as aligned inclusions, elongated grains, and crystallographic texture influence the orientation dependence of mechanical properties in the pipelines [20], likewise, special processes to fabricate pipelines" → This sentence has an unclear meaning, is too long and seems to be incomplete. Please revise.
• "It is well known that seamless pipes are limited to smaller diameters and are more costly" → Please cite the source of this information.
• It is recommended to emphasize the significance of this research project in the last paragraph of Introduction. Please emphasize why it is important to study API 5L X52 pipelines.
• The authors mention that Charpy specimens were taken in "all directions". However, Figure 1 shows that actually a total of 4 or 5 directions were selected for the specimen directions. I recommend replacing the statement "all directions" with the actual number of directions as shown in Figure 1.
• The total number of tested specimens should be indicated in the Abstract.
• Please remove lines 138 to 152.
• Please mention briefly whether the authors investigated the effect of temperature on the Charpy impact energy or not.
Comments on the Quality of English Language
Minor English language editing needed.
Author Response
The response to the comments are in the attached file
Author Response File: 
Author Response.pdf
Reviewer 2 Report
Comments and Suggestions for Authors
Dear Authors,
Please refer to the comments in the attached document.
Comments for author File: Comments.pdf
Author Response
The responses to the comments are in the attached file
Author Response File: Author Response.pdf
Reviewer 3 Report
Comments and Suggestions for Authors
The work represents a comparative study on the mechanical properties of welded and seamless pipes. In general, the work fulfills the requirements of a scientific work, but there are still some problems to be solved/clarified:
1. It is not clearly defined what the purpose of the work is.
2. When a notation appears for the first time, explain it, what does it mean? For example, it is the case of TIG.
3. The (thick) points in Fig. 3 (according to the direction of hardness), what does it represent?
4. Attention, Fig. 4 does not exist.
5. Table 2 appears twice (maybe the second is Table 3)
6. Inclusions are those tiny black dots. If so, the indications with an arrow.
7. In line 209 appears "... Rockwell B..." what does it mean/represent?
8. I thought that in the "Conclusions" section it is specified what this comparative study helps with, what is its practical utility and what is meant in the future (from the point of view of research in the field)?
Author Response
The responses to the comments are in the attached files
Author Response File: Author Response.pdf
