Dear Dr. Huang,

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Kind regards,

Van Thanh Tien Nguyen, Ph.D.

Academic Editor

PLOS One

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Reviewers' comments:

Reviewer's Responses to Questions

Comments to the Author

1. Is the manuscript technically sound, and do the data support the conclusions?

Reviewer #1: Yes

Reviewer #2: Yes

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2. Has the statistical analysis been performed appropriately and rigorously? -->?>

Reviewer #1: Yes

Reviewer #2: Yes

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3. Have the authors made all data underlying the findings in their manuscript fully available??>

The PLOS Data policy

Reviewer #1: Yes

Reviewer #2: Yes

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4. Is the manuscript presented in an intelligible fashion and written in standard English??>

Reviewer #1: Yes

Reviewer #2: Yes

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Reviewer #1: This paper takes the double shoulder drill pipe joint with NC38 and TM40 thread as the research object, establishes a three-dimensional finite element model, and adopts the method of combining experiments and numerical simulation to explore the failure mechanism under combined working conditions such as upper locking torque, axial load, internal pressure and bending moment. This work is quite outstanding, and the obtained conclusions have significant engineering practical value and have been verified by actual engineering applications. The article is well-argued.

1.However, there is no explanation given for choosing the double shoulder drill pipe joint with NC38 and TM40 thread profiles as the research object. If the author had carefully studied the literature, they would have found that the NC38 thread is an important component for wellbore connection. Its diameter is 3 1/2 inches, the thread profile is that of the drill pipe, the pitch is 3.175 millimeters, and the thread height reaches 1.524 millimeters. This thread design aims to ensure sealing performance, while also having good connection stability and shock resistance, making it the preferred choice in the oil drilling industry. And then, explaining the characteristics of the TM40 thread, and making these points clear, can demonstrate that this research has universal applicability value.

2.The abstract needs to be revised to better reflect the research content and innovation points of this paper.

3.Table 1 is not coherent from top to bottom and should be placed on one page.

Reviewer #2: This study addresses the performance analysis and structural optimization of drill pipe connections under complex operating conditions. By integrating theoretical analysis, numerical simulation, and experimental testing, it establishes three-dimensional finite element models of existing NC388 threaded drill pipe connections (single-shoulder and double-shoulder types) and conducts comparative analyses. The research further proposes a novel TM40 joint and evaluates the mechanical properties of its shoulder and threaded sections, demonstrating a certain degree innovation. The study closely aligned with practical engineering requirements, it hold both theoretical and practical importance for enhancing the reliability and safety of drill pipe connections. However, the following issues should be addressed before publication:

1. Are the material properties in the finite element model directly based on experimental averages, and does it account for the material’s hardening behavior? In this section, it should be clarified how the material parameters used in the model (e.g., elastic modulus, Poisson’s ratio, yield strength, etc.) were determined and their relationship to the experimental data should be explicitly stated.

2. The simulation should accurately replicate the actual constraints of the drill pipe within the wellbore, including accounting for the elastic support of surrounding rock formations or simulating wellbore wall resistance through multi-point support configurations rather than simple rigid fixation. Clearly specify the application method of loads (torque, bending moment)—whether directly applied to the end face or transmitted via coupling nodes—and indicate whether transmission efficiency during thread engagement is considered.

3. Where in the text are the conclusions mentioned in the abstract—such as “superior sealing performance” and “significant reduction in jamming risk” —specifically demonstrated? Please provide details. Additionally, these metrics lack quantitative evaluation or simulation. It is recommended to incorporate a leakage analysis by simulating fluid permeation under specific pressure differentials to quantify the sealing performance differences among various structures.

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what does this mean?). If published, this will include your full peer review and any attached files.

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Reviewer #1: No

Reviewer #2: No

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To ensure your figures meet our technical requirements, please review our figure guidelines: https://journals.plos.org/plosone/s/figures

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Performance analysis and structural optimization of drill pipe connections under complex operating conditions

PONE-D-25-66662R1

Dear Dr. Huang,

We’re pleased to inform you that your manuscript has been judged scientifically suitable for publication and will be formally accepted for publication once it meets all outstanding technical requirements.

Within one week, you’ll receive an e-mail detailing the required amendments. When these have been addressed, you’ll receive a formal acceptance letter and your manuscript will be scheduled for publication.

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Kind regards,

Van Thanh Tien Nguyen, Ph.D.

Academic Editor

PLOS One

Additional Editor Comments (optional):

Reviewers' comments:

Reviewer's Responses to Questions

Comments to the Author

Reviewer #2: All comments have been addressed

Reviewer #3: All comments have been addressed

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2. Is the manuscript technically sound, and do the data support the conclusions??>

Reviewer #2: Yes

Reviewer #3: Yes

**********

3. Has the statistical analysis been performed appropriately and rigorously? -->?>

Reviewer #2: Yes

Reviewer #3: Yes

**********

4. Have the authors made all data underlying the findings in their manuscript fully available??>

The PLOS Data policy

Reviewer #2: Yes

Reviewer #3: Yes

**********

5. Is the manuscript presented in an intelligible fashion and written in standard English??>

Reviewer #2: Yes

Reviewer #3: Yes

**********

Reviewer #2: (No Response)

Reviewer #3: All concerns have been addressed. I suggest the revised manuscript could be accepted for publishing.

Thank you.

**********

what does this mean?). If published, this will include your full peer review and any attached files.

If you choose “no”, your identity will remain anonymous but your review may still be made public.

Do you want your identity to be public for this peer review?  For information about this choice, including consent withdrawal, please see our Privacy Policy

Reviewer #2: No

Reviewer #3: No

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