A HAZOP-based hazard identification model for urban gas accidents: Development and empirical validation

Bin Tian; Haibing Li; Xiaojun Cui; Zhihong Hu; Zibo Zhou; Wei Shi

doi:10.1371/journal.pone.0333431

Peer Review History

Original SubmissionJuly 28, 2025
24 Aug 2025 Decision Letter - Muhammad Athar, Editor Dear Dr. Tian, Thank you for submitting your manuscript to PLOS ONE. After careful consideration, we feel that it has merit but does not fully meet PLOS ONE’s publication criteria as it currently stands. Therefore, we invite you to submit a revised version of the manuscript that addresses the points raised during the review process. Please submit your revised manuscript by Oct 08 2025 11:59PM. If you will need more time than this to complete your revisions, please reply to this message or contact the journal office at plosone@plos.org . When you're ready to submit your revision, log on to https://www.editorialmanager.com/pone/ and select the 'Submissions Needing Revision' folder to locate your manuscript file. A rebuttal letter that responds to each point raised by the academic editor and reviewer(s). You should upload this letter as a separate file labeled 'Response to Reviewers'. 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If the funders had no role, please state: "The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript." If this statement is not correct you must amend it as needed. Please include this amended Role of Funder statement in your cover letter; we will change the online submission form on your behalf. 6. Please note that funding information should not appear in any section or other areas of your manuscript. We will only publish funding information present in the Funding Statement section of the online submission form. Please remove any funding-related text from the manuscript. 7. We note you have included a table to which you do not refer in the text of your manuscript. Please ensure that you refer to Table 1 in your text; if accepted, production will need this reference to link the reader to the Table. 8. If the reviewer comments include a recommendation to cite specific previously published works, please review and evaluate these publications to determine whether they are relevant and should be cited. There is no requirement to cite these works unless the editor has indicated otherwise. 9. Please review your reference list to ensure that it is complete and correct. If you have cited papers that have been retracted, please include the rationale for doing so in the manuscript text, or remove these references and replace them with relevant current references. Any changes to the reference list should be mentioned in the rebuttal letter that accompanies your revised manuscript. If you need to cite a retracted article, indicate the article’s retracted status in the References list and also include a citation and full reference for the retraction notice. [Note: HTML markup is below. Please do not edit.] 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 ******** 2. Has the statistical analysis been performed appropriately and rigorously? -->?> Reviewer #1: N/A Reviewer #2: Yes ****** 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 ****** 4. Is the manuscript presented in an intelligible fashion and written in standard English??> Reviewer #1: Yes Reviewer #2: Yes ****** Reviewer #1: The manuscript presents an interesting application of HAZOP for urban gas accident risk analysis by integrating identified hazards with potential accident scenarios. The use of a case study to validate the framework is a commendable approach. However, the validation strategy could be further strengthened by involving subject matter experts to independently assess the proposed framework. Additionally, incorporating more case studies conducted by individuals or teams not involved in the development of the method would help minimize potential bias and enhance the credibility of the findings. Reviewer #2: This manuscript addresses an important and timely issue of urban gas safety by proposing a hazard identification model based on HAZOP deviation theory. The integration of human, machine, environment, and management dimensions into a structured hazard identification framework is innovative and practically valuable. The case study demonstrates strong potential for real-world application. The paper is generally well-written, logically structured, and supported by relevant literature. However, there are some issues that need to be modified: 1. The introduction reviews urban gas accident statistics and prior methodologies but could better highlight why HAZOP, specifically, is superior compared to other structured methods (FMEA, bow-tie, etc.). 2. Figures and tables are informative, but caption styles are inconsistent (e.g., “Fig.” vs. “Figure”). 3. References are not arranged in order. 4. Overuse of capitalization in heading: "Construction of the Hazard Identification Model". It should not capitalize every word. Please revise this for other headings. 5. keywords are not in alphabetical order. please revise. 6. In introduction section, numbers are inconsistent. sometimes with two decimals (20.79 billion m³), three and four decimals (94.394 million to 558.3287 million) and sometimes none (31 deaths). Must standardize this. ****** 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 #1: Yes: Noor Diana Binti Abdul Majid Reviewer #2: Yes: Muhammad Arslan Jameel Malik ******** [NOTE: If reviewer comments were submitted as an attachment file, they will be attached to this email and accessible via the submission site. Please log into your account, locate the manuscript record, and check for the action link "View Attachments". If this link does not appear, there are no attachment files.] While revising your submission, please upload your figure files to the Preflight Analysis and Conversion Engine (PACE) digital diagnostic tool, https://pacev2.apexcovantage.com/ . PACE helps ensure that figures meet PLOS requirements. To use PACE, you must first register as a user. Registration is free. Then, login and navigate to the UPLOAD tab, where you will find detailed instructions on how to use the tool. If you encounter any issues or have any questions when using PACE, please email PLOS at figures@plos.org https://doi.org/10.1371/journal.pone.0333431.r001
Revision 1
28 Aug 2025 Author Response Dear Editor and reviewers� On behalf of all authors, we thank the Academic Editor and reviewers for their constructive comments and suggestions, which have helped us improve the quality and clarity of the manuscript. Below, we provide a point-by-point response to all comments. All changes in the manuscript are highlighted in the revised version with track changes. Journal Requirements: 1. [PLOS ONE style] Response: We have carefully reviewed the PLOS ONE formatting guidelines and reformatted the manuscript accordingly, including file naming, section headings, and reference style. 2. [ORCID] Response: The corresponding author (Bin Tian) has verified his ORCID iD (https://orcid.org/0009-0001-3391-9158) in Editorial Manager. 3. [Code sharing] Response: This study does not involve author-generated code. Therefore, this requirement does not apply. 4. [Data availability] Response: All data underlying the findings of this study are fully available within the manuscript. As this is a methodological study based on a HAZOP-based hazard identification framework, no external data collection or computational simulations were conducted. The model application, including all relevant parameters, deviation analyses, and resulting hazard identifications, is fully described in the text. Therefore, the manuscript itself constitutes the complete minimal data set, and no additional data deposition is required. 5. [Role of funders] Response: We have added the following statement in the cover letter: "The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript." 6. [Funding in manuscript] Response: All funding-related text has been removed from the manuscript. Funding information is now only included in the submission system. 7. [Table reference] Response: We have added a reference to Table 1 in Section 2.4: " The main definitions are summarized below as Table 1." 8. [Citation recommendations] Response: No specific citations were recommended by the reviewers. All references have been verified for accuracy and relevance. 9. [Reference list] Response: The reference list has been checked and formatted according to PLOS ONE’s sequential numbering style. All citations are accurate, and no retracted papers are cited. --- Reviewer #1: Comment: The validation strategy could be further strengthened by involving subject matter experts and more external case studies to reduce bias. Response: We fully agree with this insightful comment. In response, we have revised the subsection (4.2 Limitations of the Model), in which we explicitly acknowledge the limitation of single-case validation and emphasize the need for future multi-case and independent-team validation to enhance objectivity and generalizability. The following text has been added to Section 4.2(2): "To better evaluate the model’s applicability and stability, future work should include multi-case comparative analyses conducted across diverse environments and ideally by independent teams. Such efforts would help minimize potential bias and strengthen the empirical foundation of the proposed framework [26,27]." --- Reviewer #2: Comment 1: Better highlight why HAZOP is superior compared to other methods (e.g., FMEA, bow-tie). Response: We have added a comparative statement in the Introduction: " Although several structured risk assessment methods—such as Failure Mode and Effects Analysis (FMEA), bow-tie analysis, and Fault Tree Analysis (FTA)—have been applied in safety engineering, each has limitations that constrain their effectiveness in complex urban gas systems [22]. FMEA primarily focuses on equipment failure modes and their consequences, but often neglects systemic issues related to human behavior, organizational processes, and environmental conditions. Bow-tie analysis and FTA, while effective in visualizing causal pathways and mitigation barriers, typically requires prior knowledge of initiating events and is less suited for proactively identifying unknown or unanticipated hazards. These approaches may therefore fall short in contexts where risks emerge from dynamic interactions across technical, human, and managerial domains. In contrast, Hazard and Operability Analysis (HAZOP) offers a more systematic and structured framework for hazard identification. By systematically applying guide words (e.g., “no,” “more,” “less,” “reverse”) to predefined parameters across multiple dimensions—such as human, machine, environment, and management—HAZOP enables a comprehensive examination of potential deviations, even in the absence of historical incident data. This deviation-driven approach supports proactive, thorough, and scenario-independent hazard detection, making it particularly well-suited for socio-technical systems like urban gas networks." Comment 2: Inconsistent figure captions (e.g., “Fig.” vs “Figure”). Response: All figure captions have been standardized to “Fig X.” format, in accordance with PLOS ONE guidelines. Comment 3: References are not in order. Response: The reference list has been re-ordered according to the sequence of citation in the text, following PLOS ONE’s numbering system. Comment 4: Overuse of capitalization in headings. Response: All section headings have been revised to sentence case (only first word capitalized), e.g., “Construction of the hazard identification model”. Comment 5: Keywords not in alphabetical order. Response: The keywords have been re-ordered alphabetically: "Case study; Framework development; Hazard identification model; HAZOP; Urban gas accident" Comment 6: Inconsistent number formatting in Introduction. Response: All numerical values have been standardized: � “94.394 million” → “94.39 million” � “558.3287 million” → “558.33 million” � Other values (e.g., 27.90%, 20.79 billion m³) were already appropriately formatted. --- We believe that the revised manuscript has addressed all concerns and is now suitable for publication in PLOS ONE. Thank you again for the opportunity to improve our work. Attachments Attachment Submitted filename: Response to Reviewers.docx https://doi.org/10.1371/journal.pone.0333431.r002
15 Sep 2025 Decision Letter - Muhammad Athar, Editor A HAZOP-based hazard identification model for urban gas accidents: Development and empirical validation PONE-D-25-41119R1 Dear Dr. Tian, 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. An invoice will be generated when your article is formally accepted. Please note, if your institution has a publishing partnership with PLOS and your article meets the relevant criteria, all or part of your publication costs will be covered. Please make sure your user information is up-to-date by logging into Editorial Manager at Editorial Manager® and clicking the ‘Update My Information' link at the top of the page. For questions related to billing, please contact billing support . If your institution or institutions have a press office, please notify them about your upcoming paper to help maximize its impact. If they’ll be preparing press materials, please inform our press team as soon as possible -- no later than 48 hours after receiving the formal acceptance. Your manuscript will remain under strict press embargo until 2 pm Eastern Time on the date of publication. For more information, please contact onepress@plos.org. Kind regards, Muhammad Athar, PhD Academic Editor PLOS ONE Additional Editor Comments (optional): Reviewer #1: Reviewer #2: Reviewers' comments: Reviewer's Responses to Questions Comments to the Author Reviewer #1: All comments have been addressed Reviewer #2: All comments have been addressed ******** 2. Is the manuscript technically sound, and do the data support the conclusions??> Reviewer #1: Yes Reviewer #2: Yes ****** 3. Has the statistical analysis been performed appropriately and rigorously? -->?> Reviewer #1: Yes Reviewer #2: Yes ****** 4. Have the authors made all data underlying the findings in their manuscript fully available??> The PLOS Data policy Reviewer #1: Yes Reviewer #2: Yes ****** 5. Is the manuscript presented in an intelligible fashion and written in standard English??> Reviewer #1: Yes Reviewer #2: Yes ****** Reviewer #1: The authors have carefully revised the manuscript according to the reviewers’ comments. All suggested changes and clarifications have been incorporated, ensuring that the issues raised have been thoroughly addressed. The language has been refined, additional explanations have been provided where necessary, and supporting references have been included to strengthen the arguments. Technical corrections and formatting improvements were also made to enhance readability. The revised version reflects the reviewers’ constructive feedback and demonstrates significant improvement in content, structure, and clarity. We believe the manuscript now meets the required standards for publication and respectfully resubmit for consideration. Reviewer #2: (No Response) ****** 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 #1: Yes: Noor Diana Binti Abdul Majid Reviewer #2: Yes: Muhammad Arslan Jameel Malik ******** https://doi.org/10.1371/journal.pone.0333431.r003
Formally Accepted
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