Review Reports

Round 1

Reviewer 1 Report

This paper presents the operation strategy of the truck unloading system, the failure modes of the components within the system, and a bottom-up approach to the reliability of the system. It assess the truck unloading system reliability during the operating lifecycle to the end of its useful life, investigates the effect of the preventive maintenance on the truck unloading system reliability, and identifies the major contributors to the system reliability for design improvement purposes. It is suitable for publication after modification. Listed below are some comments that might be considered beforehand.

- the results were not presented on the abstract. The authors needs to describe the main results in the abstract.

-the technical features, measuring ranges and accuracy of the measuring devices are not stated,

- fig.1. - unloading system piping and instrumentation diagram - bad quality, please correct.

- in the part of Conclusions and Future work, the authors described the phenomenon of experimental results more, and some analysis on the mechanism and reasons of its occurrence was neglected,

- add more references with similar problem,

- however, my main concern is the novelty of the work, which the authors have not highlighted well enough. Similar works exist in the literature, so that it is not clear what new the current work brings. Perhaps the authors could make a few conclusions based on their results or otherwise express the importance of the results in a relevant context, instead of just presenting them and stating that they agree with those reported earlier by others.

Author Response

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Author Response File: Author Response.pdf

Reviewer 2 Report

From my point of view the article has good quality and it is interested. In the line 68 picture should have number figure 3 (now is figure 2). In the line 263 there is a mistake (should be negligible).

Author Response

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Author Response File: Author Response.pdf

Reviewer 3 Report

The paper is well written and it is rather interesting although the authors should be more specific in case of their experiments. The paper has a good overview of the topic of predictive maintenance and the relevant studies are described in detail.

In section 3.2. data collection should be described more precisely. What is the "one of the largest oil and gas operation companies in the middle east" (page 8, line 26)? which "data were taken from OREDA"(page 8, line 28)? It should also be added references to the OREDA data.

In table 2 there is a test duration time 9324700 hours and it makes over 1000 years. How can it happen? I assume that it is rather the sum of products (number of units tested times duration of test for the units). It should be clarified.

The equation (4) and (5) should be corrected:
1) there is a lack of indexes in the products;
2) what is the r_1(t)...r_n(t) small letters (lower case)? What is n?

page 12 line 104 "Assuming linear relation between consecutive time intervals considered in this study" how can you justify this assumption? Why the authors did not draw an exact plot in fig.4 since the reliability function is known?

page 13 line 126 "to maintain the system reliability above 0.9, the system components should be maintained in a quarterly basis (every three months)" - Was this value calculated on the basis of the linear approximation or the exact exponential function (reliability)?

page 13 line 126 "Fig. 5 shows the system reliability when preventive maintenance for the three critical components is conducted in a quarterly basis (every three months)." How these numbers were calculated?

Some minor flaws should also be corrected, such as (among others)

page 6, line 263 "the determination of the failure rate is negligibl"-> negligible.
page 8, line 10 "A parallel system fail" -> fails
page 8, line 11 "components are fail." -> components fail.
page 9, line 40 "the study will provides" -> provide
page 13, line 115 "the preventeve maintenece schedule" -> preventive maintenance
page 13, line 116 or 126 "in a quarterly basis" -> on

Author Response

Please see the attachment

Author Response File: Author Response.pdf

Round 2

Reviewer 1 Report

The authors' manuscript is significantly improved. In the revised document, they clarified and highlighted the elements of the novelty of their work. For this reason, I recommend the manuscript in present form.