Repair Reliability Analysis of a Special-Shaped Epoxy Steel Sleeve for Low-Strength Tee Pipes

Round 1

Reviewer 1 Report

The paper is about a practical method to repair pipe fittings in a natural gas station. Introduced method guarantee the safe operation of this pipes in practise. The authors designed a special-shaped epoxy steel sleeve (SSESS) that was later on checked numerically and experimentally. The result indicated that introduced repair tee's yielding and burst 22 pressure increased, demonstrating its repair reliability.

The detailed comment are collected and introduced in the pdf file attached (in form of windows messages in the pdf file). The authors need to read them all, improve the paper and answear to them in the rebuttal to the reviewer.

Comments for author File: Comments.pdf

Author Response

Dear editor and reviewer:

Thank you very much for your careful reviews and constructive suggestions regarding our manuscript “Repair reliability analysis of special-shaped epoxy steel sleeve for low-strength tee pipe” (ID: metals-2047978). Those comments are very helpful for authors to revise and improve this manuscript. The references have been revised according to the house style. The main corrections are made in a highlighted font in the revised manuscript.  Yours sincerely,

Jun Cao, Ph.D.

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The following is a point-to-point response to the editor and reviewer’s comments.

Reviewer #1

1. However, solutions with steel repair fittings are known to be used for smaller diameter hoses in hydraulic systems [Karpenko Mykola; Prentkovskis Olegas; Šukevičius Šarūnas. Research on high-pressure hose with repairing fitting and influence on energy parameter of the hydraulic drive. Eksploatacja i Niezawodnosc - Maintenance and Reliability. Lublin: Polish Maintenance Society. ISSN 1507-2711. vol. 24, iss. 1 (2022), p. 25-32.].

Respond: Thanks, this important literature is a supplement to the repair method of pipes, which has been cited in the revised manuscript.

 

2. It is important to approximate the conditions of the tests performed.

Respond: Yes, I agree with this comment, which has been added in the revised manuscript.

 

• I suggest that in the introduction als the new research discussed in the work:

Jaszak P., Skrzypacz J., Borawski A., Grzejda R., Methodology of leakage prediction in gasketed flange joints at pipeline deformations, Materials, 15, 12, 2022, Paper No. 4354, https://doi.org/10.3390/ma15124354 is discussed.

Respond: Thanks, this literature is critical to enriching the introduction, and the repair method is a supplement for the special-shaped fitting, so it is cited in the revised manuscript.

      

• The prograssive failure analysis approach is presented in the paper [Ahmad, K., Baig, Y., Rahman, H., & Hasham, H. J. (2020). Progressive failure analysis of helicopter rotor blade under aeroelastic loading. Aviation, 24(1), 33-41. https://doi.org/10.3846/aviation.2020.12184]. I suggest to cite and describe in the manuscript.

Respond: Thanks, this important literature has been cited and described in the revised manuscript.

 

5. D is not described coefficient?

Respond: Thanks,  is the outer diameter of the pipe, which has been added in the revised manuscript.

 

         6 numerically veryficated：Figure 2. The six SSESS repair modes.

Respond: The figure label has been modified based on the suggestion of the reviewer.

 7 If the flow of the medium inside the duct is pulsatile then shouldn't tests also be done with variable loads? I would like to ask the authors to respond to this concern.

Respond: Thanks, the six numerical simulations with different lengths between the end of the tee and girth weld were made to find the optimizing size of the steel sleeve. The internal pressure is linearly loaded in the numerical simulations. If the flow of the medium inside the duct is pulsatile, the loading process will be simplified by using uniform internal pressure.

 

8 In this work authors didn't mention what kind of bolts they used and how they pretensioning them. Was the bolt pretension selected from the standards or calculated? With this topic they should refer to work: https://doi.org/10.12913/22998624/104657

Respond: Thanks, the design and material grade of equal-length studs and hexagon nuts are based on the standards of GB/T 901 (Equal-length studs) and GB/T 6170 (Hexagon nuts) in China, respectively.  The material grade of equal-length studs and hexagon nuts are 10.9 and 10, respectively. These modification has been added in the revised manuscript.

 

9. rewrite this sentence：“As the simulations predictive results in Figure 16 and Figure 17, the stress contour of burst time for unrepair and repair tees are both concentrated in the belly, which represents 215 the origin of burst should be in the belly.”

Respond: Thanks, the sentence has been rewritten as “As shown in the simulations results in Figure 16 and Figure 17, the maximum equivalent stress areas of the unrepaired and repaired tees both are in the belly, which represents the origin of burst should be in the belly.”.

 

10. two times pointed for fig. 16!

Respond: Thanks, the error of two times pointed for fig.16 has been modified in the revised manuscript. The sentence has been revised as “As the experimental burst appearance of the two tees in Figure 16 and Figure 17…”

 

11. 1.5P ; 2P?

Respond: Thanks, sorry for my unclear description, the sentence has been modified in the revised manuscript. 1.5P is three-half times design pressure and 2P is two times design pressure.

 

Author Response File: Author Response.pdf

Reviewer 2 Report

The manuscript entitled "Repair Reliability Analysis of Special-Shaped Epoxy Steel Sleeve for Low-Strength Tee Pipe” presented a design for a special-shaped epoxy steel sleeve to repair low-strength tee pipes.

The manuscript is well-written and presents valuable experimental results. However, the following comments must be addressed before any further action.

Technical comments:

1-     The literature should be expanded to highlight how their study is providing a different approach or adding significantly to what has been done and include the most related studies to highlight the new approach developed in this manuscript.

2-     Section 2: The material properties are missed in this section.

3-     Lines 134-135: More comments about the selection of these locations for the strain gauges are recommended.

4-     Line 151: What was this "certain mass ratio"? Also, more information about these components like names, properties, and features.

5-     The number of tested tees was two, which is very low. One of them was without repair and the second one with repair. This reviewer thinks that this number of specimens is very low to verify or confirm the experimental results. Therefore, more detailed FE simulations should be used to compensate for this lack of experimental results.

6-     Section 2.4: The developed FE model lacks clarity and more details should be provided like the simulation of the bond between the parts of the model as well as the material constitutive models. Moreover, the developed FE should be verified using the experimental results in terms of strains.

7-     Lines 182-183: This reviewer cannot understand the reason for using "respectively" in this sentence.

8-     This reviewer recommends adding a new section to present a parametric study using the verified FE model to enrich this manuscript.

Author Response

Dear editor and reviewer:

Thank you very much for your careful reviews and constructive suggestions regarding our manuscript “Repair reliability analysis of special-shaped epoxy steel sleeve for low-strength tee pipe” (ID: metals-2047978). Those comments are very helpful for authors to revise and improve this manuscript. The references have been revised according to the house style. The main corrections are made in a highlighted font in the revised manuscript.  Yours sincerely,

Jun Cao, Ph.D.

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The following is a point-to-point response to the editor and reviewer’s comments.

Reviewer #2

1 The literature should be expanded to highlight how their study is providing a different approach or adding significantly to what has been done and include the most related studies to highlight the new approach developed in this manuscript.

Respond: Thanks, more references have been added in the introduction to enrich the significance of this manuscript.

2 Section 2: The material properties are missed in this section.

Respond: Thanks, the material properties have been added in the section of Materials and Methods.

 3 Lines 134-135: More comments about the selection of these locations for the strain gauges are recommended.

Respond: Thanks, the locations of these strain gauges are designed to study the critical regions: the girth weld region (#1,#2, #3, #4, #7, #8,), shoulder(#3 and #5), belly (#12), the bottom of the main pipe (#9), and the reference area (#10 and #11). The comment has been added to the revised manuscript.

 4 Line 151: What was this "certain mass ratio"? Also, more information about these components like names, properties, and features.

Respond: Thanks, sorry for the unclear description, the mass ratio of A and B components (100:30). The A and B components are mixed as epoxy resin adhesive. The epoxy resin adhesive needs to meet the following requirements.

Properties	unit	requirements
Hardness of resin after curing	Shore D	80±10
Mass solid content	%	≥99.5
Curing shrinkage	%	≤0.4
Compressive strength of resin after curing	MPa	≥50
(50% deformation)	MPa	≥10
Shear strength	MPa	≥10

 5 The number of tested tees was two, which is very low. One of them was without repair and the second one with repair. This reviewer thinks that this number of specimens is very low to verify or confirm the experimental results. Therefore, more detailed FE simulations should be used to compensate for this lack of experimental results.

Respond: Thanks, the more detailed FE simulation have added in the revised manuscript based on the suggestion of the reviewer.

 6 Section 2.4: The developed FE model lacks clarity and more details should be provided like the simulation of the bond between the parts of the model as well as the material constitutive models. Moreover, the developed FE should be verified using the experimental results in terms of strains.

Respond: Thanks, more details of bond, constraints, and material constitutive models have been added in the revised manuscript. The material constitutive model used the stress-strain data of S1, S2, and S3 in Section 2.1. In addition, the FE model validation process in terms of strain has been added.

 7 Lines 182-183: This reviewer cannot understand the reason for using "respectively" in this sentence.

Respond: Thanks, sorry for this mistake, which has been modified in the revised manuscript.

 

8 This reviewer recommends adding a new section to present a parametric study using the verified FE model to enrich this manuscript.

Respond: Thanks, more parametric results of FEM have been added in the revised manuscript based on the suggestion of the reviewer.

 

 

Author Response File: Author Response.pdf

Round 2

Reviewer 1 Report

The authors corrected the paper according to the reviewers sugestion. Now the paper looks improved and can be considered for publication.

Author Response

Dear editor and reviewer:

Thank you very much for your careful reviews and constructive suggestions regarding our manuscript “Repair reliability analysis of special-shaped epoxy steel sleeve for low-strength tee pipe” (ID: metals-2047978). Those comments are very helpful for authors to revise and improve this manuscript. The references have been revised according to the house style. The main corrections are made in a highlighted font in the revised manuscript.  Yours sincerely,

Jun Cao, Ph.D.

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The following is a point-to-point response to the editor and reviewer’s comments.

Reviewer #1

1. The authors corrected the paper according to the reviewer’s suggestion. Now the paper looks improved and can be considered for publication.

Respond: Thank the reviewer.

Reviewer 2 Report

The authors have addressed most of the reviewer's comments. However, the following comment still needs more attention.

Section 2.4: The developed FE model still lacks clarity and more details should be provided. The authors mentioned, “the material constitutive model used the stress-strain data of S1, S2, and S3 in Section 2.1”.

-        The meaning of the constitutive model is how the authors represented the stress-strain relationships. Was it elastic perfectly plastic or bi-linear or what? The stress-strain relationship should be provided in this section to be clear.

-        The authors used solid elements (C3D8R) and 10-node modified quadratic tetrahedron elements (C3D10M). The authors mentioned, “The structural parts of straight pipes and the tee are created in an overall model instead of a combination of these parts”. How did the authors model the bond between the two elements? Was it a full bond or what?

Author Response

Dear editor and reviewer:

Thank you very much for your careful reviews and constructive suggestions regarding our manuscript “Repair reliability analysis of special-shaped epoxy steel sleeve for low-strength tee pipe” (ID: metals-2047978). Those comments are very helpful for authors to revise and improve this manuscript. The references have been revised according to the house style. The main corrections are made in a highlighted font in the revised manuscript.  Yours sincerely,

Jun Cao, Ph.D.

-------------------------------------------------------------------------------------------------------

The following is a point-to-point response to the editor and reviewer’s comments.

Reviewer #2

1. The authors have addressed most of the reviewer's comments. However, the following comment still needs more attention.Section 2.4: The developed FE model still lacks clarity and more details should be provided. The authors mentioned, “the material constitutive model used the stress-strain data of S1, S2, and S3 in Section 2.1”.The meaning of the constitutive model is how the authors represented the stress-strain relationships. Was it elastic perfectly plastic or bi-linear or what? The stress-strain relationship should be provided in this section to be clear.

Respond: Thanks, the material constitutive model used the elasto-plastic hardening material model of S1, S2, and S3 in Section 2.1 by fitting the stress-strain data. The stress-strain relationship of S1, S2, and S3 have been added in the Section 2. More details have been provided in the revised manuscript.

 

2. The authors used solid elements (C3D8R) and 10-node modified quadratic tetrahedron elements (C3D10M). The authors mentioned, “The structural parts of straight pipes and the tee are created in an overall model instead of a combination of these parts”. How did the authors model the bond between the two elements? Was it a full bond or what?

Respond: Thanks, the overall part in ABAQUS can be cut into four parts, which are three straight parts and one tee part, respectively. The three straight parts and the tee used C3D8R and C3D10M element type, respectively. Then, the elements of C3D8R and C3D10M are bonded by using the operation of “mesh part” automatically. The mesh results can be shown in the following figure(find the attachment). These details have been added in the revised manuscript.

 

 

Author Response File: Author Response.pdf