Effect of CFRP Geometry on the Repair Performance of Corroded Steel Pipelines: A Finite Element Study

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

This paper investigates the effect of CFRP thickness and repair length on hoop stress during the repair of corroded steel pipes using CFRP, employing the finite element method. The subject of this study is of industrial importance and provides useful results, particularly in demonstrating the dominant effect of CFRP thickness on repair effectiveness.

(1) The article concludes that CFRP thickness has a more dominant effect on repair effectiveness than repair length. The authors should more clearly discuss how the present study differs from similar finite element analyses in the literature. In particular, it should be clarified what kind of additional contribution the (t_c/a) ratio—presented as a “normalized thickness guideline”—provides compared to existing design approaches in the literature.

(2) To demonstrate that the model accurately represents the actual CFRP repair behavior, a comparison should be made with experimental pipe burst tests, pressure tests, or independent 3D FE studies in the literature. At a minimum, a separate subsection should be included in which the present numerical results are quantitatively compared with previous experimental/numerical findings.

(3) Since the study is interpreted from the perspective of repair design, plasticization, CFRP damage, epoxy/filler behavior, and possible nonlinear effects under pressure increase should be discussed.

(4) The study used only a single pipe diameter, a single pressure level, a single CFRP orientation, a limited defect length, and limited thickness ratios. To ensure the generalizability of the results, additional analyses are recommended for variables such as the D/t ratio, internal pressure level, CFRP elastic modulus, epoxy thickness, defect shape, and CFRP fiber orientation.

(5) The abstract should include a statement indicating that the model is based on the assumptions of idealization, elasticity, and perfect bonding.

(6) The readability of the figures should be improved. In particular, the axis labels and numerical values in Figures 6–12 appear too small.

(7) To enable comparison of different repair scenarios, the same color scale should be used in all contour plots, and the minimum–maximum stress ranges should be clearly indicated.

Author Response

Please see the attachment.

Author Response File: Author Response.pdf

Reviewer 2 Report

Comments and Suggestions for Authors

(1) Figure 1 shows the CFRP repaired pipe model. The corrosion defect of pipe is located outside of the steel pipe. How are these corrosion defects formed?

(2) In Figure 3 and Figure 6, the hoop stress contours of steel pipe were observed. What’s about the hoop stress in the repaired areas (epoxy and CFRP parts)?

(3) In Figure 4, the finite element model of repaired steel pipe was observed. Is there any considerations about the interfacial behavior between steel and epoxy or epoxy and CFRP in this model?

 

Author Response

Please see the attachment.

Author Response File: Author Response.pdf

Round 2

Reviewer 1 Report

Comments and Suggestions for Authors

Thanks for response. There is not additional comment.