Assessment of failure pressure of a GFRP composite repair system for wall loss defect in metallic pipelines

Abstract

The present paper is concerned with the failure pressure assessment of a newly developed GFRP matrix laminated composite repair of metallic pipelines with 80 % wall loss defect. The main motivation is to validate the experimental failure pressure with the theoretical one. Wall loss defects were manufactured into the tube specimen and the performance of the repaired pipe was assessed by hydrostatic tests as per ISO/TS 24817 standard. Results reveal that the theoretical failure pressure as per ISO/TS 24817 standard is found to be conservative. A wide range of failure pressure values was obtained using different criteria. Only RSTRENG 0.85* modified criterion provides a closer value towards the experimental one. However, the criterion selection for damage factor and flow stress condition is an open question as it gives dispersed values of failure pressure. The prediction of the failure pressure must be accurate without being overly conservative. Plastic deformation of the tube occurs towards the end of the tube, consequently, it is necessary to account for this behavior in failure pressure analysis for an accurate prediction. The application of loading‐unloading cycles before the failure burst test should be also accounted in order to predict the failure pressure.

Numerical analysis of repaired wall loss defect pipelines for optimum composite wrap thickness

“…The failure pressure of 34 MPa was found by numerical analysis, which is little closer to the experimental failure pressure. Neglecting plastic deformation (strain hardening) in theoretical analysis of ISO/TS 24817 and other parameters such as damage factor and material properties are the possible reason for the deviation in failure pressure between numerical and experimental results [7]. However, the calculated analytical failure pressure using standard ISO/TS 24817 code is conservative compared to the numerical and experimental results.…”

“…These standard methods are in practices for composite repair of damaged pipeline for both wall loss and through wall defect in all sectors. In regard to the design code, researchers performed hydrostatic test as per standards for the assessment of different composite materials, geometrical parameters, etc [4][5][6][7][8]. The research focuses on improving the existing methodology/procedure of ISO/TS 24817 and ASME-PCC2 design code for qualification of composite materials, putty materials and geometrical parameter of composite repair wrap.…”

Prediction of the burst pressure for defective pipelines using different semi-empirical models

“…There is quite a significant variation of the theoretical burst pressure between the different semi-empirical models for the same test specimen. This is related to the assumptions of remaining strength function ( ) and flow stress material ( ), which leads to a variation in burst pressure even for the same defect pipe.In most of the semi empirical model the defect width in pipeline is not accounted, however some results found the influence of width on final burst pressure [9,24,34]. In addition to that the complicated geometry of corroded region to represent in analysis is quite complicated and leads in the variation in experimental and theoretical results.…”

“…There are many semi-empirical models which include: ASME B31G, modified ASME B31G, RSTRENG 0.85, SHELL92, DNV, PCORRC, Chell limit, Sims pressure and Ritchie, etc. to assess the durability condition of corroded pipelines [6][7][8][9][10][11]. The basic assumption of an empirical model is that the reduction of strength due to corrosion is corresponding to the amount of material loss measured along the length of the pipe.…”

Analysis of Failure Pressure of Defective Pipes Repaired with Composite Systems Considering the Plastic Deformation of Pipe

“…Many researchers investigated the performance of composite repair system with respect to material (composite material, adhesive and putty) and geometrical (pipe defect geometry, 2 sleeve repair thickness, fiber orientation) parameters of the repaired system through experimental (hydrostatic tests) and numerical analysis [11][12][13][14][15]. Many researchers have been working to improve and modify the design codes over the selection of composite materials and design factors such as design pressure and composite repair thickness for a better performance of the composite repair system of corroded pipelines [16][17][18][19]. Composite repair thickness is one of the most important repair design parameters and a conservative thickness is necessary for safe repair design.…”