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The temperature change, internal pressure and corrosion are main reason of cracks in pipes. Removal of damaged pipes with new ones gives rise to major disruption during operation. This causes loss of time and cost. This study aims to prevent crack propagation and to obtain fast repair in damaged area, at the beginning of the damage. Repair of small...
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Citations
... Theisen and Keller [34] conducted numerical and experimental tests for both patch and wrap repairs on through-wall defects and they reported the maximum strain of patch is higher than with composite wrap type system [34]. Ayaz et al. [35] showed that the increment in overlap length could enhance the failure strength in composite patch repair system for a through wall defect. This indicate, the FRP patch repair system can be a good choice for small-area though wall defect and wall loss defect. ...
The paper presents the numerical analysis of failure pressure of wall loss defect metallic pipelines and validate it with experimental results. An optimization of composite thickness for repair of wall loss defect pipeline is also carried out using numerical analysis. A nonlinear explicit FE code with constitutive models for metallic steel and composite material to failure modelling was used. Three different cases: non-defective pipe, wall loss defective pipe and composite repaired of defective pipe are considered. It was found that the numerical results are in good agreement with the analytical results in all the three cases. The theoretical failure pressure determined by ISO/TS 24817 standard for wall loss defect pipe is highly conservative compared to the numerical failure pressure for the given composite repair thickness. Additionally, the numerical study on optimization of repair thickness revealed that lower composite repair thickness can also sustain the designed failure pressure (composite repair thickness of 8.4 mm can sustain the same designed pressure instead of 16.1 mm thickness), which implies there is scope to further reduce the composite thickness, which ultimately reduce the repair cost.
... Surface roughness also influences bonded strength. The use of composite patch repair was performed by Ayaz et al. [22]. Carbon fiber and acrylic adhesive were used as patch to repair galvanized steel pipes. ...
This work investigates the repair of corrosion damage in metallic pipes using glass fiber reinforced plastic (GFRP) patches. The main idea is to analysis of the effect of the thickness of the GFRP patch and the patch surface roughness on the effectiveness of the repair. Commonly, to perform such repair, a composite sleeve wrap is used according to international standards. The work shows that is not necessary a composite sleeve to repair low pressure leaking metallic pipes, only a bonded GFRP patch is sufficient.
Burst tests were performed on API 5L gr.B steel hydrostatic specimens with a 10, 15 and 25 mm hole repaired with 100 mm X 100 mm GFRP patches with three different surface roughness. The effectiveness of the repair is strongly dependent on its thickness and surface roughness of GFRP patches. Experimental results show a relation with failure pressure GFRP patch thickness and surface roughness. Higher GFRP patch thickness, elevated failure pressures are presented. Also, high values of surface roughness produce increased failure pressures. A model based on the Linear Elastic Fracture Mechanics is used to obtain an estimate failure pressure using only one algebraic equation.
... Ayaz et al. studied the composite patch repair for a small through-wall hole. The results showed that the increment in overlap length could enhance the failure strength [35]. In general, the FRP patch repair strategy is mainly used for small-area through-wall defects at present. ...
Carbon fiber reinforced polymer (CFRP) matrix composite overwrap repair systems have been introduced and accepted as an alternative repair system for steel pipeline. This paper aimed to evaluate the mechanical behavior of damaged steel pipeline with CFRP repair using finite element (FE) analysis. Two different repair strategies, namely wrap repair and patch repair, were considered. The mechanical responses of pipeline with the composite repair system under the maximum allowable operating pressure (MAOP) was analyzed using the validated FE models. The design parameters of the CFRP repair system were analyzed, including patch/wrap size and thickness, defect size, interface bonding, and the material properties of the infill material. The results show that both the stress in the pipe wall and CFRP could be reduced by using a thicker CFRP. With the increase in patch size in the hoop direction, the maximum von Mises stress in the pipe wall generally decreased as the maximum hoop stress in the CFRP increased. The reinforcement of the CFRP repair system could be enhanced by using infill material with a higher elastic modulus. The CFRP patch tended to cause higher interface shear stress than CFRP wrap, but the shear stress could be reduced by using a thicker CFRP. Compared with the fully bonded condition, the frictional interface causes a decrease in hoop stress in the CFRP but an increase in von Mises stress in the steel. The study results indicate the feasibility of composite repair for damaged steel pipeline.
... Ayatollahi predicted failure load of single-lap adhesive joints with various overlap length [12]. Ayaz et al. [13] used adhesive bonding for repairing of the small damages in steel pipes subjected to internal pressure using composite patches and investigated the effect of overlap length and overlap angle by using the finite element method. Çitil et al. [14] investigated the effects of patch thickness, overlap length, adherent thickness, and gap length of adhesively bonded double strap aluminum joints with and without intermediate part subjected to tensile loading by using finite element method. ...
The configuration of adhesive bonding, especially adhesive–adherent interface, is very important in adhesive bonding. Adherend thickness, overlap length and adherend width have a great effect on failure load. It is important to know the effect of these parameters in the estimation of failure load. In this study, two models based on data mining techniques were generated for the estimation of the effect of adherend thickness, width and overlap length on failure load in adhesively bonding joints. One of the models is based on the M5P model tree and the other is based on the M5 rule algorithm. Experimental data were used to evaluate the performance of the models. The correlation coefficient parameter was used to compare the models’ performance. The evaluated correlation coefficient is 93% for the M5P model tree and 96% for the M5 rule.
... In addition, the experimental and numerical results data are very similar. The repair of small holes using composite patches was studied by Ayaz et al. [10]. The repaired pipes were subjected to internal pressure until damage occurred. ...
... The failure load also increased when the patches thickness increased. Small diameters (13.45 mm of internal and 16.85 mm of external diameter) were used in both works ( [9,10]). ...
This work aims to study the resistance of repairs with bonded plates in pipes with holes subjected to hydrostatic pressure. It is a promising alternative for application in low-risk repairs (up to 1 MPa). Due to the differences between the circumferential and transverse stresses in the pipes, the influence of the bonded plate area in the joint strength was evaluated, checking whether the shape factor occurs. The effect of plate thickness in the repair strength, besides the addition of silane on the plate surfaces, were also studied. Finally, considering a control plate based in the performed experiments, the surface treatment influence on the tubes was evaluated in the face of rupture pressure of the system. High hydrostatic resistance values were found, demonstrating the efficiency of the procedures used in the repair. The studies show little influence on the repair strength due to dimensions variation in different directions, and high influence on the surface treatment, stiffness and bonded area increase. The work aims to initiate the development of a new procedure for contingency repair with low risk.
... One of the most important applications of composite materials in these areas is the damage repair of pipes due to internal pressure and varying temperature rates. In the repair of damaged galvanized steel pipes, three different types of patch materials, composite, aluminum and steel, were selected and the effect of these types on one type of adhesive was investigated [5,6]. ...
... [3] Adhesives are used to repair failed pipes with patches and polymer composites, which is a quick and practical method. [6,[9][10][11] Creating a strongly bond depends on the type of adhesive and bonded parts, the bonded surface, overlap length, thickness, temperature, and type of joint. [12][13][14][15] In addition, proper joint design is important for adhesive joints because it can reduce the stresses that damage the joint and is the basis for creating a secure and strong adhesive joint. ...
This study evaluates adhesively bonded pipes with curved-surface lap joints subjected to internal pressure. To test the effects of curvilinear radii on the strength of the adhesive bond, steel pipes (St 37) with curved surfaces of the same lap length and different radii were bonded with the adhesive DP 810. Internal pressure was applied until failure and the mechanical behavior of the bonds was examined experimentally and numerically. Numerical analyses used Cohesive Zone Materials Models (bilinear, exponential, and mixed mode) to estimate the strength of the adhesive bonding. The parameters required for material models were determined experimentally and then experiments were run to verify the models with the finite elements. The results show that the curvature radius has considerable influence on failure pressure.
... Ayaz ve ark. [8] çalışmalarında düşük hasarlı çelik boruların kompozit yama ile tamirini gerçekleştirmiş ve değişik yama sarım açıları ile yama bindirme uzunlukları için hem deneysel çalışmalar hem de nümerik analizler yapmışlardır. Ayrıca çalışmalarına ilaveten birleştirme işleminde hasarlı boru ile kompozit yama arasındaki yapıştırıcının mekanik davranışlarına etki eden parametreleri ortaya koymuşlardır. ...
Bu çalışmanın amacı iç basınca maruz hasarlı galvanizli boruların epoksi esaslı yapıştırıcı ile tamirinde en uygun yama açılarının ve bindirme uzunluklarının tespit edilmesidir. Hasarlı borular, borularda oluşturulan çatlakların yapıştırma bağlantıları tekniği ile tamiratı için en uygun yama geometrisinin tespit edilmesi amacıyla farklı geometrideki yamalar kullanılarak epoksi yapıştırıcı ile tamir edilmiştir. Farklı boyutlardaki yamalarla tamiratı yapılmış galvanizli izotropik borular iç basınç testlerine tabi tutulmuş ve boru patlama basınçları elde edilmiştir. Boru patlama mukavemetleri ayrıca ANSYS yazılımı ile elde edilmiş ve deneysel ve nümerik değerlerler karşılaştırmalı olarak verilmiştir. Bu çalışmada, elde edilen deneysel ve sayısal sonuçlar birbirlerine çok yakın olarak ortaya çıkmıştır. Bu çalışma ile yama bindirme açılarının ve yama bindirme uzunluklarının boru patlama basıncı üzerindeki etkileri deneysel ve nümerik olarak ortaya konmuştur.
Nowadays, adhesive joints are largely applied in the automotive, aircraft and aerospace, civil, and naval industries. Although several applications involve flat (plane) adherends, curved joints play an important role in many engineering applications like civil and aircraft construction. This work aims to investigate three structural adhesives, ranging from brittle to ductile, applied in curved joggle-lap joints between carbon fibre reinforced polymer adherends and subjected to internal pressure, to validate a robust design procedure and provide project guidelines for this complex structural, geometrical, and loading system, which constitute the main novelty of the proposed work. A numerical cohesive zone model parametric analysis was undertaken by varying the overlap length, thickness of the adherends, and adherends’ curvature, including the evaluation of peel and shear stresses in the adhesive, failure mode comparison, maximum load, and energy dissipated after failure. Validation of the cohesive zone model technique was initially performed using flat single-lap joint under tensile loads. A significant effect of the overlap length and thickness of the adherends on the maximum load was found, while the adherends’ curvature effect on the maximum load was negligible. Ductile adhesives, although less strong, generally performed better in terms of maximum load and dissipated energy.
This paper is concerned with the repair of through-wall corrosion damage in metallic pipes using bonded metallic patches. The focus is on the analysis of the influence of the thickness of the patch on the effectiveness of the repair. The goal is to assure that the pipe won’t leak once the repair is completed. Usually, in practical applications, a composite sleeve is used combined with a metallic patch. The study shows that only a bonded metallic patch can be sufficient to avoid leaking (no composite sleeve is necessary), but the effectiveness of the repair is strongly dependent on its thickness. Experimental results show that the failure pressure using patches with the same area but with different thicknesses can be very different. Burst tests were performed on API 5 L grB steel hydrostatic specimens with a 25 mm hole repaired with 100 mm × 100 mm patches. Depending on the thickness, the failure pressure can vary from 70 to 270 bar. A model based on the Linear Elastic Fracture Mechanics is proposed to obtain an estimate of the failure pressure using only one algebraic equation. The experimental results are in good agreement with model predictions.
