Fig 1 - uploaded by Oleg V. Trifonov
Content may be subject to copyright.
Source publication
In this paper, strengthening of a steel pipe with a composite wrap is analyzed. An analytical model taking into account joint reaction of the pipe and the wrap, two-dimensional stress state and plastic strains in the pipe wall is developed. Verification of the model is performed by comparison of the numerical results to the full-scale test results...
Contexts in source publication
Context 1
... radial stresses are neglected, and the stress-state in the steel pipe is regarded as plane stress state. The essential components of the stress tensor are the longitudinal (axial) stress (Fig.1). ...
Context 2
... the equilibrium of a half-cylinder of a unit length cut from the wrapped pipe (Fig. 1). The equilibrium equation in the hoop direction takes the ...
Context 3
... the use of composite wrap presents an effective tool for strengthening of the pipeline subjected to the internal pressure. Fig .10 Illustrates the relation between the hoop strain 2 and the wrap thickness w t for three levels of internal pressure p = 13, 15, and 17 MPa (curves 1, 2, and 3, correspondingly). ...
Context 4
... higher pressures the effect of strain reduction with the growth of w t becomes more pronounced. The relation between the hoop stress and the wrap thickness is depicted in Fig.11, a for the steel pipe, and Fig 11, b for the composite wrap. ...
Context 5
... higher pressures the effect of strain reduction with the growth of w t becomes more pronounced. The relation between the hoop stress and the wrap thickness is depicted in Fig.11, a for the steel pipe, and Fig 11, b for the composite wrap. The results are given in non-dimensional form. ...
Context 6
... example, for the pressure p = 17 MPa, the growth of w t from 5 to 25 mm produces the reduction of hoop stress in pipe wall from 0.95 u to 0.82 u , and the reduction of hoop stress in composite wrap from 0.96 uw 2 to 0.27 uw 2 . The effect of pressure level in Fig.11 is analogous to It can be noted that the correspondence of the analytical and the finite-element results is better for the composite wrap. The curves representing the finite-element results for the pipe wall hoop stress go higher than the analytical curves. ...
Context 7
... pipe and the wrap materials are modeled with a number of finite elements through the thickness with no special assumption on the strain distribution. As can be seen from Fig.7 -11, the analytical and the finite-element results are rather close which support the adopted assumption. On the other hand, as stated in Section 2, the relative error from the constant hoop strain assumption has the order of thickness to diameter ratio. ...
Similar publications
Conventional pipeline integrity solutions quantify the defect geometry in a pipeline wall, relying, for example on the identification of a defect category (crack, or corrosion) and its size (wall thickness loss). However, the most important dimension for integrity decision-making concerns the underlying quantity of stress. Defect geometry is often...
Citations
... Table 1 lists the thermal and mechanical parameters of steel Q345 at different temperatures (Cao et al., 2019;Cui et al., 2018). As shown in Figure 17, the bilinear isotropic hardening (BISO) material model of steel Q345 is used in the thermal-structural analysis for the welding process (Trifonov & Cherniy, 2014). In the figure, r and e represent stress and strain, respectively. ...
Fatigue cracks were found at the diaphragm cutouts in the orthotropic steel deck (OSD) of a self-anchored suspension bridge while the in-service time of the bridge was less than 10 years. The causes of fatigue cracks of the diaphragm cutout are investigated in this study. The fatigue cracks initiated from the intersections of the arc curves and the straight lines, which form the geometrical discontinuity to the cutout edge. The in situ monitoring and finite element analysis under fatigue load model indicate that the cracking region in the cutout is in bidirectional compression. However, the thermal-structural analysis and tests show that the rib-to-diaphragm welding process produces high tension residual stress at the cracking points of the cutouts. The cutouts are under tension-compression cyclic loading because of the coupled stress, which is derived from the vehicle-induced stress and the welding residual stress. The results show that the strain energy method can present a reasonable fatigue life estimation for the diaphragm cutouts with full consideration of the residual stress.
... Based on the theory of small elastoplastic deformations, 26 the expressions of the relationship between the stress and the strain components in longitudinal and circumferential directions are as follows ...
... It is estimated that σ 1w < 0.005 σ 1s and σ 1w < 0.05 σ 2w . 26 As a result, reasonably, we neglect σ 1w to achieve a more convenient presentation for the failure pressure. Under the condition σ 1w ¼ 0, equation (11) becomes ...
While around 60% of pipelines transmitting oil and gas worldwide experience corrosion and metal loss, the composite repair technique has become a popular option developed in recent decades. Employing a theoretical methodology, this study deals with corroded metallic pipes repaired by composite repair systems such that the focus is the impact of elastoplastic deformations on the failure pressure. In this methodology, the elastoplastic strains are taken into account by employing the bilinear isotropic hardening plastic flow theory with the von Mises yield criterion. Three modes are recognized based on the region where failure occurs, and the results are presented. The findings revealed that when the failure happens in the defect region, the proposed formula estimates the failure pressure more accurately than when it occurs either far from the defect or in the composite sleeve. Moreover, studying the bonding strength between the pipe, infill material, and composite patch shows that the interface bonding strength between the pipe and the polymer filler plays a more significant role than the interface bonding strength between the polymer filler and the composite repair. The results of this study can assist maintenance engineers in better evaluating the reliability of composite repaired pipelines.
... The relations based on the deformation theory of plasticity [1,2,5] or Prandtl-Reuss flow rule with isotropic hardening [6,7] are mostly used in many publications. The application of these mentioned approaches does not allow to adequately describe the unloading and repeated loading of pressure vessel type 3. ...
... l tmax -the length of the transition section of the horizontal corner pipe section under the design temperature and the installation temperature difference, m -the angle between the slope and the water level, rad To set l 1 and l 2 be the lengths of the two arms of the elbow, and l c1 and l c2 are the calculated arm lengths of the elbow, then the average calculated arm length l cm is calculated by the formula (12): 2 c2 c1 cm l l l (12) When l 1 ≥l 2 ≥l tmax , l c1 =l c2 =l tmax When l 1 ≥l tmax >l 2 , l c1 =l tmax , l c2 =l 2 When l tmax >l 1 ≥l 2 , l c1 =l 1 , l c2 =l 2 (3)Hoop stress generated by bending moment The maximum hoop stress under bending moment is calculated according to formula (13), formula (14), formula (15), and formula (16). ...
The landform of the buried long-distance pipeline is complex and variable, especially in case of mountainous areas, the forces acting on the pipeline is not uniform. We make a calculation on how the gravity of pipeline and fluid in pipeline affects the stress in the bend connected to the front end of the pipeline, and make an analysis of how pipeline parameters and soil parameters affects the stress. We make a stress calculation on the bend with the method of the elastic bending method, and make an analysis of how diameter, thickness of pipeline and angle of slope affect the result of the calculation.
... The aramid fiber reinforced layer is modeled by composite material lamination in the finite element model. The commonly used Mises yield criterion is no longer applicable to judge the failure of composite materials, so that we should use the failure criteria in composite mechanics [14], the commonly used failure criterion are shown as below： Maximum stress failure criterion: ...
Reinforced thermoplastic pipe (RTP) is used in the oil and gas industry for its good flexibility, corrosion resistance and wear resistance, especially in offshore oil and gas production process. However, they are subject to internal pressure, external pressure and tension loads that are important aspects affecting the integrity and security of the flexible pipe. Their reinforced layers are designed for bearing internal pressure and tension. In this paper, the mechanical behaviors of reinforced thermoplastic pipe with 3 layers, where the reinforced layer is aramid fiber braid layers, is investigated by numerical methods. The internal pressure burst test of reinforced thermoplastic pipes was carried out to determine the burst internal pressure and failure behaviors of RTP. A finite element model that considers the material nonlinearity as well as the friction interactions between layers was created using ABAQUS. The mechanical behavior of reinforced flexible pipe subjected to internal pressure and tension load as well as its failure model was investigated in detail. Effects of the braided angle of aramid fiber braid layers were elucidated. This study can be referenced for the applications of reinforced thermoplastic pipe in marine oil and gas production.
... The aramid fiber reinforced layer is modeled by composite material lamination in the finite element model. The commonly used Mises yield criterion is no longer applicable to judge the failure of composite materials, so that we should use the failure criteria in composite mechanics [14], the commonly used failure criterion are shown as below： Maximum stress failure criterion: ...
... The putty acts as load transfer medium between steel pipe and composite wrap. Usage of composite wrap together will putty for repairing damaged pipes have been done for years because it is capable to restrain the high pressure of the pipeline from yield (Ma et al., 2011;Trifonov and Cherniy, 2014;Shamsuddoha et. al., 2016). ...
Underground pipelines are the most preferable way to transport oil and gas over a long distance. These steel pipelines often suffered from several deteriorations including corrosion. Corrosion causes the outer lining of a pipeline to thin and subsequently reducing pipeline strength. In order to prevent this loss of strength, repair is required. Composite wrap repair is a technique that can be used to repair damage pipeline. Composite wrap repair consist of Fibre Reinforced Polymer (FRP) composite wrap and putty as infill material to restore the strength of a damaged steel pipe. Recently, there is tendency in reducing the usage of composite wrapping layer due to several reasons. Ultimately, it is hoped that one day the repair can be done without composite wrapping. Thus, the purpose of this research is to explore the potential of using putty alone as a repair material in repairing corroded pipeline without composite wrap via finite element analysis. Difference geometrical defects that simulating external corrosion were investigated to study the influence of defect sizes towards the burst pressure of corroded pipeline. Two infill materials which both have difference mechanical properties are used in this research to investigate their influence towards the performance of the repaired pipes. Finite element analysis has been conducted to determine the behaviour of the defected pipeline with a patch of the infill covered the defected area. The analysis was conducted for three defect sizes: 100mm x 100mm, 75mm x 150mm, and 25mm x 150mm for both putties. It was found that the narrow defect of the pipeline causing the pipe to burst at lower pressure as compared to defect that have the same dimension area for both of the infill material. This may due to high stress concentration at small area of the defect. Furthermore, it was also revealed that infill with higher ultimate tensile strength able to withstand higher pressure. The finding of the research shows that by using appropriate infill, there are potential to increase the burst pressure by about 5%. The findings of this research can serve as stepping stone to study the feasibility of repairing damaged pipeline using putty alone.
... The application of composite wraps for strengthening of relatively long pipeline segments was first analyzed in the paper [32]. A new analytical model for stress-strain analysis of a wrapped pipe under the action of internal pressure and temperature was developed and verified against test results obtained for a pipe with elliptical end plugs (pressure vessel). ...
... It was shown that composite wrappings can be effectively used as a regular reinforcement on relatively long pipeline segments subjected to the internal pressure and temperature loads. In [32] it was suggested that the application of composite wraps can be considered as a strengthening measure for pipelines crossing active tectonic faults or laid in other harsh environmental conditions. ...
... Such materials are typical for applications considered in the present paper. The elastic moduli in axial and hoop directions in Table 2 are also close to the experimentally determined value (20.4 GPa) of the elastic modulus in the hoop direction for the composite wrap in the paper [32]. ...
In the paper, the efficiency of strengthening of a buried steel pipeline with a composite wrap subjected to an active faults action is analyzed. A three-dimensional numerical model of the pipeline is developed. The pipeline is considered as an elastoplastic steel shell, while the composite wrap is represented as an orthotropic elastic shell. The model takes into account elastoplastic behavior of soil, contact interaction between the soil and the pipe, large inelastic strains, distortion of the pipeline cross-section and local buckling formation. A normal-slip fault kinematics with large fault offsets is considered in numerical modeling. The effect of the wrap thickness, length, and position relative to the fault plane is analyzed.
