Finite Element Models for the Prediction of the Failure Pressure of Pipelines With Long Corrosion Defects

2002 ◽  
Author(s):  
Dauro Braga Noronha ◽  
Adilson Carvalho Benjamin ◽  
Edmundo Queiroz de Andrade
Keyword(s):  
Finite Element ◽  
Shell Model ◽  
Solid Model ◽  
Second Phase ◽  
Finite Element Models ◽  
Flat Bottom ◽  
Failure Pressure ◽  
Pipe Burst ◽  
Corrosion Defects ◽  
Tubular Specimens

PETROBRAS is conducting a research project with the purpose of investigating the behavior of pipelines with long corrosion defects. In the first phase of this project a database containing the results of nine burst tests of tubular specimens with flat bottom defects was generated. The second phase of the project aims at appraising the performance of two different finite element models: a shell model and a solid model. This paper describes the application of these models in the analysis of four tubular specimens of the PETROBRAS database. The failure pressures predicted by the two types of finite element models are compared with the burst pressures measured in the laboratory tests. Also a comparison between the results obtained by these models is presented. It is concluded that the solid model is more accurate than the shell model, but both models proved to be capable of simulating the corroded pipe burst tests adequately.

Predicting the Failure Pressure of Pipelines Containing Nonuniform Depth Corrosion Defects Using the Finite Element Method

2003 ◽  
Author(s):  
Adilson Carvalho Benjamin ◽  
Edmundo Queiroz de Andrade
Keyword(s):  
Finite Element ◽  
Shell Model ◽  
Failure Behavior ◽  
Solid Model ◽  
Second Phase ◽  
The Finite Element Method ◽  
Spark Erosion ◽  
Corrosion Defects ◽  
Tubular Specimens ◽  
Deep Defects

PETROBRAS is conducting a research project with the purpose of investigating the behavior of pipelines containing long nonuniform depth corrosion defects. In the first phase of this project, burst tests of two tubular specimens were carried out. Each of the two specimens had one external nonuniform depth corrosion defect, machined using spark erosion. This defect consists of two short and deep defects within a long and shallow corrosion patch, longitudinally oriented. The second phase of the project aims at appraising the performance of two different finite element models: a shell model and a solid model. This paper describes the application of these models in the analysis of the two tubular specimens containing a long nonuniform depth defect that were tested in the first phase of this project. The failure pressures predicted by the two types of FE models are compared with the burst pressures measured in the laboratory tests. Also a comparison between the results obtained by these models is presented. It is concluded that the solid model is more accurate than the shell model, but both models proved to be capable of simulating the failure behavior of defects constituted by a long and shallow corrosion patch with deep defects over it.

Finite Element Modeling of the Failure Behavior of Pipelines Containing Interacting Corrosion Defects

2006 ◽  
Author(s):  
Edmundo Q. de Andrade ◽  
Adilson C. Benjamin ◽  
Paulo R. S. Machado ◽  
Leonardo C. Pereira ◽  
Breno P. Jacob ◽  
...  
Keyword(s):  
Finite Element ◽  
Finite Element Modeling ◽  
Large Strains ◽  
Failure Behavior ◽  
Finite Element Models ◽  
Contour Plots ◽  
X80 Steel ◽  
Corrosion Defects ◽  
Tubular Specimens ◽  
Outside Diameter

This paper describes the application of solid finite element models in the analysis of five tubular specimens containing interacting corrosion defects. Each of these specimens has been submitted to hydrotest up to failure as part of a previous research project. The specimens were cut from longitudinal welded tubes made of API 5L X80 steel with a nominal outside diameter of 457.2 mm (18 in) and a nominal wall thickness of 7.93 mm (0.312 in). The analyses accounted for large strains and displacements, stress-stiffening and material nonlinearity. The failure pressures predicted by the solid finite element models are compared with the failure pressures of these specimens measured in the laboratory burst tests carried out previously. Also the failure behavior of each specimen is described and illustrated by contour plots of stresses.

Experimental and numerical studies on failure and energy absorption of composite thin-walled square tubes under quasi-static compression loading

2020 ◽  
Vol 21 (6) ◽  
pp. 623-634
Author(s):  
Haolei Mou ◽  
Zhenyu Feng ◽  
Jiang Xie ◽  
Jun Zou ◽  
Kun Zhou
Keyword(s):  
Finite Element ◽  
Shell Model ◽  
Energy Absorption ◽  
Failure Mode ◽  
Failure Criterion ◽  
Finite Element Models ◽  
Static Compression ◽  
Compression Loading ◽  
Thin Walled ◽  
Simulation Results

AbstractTo analysis the failure and energy absorption of carbon fiber reinforced polymer (CFRP) thin-walled square tube, the quasi-static axial compression loading tests are conducted for [±45]3s square tube, and the square tube after test is scanned to further investigate the failure mechanism. Three different finite element models, i.e. single-layer shell model, multi-layer shell model and stacked shell mode, are developed by using the Puck 2000 matrix failure criterion and Yamada Sun fiber failure criterion, and three models are verified and compared according to the experimental energy absorption metrics. The experimental and simulation results show that the failure mode of [±45]3s square tube is the local buckling failure mode, and the energy are absorbed mainly by intralaminar and interlaminar delamination, fiber elastic deformation, fiber debonding and fracture, matrix deformation cracking and longitudinal crack propagation. Three different finite element models can reproduce the collapse behaviours of [±45]3s square tube to some extent, but the stacked shell model can better reproduce the failure mode, and the difference of specific energy absorption (SEA) is minimum, which shows the numerical simulation results are in better agreement with the test results.

Failure Pressure Prediction of Cracks in Corrosion Defects Using XFEM

2020 ◽  
Author(s):  
Xinfang Zhang ◽  
Allan Okodi ◽  
Leichuan Tan ◽  
Juliana Leung ◽  
Samer Adeeb
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Extended Finite Element Method ◽  
Crack Depth ◽  
Average Error ◽  
Extended Finite Element ◽  
Defect Depth ◽  
Failure Pressure ◽  
Corrosion Defects ◽  
Element Method

Abstract Coating and cathodic protection degradation can result in the generation of several types of flaws in pipelines. With the increasing number of aging pipelines, such defects can constitute serious concerns for pipeline integrity. When flaws are detected in pipelines, it is extremely important to have an accurate assessment of the associated failure pressure, which would inform the appropriate remediation decision of repairing or replacing the defected pipelines in a timely manner. Cracks-in-corrosion (CIC) represent a class of defect, for which there are no agreed upon method of assessment, with no existing analytical or numerical models to predict their failure pressures. This paper aims to create a set of validated numerical finite element analysis models that are suitable for accurately predicting the failure pressure of 3D cracks-in-corrosion defects using the eXtended Finite Element Method (XFEM) technique. The XFEM for this study was performed using the commercially available software package, ABAQUS Version 6.19. Five burst tests of API 5L X60 specimens with different defect depths (varying from 52% to 66%) that are available in the literature were used to calibrate the XFEM damage parameters (the maximum principal strain and the fracture energy). These parameters were varied until a reasonable match between the numerical results and the experimental measurements was achieved. Symmetry was used to reduce the computation time. A longitudinally oriented CIC defect was placed at the exterior of the pipe. The profile of the corroded area was assumed to be semi-elliptical. The pressure was monotonically increased in the XFEM model until the crack or damage reached the inner surface of the pipe. The results showed that the extended finite element predictions were in good agreement with the experimental data, with an average error of 5.87%, which was less conservative than the reported finite element method predictions with an average error of 17.4%. Six more CIC models with the same pipe dimension but different crack depths were constructed, in order to investigate the relationship between crack depth and the failure pressure. It was found that the failure pressure decreased with increasing crack depth; when the crack depth exceeded 75% of the total defect depth, the CIC defect could be treated as crack-only defects, since the failure pressure for the CIC model approaches that for the crack-only model for ratios of the crack depth to the total defect depth of 0.75 and 1. The versatility of several existing analytical methods (RSTRENG, LPC and CorLAS) in predicting the failure pressure was also discussed. For the corrosion-only defects, the LPC method predicted the closest failure pressure to that obtained using XFEM (3.5% difference). CorLAS method provided accurate results for crack-only defects with 7% difference. The extended finite element method (XFEM) was found to be very effective in predicting the failure pressure. In addition, compared to the traditional Finite Element Method (FEM) which requires extremely fine meshes and is impractical in modelling a moving crack, the XFEM is computationally efficient while providing accurate predictions.

Numerical Analysis of API 5L X42 and X52 Vintage Pipes with Cracks in Corrosion Defects Using Extended Finite Element Method

2021 ◽  
Author(s):  
Xinfang Zhang ◽  
Meng Lin ◽  
Allan Okodi ◽  
Leichuan Tan ◽  
Juliana Leung ◽  
...  
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Extended Finite Element Method ◽  
Pipe Wall ◽  
Crack Depth ◽  
Initial Crack ◽  
Extended Finite Element ◽  
Failure Pressure ◽  
Corrosion Defects ◽  
Element Method

Abstract Cracks and corrosion in pipelines can occur simultaneously, representing a hybrid defect known as cracks in corrosion (CIC), which is often difficult to model using the available assessment codes or methods. As a result, detailed modeling of CIC has not been studied extensively. In this study, the extended finite element method (XFEM) has been applied to predict the failure pressures of CIC defects in API 5L Grade X42 and X52 pipes. The pipes were only subjected to internal pressure and the XFEM models were validated using full-scale burst tests available in the literature. Several CIC models with constant total defect depths (55%, and 60% of wall thickness) were constructed to investigate the effect of the initial crack depth on the failure pressure. The failure criterion was defined when wall penetration occurred due to crack growth, i.e., the instance the crack reached the innermost element of the pipe wall mesh. It was observed that for shorter cracks, the failure pressure decreased with the increase of the initial crack depth. The results indicated that the CIC defect could be treated as crack-only defects when the initial crack depth exceeded 50% of the total defect depth. However, for longer cracks, the initial crack depth was found to have a negligible effect on the failure pressure, implying that the CIC defect could be treated as either a crack or a corrosion utilizing the available assessment methods.

scholarly journals Failure Pressure Prediction of a Corroded Pipeline with Longitudinally Interacting Corrosion Defects Subjected to Combined Loadings Using FEM and ANN

2021 ◽  
Vol 9 (3) ◽  
pp. 281
Author(s):  
Michael Lo ◽  
Saravanan Karuppanan ◽  
Mark Ovinis
Keyword(s):  
Neural Network ◽  
Finite Element ◽  
Training Data ◽  
Percentage Error ◽  
Learning Tools ◽  
Ann Model ◽  
Element Analysis ◽  
Failure Pressure ◽  
Corrosion Defects ◽  
Artificial Neural Network Ann

Machine learning tools are increasingly adopted in various industries because of their excellent predictive capability, with high precision and high accuracy. In this work, analytical equations to predict the failure pressure of a corroded pipeline with longitudinally interacting corrosion defects subjected to combined loads of internal pressure and longitudinal compressive stress were derived, based on an artificial neural network (ANN) model trained with data obtained from the finite element method (FEM). The FEM was validated against full-scale burst tests and subsequently used to simulate the failure of a pipeline with various corrosion geometric parameters and loadings. The results from the finite element analysis (FEA) were also compared with the Det Norske Veritas (DNV-RP-F101) method. The ANN model was developed based on the training data from FEA and its performance was evaluated after the model was trained. Analytical equations to predict the failure pressure were derived based on the weights and biases of the trained neural network. The equations have a good correlation value, with an R2 of 0.9921, with the percentage error ranging from −9.39% to 4.63%, when compared with FEA results.

Effects of depth in external and internal corrosion defects on failure pressure predictions of oil and gas pipelines using finite element models

2020 ◽  
Vol 23 (14) ◽  
pp. 3128-3139
Author(s):  
Selene Capula Colindres ◽  
Gerardo Terán Méndez ◽  
Julio Cesar Velázquez ◽  
Roman Cabrera-Sierra ◽  
Daniel Angeles-Herrera
Keyword(s):  
Finite Element ◽  
Oil And Gas ◽  
Effective Area ◽  
The Finite Element Method ◽  
Internal Corrosion ◽  
Failure Pressure ◽  
Corrosion Defect ◽  
Corrosion Defects ◽  
Pipeline Failure ◽  
First Time

This study presents, for the first time, the mechanical behavior of API 5L pipeline steels X42, X52, X60, X70, X80, and X100 with external and internal corrosion defects as well as a combination of both defects that has been named external–internal corrosion defects. The conventional methods to predict failure pressure in corroded pipes, such as B31G, RSTRENG-1, SHELL, DNV-99, PCORRC, and FITNET FFS, have also been discussed in this article. In addition, pipeline failure pressure has been estimated using the finite element method, considering that it is the best approach to calculate actual failure pressure. The external and internal corrosion defect investigated in this research manifests as a rectangular shape with spherical ends at the edges. When the external–internal corrosion defect appears, failure pressure data decrease dramatically because of severe damage. This is due to the decrease in the ligament (effective area) caused by the corrosion defect. To have a good estimation of the pipeline failure pressure with an external–internal corrosion defect, DNV-99 method can be used with acceptable certainty.

Physical Level Simulation of PolyMUMPs Based Monolithic Tri-Axis MEMS Capacitive Accelerometer Using FEM Technique

2011 ◽  
Vol 403-408 ◽  
pp. 4625-4632
Author(s):  
M.S. Khan ◽  
A. Iqbal ◽  
S.A. Bazaz ◽  
M. Abid
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Excellent Agreement ◽  
High Sensitivity ◽  
Solid Model ◽  
Finite Element Models ◽  
Capacitive Accelerometer ◽  
Physical Level ◽  
3D Layout ◽  
2D Model

In this paper, we present the design verification of PolyMUMPs based monolithic tri-axis MEMS capacitive accelerometer. The physical level simulation has been done using the analyzer module of Coventorware to verify the performance of the three-axis accelerometer using Finite Element Method (FEM) and compared with the optimized results obtained in ANSYS and in MATLAB. The 2D model is created in the designer module of Coventorware. The 3D layout is generated in the preprocessor module and mesh is created on solid model. Proposed three axis accelerometer has three individual single axis accelerometers, integrated on a single substrate uniformly centered on single axis. Low mechanical noise, high sensitivity and sense capacitance have been measured for all axes individually and presented. The results obtained from both the analytical and finite element models are found to be in excellent agreement.

Remaining Collapse Capacity of Corroded Pipelines

2011 ◽  
Author(s):  
Qishi Chen ◽  
Mark Marley ◽  
Joe Zhou
Keyword(s):  
Experimental Data ◽  
Finite Element ◽  
Wall Thickness ◽  
Numerical Models ◽  
Substantial Reduction ◽  
Assessment Method ◽  
Full Scale ◽  
Finite Element Models ◽  
Pipe Material ◽  
Corrosion Defects

It is known that, for given pipe material and diameter, collapse capacity of a plain pipe subjected to external pressure is proportional to the second or third power of wall thickness. In lieu of sophisticated numerical models and experimental data, conservative approaches such as those in which thickness losses at corrosion defects are extended to the entire circumference have been adopted in practices to assess the collapse resistance of corroded pipes. This reduced wall thickness is then used in the design equation of plain pipe to predict remaining collapse capacity. Such conservative assumptions result in substantial reduction of collapse capacity for pipelines with localized corrosion defects. During the course of a multiple-year PRCI research project, results of full-scale collapse tests and three-dimensional finite element analysis demonstrated that the reduction of collapse capacity was less than 10% for defects with a depth of 50% wall thickness, an axial length of one diameter and a circumferential width of half a diameter. These findings illustrated that the actual collapse capacity of corroded pipes is significantly higher than that estimated according to the conservative assumptions. This paper presents the development of a reliability-based, practical assessment method that allows remaining collapse capacity of corroded pipelines be determined based on defect size data obtained from in-line inspections. Work involved included characterization of corrosion defects, full-scale collapse tests, validation of finite element models using experimental data, analysis of parametric cases using finite element models, development of empirical equation based on experimental and numerical results, and calibration of partial safety factors which addressed the uncertainties associated with model error, load variation, and sizing inaccuracy of corrosion defects. Practical implications of the proposed assessment method were evaluated based on selected examples.

Micro-CT Based Imaging and Numerical Analysis of Bone Healing

2014 ◽  
Vol 606 ◽  
pp. 141-144 ◽  
Author(s):  
Kamil Řehák ◽  
Bjørn Skallerud
Keyword(s):  
Finite Element ◽  
Numerical Analysis ◽  
Fracture Healing ◽  
Threshold Value ◽  
Second Phase ◽  
Finite Element Models ◽  
Micro Ct ◽  
Threshold Values ◽  
Tissue Properties ◽  
Load Carrying

During distraction osteogenesis (bone lengthening) one phase is lengthening and a second phase is consolidation (fixed length, bone maturation). In this second phase of fracture healing, the callus consists of several tissue types. The response of callus bone to mechanical loading can determine the progress of treatment. The mechanical strain distribution could provide additional information of fracture healing in the same way as for bone remodeling. The architecture and tissue properties significantly affect the strength of the whole callus bone. This article focuses on imaging and numerical analysis of bone fracture healing based on input information obtained from micro-CT scans. The objective of this study is to focus on how different stiffness threshold values affect the load carrying tissue architecture and how this further influences the strain distributions within the callus. Finite element simulations are employed to investigate this. A rabbit tibia fracture callus was micro-CT scanned 30 days after osteotomy using an isotropic voxel size of 20 μm. Four computational models were created with different pixel threshold values to cover a wide range of callus tissue properties, with the purpose of finding an optimal threshold value. Optimal means here a finite element model which is computationally feasible and still contains the main load carrying tissue.The values of bone volume/total callus volume (BV/TV), bone area/total callus area (BA/TA), trabecular thickness, structure model index (SMI) were quantified to compare the differences between models. All finite element models were axially loaded to investigate the influence of threshold value on the callus reaction and influence of including the soft tissue. The BV/TV and BA/TA values indicate that for a certain threshold level, finite element models are suitable. However, a too high threshold leads to invalid finite element models. The finite element method (FEM) could be useful tool in understanding of fracture healing process.

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