Axial Compressive Loading Capacity of Pressurized Energy Pipeline With Corrosion Defects

2020 ◽  
Author(s):  
Bing Liu ◽  
Xiao Tan ◽  
Dinaer Bolati ◽  
Hang An ◽  
Jinxu Jiang
Keyword(s):  
Internal Pressure ◽  
Compressive Strain ◽  
Compressive Loading ◽  
Local Buckling ◽  
Simulation Method ◽  
Support Vector ◽  
Loading Capacity ◽  
Strain Capacity ◽  
Corrosion Defect ◽  
Corrosion Defects

Abstract Corrosion defects are dreadfully damaging to the stability of pipelines. Using the finite element (FE) simulation method, a model of API 5L X65 steel pipeline is established in this work to study its buckling behavior subjected to axial compressive loading. The local buckling state of the pipe at the ultimate axial compressive capacity was captured. Compared with the global compressive strain capacity (CSCglobal), the local compressive strain capacity (CSClocal) is more conservative. Extensive parametric analysis, including approximately 115 FE cases, was conducted to study the influence of the corrosion defect sizes and internal pressure on the corroded pipe’s compressive loading capacity (CLC) and CSC. Results show that the enlarged size of the corrosion defect decreases both the CLC and the CSC of the pipeline, but the CLC almost keeps unchanged as the length of corrosion defects increases. The CLC decreases with the increase of the length of corrosion defects when the length is less than 1.5Dt and greater than 0.7Dt. The CSC drops significantly until the length of the corrosion defect reached 1.8Dt. The deeper the corrosion defect, the smaller the CLC and the CSC. An increase in the width of corrosion defects tends to correspond to a decrease in the CLC and the CSC. With the increase of internal pressure, the CSC of the pipe gets greater while the CLC gets smaller. Based on the 115 FE results, a machine learning model based on support vector regression theory was developed to predict the pipe’s CSC. The regression coefficient between SVR predicted value and FEM actual value is 98.87%, which proves that the SVR model can predict the CSC with high accuracy and efficiency.

Compressive Strain Limit of Aged API-X100 Linepipe

2009 ◽  
Author(s):  
Woo Yeon Cho ◽  
Dong-Han Seo ◽  
Jang-Yong Yoo
Keyword(s):  
Finite Element ◽  
Yield Point ◽  
Numerical Solutions ◽  
Numerical Models ◽  
Compressive Strain ◽  
Local Buckling ◽  
Strain Curve ◽  
Element Model ◽  
Stress Strain ◽  
Strain Capacity

In compressive strain capacity, high deformable linepipe steel, which is able to delay or evade local buckling, is needed. The objective of this paper is to present the results of an experimental and a finite-element investigation into the behavior of pipes subjected to bending behavior of aged API-X100 linepipe. The comparative behavior of aged and non aged specimens was recorded. The Results from numerical models are checked against the observations in the testing program and the ability of numerical solutions to predict pipe compressive strain capacity, curvatures, and buckling modes is improved. A finite-element model was developed using the finite-element simulator ABAQUS to predict the local buckling behavior of pipes. The input stress-strain relations of the material were discussed using the indexed yield point elongations. The comparison between the results of yield point elongation type material and those of material of smooth stress-strain curve near yield was done.

Strain Capacity of X100 High-Strain Linepipe for Strain-Based Design Application

2008 ◽  
Author(s):  
Satoshi Igi ◽  
Joe Kondo ◽  
Nobuhisa Suzuki ◽  
Joe Zhou ◽  
Da-Ming Duan
Keyword(s):  
Tensile Strain ◽  
Large Scale ◽  
High Strain ◽  
Compressive Strain ◽  
Local Buckling ◽  
Ground Movement ◽  
Frozen Ground ◽  
Long Distance ◽  
Element Analysis ◽  
Strain Capacity

In recent years, several natural gas pipeline projects have been planned for permafrost regions. Pipelines laid in such areas are subjected to large plastic deformation as a result of ground movement due to repeated thawing and freezing of the frozen ground. Likewise, in pipeline design methods, research on application of strain-based design as an alternative to the conventional stress-based design method has begun. Much effort has been devoted to the application of strain-based design to high strength linepipe materials. In order to verify the applicability of high-strain X100 linepipe to long distance transmission, a large-scale X100 pipeline was constructed using linepipe with an OD of 42″ and wall thickness of 14.3mm. This paper presents the results of experiments and Finite Element Analysis (FEA) focusing on the strain capacity of high-strain X100 linepipes. The critical compressive strain of X100 high-strain linepipes is discussed based on the results of FEA taking into account geometric imperfections. The critical tensile strain for high-strain X100 pipelines is obtained based on a curved wide plate (CWP) tensile test using specimens taken from girth welded joints. Specifically, the effect of external coating treatment on the strain capacity of X100 high-strain linepipe is investigated. The strain capacity of the 42″ X100 pipeline is considered by comparing the tensile strain limit obtained from girth weld fracture and critical compressive strain which occurs in local buckling under pure bending deformation.

Integrity of Pipeline in Area of Mine Subsidence

2012 ◽  
Author(s):  
Fan Zhang ◽  
Ming Liu ◽  
Yong-Yi Wang ◽  
Zhifeng Yu ◽  
Lei Tong
Keyword(s):  
Compressive Strain ◽  
Local Buckling ◽  
Base Material ◽  
Companion Paper ◽  
Parametric Models ◽  
Ground Subsidence ◽  
Strain Capacity ◽  
Weld Properties ◽  
Bending Loads ◽  
Girth Welds

Ground subsidence can threaten the integrity of buried pipelines in areas with prior and on-going mining activities. The integrity can be assessed by comparing the strain demand and the strain capacity. The Tensile Strain Capacity (TSC) of the pipeline is dominated by the girth welds due to their relatively inferior property in comparison to the base pipe materials. Parametric models developed at CRES for US DOT and PRCI allow the evaluation of girth welds TSC based on pipe dimensions, base material and weld properties and flaw size. The local buckling of the pipeline under compressive or bending loads determines the Compressive Strain Capacity (CSC). Three existing standards are used to evaluate CSC, including DNV OS-F101, CSA Z662 and API RP 1111. The strain demand analysis of the pipeline under multiple subsidence scenarios is presented in a companion paper. The strain demand is compared with TSC and CSC separately to evaluate the pipeline integrity. The use of CRES TSC models for selecting a variety of design and material parameters to improve TSC is illustrated.

Application of Compressive Strain Capacity Models to Multiple Grades of Pipelines

2014 ◽  
Author(s):  
Zhenyong Zhang ◽  
Zhifeng Yu ◽  
Ming Liu ◽  
Kunal Kotian ◽  
Fan Zhang
Keyword(s):  
Compressive Strain ◽  
Local Buckling ◽  
High Strength ◽  
Experimental Tests ◽  
Test Results ◽  
Longitudinal Compression ◽  
Experimental Database ◽  
Strain Capacity ◽  
Testing Data ◽  
Experimental And Numerical Modeling

Local buckling due to excessive compressive strain generated by bending and/or longitudinal compression is one of the main threats to pipeline integrity. Strain-based design and assessment (SBDA) methods have been developed for designing and maintaining pipelines under high longitudinal strain. In SBDA, the resistance to local buckling is often measured by compressive strain capacity. Extensive work has been performed on the compressive strain capacity of pipes through both experimental and numerical modeling. Models for calculating the compressive strain capacity have been developed over many decades. Some earlier models were developed using experimental test data of low strength linepipes. High strength linepipes are being increasingly used for the construction of new pipelines. The applicability of the existing models to modern high strength pipelines needs to be evaluated. In this paper, selected compressive strain capacity models were reviewed and evaluated. An experimental database of 61 experimental tests from public-domain publications was created. Approximately 34% of the testing data are from high strength pipes (primarily X80). The calculated compressive strain capacity from the selected models was compared with the test results. The performance of the selected models was evaluated and the applicability of the models to the linepipes of different strengths was discussed.

Refined Modeling Processes and Compressive Strain Capacity Models

2014 ◽  
Author(s):  
Ming Liu ◽  
Fan Zhang ◽  
Kunal Kotian ◽  
Steve Nanney
Keyword(s):  
Experimental Data ◽  
Numerical Modeling ◽  
Compressive Strain ◽  
Local Buckling ◽  
Modeling Processes ◽  
Safety Factors ◽  
Longitudinal Compression ◽  
Comprehensive Review ◽  
Strain Capacity ◽  
Sensitivity Studies

Local buckling generated by excessive bending and/or longitudinal compression is one of the main threats to pipeline integrity. The resistance to local buckling is usually measured by compressive strain capacity (CSC). Extensive work has been performed on the CSC of pipes through both experiments and numerical modeling. Many CSC models have been developed to compute the CSC. The comparison of the existing CSC models often shows (1) large differences in recognized input parameters and their applicable ranges, (2) large differences in computed CSC, especially for pressurized conditions, (3) large differences in recommended safety factors; and (4) inconsistent trends on model conservatism. Refined compressive strain models were developed recently. The development involves comprehensive review of existing CSC models, selecting modeling processes that represent field conditions, sensitivity studies on parameters affecting the CSC, and the model evaluation against experimental data. In this paper, the refined compressive strain models and the key improvement to the modeling processes are summarized.

Compressive and Tensile Strain Capacities of 48” X80 Line Pipes

2012 ◽  
Author(s):  
Hisakazu Tajika ◽  
Satoshi Igi ◽  
Takahiro Sakimoto ◽  
Shigeru Endo ◽  
Seishi Tsuyama ◽  
...  
Keyword(s):  
Tensile Strain ◽  
High Strain ◽  
Uniform Elongation ◽  
Compressive Strain ◽  
Experimental Studies ◽  
Local Buckling ◽  
Base Material ◽  
Pipe Surface ◽  
Strain Capacity ◽  
Strain Limit

This paper presents the results of experimental studies focused on the strain capacity of X80 linepipe. A full-scale bending tests of X80 grade, 48″ high-strain linepipes pressurized to 60% SMYS were conducted to investigate the compressive strain limit and tensile strain limit. The tensile properties Y/T ratios and uniform elongation of the pipes had variety. Three of four pipes are high strain pipes and these Y/T ratios are intentionally low with manufacturing method. One of these high-strain pipe was girth welded in its longitudinal center to investigate the effect of girth weld to strain capacity. The other was set as a conventional pipe that have higher Y/T ratio to make comparative study. The compressive strain limit focused on the critical strain at the formation of local buckling on the compression side of bending. After pipe reaches its endurable maximum moment, one large developed wrinkle and some small wrinkles on the pipe surface during bending deformation were captured relatively well from observation and strain distribution measurement. The tensile strain limit is discussed from the viewpoint of competition of two fracture phenomena: ductile crack initiation/propagation from an artificial notch at the HAZ of the girth weld, and strain concentration and rupture in the base material at the tension (opposite) side of the local buckling position.

scholarly journals Safety assessment of corrosion-defective natural gas pipeline under ground overload based on FEM

2021 ◽  
Vol 37 (1) ◽  
Author(s):  
T, Zheng ◽  
Z. Liang ◽  
J. Zhang ◽  
S. Tang ◽  
X. Xiao
Keyword(s):  
Internal Pressure ◽  
Young’S Modulus ◽  
Young's Modulus ◽  
Local Stress ◽  
Von Mises Stress ◽  
Stress And Strain ◽  
Failure Pressure ◽  
Corrosion Defect ◽  
Corrosion Defects ◽  
Von Mises

Aiming at the safety problem of the pipeline containing corrosion defects caused by ground overload, a novel method is developed to assess the safety of buried pipelines with corrosion defects and predict the failure pressure. The effects of parameters including internal pressure, ground overload, length of the loading area, corrosion defect depth, buried depth and soil Young’s modulus, are discussed. Ground overload greatly increases the von Mises stress and strain at the corrosion defect location and decreases the internal pressure threshold. The von Mises stress and strain are an obvious nonlinear relationship with internal pressure. The high stress and strain area expand along the diagonal direction of the defect area. The local stress and strain concentration at the corrosion defect increases with the increase of ground overload, length of the loading area and corrosion defect depth, which reduces the failure pressure of the pipeline. Increasing the buried depth and soil Young’s modulus would effectively reduce local stress and strain concentration, and increase the failure pressure of the pipeline. The pipeline settlement displacement increases with the increase of internal pressure, ground overload, length of the loading area, and decreases with the increase of pipeline buried depth and soil Young’s modulus.

Combination of Support Vector Machine and K-Fold cross-validation for prediction of long-term degradation of the compressive strength of marine concrete

2018 ◽  
Vol 1 (1) ◽  
pp. 120-130 ◽  
Author(s):  
Chunxiang Qian ◽  
Wence Kang ◽  
Hao Ling ◽  
Hua Dong ◽  
Chengyao Liang ◽  
...  
Keyword(s):  
Support Vector Machine ◽  
Environmental Factors ◽  
Cross Validation ◽  
Concrete Strength ◽  
Simulation Method ◽  
Support Vector ◽  
Svm Model ◽  
Artificial Neural Network Ann ◽  
Influence Degree ◽  
Fold Cross Validation

Support Vector Machine (SVM) model optimized by K-Fold cross-validation was built to predict and evaluate the degradation of concrete strength in a complicated marine environment. Meanwhile, several mathematical models, such as Artificial Neural Network (ANN) and Decision Tree (DT), were also built and compared with SVM to determine which one could make the most accurate predictions. The material factors and environmental factors that influence the results were considered. The materials factors mainly involved the original concrete strength, the amount of cement replaced by fly ash and slag. The environmental factors consisted of the concentration of Mg2+, SO42-, Cl-, temperature and exposing time. It was concluded from the prediction results that the optimized SVM model appeared to perform better than other models in predicting the concrete strength. Based on SVM model, a simulation method of variables limitation was used to determine the sensitivity of various factors and the influence degree of these factors on the degradation of concrete strength.

Investigation Into Applications of Local Failure Criterion for X70 Pipeline With Corrosion Defect

2018 ◽  
Author(s):  
Ji-Hee Moon ◽  
Nam-Su Huh ◽  
Ki-Seok Kim
Keyword(s):  
Internal Pressure ◽  
Failure Criterion ◽  
Large Scale ◽  
Ductile Failure ◽  
Limit Load ◽  
Local Failure ◽  
Ground Movement ◽  
Freezing And Thawing ◽  
Corrosion Defect ◽  
Longitudinal Length

In this paper, the local failure criterion using stress modified critical strain method based on annex B of API 579 is applied to evaluate the ductile failure of API X70 pipelines with a volumetric corrosion defect. Ductile failure is quantified in terms of strain, representing the tensile strain capacity (TSC) which is commonly used in strain-based assessment for fitness-for-service of pipelines installed in frozen area where large-scale ground movement can arise due to earthquakes, freezing and thawing. Based on the local failure criterion suggested for API X70 steel material, the TSCs of the corroded pipelines are evaluated by using the detailed finite element (FE) analyses. The effects of internal pressure and defect size (such as longitudinal length, circumferential width and depth in the direction of thickness) on TSC of pipelines subjected to axial displacement are systematically investigated. In addition, TSCs based on local failure criterion are compared with those based on net-section limit load. The TSCs from the present FE analyses for various defect geometries and internal pressure can be used to predict ductile failure of corroded pipelines and to build the framework for a strain-based assessment for in-service pipelines.

Remaining Local Buckling Resistance of Corroded Pipelines

2010 ◽  
Author(s):  
Qishi Chen ◽  
Heng Aik Khoo ◽  
Roger Cheng ◽  
Joe Zhou
Keyword(s):  
Finite Element ◽  
Wall Thickness ◽  
Phase 1 ◽  
Compressive Strain ◽  
Research Work ◽  
Local Buckling ◽  
Model Verification ◽  
Metal Loss ◽  
General Corrosion ◽  
Buckling Resistance

This paper describes a multi-year PRCI research program that investigated the local buckling (or wrinkling) of onshore pipelines with metal-loss corrosion. The dependence of local buckling resistance on wall thickness suggests that metal-loss defects will considerably reduce such resistance. Due to the lack of experimental data, overly conservative assumptions such as a uniform wall thickness reduction over the entire pipe circumference based on the defect depth have been used in practice. The objective of this research work was to develop local buckling criteria for pipelines with corrosion defects. The work related to local buckling was carried out in three phases by C-FER and the University of Alberta. The first phase included a comprehensive finite element analysis to evaluate the influence of various corrosion defect features and to rank key parameters. Based on the outcome of Phase 1 work, a test matrix was developed and ten full-scale tests were carried out in Phase 2 to collect data for model verification. In Phase 3, over 150 parametric cases were analyzed using finite element models to develop assessment criteria for maximum moment and compressive strain limit. Each criterion includes a set of partial safety factors that were calibrated to meet target reliabilities selected based on recent research related to pipeline code development. The proposed criteria were applied to in-service pipeline examples with general corrosion features to estimate the remaining load-carrying capacity and to assess the conservatism of current practice.

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