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.

Reelability and Wall Thickness Optimization of HFI Pipeline Against the Sensitivity of Variation in Mismatch Parameters

2017 ◽  
Author(s):  
Dasharatha Achani ◽  
Vladimir Andreev
Keyword(s):  
Wall Thickness ◽  
Steel Strip ◽  
Compressive Strain ◽  
Local Buckling ◽  
Thickness Optimization ◽  
Cold Forming ◽  
Typical Design ◽  
Longitudinal Seam ◽  
Pipe Joint

High frequency Induction welded (HFW/HFI) linepipe is produced by cold forming from steel strip, bent into pipe and longitudinal seam welded. HFW/HFI linepipe has been attractive due to less expensive, improved lead time and tighter wall thickness tolerances and better control of mechanical properties compared to the seamless. Typical design drivers for wall thickness optimization of reeled pipeline are geometric and strength mismatch. HFI pipes gained the attention of reeling contactors because of tighter mismatch tolerances of geometry and strength. However, the limitation of wall thickness in producing the larger diameter pipes needs optimized wall thickness considering the sensitivity of the variation in mismatch properties and stress ratio. The present work is intended to check the capacity of the pipeline against the sensitivity of variation in mismatch parameters. A case study has performed for the reelability of 16” HFW pipe for a selected limiting wall thickness. The different cases of variation in mismatch parameters are considered for the sensitivity check. Finite element (FE) analyses using ABAQUS tool were performed to reel the sections of the pipe joint over the reel hub of the selected installation vessel. The model predictions for axial compressive strain are compared and discussed against the DNV local buckling criterion for displacement control.

Finite Element Analysis on the Failure Behavior of Straight Pipe With Wall Thinning

2004 ◽  
Author(s):  
Ken Inoue ◽  
Koji Takahashi ◽  
Kotoji Ando ◽  
Seok Hwan Ahn ◽  
Ki Woo Nam ◽  
...  
Keyword(s):  
Finite Element ◽  
Failure Modes ◽  
Local Buckling ◽  
Metal Loss ◽  
Failure Behavior ◽  
Straight Pipe ◽  
Element Analysis ◽  
Deformation And Failure ◽  
Wall Thinning ◽  
Local Wall Thinning

Monotonic four-point bending tests were conducted using straight pipe specimens 102 mm in diameter with local wall thinning in order to investigate the effects of the depth, shape, and location of wall thinning on the deformation and failure behavior of pipes. The local wall thinning simulated erosion/corrosion metal loss. The deformation and fracture behavior of the straight pipes with local wall thinning was compared with that of non wall-thinning pipes. The failure modes were classified as local buckling, ovalization, or crack initiation depending on the depth, shape, and location of the local wall thinning. Three-dimensional elasto-plastic analyses were carried out using the finite element method. The deformation and failure behavior, simulated by finite element analyses, coincided with the experimental results.

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.

ILI to ILI Comparisons: Quantifying the Impact of Multiple Inspections

2016 ◽  
Author(s):  
Pamela J. Moreno ◽  
Matthew A. Ellinger ◽  
Thomas A. Bubenik
Keyword(s):  
Wall Thickness ◽  
Magnetic Flux Leakage ◽  
Metal Loss ◽  
Data Sets ◽  
General Corrosion ◽  
Pipeline Segment ◽  
One To One ◽  
Pipe Geometry ◽  
The Impact ◽  
Flux Leakage

Det Norske Veritas (U.S.A.), Inc. (DNV GL) prepared this paper in order to study the repeatability of inspection results between subsequent in-line inspections. DNV GL has access to a significant amount of data that spans many different pipeline operators, ILI vendors, inspection years, and inspection technologies. DNV GL is well suited to complete this study as a result of our access to these various data sets. Over 55,000 one-to-one metal loss defect comparisons were assembled from ILI-to-ILI analyses. Reported metal loss defect depths, lengths, and widths spanning from 2003 through 2015 from 13 pipeline operators and 36 pipeline segments were compiled to meet the objectives of this paper. Inspection technologies include axial magnetic flux leakage (MFL), ultrasonic wall thickness (UTWT), spiral MFL, and circumferential MFL ILI. From analyses of these data, the following conclusions were generated: • Effect of ILI vendor: ILI repeatability is generally improved when the same ILI vendor is used (when compared to using two different ILI vendors in subsequent inspections), but this is not always true. • Reported metal loss depths: ILI repeatability decreases with increasing metal loss depth. • Pipe geometry and type: ILI repeatability is better in larger diameter pipelines and with increasing wall thickness. • POF classification: ILI repeatability is better for pitting, general corrosion, and axial grooving defects as compared to the other POF classifications. Based on these insights, the authors make the following recommendations: • Pipeline operators should consider using the same ILI vendor and tool if the goal is to identify change and/or corrosion growth in the pipeline segment. A raw signal review is encouraged in order to verify the presence, or lack thereof, changes in metal loss morphologies. The raw data review is especially important when comparing inspections from two different ILI vendors. • If the goal is to identify corrosion growth, and a pipeline operator uses different ILI vendors, it is recommended that a statistical review of one-to-one matched metal loss features take place to identify candidate locations that are more likely to be growing. The candidate locations should have a raw signal review in order to verify whether or not growth is taking place.

End Boundary Effects on Local Buckling Response of High Strength Linepipe

2010 ◽  
Author(s):  
Ali Fatemi ◽  
Shawn Kenny ◽  
Farid Taheri ◽  
Da-Ming Duan ◽  
Joe Zhou
Keyword(s):  
Finite Element ◽  
Yield Stress ◽  
Large Scale ◽  
Stress Ratio ◽  
Compressive Strain ◽  
Local Buckling ◽  
High Strength ◽  
End Effects ◽  
Industry Practice ◽  
Post Buckling

In this paper, the significance of the length to diameter ratio (L/D) on the local buckling response was evaluated using continuum finite element modelling procedures. A numerical model was developed, using the finite-element simulator ABAQUS/Standard, to predict the local buckling and post-buckling response of high strength pipelines subject to combined state of loading. The numerical procedures were calibrated using test data from large-scale experiments examining the local buckling of high strength linepipe. The numerical model’s response was consistent with the measured experimental response for predicting the local buckling behavior well into the post-yield range. A parametric study was conducted to examine the significance of the linepipe L/D ratio with respect to the yield stress to ultimate stress ratio (Y/T) and hoop yield stress to longitudinal yield stress ratio or anisotropy factor (R). As the models with high L/D ratio exhibit global Euler-type response, a numerical algorithm was developed to calculate the local section moment response for the FE analysis. The analysis conducted provides insight on the significance of end effects on the local buckling response. There are questions on the approach taken by current industry practice with respect to establishing compressive strain limits for local buckling when using shorter linepipe segment lengths. The results from this study suggest end effects require assessment and potential mitigation.

New Procedures for the Residual Strength Assessment of Corroded Pipe Subjected to Combined Loads

1996 ◽  
Author(s):  
Marina Q. Smith ◽  
Stephen C. Grigory
Keyword(s):  
Finite Element ◽  
Failure Criterion ◽  
Failure Modes ◽  
Model Development ◽  
Metal Loss ◽  
General Corrosion ◽  
Moment Capacity ◽  
Strength Assessment ◽  
Global Buckling ◽  
Buckling Failure

Motivated by the inability to accurately address non-pressure related stresses within the framework of current assessment guidelines, a three phase study aimed at the progressive development of a reliable and readily-useable procedure suitable for the analysis of internally pressurized degraded pipes which sustain large settlement and/or axial loads was performed. To ensure accuracy of the resulting procedure, full-scale experiments and finite element numerical simulations of artificially corroded 48-inch (122-cm) diameter X65 pipes subjected to combined loadings were designed to produce upper and lower bound rupture and global buckling failure envelopes for a given set of representative corrosion dimensions. The evaluation model accommodates combined stresses arising from internal pressure, axial bending, and axially compressive loadings to predict operational margins of safety for a pipe containing discrete or multiple metal loss regions guided by failure criteria which considers two critical failure modes: 1) a von Mises type failure criterion for rupture moment capacity determination, and 2) a global buckling failure criterion for identification of the critical moment capacity approximating collapse of the pipe mid-section due to a reduction in bending stiffness attributed in part to ovalization of the cross-section. The new methodology has been incorporated in the personal computer based program SAFE (Shell Analysis Failure Envelope), developed by Southwest Research Institute (SwRI) for the Alyeska Pipeline Service Company. The user-friendly program allows for definition of combined applied stresses and geometry of the degraded region through implementation of field-obtainable pre-or post-excavation measurements, and employs unique features which provide for the examination of pipe sections exhibiting distinct areas of general corrosion, or “patches,” separated both longitudinally and circumferentially, in a single analysis run. This paper outlines the model development and validation with supporting experiments and numerical analyses, and extension of the new procedure through sophisticated numerical techniques embodied in SAFE to actual corrosion profiles and service loadings. Detailed information included in the review are the finite element and SAFE program failure predictions for pipes analyzed with a given set of corrosion dimensions and load magnitudes, and a thorough discussion of the practical application of the SAFE program.

Limit Load Capacity of Thick-Walled Pipe Loaded by Internal Pressure and Bending

2021 ◽  
Author(s):  
Ruud Selker ◽  
Joost Brugmans ◽  
Ping Liu ◽  
Carlos Sicilia
Keyword(s):  
Finite Element ◽  
Internal Pressure ◽  
Wall Thickness ◽  
Load Capacity ◽  
Limit State ◽  
Local Buckling ◽  
Limit Load ◽  
Combined Loading ◽  
Fe Model ◽  
State Equations

Abstract Internally pressurised pipe behaves differently than externally pressurised pipe. DNVGL-ST-F101 [4], a prevailing standard for the design of submarine pipelines, provides limit-state equations for combined loading that are valid only if the diameter-to-wall-thickness ratio (D/t) is between 15 and 45. A recent study has shown that the results are increasingly conservative for lower values of this ratio if the nett pressure is acting on the pipe’s outside [8], especially if it is below 20. In this paper, the applicability of the limit-state equations for thick-walled pipe with D/t less than 15 and loaded by a nett internal pressure has been investigated. The first step was a fundamental review of the formulations. Next, the predicted capacities were compared with those estimated using a finite-element (FE) model. The results greatly coincided, which indicates that the conservatism underlying the formulations does not depend on D/t. Hence they can be used for design against local buckling under internal overpressure, too, when the ratio is below 15.

HotPipe JI Project: Experimental Test and FE Analyses

2005 ◽  
Author(s):  
Luigino Vitali ◽  
Lorenzo Bartolini ◽  
Dag Askheim ◽  
Ralf Peek ◽  
Erik Levold
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Internal Pressure ◽  
Phase 1 ◽  
Local Buckling ◽  
Experimental Tests ◽  
Element Model ◽  
Thickness Ratio ◽  
Outer Diameter ◽  
Test Configuration

In the last twenty years, experimental tests and FEM-based theoretical studies have been carried out to investigate the buckling mechanisms of thin-walled pipes subject to internal pressure, axial force and bending moment. Unfortunately, these studies do not completely cover the scope relevant for offshore pipelines i.e. outer diameter to thickness ratio lower than 50. In the HotPipe Phase 2 JI Project, full-scale bending tests were performed on pressurized pipes to verify the Finite Element Model predictions from HotPipe Phase 1 of the beneficial effect of internal pressure on the capacity of pipes to undergo large plastic bending deformations without developing local buckling. A total of 4 pipes were tested, the key test parameters being the outer-diameter-to-wall-thickness ratio (seameless pipes with D/t = 25.6, and welded UOE pipes with D/t = 34.2), and the presence of a girth weld in the test section. For comparison a Finite Element Model was developed with shell elements in ABAQUS. The test conditions were matched as closely as possible: this includes the test configuration, the stress-strain curves (i.e. using measured curves as input), and the loading history. The FE results very realistically reproduce the observed failure mechanisms by formation and localization of wrinkles on the compression side of the pipe. Good agreement is also achieved in the moment capacities (with predictions only 2.5 to 8% above measured values), but larger differences arose for the deformation capacity, suggesting that the DNV OS-F101 formulation for the characteristic bending strain (which is based on FE predictions from HotPipe Phase I) may be non-conservative in certain cases.

scholarly journals An Optimum Fatigue Design of Polymer Composite Compressed Natural Gas Tank Using Hybrid Finite Element-Response Surface Methods

Polymers ◽  
2021 ◽  
Vol 13 (4) ◽  
pp. 483
Author(s):  
Kazem Reza Kashyzadeh ◽  
Seyed Saeid Rahimian Koloor ◽  
Mostafa Omidi Bidgoli ◽  
Michal Petrů ◽  
Alireza Amiri Asfarjani
Keyword(s):  
Finite Element ◽  
Fatigue Life ◽  
Natural Gas ◽  
Response Surface ◽  
Polymer Composite ◽  
Wall Thickness ◽  
Composite Shell ◽  
Compressed Natural Gas ◽  
Fiber Angle ◽  
Composite Tank

The main purpose of this research is to design a high-fatigue performance hoop wrapped compressed natural gas (CNG) composite cylinder. To this end, an optimization algorithm was presented as a combination of finite element simulation (FES) and response surface analysis (RSA). The geometrical model was prepared as a variable wall-thickness following the experimental measurements. Next, transient dynamic analysis was performed subjected to the refueling process, including the minimum and maximum internal pressures of 20 and 200 bar, respectively. The time histories of stress tensor components were extracted in the critical region. Furthermore, RSA was utilized to investigate the interaction effects of various polymer composite shell manufacturing process parameters (thickness and fiber angle) on the fatigue life of polymer composite CNG pressure tank (type-4). In the optimization procedure, four parameters including wall-thickness of the composite shell in three different sections of the CNG tank and fiber angle were considered as input variables. In addition, the maximum principal stress of the component was considered as the objective function. Eventually, the fatigue life of the polymer composite tank was calculated using stress-based failure criterion. The results indicated that the proposed new design (applying optimal parameters) leads to improve the fatigue life of the polymer composite tank with polyethylene liner about 2.4 times in comparison with the initial design.

Study on the Local Buckling Behavior of Steel Equal Angle Members under Axial Compression with the Steel Strength Variation

2011 ◽  
Vol 374-377 ◽  
pp. 2430-2436
Author(s):  
Gang Shi ◽  
Zhao Liu ◽  
Yong Zhang ◽  
Yong Jiu Shi ◽  
Yuan Qing Wang
Keyword(s):  
Finite Element ◽  
Axial Compression ◽  
High Strength Steel ◽  
Local Buckling ◽  
Steel Structures ◽  
High Strength ◽  
Element Analysis ◽  
Equal Angle ◽  
Buckling Behavior ◽  
Steel Strength

High strength steel sections have been increasingly used in buildings and bridges, and steel angles have also been widely used in many steel structures, especially in transmission towers and long span trusses. However, high strength steel exhibits mechanical properties that are quite different from ordinary strength steel, and hence, the local buckling behavior of steel equal angle members under axial compression varies with the steel strength. However, there is a lack of research on the relationship of the local buckling behavior of steel equal angle members under axial compression with the steel strength. A finite element model is developed in this paper to analyze the local buckling behavior of steel equal angle members under axial compression, and study its relationship with the steel strength and the width-to-thickness ratio of the angle leg. The finite element analysis (FEA) results are compared with the corresponding design method in the American code AISC 360-05, which provides a reference for the related design.

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