Buckling and Tensile Strain Capacity of Girth Welded 48″ X80 Pipeline

2013 ◽  
Author(s):  
Satoshi Igi ◽  
Mitsuru Ohata ◽  
Takahiro Sakimoto ◽  
Junji Shimamura ◽  
Kenji Oi
Keyword(s):  
Crack Growth ◽  
Tensile Strain ◽  
Compressive Strain ◽  
Bending Test ◽  
Ductile Crack ◽  
Pipe Surface ◽  
Strain Capacity ◽  
Ductile Crack Growth ◽  
Strain Limit ◽  
Tensile Strain Capacity

This paper presents the experimental and analytical results focused on the compressive and tensile strain capacity of X80 linepipe. A full-scale bending test of girth welded 48″ OD X80 linepipes was conducted to investigate the compressive strain limit regarding to the local buckling and tensile strain limit regarding to the girth weld fracture. As for the compressive buckling behavior, one large developing wrinkle and some small wrinkles on the pipe surface were captured relatively well from observation and strain distribution measurement after pipe reaches its endurable maximum bending moment. 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 necking / rupture in the base material. The ductile crack growth behavior from the girth weld notch is simulated by FE-analysis based on the proposed damage model, and compared with the experimental results. In this report, it is also demonstrated that the simulation model can be applicable to predicting ductile crack growth behaviors from a circumferentially notched girth welded pipe with internal high pressure subjected to post-buckling loading.

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.

Tensile and Compressive Strain Capacity of Pipelines With Corrosion Anomalies

2016 ◽  
Author(s):  
Honggang Zhou ◽  
Ming Liu ◽  
Brent Ayton ◽  
Jason Bergman ◽  
Steve Nanney
Keyword(s):  
Numerical Analysis ◽  
Tensile Strain ◽  
Compressive Strain ◽  
General Corrosion ◽  
Test Results ◽  
Strain Capacity ◽  
Circumferential Groove ◽  
Compressive Buckling ◽  
Longitudinal Strains ◽  
Tensile Strain Capacity

Strain-based design and assessment (SBDA) methods have been developed to address integrity issues for pipelines subjected to ground movement hazards. The current practice of strain capacity assessment focuses on the tensile rupture of girth welds and compressive buckling of pipes. The integrity management of in-service pipelines often involves assessing pipe segments with anomalies, such as mechanical damage and corrosion. The existing strain capacity models do not yet include the impact of those anomalies. This paper covers a part of the outcome from a comprehensive research effort aimed at developing assessment procedures for pipelines containing corrosion anomalies and simultaneously subjected to large longitudinal strains. The resistance to tensile rupture and compressive buckling are the focus of the paper. Recommendations for the assessment of strain capacities were provided based on numerical analysis which identified key influencing parameters and controlling mechanisms. Full-scale experimental tests were also conducted to demonstrate the identified mechanisms and evaluate the assessment methods. Both numerical analysis and experimental test results demonstrate that: (1) corrosion anomalies can significantly reduce the tensile strain capacity (TSC) and compressive strain capacity (CSC) of pipes, (2) in addition to the depth and longitudinal length, the circumferential width of the corrosion anomalies has a significant impact on the TSC and CSC of pipes, (3) circumferential-groove corrosion anomalies reduce the tensile strain capacity more than general corrosion anomalies of the same depth and circumferential width, and (4) general corrosion anomalies reduce the compressive strain capacity more than the circumferential-groove anomalies of the same depth and circumferential width. The analysis and experimental test results shown in this paper can support development of SBDA procedures and guidelines of pipelines subjected to large longitudinal strains.

Analysis of Ductile Crack Growth in Pipe Test in STYLE Project

2012 ◽  
Author(s):  
Shengjun Yin ◽  
Paul T. Williams ◽  
Hilda B. Klasky ◽  
B. Richard Bass
Keyword(s):  
Finite Element ◽  
Crack Growth ◽  
Large Scale ◽  
Structural Integrity ◽  
Bending Test ◽  
Ductile Crack ◽  
Oak Ridge ◽  
Integrity Assessment ◽  
Ductile Crack Growth ◽  
Bending Load

The Oak Ridge National Laboratory (ORNL) is conducting structural analyses, both deterministic and probabilistic, to simulate a large scale mock-up experiment planned within the European Network for Structural Integrity for Lifetime Management – non-RPV Components (STYLE). The paper summarizes current ORNL analyses of STYLE’s Mock-Up3 experiment to simulate/evaluate ductile crack growth in a cladded ferritic pipe. Deterministic analyses of the large-scale bending test of a ferritic surge pipe, with an internal circumferential crack, are being simulated with a number of local micromechanical approaches, such as Gurson-Tvergaard-Needleman (GTN) model. Both FEACrack [1] and ABAQUS [2] general purpose finite element programs are being used to predict the failure load and the failure mode, i.e. ductile tearing or net-section collapse, as part of the pre-test phase of the project. Companion probabilistic analyses of the experiment are utilizing the ORNL developed open-source Structural Integrity Assessment Modular - Probabilistic Fracture Mechanics (SIAM-PFM) framework. SIAM-PFM contains engineering assessment methodologies such as the tearing instability (J-T analysis) module developed for inner surface cracks under bending load. The driving force J-integral estimations are based on the SC.ENG1 or SC.ENG2 models. The J-A2 methodology is used to transfer (constraint-adjust) J-R curve material data from standard test specimens to the Mock-Up3 experiment configuration. The probabilistic results of the Mock-Up3 experiment obtained from SIAM-PFM will be compared to those generated using the deterministic finite element modeling approach. The objective of the probabilistic analysis is to provide uncertainty bounds that will assist in assessing the more detailed 3D finite-element solutions and to also assess the level of confidence that can be placed in the best-estimate finite-element solutions.

Ductile Crack Extension Analysis for X80 Bending Deformation Using Damage-Based Model

2014 ◽  
Author(s):  
Satoshi Igi ◽  
Mitsuru Ohata ◽  
Takahiro Sakimoto ◽  
Kenji Oi ◽  
Joe Kondo
Keyword(s):  
Plastic Strain ◽  
Simulation Model ◽  
Crack Growth ◽  
Crack Extension ◽  
Damage Model ◽  
Stress Triaxiality ◽  
Crack Growth Behavior ◽  
Ductile Crack ◽  
Ductile Crack Growth ◽  
Notch Tip

This paper presents experimental and analytical results focusing on the strain limit of X80 linepipe. Ductile crack growth behavior from a girth weld notch is simulated by FE analysis based on a proposed damage model and is compared with the experimental results. The simulation model for ductile crack growth accompanied by penetration through the wall thickness consists of two criteria. One is a criterion for ductile crack initiation from the notch-tip, which is described by the plastic strain at the notch tip, because the onset of ductile cracking can be expressed by constant plastic strain independent of the shape and size of the components and the loading mode. The other is a damage-based criterion for simulating ductile crack extension associated with damage evolution influenced by plastic strain in accordance with the stress triaxiality ahead of the extending crack tip. The proposed simulation model is applicable to prediction of ductile crack growth behaviors from a circumferentially-notched girth welded pipe with high internal pressure, which is subjected to tensile loading or bending (post-buckling) deformation.

Multi-Tier Tensile Strain Models for Strain-Based Design: Part 2 — Development and Formulation of Tensile Strain Capacity Models

2012 ◽  
Author(s):  
Ming Liu ◽  
Yong-Yi Wang ◽  
Yaxin Song ◽  
David Horsley ◽  
Steve Nanney
Keyword(s):  
Driving Force ◽  
Tensile Strain ◽  
Weld Strength ◽  
Experiment Data ◽  
Pipe Wall Thickness ◽  
Crack Driving Force ◽  
Strain Capacity ◽  
Welding Processes ◽  
Tensile Strain Capacity

This is the second paper in a three-paper series related to the development of tensile strain models. The fundamental basis of the models [1] and evaluation of the models against experiment data [2] are presented in two companion papers. This paper presents the structure and formulation of the models. The philosophy and development of the multi-tier tensile strain models are described. The tensile strain models are applicable for linepipe grades from X65 to X100 and two welding processes, i.e., mechanized GMAW and FCAW/SMAW. The tensile strain capacity (TSC) is given as a function of key material properties and weld and flaw geometric parameters, including pipe wall thickness, girth weld high-low misalignment, pipe strain hardening (Y/T ratio), weld strength mismatch, girth weld flaw size, toughness, and internal pressure. Two essential parts of the tensile strain models are the crack driving force and material’s toughness. This paper covers principally the crack driving force. The significance and determination of material’s toughness are covered in the companion papers [1,2].

Ductile Damage Model Based On Void Growth Analysis for Application to Ductile Crack Growth Simulation

2021 ◽  
Author(s):  
Takehisa Yamada ◽  
Mitsuru Ohata
Keyword(s):  
Crack Growth ◽  
Void Growth ◽  
Damage Evolution ◽  
Damage Model ◽  
Crack Growth Resistance ◽  
Growth Behavior ◽  
Ductile Crack ◽  
Growth Simulation ◽  
Crack Growth Simulation ◽  
Ductile Crack Growth

Abstract The aim of this study is to propose damage model on the basis of the mechanism for ductile fracture related to void growth and to confirm the applicability of the proposed model to ductile crack growth simulation for steel. To figure out void growth behavior, elasto-plastic finite element analyses using unit cell model with an initial void were methodically performed. From the results of those analyses, it was evident that the relationships between normalized void volume fraction and normalized strain by each critical value corresponding to crack initiation were independent of stress-strain relationship of material and stress triaxiality state. Based on this characteristic associated with void growth, damage evolution law was derived. Then, using the damage evolution law, simple and phenomenological ductile damage model reflecting void growth behavior and ductility of material was proposed. To confirm the validation and application of proposed damage model, the damage model was implemented in finite element models and ductile crack growth resistance was simulated for cracked components were performed. Then, the simulated results were compared with experimental ones and it was found that the proposed damage model could accurately predict ductile crack growth resistance and was applicable to ductile crack growth simulation.

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