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.

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.

Ultimate strain capacity assessment of local buckling of pipelines with kinked dents subjected to bending loads

2021 ◽  
Vol 169 ◽  
pp. 108369
Author(s):  
Junqiang Wang ◽  
Yi Shuai ◽  
Renyang He ◽  
Xiran Dou ◽  
Ping Zhang ◽  
...  
Keyword(s):  
Local Buckling ◽  
Ultimate Strain ◽  
Capacity Assessment ◽  
Strain Capacity ◽  
Bending Loads

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.

A Study of Deformation Behavior of Double Jointing Girth Welds

2012 ◽  
Author(s):  
Tomoyuki Yokota ◽  
Yoshiaki Murakami ◽  
Takahiro Sakimoto ◽  
Igi Satoshi ◽  
Shigeru Endo
Keyword(s):  
Weld Metal ◽  
Weld Joint ◽  
Arc Welding ◽  
Deformation Behavior ◽  
Base Material ◽  
High Strength ◽  
Strain Capacity ◽  
Girth Welds ◽  
Submerged Arc ◽  
Softening Region

Demand for double jointing technology is increasing to improve pipeline construction productivity. Submerged arc welding (SAW) utilized for double jointing is likely to cause a much wider heat affected zone (HAZ) than those of typical field welding by gas metal arc welding (GMAW), and it should be taken into account for strain-based design of high strength line-pipes. However, guidelines for SAW welds properties to ensure strain capacity of high strength line-pipes such as X80 have not been established yet. In this study, a submerged arc weld joint was produced using tensile strength (TS) over-matching welding consumable. API standard type transverse weld tension test was conducted to measure local elongation at weld metal, HAZ, and base material. Elongation at weld metal increases prior to base material, but soon after that elongation at the HAZ softening region and base material adjacent to the HAZ catch up with the elongation in the weld metal, and finally, deformation concentrates at the HAZ softening region before final fracture. Deformation behavior of the joint was analyzed to verify applicability to double jointing girth welds for strain-based design. From finite element (FE) analysis of notched wide plate test which characterizes tensile strain capacity of a pipeline, it is suggested that ductile crack would not initiate before base material start necking in this particular TS over-matching weld joint in which the defect size is 1mm of notch depth and 25mm of notch length. Thus, the weld joint would be applicable for double jointing girth welds based on strain-based design.

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.

Assessment of Stress Based Design Pipelines Experiencing High Axial Strains

2018 ◽  
Author(s):  
Robert Andrews ◽  
Mark Stephens ◽  
Malcolm Carr ◽  
Johannes Brückner
Keyword(s):  
Gap Analysis ◽  
Axial Strain ◽  
Local Buckling ◽  
Strain Capacity ◽  
Design Concepts ◽  
Metal Fracture ◽  
Discontinuous Permafrost ◽  
Girth Welds ◽  
Subsea Pipelines ◽  
Assessment Of Stress

Strain based design concepts have been extensively used for subsea pipelines for both installation and service. However, most onshore transmission pipelines are designed assuming a maximum longitudinal stress, typically 90% SMYS. Some onshore pipelines have been designed for a limiting axial strain generated by causes such as seismic activity, frost heave, discontinuous permafrost or landslides. Models have been developed to predict the axial strain capacity in both tension (usually limited by the girth welds) and compression (where the limit is local buckling of the pipe wall). In service monitoring of a pipeline initially designed on a stress basis may reveal that strains approaching or exceeding the design level are occurring, or are predicted to occur in the future. In these cases the pipeline operator will have to assess if the pipeline is fit for continued service. In principle strain based design approaches could be adapted for such an assessment. Strain based design approaches place more onerous demands on the linepipe and the girth welds, but for a new pipeline these requirements can be addressed during design, material specification, procurement and weld procedure qualification. However, for an existing pipeline the data required to use strain based approaches may not be readily available. Some strain capacity models are only valid over a restricted range of inputs and so cannot be used in all cases. Hence there is a need to develop guidance for assessing the fitness for purpose of a stress based design pipeline that is found to be experiencing high axial strains. The European Pipeline Research Group (EPRG) has initiated a program to develop such guidance. This paper presents the results of the first stage of this program. The requirements for data such as inspection records, weld metal fracture toughness and parent pipe mechanical properties are considered. A flow chart has been developed to guide operators when assessing an existing pipeline found to be subject to high strains, and a gap analysis identifies areas where additional work is required.

Effects of Weld Strength Heterogeneity on Crack Driving Force in Stress and Strain Based Design Scenarios

2014 ◽  
Author(s):  
Stijn Hertelé ◽  
Noel O’Dowd ◽  
Matthias Verstraete ◽  
Koen Van Minnebruggen ◽  
Wim De Waele
Keyword(s):  
Driving Force ◽  
Large Scale ◽  
Limit State ◽  
Weld Strength ◽  
Force Response ◽  
Crack Driving Force ◽  
Key Factor ◽  
Weld Properties ◽  
Girth Welds ◽  
Strain Hardening Behavior

Weld strength mismatch is a key factor with respect to the assessment of a flawed girth weld. However, it is challenging to assign a single strength mismatch value to girth welds, which are generally heterogeneous in terms of constitutive behavior. The authors have recently developed a method (‘homogenization’) to account for weld strength property variations in the estimation of crack driving force response and the corresponding tensile limit state. This paper separately validates the approach for stress based and strain based assessments. Whereas homogenization is reliably applicable for stress based assessments, the strain based crack driving force response is highly sensitive to effects of actual heterogeneous weld properties. The sensitivity increases with increased weld width and decreased strain hardening behavior. For strain based design, a more accurate methodology is desirable, and large scale testing and/or advanced numerical modeling remain essential.

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