bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effects of Notch Type and Loading Rate on CTOA of Modern X65 and X70 Pipe Steels
Authors: Xu S. , Sollen J. , Liang J. , Zavadil R. , Tyson W. R. 
Published: December 2014

The crack-tip opening angle (CTOA) has been investigated as a fracture propagation resistance parameter for prevention of fast ductile fracture in gas pipelines. A CANMET simplified single specimen CTOA method has been proposed as a mill test and is being applied to characterize critical CTOA (CTOAc) of typical pipe steels to develop a toughness database and improve the test method.
In this work, tests using standard machined V-notch and API pressed notch (PN) drop-weight tear test (DWTT) specimens at quasi-static and impact rates were performed on modern X65 and X70 pipe steels typical of those used for CO2 pipelines. The rotation factor of the X65 steel deduced from the deformed ligament geometry is equivalent to those of X70 to X100 steels. Pressed-notch DWTT specimens were successfully fractured in impact and yielded CTOAc values equivalent to those of V-notched specimens following the CANMET recommended practice for determination of CTOAc. The effect of loading rate on CTOAc between the quasi-static and impact rates (covering five orders of magnitude) is small or negligible, being within experimental scatter. This is in agreement with data in the CANMET database, except for a low-toughness X52 steel that showed an increase in CTOAc between quasi-static and impact loading rates. The effect of flattening on CTOAc was also investigated and is small or negligible for the large-diameter (at least 508 mm) pipes tested in this work. The results may be used to support and improve a proposed test method for determination of CTOAc being considered by an ASTM Task Group and currently being evaluated in a round-robin testing program.
Verification and Validation of Pipeline Terminal Simulation Models
Authors: Lin Frank , Chegus Allan , Cernelev Dumitru 
Published: December 2014

The problem of validating a complex simulation model represents pipeline terminal performance with verifiable accuracy is a difficult problem requiring extensive testing and calibration.
This paper discusses a case study of the verification and validation of a terminal simulation model. The approach to deciding model validity is presented as well as the process of verifying and validating the model including methodology and thresholds for acceptance. Ultimately the paper demonstrates the ability of commercial simulation and optimization software to work collaboratively to determine an optimal business solution.
Achieving Efficiency in Environmental Assessment Through Focused Selection of Valued Components
Authors: Prystay Ward , Pomeroy Andrea , Webster Sandra 
Published: December 2014

Some of the largest oil and gas projects in Canada are currently being proposed in British Columbia. Establishing a fulsome and scientifically and socially defensible scope for environmental assessments in the oil and gas sector is a serious challenge for government and proponents. The approach taken by the federal National Energy Board to scope effects assessments on pipelines is quite different than the approach taken by the British Columbia Environmental Assessment Office on other types of oil and gas projects.
The NEB has published guidelines for scoping and conducting environmental and socio-economic assessments within its Filing Manual (National Energy Board [NEB] 2014). This manual sets out the expectations for scoping, baseline information, and effects assessments to be submitted as part of approval applications. Proponents are expected to provide all information necessary to meet the guidelines.
In British Columbia, the environmental assessment process is dictated by the British Columbia Environmental Assessment Act and includes a negotiated terms of reference for the assessment, called the Application Information Requirements (AIR). The approach to selection of valued components is guided by provincial guidelines (EAO, 2013). The first draft of the AIR is prepared by the proponent and is then amended to address matters raised by federal and provincial agencies, local governments, and representatives of potentially affected First Nations. Through two to three revisions, the scope of assessment is jointly established and then formally issued by the government.
While there are valid reasons for the differing federal and provincial approaches to scoping environmental assessments, each of these processes create risks for proponents in terms of project timelines and costs for preparing the environmental assessment. More specifically, the use of generic and negotiated guidelines can result in a number of issues including:
• A scope of assessment that is broader than necessary to understand the potential for significant adverse effects
• Inclusion of issues that are “near and dear” to a specific regulator or community but has no direct relationship to the effects of the project itself
• Selection of valued components that do not allow for defensible quantification of effects or use of directly relevant significance thresholds
• Selection of valued components that are only of indirect concern as opposed to focusing the assessment on the true concern.
• Double counting of environmental effects
• Risks in assessing cumulative effects
This paper discusses where and how these risks occur, and provides examples from recent and current environmental assessments for pipelines and facilities in British Columbia. Opportunities to manage the scope of assessment while providing a fulsome, efficient, effective and scientifically/socially defensible assessment are discussed.
Markovian Analysis of Aging Distributed Systems Remaining Life
Authors: Bushinskaya Anna , Timashev Sviatoslav 
Published: December 2014

Correct assessment of the remaining life of distributed systems such as pipeline systems (PS) with defects plays a crucial role in solving the problem of their integrity.
Authors propose a methodology which allows estimating the random residual time (remaining life) of transition of a PS from its current state to a critical or limit state, based on available information on the sizes of the set of growing defects found during an in line inspection (ILI), followed by verification or direct assessment.
PS with many actively growing defects is a physical distributed system, which transits from one physical state to another. This transition finally leads to failure of its components, each component being a defect. Such process can be described by a Markov process.
The degradation of the PS (measured as monotonous deterioration of its failure pressure Pf (t)) is considered as a non-homogeneous pure death Markov process (NPDMP) of the continuous time and discrete states type. Failure pressure is calculated using one of the internationally recognized pipeline design codes: B13G, B31Gmod, DNV, Battelle and Shell-92.
The NPDMP is described by a system of non-homogeneous differential equations, which allows calculating the probability of defects failure pressure being in each of its possible states. On the basis of these probabilities the gamma-percent residual life of defects is calculated. In other words, the moment of time tγ is calculated, which is a random variable, when the failure pressure of pipeline defect Pf (tγ) > Pop, with probability γ, where Pop is the operating pressure. The developed methodology was successfully applied to a real life case, which is presented and discussed.
Modern Approach to the Microstructure Characterization of Large Diameter Linepipes
Authors: Stallybrass Charles , Frommert Matthias , Konrad Joachim , Meuser Heike , Schröder Jens 
Published: December 2014

Over the past decades, the complexity of requirements regarding the properties of large-diameter linepipes has increased steadily. This is driven by factors such as increasing operating pressures or more hostile environmental conditions. Steel producers all over the world have responded to these demands by continuous development along the entire processing route from steelmaking to thermomechanical rolling and pipe production. Understanding the influence of the microstructure on pipe properties is a key element to extend the use of linepipe steels to more challenging conditions. For this reason, the techniques that are used for microstructure characterization are constantly refined.
The microstructure of modern microalloyed linepipe steels that are produced by thermomechanical rolling in combination with accelerated cooling depends strongly on the processing parameters during production. The grain size of the base metal is typically below 10 μm and may contain fractions of ferrite, bainite and M/A-constituents. Because of their size, these microstructure constituents are often not readily accessible to a quantitative analysis by classical light-optical microscopy. This was also found to be true within the heat-affected zone (HAZ) of large-diameter pipes. High-resolution scanning electron microscopy in combination with electron backscatter diffraction was found to offer a wide range of possibilities to characterize the microstructure quantitatively with regard to the effective grain size, the volume fraction of constituents and their variation over the wall thickness. The effects of variations in processing parameters in laboratory-scale trials on the microstructure and properties are illustrated. Based on these investigations, it was possible to refine the alloy design and processing parameters in order to improve the low-temperature toughness of the base metal of high strength plate material and the HAZ of longitudinal weld seams.
Intentional Destructive Testing: A Means for Establishing Mechanical Integrity
Authors: Alexander Chris , Vyvial Brent 
Published: December 2014

Pipeline operators have at their disposal multiple resources for evaluating the integrity of identified features and anomalies. With advances in in-line inspection technology, the pipeline industry is being called upon to evaluate an ever-increasing number of features. When a feature is identified as a threat and severe enough to warrant further investigation, operators are faced with sometimes significant costs, including those associated with excavation activities.
In this paper the authors provide guidance on the benefits associated with full-scale testing for evaluating mechanical integrity, referred to Intentional Destructive Testing (IDT). Unlike many assessment techniques that require the development and implementation of assumed operating and boundary conditions, well-designed IDT programs are able to replicate in situ conditions to provide operators with a clear understanding regarding the behavior of pipeline features and anomalies by simulating operating conditions and loading.
Three case studies are included in this paper to demonstrate the merits of the IDT approach including the assessment of dents subjected to cyclic pressures, burst testing vintage pipes having long seam weld crack-like features, and evaluating the reinforcement of girth welds using composite materials. In using IDT operators have improved confidence in predicting the behavior of identified features to ensure that maintenance resources are properly allocated for excavating and repairing anomalies.
Mechanical Damage and Fatigue Assessment of Dented Pipelines Using FEA
Authors: Hanif W. , Kenny S. 
Published: December 2014

Onshore and offshore pipelines may be subjected to mechanical damage during installation and operation due to environmental loads, external forces and third party interference. Pipelines in offshore environment may be prone to mechanical damage from events such as ice gouging, frost heave, and seismic fault movement. For conventional pipelines, the assessment of mechanical damage plays an important role in the development of integrity management programs that may be of greater significance for pipeline systems located in remote harsh environments and that are more prone to anchor drag, seismic loading and ice gouging.
This study examines the effect of dents and corrosion loss on pipe mechanical response using continuum finite element methods. ABAQUS/Standard (6.10-1) environment was used to simulate damage events and pipe response. Modelling procedures developed and calibrated against physical and numerical data sets available in public domain were reported previously in Hanif & Kenny 2012, 2013. Once confidence in numerical procedures was established, an analysis model matrix was established to account for a range of influential parameters including pipe/indenter geometry and pressure factor. A nonlinear multivariate regression analysis was conducted to develop strain based empirical tools that characterize the effects of local damage and applied loads on pipeline mechanical response for unconstrained dent conditions. Coupled affect of dent and artificial corrosion loss (in terms of wall thickness reduction in the damage zone) was also analyzed and a sensitivity study was conducted to see the effect of percentage wall loss on pipe response. Finally, operational parameters were varied and resulting stress concentration factors were calculated, that took into account indentations and wall loss, to predict fatigue life of dented pipe segments for both constrained and unconstrained dent conditions.
Application and Advancement of EMAT ILI Technologies for the Inspection of Cracks in Dents
Authors: Sutherland Jeff , Mann Andrew , Vignal Geoff , Maier Arne , Keane Sean 
Published: December 2014

Pipeline dents and mechanical damage remain an integrity threat within the Oil & Gas pipeline industry. Such features typically consist of a localized deformation of the pipe wall.
Under certain conditions, cracking may develop within or adjacent to the area of deformation due to stress concentration factors resulting from the deformation itself or from secondary damage such as a scrape or gouge.
Conventional inline inspection technologies consistently to date have not explicitly addressed inspection capabilities for cracking within dents.
This paper presents the results of a collaborative technical effort to assess and advance the abilities of EMAT inline inspection technologies to identify and characterize such mechanical damage features as found in liquid pipelines.
The background and application of these advanced technologies for the targeted threats is discussed, as well as the experimental testing performed and results achieved.
Structural Reliability of Free Spanning Pipelines
Authors: Van den Abeele F. , Boël F. , Vanden Berghe J.-F. 
Published: December 2014

When installing subsea pipelines on an uneven seabed, the free spans can be vulnerable to fatigue damage caused by vortex induced vibrations (VIV). Indeed, even moderate currents can induce vortex shedding, alternately at the top and the bottom of the pipeline, at a rate determined by the flow velocity. Each time a vortex sheds, a force is generated in both the in-line and cross-flow direction, causing an oscillatory multi-mode vibration. This vortex induced vibration can give rise to fatigue damage of submarine pipeline spans, especially in the vicinity of the girth welds. Traditional design for VIV is recommended in DNV-RP-F105, which limits the allowable free span length and implies whether (and when) seabed interventions are required.
The traditional DNV-RP-F105 design method is based on a semi-empirical approach, where the allowable span length depends on the pipe properties (diameter, wall thickness, coating, steel SN_curves, …), the sea state (current velocity, wave induced velocity and period) and the soil conditions (submerged unit weight, undrained shear strength, bearing capacity,…). All these input parameters, however, exhibit a certain extent of scatter and uncertainty.
This paper presents a risk based evaluation of free spans, by applying the principles of structural reliability theory to the problem of long free spanning pipelines subjected to VIV. First, a fully deterministic on-bottom roughness analysis is performed to introduce numerical tools for free span analysis. Then, a sensitivity analysis on soil parameters is presented to show significant influence of soil properties on free span predictions.
To study the implications of uncertainty in soil properties, a First Order Reliability Method (FORM) analysis is presented at the end of this paper, where the soil properties are introduced as stochastic variables.
Implementing a Geohazard Integrity Management Program: Statistics and Lessons Learned Over 15 Years
Authors: Baumgard Alex J. , Coultish Tara L. , Ferris Gerry W. 
Published: December 2014

Over the last 15 years, BGC Engineering Inc. has developed and implemented a geohazards Integrity Management Program (IMP) with 12 major pipeline operators (consisting of gas and oil pipelines and of both gathering and transmission systems). Over this time, the program has been applied to the assessment of approximately 13,500 individual hydrotechnical and geotechnical geohazard sites spanning approximately 63,000 km of operating pipelines in Canada and the USA. Hydrotechnical (watercourse) and geotechnical (slope) hazards are the primary types of geohazards that have directly contributed to pipeline failures in Canada.
As with all IMPs, the core objectives of a geohazard management system are to ensure a proactive approach that is repeatable and defensible. In order to meet these objectives, the program allows for varying levels of intensity of inspection and a recommended timescale for completion of actions to manage the identified geohazards in accordance with the degree of hazard that the site poses to the pipeline. In this way, the sites are managed in a proactive manner while remaining flexible to accommodate the most current conditions at each site.
This paper will provide a background to the key components of the program related specifically to existing operating pipeline systems, present pertinent statistics on the occurrence of various types of geohazards based on the large dataset of inspections, and discuss some of the lessons learned in the form of program results and program challenges from implementing a geohazard integrity management system for a dozen operators with different ages of systems, complexity of pipeline networks, and in varied geographic settings.
Effects of Data Preparation on Leak Sensitivity Analysis
Authors: Noguerol Rafael , Unriza Juan Carlos , Acevedo Alberto 
Published: December 2014

Determining the leak detection sensitivity for a particular system, or suggesting strategies to improve it are common challenges for leak detection professionals.
As an alternative to statistical analysis, an empirical approach can be employed: use an offline hydraulic simulator to model the pipeline system, including all the inaccuracies due to the instruments and communication systems. Using such an approach the sensitivity can be inferred by running some scenarios representative of leak and non-leak conditions. Furthermore, not only can normal operating conditions be considered but also emergency and/or upset operating conditions can also be taken into account.
Ecopetrol (the national Oil Company of Colombia) utilized this practical approach during the commissioning phase of a new pipeline allowing Ecopetrol to calculate the sensitivity prior to the commencement of operations. Analysis was also undertaken the results of which were recommendations on how to improve the system sensitivity.
This paper describes the methodology; the construction of the hydraulic model; the assumptions made, and presents the final results. A discussion about the validity of the procedure and its generic application is also presented.
Evaluation of Pressurized Cold Bend Pipe Body Tensile Fractures Under Bending Loads
Authors: Cakiroglu Celal , Kainat Muntaseer , Adeeb Samer , Cheng J. J. Roger , Sen Millan 
Published: December 2014

Cold bending is applied at locations where the pipeline direction has to be changed in a horizontal or vertical plane. The process of cold bending usually results in residual stresses as well as changes in the material properties at the vicinity of the cold bend location which makes the study of the mechanical behaviour of cold bends indispensable. Due to discontinuous permafrost in arctic regions as well as slope instabilities and earthquakes cold bends within pipelines constructed in such locations can be subjected to significant tensile or compressive forces.
Experimental studies were carried out by Sen et al [1][2][3]in order to investigate the buckling behaviour of pressurized cold bends. In these experiments the curvature of the cold bend is increased in the presence of a constant internal pressure. In their experimental study a total of 8 full scale tests were conducted with a variety of pipe diameters, diameter to wall thickness ratio and steel grade. In this set of full scale tests one of the pipes with grade X65 failed due to fracture at the extrados after buckling and formation of wrinkles at the intrados[1].
Our previous work [4], [5] on this subject showed the simulations of this case using finite element analysis. These simulations demonstrated that indeed pipe body tensile side fracture can be observed for this particular pipe specification. Whereby the tension side fractures are expected starting from a specific internal pressure level. The simulation results showed that the equivalent plastic strain values at the cold bend extrados increase dramatically starting from a certain level of applied curvature in load cases with an internal pressure higher than a transition value. In this paper the effect of steel grade on this transition from compressive to tensile failure is investigated. Parametric studies are conducted for the entire range of steel grades tested in the experimental study of Sen et al. It is found that there is a linear proportionality between the steel grade and the transition internal pressure for steel grades between X60 and X80.
Enhancing Tensile Strain Capacity Through the Optimization of Weld Profiles
Authors: Wang Yong-Yi , Chen Yaoshan , Salama Mamdouh 
Published: December 2014

In order to optimize cost and performance of high pressure gas pipelines by reducing the wall thickness, pipeline companies are considering the use of higher grade (X70 or above) steels or a composite pipe of thin steel liner and fiber wrap. The use of high strength steels and thinner pipes can result in challenges when the pipe is installed in areas imposing high strain demand such as discontinuous permafrost regions. For high strength steels, the difficulty of ensuring the strength overmatching of the weld metal and the potential softening of the heat affected zone (HAZ) can result in gross strain concentration in the weld region and thus reduce the strain capacity of the pipeline in the presence of weld defects. Also, a thinner pipe has lower strain capacity than a thicker pipe for the weld defect of the same dimensions. One of the economical and effective ways of mitigating the possibility of gross strain concentration and increasing the strain capacity of a weld region containing weld defects is through the use of appropriate weld profiles. For instance, adding a smooth and wide layer of weld reinforcement (termed weld overbuild) can increase the effective strength of the weld.
The effectiveness of the weld overbuild in improving the tensile strain capacity of girth welds is evaluated using the Level 4a approach of the PRCI-CRES tensile strain models. The crack-driving force is obtained through finite element analysis (FEA) of welds with planar weld and HAZ flaws of various sizes. It was demonstrated that weld overbuild with appropriate dimensions is an effective method to increase the tensile strain capacity (TSC) of girth welds which may have limited TSC without the overbuild. The role of weld profiles in girth weld integrity is discussed from the perspectives of historical evidence and more recent analysis and experimental tests.