The Experts below are selected from a list of 360 Experts worldwide ranked by ideXlab platform
Michael A Adewumi - One of the best experts on this subject based on the ideXlab platform.
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low liquid loading multiphase flow in Natural Gas Pipelines
Journal of Energy Resources Technology-transactions of The Asme, 2003Co-Authors: Luis F Ayala, Michael A AdewumiAbstract:Pressure and temperature variations of Natural Gas flows in a pipeline may cause partial Gas condensation. Fluid phase behavior and prevailing conditions often make liquid appearance inevitable, which subjects the pipe flow to a higher pressure loss. This study focuses on the hydrodynamic behavior of the common scenarios that may occur in Natural Gas Pipelines. For this purpose, a two-fluid model is used. The expected flow patterns as well as their transitions are modeled with emphasis on the low-liquid loading character of such systems. In addition, the work re-examines previous implementations of two-flow model for Gas-condensate flow.
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simulation of transients in Natural Gas Pipelines using hybrid tvd schemes
International Journal for Numerical Methods in Fluids, 2000Co-Authors: J Zhou, Michael A AdewumiAbstract:The mathematical model describing transients in Natural Gas Pipelines constitutes a non-homogeneous system of non-linear hyperbolic conservation laws. The time splitting approach is adopted to solve this non-homogeneous hyperbolic model. At each time step, the non-homogeneous hyperbolic model is split into a homogeneous hyperbolic model and an ODE operator. An explicit 5-point, second-order-accurate total variation diminishing (TVD) scheme is formulated to solve the homogeneous system of non-linear hyperbolic conservation laws. Special attention is given to the treatment of boundary conditions at the inlet and the outlet of the pipeline. Hybrid methods involving the Godunov scheme (TVD/Godunov scheme) or the Roe scheme (TVD/Roe scheme) or the Lax–Wendroff scheme (TVD/LW scheme) are used to achieve appropriate boundary handling strategy. A severe condition involving instantaneous closure of a downstream valve is used to test the efficacy of the new schemes. The results produced by the TVD/Roe and TVD/Godunov schemes are excellent and comparable with each other, while the TVD/LW scheme performs reasonably well. The TVD/Roe scheme is applied to simulate the transport of a fast transient in a short pipe and the propagation of a slow transient in a long transmission pipeline. For the first example, the scheme produces excellent results, which capture and maintain the integrity of the wave fronts even after a long time. For the second example, comparisons of computational results are made using different discretizing parameters. Copyright © 2000 John Wiley & Sons, Ltd.
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transients in Gas condensate Natural Gas Pipelines
Journal of Energy Resources Technology-transactions of The Asme, 1998Co-Authors: J Zhou, Michael A AdewumiAbstract:Liquid condensation in Natural Gas transmission Pipelines commonly occurs due to the thermodynamic and hydrodynamic imperatives. Condensation subjects the Gas pipeline to two-phase transport. Neither the point along the pipeline at which the condensate is formed nor the quantity formed is known a priori. Hence, compositional multiphase hydrodynamic modeling, which couples the multiphase hydrodynamic model with the Natural Gas phase behavior model, is necessary to predict fluid dynamic behavior in Gas/condensate Pipelines. A transient compositional multiphase hydrodynamic model for transient Gas-condensate two-phase flow in Pipelines is presented. This model consists of our newly developed well-posed modified Soo's partial pressure model in conservative form which serves as the transient multiphase hydrodynamic model, and the phase behavior model for Natural Gas mixtures.
Joe Zhou - One of the best experts on this subject based on the ideXlab platform.
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application of reliability based design and assessment to maintenance and protection decisions for Natural Gas Pipelines
2010 8th International Pipeline Conference Volume 4, 2010Co-Authors: Maher Nessim, Howard Kaho Yue, Joe ZhouAbstract:This paper describes a detailed assessment that was carried out to investigate the practical implications of using the Reliability Based Design and Assessment (RBDA) methodology, as described in Annex O of CSA Z662, as a basis for evaluating existing Pipelines and making decisions on maintenance planning and damage prevention strategies. Two key pipeline failure threats are addressed, namely corrosion and equipment impact. The assessment was based on a number of test cases covering a wide range of diameters, grades, pressures, location classes and corrosion severities. The reliability levels associated with these cases were calculated as a function of time and compared to the reliability targets. Cases that did not meet the targets were re-analyzed with increasingly enhanced maintenance measures until the targets were met. Maintenance actions considered included higher maintenance frequencies and more stringent repair criteria for corrosion, and enhancements to such parameters as right-of-way patrol frequency and condition, public awareness programs and dig notification response for equipment impact. The results demonstrate that the reliability targets can be met through the implementation of reasonable and practical maintenance measures for the cases considered. The impact of using RBDA on the expected failure rates is discussed. In addition, the diameter and class ranges of Pipelines requiring enhanced maintenance over the current norm are identified.Copyright © 2010 by ASME
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target reliability levels for design and assessment of onshore Natural Gas Pipelines
Journal of Pressure Vessel Technology-transactions of The Asme, 2009Co-Authors: Maher Nessim, Wenxing Zhou, Joe Zhou, Brian RothwellAbstract:This paper proposes a set of reliability targets that can be used in the design and assessment of onshore Natural Gas Pipelines. The targets were developed as part of a PRCI-sponsored project that aims to establish reliability-based methods as a viable alternative for pipeline design and assessment. The proposed targets are calibrated to meet risk levels that are considered widely acceptable. The proposed criteria are based on a detailed consideration of both societal and individual risk criteria. Two societal risk criteria were considered: the first based on a fixed expectation of the number of fatalities and the second based on a risk aversion function as characterized by a F /N relationship. Societal risk criteria were calibrated to match or exceed the average safety levels implied by current codes. Individual risk criteria were based on published tolerable levels. The target reliability levels corresponding to the three criteria are presented and a recommended set of targets is presented. DOI: 10.1115/1.3110017 In the last 30 years, reliability-based design principles have been used to develop limit states design codes in many industries e.g., nuclear containments, bridges, and buildings. These methods, which are still not used for Pipelines, have been shown to have significant benefits over allowable stress design methods, including improved safety, cost savings, and an ability to address unique design situations. To establish reliability-based methods as a viable design alternative for the design and assessment of Pipelines, the Pipeline Research Council International PRCI sponsored a multiyear project to develop the required technical information, communicate the approach to the industry and regulators, and facilitate its incorporation into relevant pipeline standards. The first step of this process was a technical project that was carried out by C-FER Technologies to develop a set of guidelines for reliability-based design and assessment RBDA of onshore Natural Gas Pipelines. The reliability-based design and assessment process adopted in these guidelines was described in Ref. 1
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an upheaval buckling limit state function for onshore Natural Gas Pipelines
2008 7th International Pipeline Conference Volume 3, 2008Co-Authors: Ian Matheson, Wenxing Zhou, Joe Zhou, Rick GailingAbstract:The reliability-based design and assessment (RBDA) methodology has gained increasing acceptance in the pipeline industry, largely due to a multi-year PRCI program aimed at establishing RBDA as a viable alternative for the design and assessment of onshore Natural Gas Pipelines. A key limit state of buried Pipelines that operate at elevated temperatures is upheaval buckling. The elevated temperatures generate large compressive axial forces that can cause Euler buckling susceptibility. The tendency to buckle is increased at vertical imperfections (i.e. a series of cold formed bends) that primarily occur due to topography. Upheaval buckling in itself is not an ultimate limit state but can lead to high strains, local buckling, high cycle fatigue, expensive remediation measures, and even loss of pressure integrity. The critical forces at which upheaval buckling occurs for typical hill-crest type imperfections present in onshore Pipelines cannot be readily predicted using analytical methods. A parametric study is therefore undertaken using non-linear finite element analyses to generate a matrix of upheaval buckling responses. The critical force for the onset of upheaval buckling is then developed using a series of empirical relationships to capture the influences of all key parameters. An upheaval buckling limit state function is subsequently developed by comparing the critical buckling force with applied compressive force, which is a function of operating pressure and temperature differential between the operating and tie-in conditions. The limit state function can be readily implemented in a reliability analysis framework to calculate the pipeline failure probability due to upheaval buckling.Copyright © 2008 by ASME
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Target Reliability Levels for Design and Assessment of Onshore Natural Gas Pipelines
2004 International Pipeline Conference Volumes 1 2 and 3, 2004Co-Authors: Maher Nessim, Wenxing Zhou, Joe Zhou, Brian Rothwell, Martin MclambAbstract:This paper proposes a set of reliability targets that can be used in the design and assessment of onshore Natural Gas Pipelines. The targets were developed as part of a PRCI-sponsored project that aims to establish reliability-based methods as a viable alternative for pipeline design and assessment. The proposed targets are calibrated to meet risk levels that are considered widely acceptable. The proposed criteria are based on a detailed consideration of both societal and individual risk criteria. Two societal risk criteria were considered; the first based on a fixed expectation of the number of fatalities and the second based on a risk aversion function as characterized by an F/N relationship. Societal risk criteria were calibrated to match or exceed the average safety levels implied by current codes. Individual risk criteria were based on published tolerable levels. The target reliability levels corresponding to the three criteria are presented and a recommended set of targets is presented.Copyright © 2004 by ASME
Biao Tang - One of the best experts on this subject based on the ideXlab platform.
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Chatter vibration phenomenon of pipeline inspection gauges (PIGs) in Natural Gas pipeline
Journal of Natural Gas Science and Engineering, 2015Co-Authors: Han Zhang, Xiaoxiao Zhu, Shuhai Liu, Shimin Zhang, Biao TangAbstract:Pipeline inspection gauges (PIGs) are needed for operations such as cleaning and internal inspection of the Natural Gas Pipelines to facilitate improvement in efficiency and safety. There is chatter vibrations appeared in PIGs when they run in the dry pipe with the wear of rubber sealing disc. Dry friction-induced self-excited vibration between sealing disc and pipe is the source of chatter vibration on PIG. In this paper, an experimental setup for measuring chatter vibration response signal of a typical bi-directional PIG running in a real dry steel pipe was implemented. The reason that cause self-excited vibration which manifest as chatter vibration on PIG, was explained through the analysis of classic dry-friction model. A self-excited vibration model based on LuGre friction model was proposed for better understanding of the phenomenon of chatter vibration during the process that PIG running through the Natural Gas pipeline, and the model was solved by MATLAB/SIMULINK. Our results show that the PIG runs in dry pipe with chatter vibration at a certain period within micro-vibrations in the single ladder period. Dry friction-induced self-excited vibration between sealing disc and pipe is the source of chatter vibration on PIG, and lead to the wear of PIG's sealing disc in Natural Gas pipeline; the negative damping of system in dry friction contact is the reason that causes self-excited vibration; the simulation of the numerical model can validate the PIG's self-excited phenomenon well. These results provide a better understanding of the complex behavior of PIG motion within Natural Gas Pipelines.
Farid Taheri - One of the best experts on this subject based on the ideXlab platform.
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Fluid-induced vibration of composite Natural Gas Pipelines
International Journal of Solids and Structures, 2004Co-Authors: G. P. Zou, N. Cheraghi, Farid TaheriAbstract:Abstract Advancements in materials bonding techniques have led to the use of reinforced composite Pipelines. The use of steel pipe with a fiber-reinforced composite over-wrap together has produced an exceptionally strong pipe with positive advantages in weight and corrosion resistively. Understanding the dynamic characteristics of this kind of sub-sea composite Pipelines, which often accommodate axial flow of Gas, and prediction of their response is of great interest. This paper presents a state-variable model developed for the analysis of fluid-induced vibration of composite pipeline systems. Simply supported, clamped and clamped-simply supported Pipelines are investigated. The influence of fluid’s Poisson ratio, the ratio of pipe radius to pipe-wall thickness, laminate layup, the ratio of liquid mass density to pipe-wall mass density, the fluid velocity, initial tension and fluid pressure are all considered. The results of our proposed methodology are compared with those of finite element analysis, using ANSYS software.
Maher Nessim - One of the best experts on this subject based on the ideXlab platform.
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optimal design of onshore Natural Gas Pipelines
Journal of Pressure Vessel Technology-transactions of The Asme, 2011Co-Authors: Wenxing Zhou, Maher NessimAbstract:The optimal design level for onshore Natural Gas Pipelines was explored through a hypothetical example, whereby the pipe wall thickness was assumed to be the sole design parameter. The probability distributions of the life-cycle costs of various candidate designs for the example pipeline were obtained using Monte-Carlo simulation. The life-cycle cost included the cost of failure due to equipment impact and external corrosion, and the cost of periodic maintenance actions for external corrosion. The cost of failure included both the cost of fatality and injury as well as the cost of property damage and value of lost product. The minimum expected life-cycle cost criterion and stochastic dominance rules were employed to determine the optimal design level. The allowable societal risk level was considered as a constraint in the optimal design selection. It was found that the Canadian Standard Association design leads to the minimum expected life-cycle cost and satisfies the allowable societal risk constraint as well. A set of optimal designs for a risk-averse decision maker was identified using the stochastic dominance rules. Both the ASME and CSA designs belong to the optimal design set and meet the allowable societal risk constraint.
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application of reliability based design and assessment to maintenance and protection decisions for Natural Gas Pipelines
2010 8th International Pipeline Conference Volume 4, 2010Co-Authors: Maher Nessim, Howard Kaho Yue, Joe ZhouAbstract:This paper describes a detailed assessment that was carried out to investigate the practical implications of using the Reliability Based Design and Assessment (RBDA) methodology, as described in Annex O of CSA Z662, as a basis for evaluating existing Pipelines and making decisions on maintenance planning and damage prevention strategies. Two key pipeline failure threats are addressed, namely corrosion and equipment impact. The assessment was based on a number of test cases covering a wide range of diameters, grades, pressures, location classes and corrosion severities. The reliability levels associated with these cases were calculated as a function of time and compared to the reliability targets. Cases that did not meet the targets were re-analyzed with increasingly enhanced maintenance measures until the targets were met. Maintenance actions considered included higher maintenance frequencies and more stringent repair criteria for corrosion, and enhancements to such parameters as right-of-way patrol frequency and condition, public awareness programs and dig notification response for equipment impact. The results demonstrate that the reliability targets can be met through the implementation of reasonable and practical maintenance measures for the cases considered. The impact of using RBDA on the expected failure rates is discussed. In addition, the diameter and class ranges of Pipelines requiring enhanced maintenance over the current norm are identified.Copyright © 2010 by ASME
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target reliability levels for design and assessment of onshore Natural Gas Pipelines
Journal of Pressure Vessel Technology-transactions of The Asme, 2009Co-Authors: Maher Nessim, Wenxing Zhou, Joe Zhou, Brian RothwellAbstract:This paper proposes a set of reliability targets that can be used in the design and assessment of onshore Natural Gas Pipelines. The targets were developed as part of a PRCI-sponsored project that aims to establish reliability-based methods as a viable alternative for pipeline design and assessment. The proposed targets are calibrated to meet risk levels that are considered widely acceptable. The proposed criteria are based on a detailed consideration of both societal and individual risk criteria. Two societal risk criteria were considered: the first based on a fixed expectation of the number of fatalities and the second based on a risk aversion function as characterized by a F /N relationship. Societal risk criteria were calibrated to match or exceed the average safety levels implied by current codes. Individual risk criteria were based on published tolerable levels. The target reliability levels corresponding to the three criteria are presented and a recommended set of targets is presented. DOI: 10.1115/1.3110017 In the last 30 years, reliability-based design principles have been used to develop limit states design codes in many industries e.g., nuclear containments, bridges, and buildings. These methods, which are still not used for Pipelines, have been shown to have significant benefits over allowable stress design methods, including improved safety, cost savings, and an ability to address unique design situations. To establish reliability-based methods as a viable design alternative for the design and assessment of Pipelines, the Pipeline Research Council International PRCI sponsored a multiyear project to develop the required technical information, communicate the approach to the industry and regulators, and facilitate its incorporation into relevant pipeline standards. The first step of this process was a technical project that was carried out by C-FER Technologies to develop a set of guidelines for reliability-based design and assessment RBDA of onshore Natural Gas Pipelines. The reliability-based design and assessment process adopted in these guidelines was described in Ref. 1
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Target Reliability Levels for Design and Assessment of Onshore Natural Gas Pipelines
2004 International Pipeline Conference Volumes 1 2 and 3, 2004Co-Authors: Maher Nessim, Wenxing Zhou, Joe Zhou, Brian Rothwell, Martin MclambAbstract:This paper proposes a set of reliability targets that can be used in the design and assessment of onshore Natural Gas Pipelines. The targets were developed as part of a PRCI-sponsored project that aims to establish reliability-based methods as a viable alternative for pipeline design and assessment. The proposed targets are calibrated to meet risk levels that are considered widely acceptable. The proposed criteria are based on a detailed consideration of both societal and individual risk criteria. Two societal risk criteria were considered; the first based on a fixed expectation of the number of fatalities and the second based on a risk aversion function as characterized by an F/N relationship. Societal risk criteria were calibrated to match or exceed the average safety levels implied by current codes. Individual risk criteria were based on published tolerable levels. The target reliability levels corresponding to the three criteria are presented and a recommended set of targets is presented.Copyright © 2004 by ASME
