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Abdel-hakim Bouzid - One of the best experts on this subject based on the ideXlab platform.
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Stress Analysis of Packed Stuffing-Boxes
Journal of Pressure Vessel Technology-transactions of The Asme, 2015Co-Authors: Mehdi Kazeminia, Abdel-hakim BouzidAbstract:Packed Stuffing-Boxes are mechanical sealing systems that are extensively used in pressurized equipment such as valves and pumps. Yet there is no standard design procedure in use to verify their mechanical integrity and leak tightness. It is only recently that standard test procedures to qualify packing materials have been suggested for adoption in both North America and Europe. Nonetheless the assessment of the structural integrity of the housing requires a well-documented design procedure to insure safe use of packed Stuffing-Boxes. While the packing contact stress with the side walls is predictable using existing models there is no analytical methodology to verify the stresses and strains in the Stuffing-Box housing. This paper presents an analytical model that analyzes the stresses and strains of the Stuffing-Box components including the packing rings. The developed model is validated both numerically using FEM (finite element method) and experimentally on an instrumented packed Stuffing-Box rig that is specially designed to measure the structural integrity and leakage tightness of different packing materials.
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Analysis of Stresses and Strains in Packed Stuffing-Boxes
Volume 5: High-Pressure Technology; ASME NDE Division; 22nd Scavuzzo Student Paper Symposium and Competition, 2014Co-Authors: Mehdi Kazeminia, Abdel-hakim BouzidAbstract:Packed Stuffing-Boxes are mechanical sealing systems that are extensively used in pressurized valves and pumps. Yet there is no standard design procedure that could be used to verify their mechanical integrity and leak tightness. It is only recently that standard test procedures to qualify the packing material have been suggested for adoption in both North America and Europe. While the packing contact stress with the side walls is predictable using existing models there is no analytical methodology to verify the stresses and strains in the Stuffing-Box housing.This paper presents an analytical model that analyzes the stresses and strains of all the Stuffing Box components including the packing rings. The developed model will be validated both numerically using FEM and experimentally on an instrumented packed Stuffing Box rig that is specially designed to test the mechanical and leakage performance of different packing materials.Copyright © 2014 by ASME
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Analytical and Numerical Evaluation of the Axial Stress Distribution of Two Soft-Packed Stuffing-Box Configurations
Volume 3B: Oil and Gas Applications; Organic Rankine Cycle Power Systems; Supercritical CO2 Power Cycles; Wind Energy, 2014Co-Authors: Mehdi Kazeminia, Abdel-hakim BouzidAbstract:Stuffing-Box packed valves which confine high-pressure fluids are often subjected to leakage failure. The lack of a design procedure and the vulnerability of packing ring sealing materials to withstand different operating conditions are the root cause of the problem. The sealing performance of valves with packed Stuffing-Box depends on the ability of the assembly to maintain a minimum threshold contact pressure between the packing and the stem and the packing and the housing throughout service operation. The distribution of the contact stresses in the packing materials is a key parameter to efficient sealing performance. This study presents a contact stress modeling study of two different design configurations that are helpful to produce a uniform distribution of the contact stress. The first model is based on the introduction of a variable gap between the packing and the side walls. The second model is based on a multistage loading of the packing rings. The two developed analytical models are validated by comparison with the numerical simulation using FE method and the results show a good agreement. The two design configurations can be used to improve valve sealing performance.
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Creep Constitutive Law of Packing Materials Based on Relaxation Tests
Journal of Tribology, 2012Co-Authors: Mohammed Diany, Abdel-hakim BouzidAbstract:The tightness of valves, compressors and pumps is ensured by superposed braided rings installed in a system of Stuffing-Box. The nature of the packings material and structure, which is like a rectangular braided cord, influences the proper Stuffing-Box assembly behavior. During installation, a minimum compressive load is required to ensure a minimum level of tightness. A fairly large percentage of this axial compression load is transferred to the radial direction to generate the contact pressures at the packing-stem and packing-housing interfaces necessary for sealing. The packing is considered in several studies as a viscoelastic material with its creep-relaxation behavior assumed as one-dimensional rheological model. In the present work, relaxation tests in a test-bunch containing all the components of the packed Stuffing-Box, are carried out to define a creep constitutive law for packing braids of different materials. Based on three-dimensional compression tests the developed method is applied to three different packing materials. Copyright © 2011 by ASME.
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Creep Constitutive Law of Packing Materials Based on Relaxation Tests
Journal of Tribology-transactions of The Asme, 2012Co-Authors: Mohammed Diany, Abdel-hakim BouzidAbstract:The tightness of valves, compressors and pumps is ensured by superposed braided rings installed in a Stuffing-Box system. The nature of the packing material and structure, which is like a rectangular braided cord, influences the proper Stuffing-Box assembly behavior. During installation, a minimum compressive load is required to ensure a minimum level of tightness. A fairly large percentage of this axial compression load is transferred to the radial direction to generate the contact pressures at the packing-stem and packing-housing interfaces necessary for sealing.The packing is considered in several studies as a viscoelastic material with its creep-relaxation behavior assumed as one-dimensional rheological model. In the present work, relaxation tests in a test-bunch containing all the components of the packed Stuffing-Box, are carried out to define a creep constitutive law for packing braids of different materials. Based on three-dimensional compression tests the developed method is applied to three different packing materials.
Mohammed Diany - One of the best experts on this subject based on the ideXlab platform.
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Creep Constitutive Law of Packing Materials Based on Relaxation Tests
Journal of Tribology-transactions of The Asme, 2012Co-Authors: Mohammed Diany, Abdel-hakim BouzidAbstract:The tightness of valves, compressors and pumps is ensured by superposed braided rings installed in a Stuffing-Box system. The nature of the packing material and structure, which is like a rectangular braided cord, influences the proper Stuffing-Box assembly behavior. During installation, a minimum compressive load is required to ensure a minimum level of tightness. A fairly large percentage of this axial compression load is transferred to the radial direction to generate the contact pressures at the packing-stem and packing-housing interfaces necessary for sealing.The packing is considered in several studies as a viscoelastic material with its creep-relaxation behavior assumed as one-dimensional rheological model. In the present work, relaxation tests in a test-bunch containing all the components of the packed Stuffing-Box, are carried out to define a creep constitutive law for packing braids of different materials. Based on three-dimensional compression tests the developed method is applied to three different packing materials.
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Creep Constitutive Law of Packing Materials Based on Relaxation Tests
Journal of Tribology, 2012Co-Authors: Mohammed Diany, Abdel-hakim BouzidAbstract:The tightness of valves, compressors and pumps is ensured by superposed braided rings installed in a system of Stuffing-Box. The nature of the packings material and structure, which is like a rectangular braided cord, influences the proper Stuffing-Box assembly behavior. During installation, a minimum compressive load is required to ensure a minimum level of tightness. A fairly large percentage of this axial compression load is transferred to the radial direction to generate the contact pressures at the packing-stem and packing-housing interfaces necessary for sealing. The packing is considered in several studies as a viscoelastic material with its creep-relaxation behavior assumed as one-dimensional rheological model. In the present work, relaxation tests in a test-bunch containing all the components of the packed Stuffing-Box, are carried out to define a creep constitutive law for packing braids of different materials. Based on three-dimensional compression tests the developed method is applied to three different packing materials. Copyright © 2011 by ASME.
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An Experimental-Numerical Procedure for Stuffing Box Packing Characterization and Leak Tests
Journal of Tribology-transactions of The Asme, 2010Co-Authors: Mohammed Diany, Abdel-hakim BouzidAbstract:The sealing of valve stems is ensured by the traditional systems of packed Stuffing Boxes. The performance of this type of sealing system, which is also used in rotating equipment, is dependent on the radial contact pressures generated by the packing axial compression. The mechanical behavior of a packing seal is characterized by the transmission ratio of the radial stress over the axial stress known as the lateral pressure coefficient, which is one of the required parameters used to select packing seals. However, the modeling of the packed Stuffing Box requires the knowledge of other packing seal mechanical characteristics such as compression modulus and Poisson's ratio. In this paper, the mechanical characteristics of packing seals are obtained using a hybrid experimental-numerical procedure. The experimental study is carried out on an instrumented Stuffing Box packing test bench. The tests results of the experiments are coupled to the ones obtained by a finite element simulation of the test rig to determine the packing seal mechanical characteristics. Two packing types are used: one based on Teflon and the other one based on flexible graphite. In addition, leak rates are measured.for different axial compressive stresses and gas pressures in order to estimate the tightness performance of such seals.
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An Experimental-Numerical Procedure for Stuffing Box Packing Characterization
ASME 2010 Pressure Vessels and Piping Conference: Volume 2, 2010Co-Authors: Mohammed Diany, Abdel-hakim BouzidAbstract:The sealing of valve stems is ensured by the traditional systems of packed Stuffing Boxes. The performance of this type of sealing system used also in rotating equipment is dependent on the radial contact pressures generated by the packing axial compression. The mechanical behavior of a packing seal is characterized by the transmission ratio of the axial stress over the radial stress known as the lateral pressure coefficient which is one of the required characteristic used to select packing seals. However, the modeling of the packed Stuffing Box requires the knowledge of some mechanical characteristics other than the lateral pressure coefficient. In this paper, the mechanical characteristics of packing seals are obtained using a hybrid experimental-numerical procedure. The experimental study is carried out on an instrumented Stuffing Box packing test bench. The tests results of the experiments are coupled to the ones obtained by a finite element simulation of the test rig to determine the packing seal mechanical characteristics. Two packing types are used; one based on Teflon and the other one based on flexible graphite.Copyright © 2010 by ASME
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Analytical evaluation of stresses and displacements of Stuffing-Box packing based on a flexibility analysis
Tribology International, 2009Co-Authors: Mohammed Diany, Abdel-hakim BouzidAbstract:Abstract Although Stuffing Boxes are old systems used to ensure stem valve sealing, the analytical developments of the stresses and the displacements generated during assembly and operation are very limited and seldom verified and the studies carried out on these devices are either restricted or not accessible. Moreover, even with the evolution of calculation and simulation means, studies based on numerical models are rare. This work proposes a simplified analytical approach, using the theory of thick-walled cylinders to analyse the stresses and displacements in Stuffing Box systems. The magnitude and distribution of the lateral contact pressures generated at the housing–packing–stem interfaces as a result of the application of the gland axial stress are determined as a function of the radial flexibility of the different components involved. The results of the developed approach are compared and validated against the more accurate finite elements axisymmetric models.
Jose´ C. Veiga - One of the best experts on this subject based on the ideXlab platform.
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Evaluation of Packing Drag on Knife Valves for Actuator Sizing
Volume 2: Computer Technology and Bolted Joints, 2015Co-Authors: André F. Garcia, Jose´ C. Veiga, Luiz P. Romano, Carlos D. GirãoAbstract:Knife Gate Valves (KGV) are one of many types of valves available in the fluid control industry. Initially used for handling slurry, KGV gradually became popular in many other engineering applications. Most of these valves are characterized by a particular Stuffing Box shape that require a rectangular packing installation, not so conventional in valve sealing designs where packings are installed around a cylindrical stem. The actuation methods used with KGV’s are many, from purely mechanical to pneumatic and electrically actuated. The design of those actuators is most dependent of the friction generated by the packing and, therefore, knowing more accurately how packing stress influences gate drag would be of much interest. The intent of this paper is to introduce a testing device and protocol to evaluate how packing friction behaves among distinct packing materials and to establish relations between packing gland load and actuator resistive force. Moreover, values of drag force for the different packing styles are determined with corresponding gland load.Copyright © 2015 by ASME
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The Influence on the Stuffing Box of the Forces Generated by Packing Thermal Expansion
Volume 2: Computer Technology and Bolted Joints, 2011Co-Authors: Jose´ C. Veiga, André S. Carmo, Carlos D. Girão, Carlos F. CipolattiAbstract:This paper introduces a test device and a protocol that simulates a Stuffing Box to evaluate the packing expansion under different temperatures. This test device enables the measurement of axial forces at the bottom of the Stuffing Box and at the gland follower, the torque generated upon shaft turning and the influence of the thermal expansion on these measurements. It also enables comparisons between different braiding yarns materials such as e-PTFE, e-PTFE with fillers, Flexible Graphite and others. Test results showing these comparisons and correlations are reported.Copyright © 2011 by ASME
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The Influence of Different Braided Packing Materials and Number of Rings on Stem Torque and Sealability
Volume 2: Computer Applications Technology and Bolted Joints, 2009Co-Authors: Jose´ C. Veiga, Carlos D. Gira˜o, Carlos F. CipolattiAbstract:This paper introduces a test device and a protocol that simulates packing performance in different size valve Stuffing Boxes and stems. This test device enables measurement of braided packing compression, relaxation, axial force at the bottom of the Stuffing Box, the torque generated upon stem turning and the influence of the number of packing rings on stem torque. It also enables comparisons between different braiding yarns materials, impregnations and correlations with seating stress, stem torque and sealability. Test results showing these comparisons and correlations are reported.
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VALVE PACKINGS SEATING STRESS
Volume 2: Computer Applications Technology and Bolted Joints, 2008Co-Authors: Jose´ C. Veiga, Carlos D. Girão, Carlos F. Cipolatti, Leandro Ascenco, Fabio CastroAbstract:This paper studies the seating stress required to assure the sealability in valve stems used in high pressure steam service. A test device that simulates the valve Stuffing Box and a test protocol are proposed. Actual field tests conducted according to a procedure developed from the laboratory tests are also reported.Copyright © 2008 by ASME
Mehdi Kazeminia - One of the best experts on this subject based on the ideXlab platform.
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Characterization and Modelling of Packed-Stuffing Boxes
2017Co-Authors: Mehdi KazeminiaAbstract:The global concern of the climate and environmental changes and the increase of greenhouse gases has led to the adoption of strict regulations on fugitive emissions. The industrial sector contributes significantly to the production of fugitive emissions. Aaccording to the Environmental Protection Agency (EPA), 60% of emissions from equipment devices are attributed to valves. As a result, standard organizations such as ISO and API developed new standard test procedures to qualify the sealing performance of valves. However, there remains lack of However, there remains lack of standard design procedure for Stuffing-Box valves and selection of proper materials to improve their sealing performance. The main objective of this thesis is to introduce a procedure to characterize sealing performance and develop a standard design procedure for Stuffing-Box valves. In order to fulfill these objectives, theoretical models supported by a series of experimental tests were constructed to characterize the sealing performance and evaluate the integrity of Stuffing-Boxes. The experimental investigations were carried out on a test bench equipped with high accuracy instrumentation to practically simulate real applications and to record the sealing behavior of the systems. Packing rings made of flexible graphite (which were used as a sealant), various levels of compression stress, and three different fluids (helium, argon and nitrogen) were applied in the test plan. The theoretical model for mechanical integrity was a combination of theories; thick cylinders (Lame) and the theory for beams on elastic foundations. Furthermore, three different approaches (Modified Darcy, concentric cylinders and capillary models) were used to characterize the porosity and its influence on the sealing performance of packing rings. The results, when considering the significant agreement between the theory and test measurements, proved the reliability of the proposed procedures for the characterization of mechanical integrity and sealing performance of Stuffing-Boxes valves. The results also demonstrated that an open and tapered angle on the internal wall of the housing is useful in improving the sealing performance of a Stuffing-Box.
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Stress Analysis of Packed Stuffing-Boxes
Journal of Pressure Vessel Technology-transactions of The Asme, 2015Co-Authors: Mehdi Kazeminia, Abdel-hakim BouzidAbstract:Packed Stuffing-Boxes are mechanical sealing systems that are extensively used in pressurized equipment such as valves and pumps. Yet there is no standard design procedure in use to verify their mechanical integrity and leak tightness. It is only recently that standard test procedures to qualify packing materials have been suggested for adoption in both North America and Europe. Nonetheless the assessment of the structural integrity of the housing requires a well-documented design procedure to insure safe use of packed Stuffing-Boxes. While the packing contact stress with the side walls is predictable using existing models there is no analytical methodology to verify the stresses and strains in the Stuffing-Box housing. This paper presents an analytical model that analyzes the stresses and strains of the Stuffing-Box components including the packing rings. The developed model is validated both numerically using FEM (finite element method) and experimentally on an instrumented packed Stuffing-Box rig that is specially designed to measure the structural integrity and leakage tightness of different packing materials.
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Analysis of Stresses and Strains in Packed Stuffing-Boxes
Volume 5: High-Pressure Technology; ASME NDE Division; 22nd Scavuzzo Student Paper Symposium and Competition, 2014Co-Authors: Mehdi Kazeminia, Abdel-hakim BouzidAbstract:Packed Stuffing-Boxes are mechanical sealing systems that are extensively used in pressurized valves and pumps. Yet there is no standard design procedure that could be used to verify their mechanical integrity and leak tightness. It is only recently that standard test procedures to qualify the packing material have been suggested for adoption in both North America and Europe. While the packing contact stress with the side walls is predictable using existing models there is no analytical methodology to verify the stresses and strains in the Stuffing-Box housing.This paper presents an analytical model that analyzes the stresses and strains of all the Stuffing Box components including the packing rings. The developed model will be validated both numerically using FEM and experimentally on an instrumented packed Stuffing Box rig that is specially designed to test the mechanical and leakage performance of different packing materials.Copyright © 2014 by ASME
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Analytical and Numerical Evaluation of the Axial Stress Distribution of Two Soft-Packed Stuffing-Box Configurations
Volume 3B: Oil and Gas Applications; Organic Rankine Cycle Power Systems; Supercritical CO2 Power Cycles; Wind Energy, 2014Co-Authors: Mehdi Kazeminia, Abdel-hakim BouzidAbstract:Stuffing-Box packed valves which confine high-pressure fluids are often subjected to leakage failure. The lack of a design procedure and the vulnerability of packing ring sealing materials to withstand different operating conditions are the root cause of the problem. The sealing performance of valves with packed Stuffing-Box depends on the ability of the assembly to maintain a minimum threshold contact pressure between the packing and the stem and the packing and the housing throughout service operation. The distribution of the contact stresses in the packing materials is a key parameter to efficient sealing performance. This study presents a contact stress modeling study of two different design configurations that are helpful to produce a uniform distribution of the contact stress. The first model is based on the introduction of a variable gap between the packing and the side walls. The second model is based on a multistage loading of the packing rings. The two developed analytical models are validated by comparison with the numerical simulation using FE method and the results show a good agreement. The two design configurations can be used to improve valve sealing performance.
Carlos F. Cipolatti - One of the best experts on this subject based on the ideXlab platform.
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The Influence on the Stuffing Box of the Forces Generated by Packing Thermal Expansion
Volume 2: Computer Technology and Bolted Joints, 2011Co-Authors: Jose´ C. Veiga, André S. Carmo, Carlos D. Girão, Carlos F. CipolattiAbstract:This paper introduces a test device and a protocol that simulates a Stuffing Box to evaluate the packing expansion under different temperatures. This test device enables the measurement of axial forces at the bottom of the Stuffing Box and at the gland follower, the torque generated upon shaft turning and the influence of the thermal expansion on these measurements. It also enables comparisons between different braiding yarns materials such as e-PTFE, e-PTFE with fillers, Flexible Graphite and others. Test results showing these comparisons and correlations are reported.Copyright © 2011 by ASME
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The Influence of Different Braided Packing Materials and Number of Rings on Stem Torque and Sealability
Volume 2: Computer Applications Technology and Bolted Joints, 2009Co-Authors: Jose´ C. Veiga, Carlos D. Gira˜o, Carlos F. CipolattiAbstract:This paper introduces a test device and a protocol that simulates packing performance in different size valve Stuffing Boxes and stems. This test device enables measurement of braided packing compression, relaxation, axial force at the bottom of the Stuffing Box, the torque generated upon stem turning and the influence of the number of packing rings on stem torque. It also enables comparisons between different braiding yarns materials, impregnations and correlations with seating stress, stem torque and sealability. Test results showing these comparisons and correlations are reported.
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VALVE PACKINGS SEATING STRESS
Volume 2: Computer Applications Technology and Bolted Joints, 2008Co-Authors: Jose´ C. Veiga, Carlos D. Girão, Carlos F. Cipolatti, Leandro Ascenco, Fabio CastroAbstract:This paper studies the seating stress required to assure the sealability in valve stems used in high pressure steam service. A test device that simulates the valve Stuffing Box and a test protocol are proposed. Actual field tests conducted according to a procedure developed from the laboratory tests are also reported.Copyright © 2008 by ASME
