The Experts below are selected from a list of 114 Experts worldwide ranked by ideXlab platform
F Prahl - One of the best experts on this subject based on the ideXlab platform.
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Maintenance Matters: Why a Healthy Wheel/Rail InterFace is Essential to Your Bottom Line
Mass Transit, 2005Co-Authors: F PrahlAbstract:Much has been written and done in the last ten years about creating and maintaining a healthy wheel/rail interFace. Before substantial changes were made to truck design and wheel and rail profiles, wheels lasted less than 20,000 miles; today's metro gets more than 350,000 miles of life from a wheel. The wheel/rail interFace is a small area, called the contact patch, and about the size of a dime, where the wheel meets the rail. A healthy wheel/rail interFace encompasses two things: ensures that the transverse wheel and rail profiles promote wheel set steering and spread wear evenly; and ensures that a friction management program is in place to lubricate the gauge Face and control friction at the top of rail. The article spells out that a complete friction management program means: lubrication of the gauge Face of the rail and the wheel Flange Face to bring the coefficient of friction to less than 0.2; controlling the friction coefficient on the top of the rail to a value between 0.3 and 0.4. The article also describes: how a healthy wheel/rail interFace improves system performance; how a healthy wheel/rail interFace is achieved; and how much can be saved by implementing an optimized wheel/rail interFace.
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maintenance matters why a healthy wheel rail interFace is essential to your bottom line
Mass Transit, 2005Co-Authors: F PrahlAbstract:Much has been written and done in the last ten years about creating and maintaining a healthy wheel/rail interFace. Before substantial changes were made to truck design and wheel and rail profiles, wheels lasted less than 20,000 miles; today's metro gets more than 350,000 miles of life from a wheel. The wheel/rail interFace is a small area, called the contact patch, and about the size of a dime, where the wheel meets the rail. A healthy wheel/rail interFace encompasses two things: ensures that the transverse wheel and rail profiles promote wheel set steering and spread wear evenly; and ensures that a friction management program is in place to lubricate the gauge Face and control friction at the top of rail. The article spells out that a complete friction management program means: lubrication of the gauge Face of the rail and the wheel Flange Face to bring the coefficient of friction to less than 0.2; controlling the friction coefficient on the top of the rail to a value between 0.3 and 0.4. The article also describes: how a healthy wheel/rail interFace improves system performance; how a healthy wheel/rail interFace is achieved; and how much can be saved by implementing an optimized wheel/rail interFace.
Leon K. Barry - One of the best experts on this subject based on the ideXlab platform.
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Evolution of a more reliable gasket for HF alkylation units
Sealing Technology, 2006Co-Authors: Julie L. Simonton, Leon K. BarryAbstract:The requirement to minimize Flange Face corrosion, overcome handling problems and improve sealing performance has led to the evolution of a new type of gasket for use in Hydrofluoric (HF) Alkylation Units to replace the standard spiral-wound type. The carbon steel Flange Face can now be protected from aggressive HF acid corrosion and the resulting iron fluoride scaling, accompanied by an increase in both the reliability and sealability of the Flange joints. The benefits include a reduction of costly Flange damage, potential leakage and the associated unit shutdowns required for repairs. This feature highlights the stages in the development of the new gasket design.
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Evolution of New Gasket Type Increases Reliability in HF Alkylation Unit
Volume 7: Operations Applications and Components, 2006Co-Authors: Julie L. Simonton, Leon K. BarryAbstract:The evolution of a new gasket type for use in Hydrofluoric (HF) Alkylation Units from the standard HF alkylation spiral-wound type gasket, (Monel windings, PTFE filler, and outer carbon steel ring) to a more specialized and robust gasket type was driven by a need to minimize Flange Face corrosion, overcome handling limitations and improve sealing performance. Protecting the carbon steel Flange Face from aggressive HF acid corrosion and resulting iron fluoride scaling, while increasing both the reliability and sealability of an HF connection was achieved, preventing costly Flange damage, potential leakage and associated unit shutdowns required for repairs. This paper highlights the journey taken by a major petrochemical company in determining the solution to improving gasket durability and leakage prevention, while significantly reducing Flange Face corrosion in their HF alkylation units.© 2006 ASME
M. Siddique - One of the best experts on this subject based on the ideXlab platform.
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Numerical simulation to study the effect of tack welds and root gap on welding deformations and residual stresses of a pipe-Flange joint
International Journal of Pressure Vessels and Piping, 2005Co-Authors: Muhammad Abid, M. SiddiqueAbstract:Abstract This paper presents a three dimensional sequentially coupled non-linear transient thermo-mechanical analysis to investigate the effect of tack weld positions and root gap on welding distortions and residual stresses in a pipe-Flange joint. Single-pass MIG welding for a single ‘V’ butt-weld joint geometry of a 100 mm diameter pipe with compatible weld-neck ANSI Flange class # 300 of low carbon steel is simulated. Two tack welds at circumferentially opposite locations, with the crucial effect of the tack weld's orientation from the weld start position is the focus in this study. Four different angular positions of tack welds (0 and 180°, 45 and 225°, 90 and 270°, 135 and 315°) are analyzed. In addition, four cases for root gaps (0.8, 1.2, 1.6, 2.0 mm) are considered and computational results are compared. A basic FE model is also validated with experimental data for temperature distribution and deformations. From the results, the axial displacement and tilt of the Flange Face are found to be strongly dependent on the tack weld orientation and weakly dependent on the root gap.
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Finite-element simulation of tack welds in girth welding of a pipe-Flange joint
Acta Mechanica, 2005Co-Authors: M. Abid, M. SiddiqueAbstract:Welding deformations play an important role in sealing capabilities and service life of welded pipe-Flange joints. A numerical procedure for modeling of tack welds in girth butt-welding of such joints is of vital importance for the prediction of transverse shrinkage and Flange Face deformation, which is directly related to the joint sealing capability. This paper presents a 3-D finite element simulation of a pipe-Flange joint to describe the numerical procedure for modeling of tack welds in circumferential joints. Sequentially coupled nonlinear transient thermo-mechanical analysis is performed to simulate Metal Inert Gas (MIG) welding. Single pass butt weld geometry with single “V” for 100 mm nominal diameter pipe with same sized weld neck type ANSI Flange of class no. 300 is used. Temperature dependent material properties are used and deposition of filler metal is obtained by element birth and death feature. The peak temperature of the tack during the butt-welding of the tacked model is concluded a key parameter for numerical prediction of deformations, whereas tack temperature has negligible effect on the residual stresses.
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Numerical simulation of the effect of constraints on welding deformations and residual stresses in a pipe-Flange joint
Modelling and Simulation in Materials Science and Engineering, 2005Co-Authors: Muhammad Abid, M. SiddiqueAbstract:This paper presents a detailed three-dimensional finite element (FE) study to investigate the effect of mechanical constraints on welding distortions and residual stresses in a pipe–Flange joint. The FE model of a pipe–Flange joint is subjected to sequentially couple nonlinear transient thermo-mechanical analysis to simulate complex welding phenomena. Single-pass gas metal arc welding for single 'V' butt-weld joint geometry of a 100 mm diameter pipe with compatible weld-neck ANSI Flange class #300 of low carbon steel is simulated. Two tack-welds at 90° and 270° from the weld start position are modelled. Four different constraint conditions representing the welding of unassembled joints, welding of assembled joints, welding of assembled joints with reflective symmetry and welding of perfectly constrained joints are analysed. To model the constraints and boundary conditions more realistically contact pairs are used between the matching surFaces of different structural components. Basic FE models are validated with experimental data for temperature distribution and deformations. Predicted welding distortions and residual stresses are compared and discussed in detail. From the results, axial displacement and tilt of the Flange Face are found to be strongly dependant on the constraint conditions. Minimum axial distortion on the Flange Face is found for rigidly clamped Flanges. However, residual stresses have a weak dependence on the constraints set.
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Prediction of welding distortions and residual stresses in a pipe–Flange joint using the finite element technique
Modelling and Simulation in Materials Science and Engineering, 2005Co-Authors: Muhammad Abid, M. Siddique, R A MuftiAbstract:This paper presents a comparative study of three- and two-dimensional axisymmetric finite element (FE) analyses of a welded pipe–Flange joint for residual stresses and deformations in order to identify their merits or demerits. Sequentially coupled thermal stress analysis is performed to simulate single pass metal inert gas welding. Butt weld geometry with a single 'V' for a 100 mm nominal diameter pipe and same sized weld neck type ANSI class #300 Flange is used. The heat input is modelled by using the Goldak double ellipsoidal heat source model. Temperature dependent material properties are used and deposition of filler metal is obtained by element birth and death feature. Both thermal and structural FE models are validated with experimental measurements. Residual stresses predicted by two-dimensional model are generally on the higher side and hence more conservative. However, we conclude that the three-dimensional FE model is preferable for the prediction of Flange Face distortion since it is a vital parameter for Flange joint performance.
Julie L. Simonton - One of the best experts on this subject based on the ideXlab platform.
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Evolution of a more reliable gasket for HF alkylation units
Sealing Technology, 2006Co-Authors: Julie L. Simonton, Leon K. BarryAbstract:The requirement to minimize Flange Face corrosion, overcome handling problems and improve sealing performance has led to the evolution of a new type of gasket for use in Hydrofluoric (HF) Alkylation Units to replace the standard spiral-wound type. The carbon steel Flange Face can now be protected from aggressive HF acid corrosion and the resulting iron fluoride scaling, accompanied by an increase in both the reliability and sealability of the Flange joints. The benefits include a reduction of costly Flange damage, potential leakage and the associated unit shutdowns required for repairs. This feature highlights the stages in the development of the new gasket design.
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Evolution of New Gasket Type Increases Reliability in HF Alkylation Unit
Volume 7: Operations Applications and Components, 2006Co-Authors: Julie L. Simonton, Leon K. BarryAbstract:The evolution of a new gasket type for use in Hydrofluoric (HF) Alkylation Units from the standard HF alkylation spiral-wound type gasket, (Monel windings, PTFE filler, and outer carbon steel ring) to a more specialized and robust gasket type was driven by a need to minimize Flange Face corrosion, overcome handling limitations and improve sealing performance. Protecting the carbon steel Flange Face from aggressive HF acid corrosion and resulting iron fluoride scaling, while increasing both the reliability and sealability of an HF connection was achieved, preventing costly Flange damage, potential leakage and associated unit shutdowns required for repairs. This paper highlights the journey taken by a major petrochemical company in determining the solution to improving gasket durability and leakage prevention, while significantly reducing Flange Face corrosion in their HF alkylation units.© 2006 ASME
A. Dukuze - One of the best experts on this subject based on the ideXlab platform.
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Experimental Study of Offset HSS Connections
Journal of Structural Engineering-asce, 2006Co-Authors: J. L. Dawe, R. Zhang, A. DukuzeAbstract:The structural behavior of welded hollow structural sections (HSS) connections in which one member is laterally offset from the plane of a connection is investigated experimentally and compared with corresponding planar connections. Sixteen full-scale test connections, consisting of either T or N configurations fabricated from class C HSS, were tested at load levels comparable with those expected to occur in actual trusses. In all cases the mode of failure was by localized large deflections of the Flange Face and sidewalls of the compression chord. It was found that in the case of T connections, the reduction in capacity due to offsetting a member by as much as 17% of the width of the chord member from the central plane of the truss was marginal. N configurations, whose diagonal members were offset by 8% of the width of the chord member, showed a slight increase in ultimate strength. The design values obtained using both AISC LRFD and CIDECT specifications are compared with the test results where appropriate.
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Experimental Study of Offset HSS Connections
Journal of Structural Engineering-asce, 2006Co-Authors: J. L. Dawe, R. Zhang, A. DukuzeAbstract:The structural behavior of welded hollow structural sections (HSS) connections in which one member is laterally offset from the plane of a connection is investigated experimentally and compared with corresponding planar connections. Sixteen full-scale test connections, consisting of either T or N configurations fabricated from class C HSS, were tested at load levels comparable with those expected to occur in actual trusses. In all cases the mode of failure was by localized large deflections of the Flange Face and sidewalls of the compression chord. It was found that in the case of T connections, the reduction in capacity due to offsetting a member by as much as 17% of the width of the chord member from the central plane of the truss was marginal. N configurations, whose diagonal members were offset by 8% of the width of the chord member, showed a slight increase in ultimate strength. The design values obtained using both AISC LRFD and CIDECT specifications are compared with the test results where appropriate.