The Experts below are selected from a list of 39 Experts worldwide ranked by ideXlab platform

R. E. Volker - One of the best experts on this subject based on the ideXlab platform.

  • Round buoyant jet in shallow water: bed shear velocity
    Journal of Hydraulic Research, 1994
    Co-Authors: A. J. Johnston, N. Nguyen, R. E. Volker
    Abstract:

    SummaryThis paper examines the mixing processes that develop when a buoyant jet from a round outfall Pipe Enters a shallow moving body of water in a direction perpendicular to the current and focuses on the role played by the bed shear velocity developed in the receiving water. Different velocity profiles in the receiving water were produced using a triggering fence to modify the profile and hence the bed shear velocity. These changes simulated variations in the roughness of the bed. The results of an experimental study are presented where the effects related to the magnitude of the current, the bed shear velocity, and the locations of the free and bed boundaries on the jet mixing parameters are quantified. Findings are outlined which show that the dilutions of buoyant jets are significantly influenced by these parameters. Other mixing features are discussed including a “total cross sectional dilution” parameter and a novel width parameter. The role played by the Coanda Effect in influencing the mixing of...

  • Round Buoyant Jet Entering Shallow Water in Motion
    Journal of Hydraulic Engineering, 1993
    Co-Authors: A. J. Johnston, N. Nguyen, R. E. Volker
    Abstract:

    This paper focuses on the mixing processes that develop when a buoyant jet from a round outfall Pipe Enters a shallow moving body of water. Results from a detailed experimental study quantify the effects on jet mixing produced when a current is imposed on shallow receiving water. Findings show that the dilutions of buoyant jets entering these environments are significantly different from those discharging into unconfined (deep‐water) conditions. Mixing features discussed include the application of scaling relationships in collapsing integral parameter data and the role played by the Coanda effect in influencing the mixing of jets. Patterns of jet path, centerline dilution, total dilution, horizontal and vertical half widths, and a novel width parameter are described and compared with shallow stationary and current affected deep‐water results.

Steven P. Nichols - One of the best experts on this subject based on the ideXlab platform.

  • Advances in Homopolar Welding of API Line Pipe for Deepwater Applications
    SPE Production & Facilities, 1999
    Co-Authors: R.s. Hudson, R.w. Carnes, Steven P. Nichols
    Abstract:

    Summary The University of Texas at Austin Center for Electromechanics is conducting a research program, funded by six oil companies, two industrial contractors, and two government agencies, to study homopolar welding of line Pipe for J-Lay applications. In 1995, the third year of the five year research program, the set of weld parameters, those input variables used to control weld performance and quality, was expanded to include joint geometry, with dramatic improvement in the mechanical properties of two HSLA nominal 3-in. line Pipe materials: X60 and X65. These improvements increased the Charpy V-Notch impact toughness properties to near parent metal values, while maintaining acceptable strength. After demonstrating repeatable performance with the new parameters, new research focused on real world effects including tolerancing the parameters and evaluating the effect of poor fit up resulting from misalignment and rough and wavy interfaces. During the final year of the research program, the Pipe welding program has scaled up to 12-in. nominal line Pipe, a seven-fold increase in the cross-sectional area. The paper will cover the basics of homopolar welding (HPW), weld parameters and modifications, the effects of these changes on real time process data, mechanical properties, weld upset profile, HPW metallurgy, and the studies of real world effects. Results from HPW of 12-in. Pipe will also be presented. Introduction Homopolar welding (HPW) is a resistance forge welding process that uses the high amperage direct current discharge from a homopolar generator (HPG) to produce full circumferential Pipe welds in under 5 sec without using filler metal. HPW is being developed as a candidate single station, or "one shot," welding method for J-Lay Pipe laying. With the continued discovery of deepwater oil fields, the J-Lay method was developed to overcome the problem of buckling, occurring when the Pipe Enters the water from conventional S-Lay barges. J-Lay requires the single station welding process because the Pipe is welded vertically then lowered directly into the water. 1 Besides enabling Pipe laying in deepwater fields, the reduced cycle time per weld should lower the cost.2,3 Homopolar Offshore Pipeline Welding Research Program. A consortium of six oil companies (Amoco, BP, Exxon, Mobil, Shell, and Texaco) and a welding contractor (CRC-Evans) funded this joint industry program (JIP) at The University of Texas at Austin Center for Electromechanics, beginning in February 1993, to develop homopolar welding for J-Lay applications. Since that time, an additional equipment contractor (Parker Kinetic Design) and two federal agencies (the Office of Pipeline Safety of the Department of Transportation and the Mineral Management Services of the Department of Interior) have joined the program. The major objectives of the research program have been achieved. They include:optimize weld parameters for homopolar welding 3-in. HSLA API 5L line Pipe;investigate a range of materials with varying strength, wall thickness, composition, heat treatment, and manufacturing method;produce 3-in. welds with acceptable mechanical properties;improve the finished weld profile;design and build a laboratory welding fixture for joining 12-in. Schedule 80 line Pipe;demonstrate homopolar weldability of 12-in. Pipe;transfer technology in preparation for commercialization of HPW;develop an NDE program. One of the first requirements of the research program was developing an acceptance criteria for the welding program that was compatible with existing welding codes. John Hammond, with BP Exploration of London, developed this document, known as the "Hammond Criteria," which has served to guide the research through the development of a new welding process.4 Recent Advances. During the second and third year of the program, the weld parameters, those inputs used to control the welding process and weld quality, were significantly expanded on 3-in. Pipe welds as a new approach to welding using HPGs was investigated. The results were dramatic: besides producing higher, more uniform impact toughness in two high strength materials, process robustness increased substantially. During the fourth and current years, preparation and production of 12-in. Pipe welds are underway. Homopolar Welding A homopolar welding system consists of a homopolar generator and a hydraulic welding fixture. The homopolar generator is an inertial energy storage device that provides the mega-ampere direct current (DC) electrical pulse to resistively heat the joint for welding. The hydraulic welding fixture delivers the current to the workpiece, provides the forging force to upset the heated interface material, and maintains alignment during upset. Homopolar Generators. Homopolar generators are simple industrial machines that convert the stored rotational kinetic energy of its spinning rotor to direct current electric energy by electromagnetic induction. The low voltage, high current discharge, characteristic of these machines, makes them well suited for electrical resistive heating. A magnetic field imposed across the electrically conductive rotor produces a voltage and supplies a characteristic current pulse when connected to a discharge circuit. The principle of electromagnetic induction is demonstrated in the Faraday disk, or more fundamentally by moving a straight conductor though a magnetic field.5 HPG Parameters. The parameters governing the HPG output current are the discharge speed and the field current magnitude. The discharge speed determines the magnitude of the stored inertial energy. The field current magnitude, which induces the magnetic field across the rotor, controls the shape of the current pulse. Higher field current settings shorten the pulse length and increase the magnitude of the peak discharge current. 6

  • Advances in Homopolar Welding of API LinePipe for Deepwater Applications
    All Days, 1997
    Co-Authors: R.s. Hudson, R.w. Carnes, Steven P. Nichols
    Abstract:

    Abstract The University of Texas at Austin Center for Electromechanics is conducting a research program, funded by six oil companies, two industrial contractors, and two government agencies, to study homopolar welding of line Pipe for J-Lay applications. In 1995, the third year of the five year research program, the set of weld parameters, those input variables used to control weld performance and quality, was expanded to include joint geometry, with dramatic improvement in the mechanical properties of two HSLA nominal 3-inch line Pipe materials, X60 and X65. These improvements increased the Charpy V-Notch impact toughness properties to near parent metal values, while maintaining acceptable strength. After demonstrating repeatable performance with the new parameters, new research focused on real world effects including tolerancing the parameters and evaluating the effect of poor fit up resulting from misalignment and rough and wavy interfaces. During the final year of the research program, the Pipe welding program has scaled up to 12-inch nominal line Pipe, a sevenfold increase in cross-sectional area. The paper will cover basics of homopolar welding, weld parameters and modifications, effects of these changes on real time process data, mechanical properties, weld upset profile, HPW metallurgy, and the studies of real world effects. Results from homopolar welding of 12-inch Pipe will also be presented. Introduction Homopolar Welding (HPW) is a resistance forge welding process that uses the high amperage direct current discharge from a Homopolar Generator (HPG) to produce full circumferential Pipe welds in under five seconds without using filler metal. HPW is being developed as a candidate single station, or "one shot", welding method for J-lay Pipe laying. With the continued discovery of deep water oil fields, the J-Lay method was developed to overcome the problem of buckling, occurring when the Pipe Enters the water from conventional S-lay barges. J-lay requires single station welding process because the Pipe is welded vertically then lowered directly into the water. Besides enabling Pipe laying in deep water fields, the reduced cycle time per weld should lower the cost. Homopolar Offshore Pipeline Welding Research Program. A consortium of six oil companies (Amoco, BP, Exxon, Mobil, Shell, and Texaco) and a welding contractor (CRC-Evans) funded this joint industry program (JIP) at The University of Texas at Austin Center for Electromechanics, beginning in February 1993, to develop homopolar welding for J-Lay applications. Since that time, an additional equipment contractor (Parker Kinetic Design) and two federal agencies (the Office of Pipeline Safety of the DOT and the Mineral Management Services of the DOl) have joined the program. The major objectives of the research program have been achieved. They include:–optimize weld parameters for homopolar welding 3-inch HSLA API 5L line Pipe–investigate a range of materials with varying strength, wall thickness, composition, heat treatment and manufacturing method–produce 3-inch welds with acceptable mechanical properties - improve the finished weld profile–design and build a laboratory welding fixture for joining 12-inch Schedule 80 line Pipe–demonstrate homopolar weldability of 12-inch Pipe–transfer technology in preparation for commercialization of HPW–develop an NDE program One of the first requirements of the research program was developing an acceptance criteria for the welding program that was compatible with existing welding codes. John Hammond, with BP Exploration of London, developed this document, known as the "Hammond Criteria", which has served to guide the research through the development of a new welding process. P. 953

A. J. Johnston - One of the best experts on this subject based on the ideXlab platform.

  • Round buoyant jet in shallow water: bed shear velocity
    Journal of Hydraulic Research, 1994
    Co-Authors: A. J. Johnston, N. Nguyen, R. E. Volker
    Abstract:

    SummaryThis paper examines the mixing processes that develop when a buoyant jet from a round outfall Pipe Enters a shallow moving body of water in a direction perpendicular to the current and focuses on the role played by the bed shear velocity developed in the receiving water. Different velocity profiles in the receiving water were produced using a triggering fence to modify the profile and hence the bed shear velocity. These changes simulated variations in the roughness of the bed. The results of an experimental study are presented where the effects related to the magnitude of the current, the bed shear velocity, and the locations of the free and bed boundaries on the jet mixing parameters are quantified. Findings are outlined which show that the dilutions of buoyant jets are significantly influenced by these parameters. Other mixing features are discussed including a “total cross sectional dilution” parameter and a novel width parameter. The role played by the Coanda Effect in influencing the mixing of...

  • Round Buoyant Jet Entering Shallow Water in Motion
    Journal of Hydraulic Engineering, 1993
    Co-Authors: A. J. Johnston, N. Nguyen, R. E. Volker
    Abstract:

    This paper focuses on the mixing processes that develop when a buoyant jet from a round outfall Pipe Enters a shallow moving body of water. Results from a detailed experimental study quantify the effects on jet mixing produced when a current is imposed on shallow receiving water. Findings show that the dilutions of buoyant jets entering these environments are significantly different from those discharging into unconfined (deep‐water) conditions. Mixing features discussed include the application of scaling relationships in collapsing integral parameter data and the role played by the Coanda effect in influencing the mixing of jets. Patterns of jet path, centerline dilution, total dilution, horizontal and vertical half widths, and a novel width parameter are described and compared with shallow stationary and current affected deep‐water results.

R.s. Hudson - One of the best experts on this subject based on the ideXlab platform.

  • Advances in Homopolar Welding of API Line Pipe for Deepwater Applications
    SPE Production & Facilities, 1999
    Co-Authors: R.s. Hudson, R.w. Carnes, Steven P. Nichols
    Abstract:

    Summary The University of Texas at Austin Center for Electromechanics is conducting a research program, funded by six oil companies, two industrial contractors, and two government agencies, to study homopolar welding of line Pipe for J-Lay applications. In 1995, the third year of the five year research program, the set of weld parameters, those input variables used to control weld performance and quality, was expanded to include joint geometry, with dramatic improvement in the mechanical properties of two HSLA nominal 3-in. line Pipe materials: X60 and X65. These improvements increased the Charpy V-Notch impact toughness properties to near parent metal values, while maintaining acceptable strength. After demonstrating repeatable performance with the new parameters, new research focused on real world effects including tolerancing the parameters and evaluating the effect of poor fit up resulting from misalignment and rough and wavy interfaces. During the final year of the research program, the Pipe welding program has scaled up to 12-in. nominal line Pipe, a seven-fold increase in the cross-sectional area. The paper will cover the basics of homopolar welding (HPW), weld parameters and modifications, the effects of these changes on real time process data, mechanical properties, weld upset profile, HPW metallurgy, and the studies of real world effects. Results from HPW of 12-in. Pipe will also be presented. Introduction Homopolar welding (HPW) is a resistance forge welding process that uses the high amperage direct current discharge from a homopolar generator (HPG) to produce full circumferential Pipe welds in under 5 sec without using filler metal. HPW is being developed as a candidate single station, or "one shot," welding method for J-Lay Pipe laying. With the continued discovery of deepwater oil fields, the J-Lay method was developed to overcome the problem of buckling, occurring when the Pipe Enters the water from conventional S-Lay barges. J-Lay requires the single station welding process because the Pipe is welded vertically then lowered directly into the water. 1 Besides enabling Pipe laying in deepwater fields, the reduced cycle time per weld should lower the cost.2,3 Homopolar Offshore Pipeline Welding Research Program. A consortium of six oil companies (Amoco, BP, Exxon, Mobil, Shell, and Texaco) and a welding contractor (CRC-Evans) funded this joint industry program (JIP) at The University of Texas at Austin Center for Electromechanics, beginning in February 1993, to develop homopolar welding for J-Lay applications. Since that time, an additional equipment contractor (Parker Kinetic Design) and two federal agencies (the Office of Pipeline Safety of the Department of Transportation and the Mineral Management Services of the Department of Interior) have joined the program. The major objectives of the research program have been achieved. They include:optimize weld parameters for homopolar welding 3-in. HSLA API 5L line Pipe;investigate a range of materials with varying strength, wall thickness, composition, heat treatment, and manufacturing method;produce 3-in. welds with acceptable mechanical properties;improve the finished weld profile;design and build a laboratory welding fixture for joining 12-in. Schedule 80 line Pipe;demonstrate homopolar weldability of 12-in. Pipe;transfer technology in preparation for commercialization of HPW;develop an NDE program. One of the first requirements of the research program was developing an acceptance criteria for the welding program that was compatible with existing welding codes. John Hammond, with BP Exploration of London, developed this document, known as the "Hammond Criteria," which has served to guide the research through the development of a new welding process.4 Recent Advances. During the second and third year of the program, the weld parameters, those inputs used to control the welding process and weld quality, were significantly expanded on 3-in. Pipe welds as a new approach to welding using HPGs was investigated. The results were dramatic: besides producing higher, more uniform impact toughness in two high strength materials, process robustness increased substantially. During the fourth and current years, preparation and production of 12-in. Pipe welds are underway. Homopolar Welding A homopolar welding system consists of a homopolar generator and a hydraulic welding fixture. The homopolar generator is an inertial energy storage device that provides the mega-ampere direct current (DC) electrical pulse to resistively heat the joint for welding. The hydraulic welding fixture delivers the current to the workpiece, provides the forging force to upset the heated interface material, and maintains alignment during upset. Homopolar Generators. Homopolar generators are simple industrial machines that convert the stored rotational kinetic energy of its spinning rotor to direct current electric energy by electromagnetic induction. The low voltage, high current discharge, characteristic of these machines, makes them well suited for electrical resistive heating. A magnetic field imposed across the electrically conductive rotor produces a voltage and supplies a characteristic current pulse when connected to a discharge circuit. The principle of electromagnetic induction is demonstrated in the Faraday disk, or more fundamentally by moving a straight conductor though a magnetic field.5 HPG Parameters. The parameters governing the HPG output current are the discharge speed and the field current magnitude. The discharge speed determines the magnitude of the stored inertial energy. The field current magnitude, which induces the magnetic field across the rotor, controls the shape of the current pulse. Higher field current settings shorten the pulse length and increase the magnitude of the peak discharge current. 6

  • Advances in Homopolar Welding of API LinePipe for Deepwater Applications
    All Days, 1997
    Co-Authors: R.s. Hudson, R.w. Carnes, Steven P. Nichols
    Abstract:

    Abstract The University of Texas at Austin Center for Electromechanics is conducting a research program, funded by six oil companies, two industrial contractors, and two government agencies, to study homopolar welding of line Pipe for J-Lay applications. In 1995, the third year of the five year research program, the set of weld parameters, those input variables used to control weld performance and quality, was expanded to include joint geometry, with dramatic improvement in the mechanical properties of two HSLA nominal 3-inch line Pipe materials, X60 and X65. These improvements increased the Charpy V-Notch impact toughness properties to near parent metal values, while maintaining acceptable strength. After demonstrating repeatable performance with the new parameters, new research focused on real world effects including tolerancing the parameters and evaluating the effect of poor fit up resulting from misalignment and rough and wavy interfaces. During the final year of the research program, the Pipe welding program has scaled up to 12-inch nominal line Pipe, a sevenfold increase in cross-sectional area. The paper will cover basics of homopolar welding, weld parameters and modifications, effects of these changes on real time process data, mechanical properties, weld upset profile, HPW metallurgy, and the studies of real world effects. Results from homopolar welding of 12-inch Pipe will also be presented. Introduction Homopolar Welding (HPW) is a resistance forge welding process that uses the high amperage direct current discharge from a Homopolar Generator (HPG) to produce full circumferential Pipe welds in under five seconds without using filler metal. HPW is being developed as a candidate single station, or "one shot", welding method for J-lay Pipe laying. With the continued discovery of deep water oil fields, the J-Lay method was developed to overcome the problem of buckling, occurring when the Pipe Enters the water from conventional S-lay barges. J-lay requires single station welding process because the Pipe is welded vertically then lowered directly into the water. Besides enabling Pipe laying in deep water fields, the reduced cycle time per weld should lower the cost. Homopolar Offshore Pipeline Welding Research Program. A consortium of six oil companies (Amoco, BP, Exxon, Mobil, Shell, and Texaco) and a welding contractor (CRC-Evans) funded this joint industry program (JIP) at The University of Texas at Austin Center for Electromechanics, beginning in February 1993, to develop homopolar welding for J-Lay applications. Since that time, an additional equipment contractor (Parker Kinetic Design) and two federal agencies (the Office of Pipeline Safety of the DOT and the Mineral Management Services of the DOl) have joined the program. The major objectives of the research program have been achieved. They include:–optimize weld parameters for homopolar welding 3-inch HSLA API 5L line Pipe–investigate a range of materials with varying strength, wall thickness, composition, heat treatment and manufacturing method–produce 3-inch welds with acceptable mechanical properties - improve the finished weld profile–design and build a laboratory welding fixture for joining 12-inch Schedule 80 line Pipe–demonstrate homopolar weldability of 12-inch Pipe–transfer technology in preparation for commercialization of HPW–develop an NDE program One of the first requirements of the research program was developing an acceptance criteria for the welding program that was compatible with existing welding codes. John Hammond, with BP Exploration of London, developed this document, known as the "Hammond Criteria", which has served to guide the research through the development of a new welding process. P. 953

N. Nguyen - One of the best experts on this subject based on the ideXlab platform.

  • Round buoyant jet in shallow water: bed shear velocity
    Journal of Hydraulic Research, 1994
    Co-Authors: A. J. Johnston, N. Nguyen, R. E. Volker
    Abstract:

    SummaryThis paper examines the mixing processes that develop when a buoyant jet from a round outfall Pipe Enters a shallow moving body of water in a direction perpendicular to the current and focuses on the role played by the bed shear velocity developed in the receiving water. Different velocity profiles in the receiving water were produced using a triggering fence to modify the profile and hence the bed shear velocity. These changes simulated variations in the roughness of the bed. The results of an experimental study are presented where the effects related to the magnitude of the current, the bed shear velocity, and the locations of the free and bed boundaries on the jet mixing parameters are quantified. Findings are outlined which show that the dilutions of buoyant jets are significantly influenced by these parameters. Other mixing features are discussed including a “total cross sectional dilution” parameter and a novel width parameter. The role played by the Coanda Effect in influencing the mixing of...

  • Round Buoyant Jet Entering Shallow Water in Motion
    Journal of Hydraulic Engineering, 1993
    Co-Authors: A. J. Johnston, N. Nguyen, R. E. Volker
    Abstract:

    This paper focuses on the mixing processes that develop when a buoyant jet from a round outfall Pipe Enters a shallow moving body of water. Results from a detailed experimental study quantify the effects on jet mixing produced when a current is imposed on shallow receiving water. Findings show that the dilutions of buoyant jets entering these environments are significantly different from those discharging into unconfined (deep‐water) conditions. Mixing features discussed include the application of scaling relationships in collapsing integral parameter data and the role played by the Coanda effect in influencing the mixing of jets. Patterns of jet path, centerline dilution, total dilution, horizontal and vertical half widths, and a novel width parameter are described and compared with shallow stationary and current affected deep‐water results.