The Experts below are selected from a list of 54 Experts worldwide ranked by ideXlab platform

Kenneth A. Macdonald - One of the best experts on this subject based on the ideXlab platform.

  • Guidance for Fatigue Design and Assessment of Pipeline Girth Welds
    Volume 3: Materials Technology; Ocean Engineering; Polar and Arctic Sciences and Technology; Workshops, 2003
    Co-Authors: P. J. Haagensen, S. J. Maddox, Kenneth A. Macdonald
    Abstract:

    Risers and sections of pipeline in free-span can be subjected to cyclic loading from flow-induced vibrations and other fluctuating forces leading to fatigue loading of the structure. Single-sided Welds are of particular interest, however current design codes take a pessimistic view of their fatigue performance. Improvements in the quality of the Finished Weld produced by modern pipeline Welding technology, and indeed advances made in knowledge about fatigue of such Welds, mean that revision of the design guidance is now warranted. This paper reviews the fundamental basis of the existing S-N curves used for North Sea applications and considers their applicability in the light of research on fatigue of girth Welds. Based on the review, proposals are made for revised fatigue design rules for girth Welds in pipelines.Copyright © 2003 by ASME

  • New guidance for fatigue design of pipeline girth Welds
    Engineering Failure Analysis, 2003
    Co-Authors: Kenneth A. Macdonald, S. J. Maddox
    Abstract:

    Abstract Risers and sections of pipeline in free-span can be subjected to cyclic loading from flow-induced vibrations and other fluctuating forces leading to fatigue loading of the structure. Single-sided Welds are of particular interest, however, current design codes take a pessimistic view of their fatigue performance. Improvements in the quality of the Finished Weld produced by modern pipeline Welding technology, and indeed advances made in knowledge about fatigue of such Welds, mean that revision of the design guidance is now warranted. This paper reviews the fundamental basis of the existing S–N curves used for North Sea applications and considers their applicability in the light of research on fatigue of girth Welds. Based on the review, proposals are made for revised fatigue design rules for girth Welds in pipelines.

G. E. Ridings - One of the best experts on this subject based on the ideXlab platform.

  • Prediction of multiwire submerged arc Weld bead shape using neural network modelling
    Science and Technology of Welding and Joining, 2002
    Co-Authors: G. E. Ridings, Rachel C. Thomson, G. Thewlis
    Abstract:

    AbstractA significant problem faced by today's Welding engineers is the need to relate Welding parameters to the quality of the Finished Weld. This is usually achieved by experience, and necessitates many experimental trials, eventually leading to optimal Welding parameters. Important characteristics in the evaluation of linepipe seam Weld quality are the Weld bead shape and size, which can have a significant effect on the microstructure and mechanical properties of the Weldment through heat flow effects. The present paper describes the application of neural network techniques to the prediction of the outer diameter Weld bead shape for three wire, single pass per side, submerged arc, linepipe seam Welds, using the Weld process parameters as inputs. Novel methods of digitisation of Weld macrostructures produced under different experimental conditions, used in the training of the neural network, are discussed. The contribution of a particular Welding process parameter (input relevance) to the variation in t...

  • Neural network modelling of submerged arc Weld metal properties
    2002
    Co-Authors: G. E. Ridings
    Abstract:

    There are many problems in Welding metallurgy for which it is difficult to develop a first principles scientific model due to their complexity. A significant problem faced by today's Welding engineers, is the need to relate Welding parameters to the quality of the Finished Weld. This is usually done by experience, and the need for many experimental trials, eventually leading to optimal Welding parameters. Important characteristics in the evaluation of line-pipe seam Weld quality are the Weld bead shape and size, which can have a significant effect on the microstructure and mechanical properties of the Weldment through heat flow effects. Properties of the final Weld may therefore be difficult to predict, especially quantities such as Weld metal toughness, which are known to be dependent on many factors. One approach to such complex problems is to use neural networks. A neural network is an artificial simulation of the brain which models data through a learning process and stores the information as a set of rules akin to knowledge. This research is concerned with the application of neural network techniques to the prediction of the mechanical and physical properties, including the shape of the Weld bead, of submerged arc line-pipe steel Welds. A limited experimental investigation has been carried out using optical and transmission electron microscopy to establish an understanding of the complex microstructures that result from the Welding processes used in the production of line-pipe. [Continues.]

S. J. Maddox - One of the best experts on this subject based on the ideXlab platform.

  • Guidance for Fatigue Design and Assessment of Pipeline Girth Welds
    Volume 3: Materials Technology; Ocean Engineering; Polar and Arctic Sciences and Technology; Workshops, 2003
    Co-Authors: P. J. Haagensen, S. J. Maddox, Kenneth A. Macdonald
    Abstract:

    Risers and sections of pipeline in free-span can be subjected to cyclic loading from flow-induced vibrations and other fluctuating forces leading to fatigue loading of the structure. Single-sided Welds are of particular interest, however current design codes take a pessimistic view of their fatigue performance. Improvements in the quality of the Finished Weld produced by modern pipeline Welding technology, and indeed advances made in knowledge about fatigue of such Welds, mean that revision of the design guidance is now warranted. This paper reviews the fundamental basis of the existing S-N curves used for North Sea applications and considers their applicability in the light of research on fatigue of girth Welds. Based on the review, proposals are made for revised fatigue design rules for girth Welds in pipelines.Copyright © 2003 by ASME

  • New guidance for fatigue design of pipeline girth Welds
    Engineering Failure Analysis, 2003
    Co-Authors: Kenneth A. Macdonald, S. J. Maddox
    Abstract:

    Abstract Risers and sections of pipeline in free-span can be subjected to cyclic loading from flow-induced vibrations and other fluctuating forces leading to fatigue loading of the structure. Single-sided Welds are of particular interest, however, current design codes take a pessimistic view of their fatigue performance. Improvements in the quality of the Finished Weld produced by modern pipeline Welding technology, and indeed advances made in knowledge about fatigue of such Welds, mean that revision of the design guidance is now warranted. This paper reviews the fundamental basis of the existing S–N curves used for North Sea applications and considers their applicability in the light of research on fatigue of girth Welds. Based on the review, proposals are made for revised fatigue design rules for girth Welds in pipelines.

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

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