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Gabriel Rombado - One of the best experts on this subject based on the ideXlab platform.
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Corrosion-Fatigue Crack Growth Performance of Titanium Grade 29 Welds In Tapered Stress Joints
Journal of Offshore Mechanics and Arctic Engineering, 2021Co-Authors: Gabriel Rombado, David A. Baker, Lars M. Haldorsen, Pedro Craidy, Jim Feiger, Stephen J. HudakAbstract:Abstract Design of a steel catenary riser requires the use of connection hardware to decouple the large bending moments induced by the host floater at the hang-off location. Reliability of this connection hardware is essential, particularly in applications involving high pressure and high temperature fluids. One option for this connection hardware is the metallic tapered Stress Joint. Titanium (Ti) Grade 29 has been identified as an attractive material candidate for demanding Stress Joint applications due to its “high strength, low weight, superior fatigue performance and innate corrosion resistance”.2 Titanium Stress Joints for deepwater applications are typically not fabricated as a single piece due to titanium ingot volume limitations, thus making an intermediate girth weld necessary to satisfy length requirements. As with steel, the potential effect of hydrogen embrittlement induced by cathodic and galvanic potentials must be assessed to ensure long-term weld integrity. This paper describes testing from a Joint industry project (JIP) conducted to qualify titanium Stress Joint (TSJ) welds for ultra-deepwater applications under harsh service and environmental conditions. Corrosion-fatigue crack growth rate (CFCGR) results for Ti Grade 29 flat welding-groove weld (1G/PA) gas tungsten arc welding (GTAW) specimens in seawater under cathodic potential and sour brine under galvanic potential are presented and compared to vendor recommended design curves.
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Fatigue Performance of Thick Section Titanium Grade 29 Girth Welds
Volume 3: Materials Technology, 2020Co-Authors: Gabriel Rombado, Heath W. Walker, David A. Baker, Lars M. Haldorsen, Kenneth Macdonald, Chris Caldwell, Carol JohnstonAbstract:Abstract Design of Steel Catenary Risers (SCRs) requires the use of specialized connection hardware to mitigate the high dynamic bending moments at the hang-off location induced by host floater motion. Reliability of this connection hardware is imperative, especially in those applications involving high tension loads, high pressure and elevated fluid temperature. One option for connection hardware is a monolithic, metallic tapered Stress Joint. Because of its inherent density, strength, and stiffness properties, steel is not well suited for these applications due to excessive Stress Joint length and weight requirements. Titanium Grade 29 has been identified as an attractive material candidate for demanding service applications due to its unique mechanical properties including increased flexibility, excellent fatigue performance and corrosion resistance to sour fluids. This technology is well established in the offshore industry and utilized in over 60 SCR installations with operating lives exceeding 20 years of continuous subsea operation. Large titanium Stress Joints (TSJs) for deep-water applications are typically not fabricated as a single piece due to titanium ingot volume limitations thus making one or more intermediate girth weld(s) necessary to satisfy the overall length requirements. Fatigue testing of 38 mm (1.5-in) wall thickness girth welds, utilizing an optimized GTAW welding procedure to limit defect sizes to sub-millimeter, has previously been performed in seawater (OD exposure) under cathodic protection potentials and sour service (ID exposure) under galvanic potentials. Fatigue testing results fully verified the vendor S-N fatigue design curve, in addition, no appreciable differences in fatigue performance in environments were observed allowing project-specific testing to be limited to in-air testing. This paper presents in-air fatigue testing results of 51 mm (2.0-in) wall thickness Grade 29 girth welds, using the same optimized welding procedure, to assess thickness size effect on the vendor S-N fatigue design curve. Verification of the vendor fatigue design curve was demonstrated by testing curved dog-bone specimens, extracted longitudinally across the girth weld, with production level surface finishes on inner and outer surfaces in-air up to a predefined S-N fatigue target curve with 95% confidence level.
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Corrosion-Fatigue Crack Growth Performance of Titanium Grade 29 Welds in Tapered Stress Joints
Volume 5B: Pipelines Risers and Subsea Systems, 2019Co-Authors: Gabriel Rombado, David A. Baker, Lars M. Haldorsen, Pedro Craidy, Jim Feiger, Stephen J. HudakAbstract:Abstract Design of steel catenary risers (SCRs) requires the use of connection hardware to decouple the large bending moments induced by the host floater at the hang-off location. Reliability of this connection hardware is imperative, especially in those applications involving high pressure and temperature fluids. One option for connection hardware is the metallic tapered Stress Joint. Because of its inherent density, strength and stiffness, steel is not well suited for these applications as it would result it excessive length and weight for deepwater applications. Titanium grade 29 (Ti 29) has been identified as an attractive material candidate for demanding Stress Joint applications due to its unique mechanical properties including greater flexibility, excellent fatigue performance, and high resistance to sour fluids. Industry has successfully used this technology in over 60 SCR applications. Titanium Stress Joints (TSJs) for deep-water applications are typically not fabricated as a single piece due to titanium ingot/billet volume limitations, thus making an intermediate girth weld necessary to satisfy length requirements. Fracture and fatigue performance of these welds in the presence of cathodic potential in seawater and galvanic potentials in sour production fluids that may produce hydrogen embrittlement effects must be assessed to ensure long term weld integrity. This paper describes a Joint industry project (JIP) performed to qualify titanium Stress Joints welds for ultra-deep water applications under harsh service and environmental conditions. Fatigue crack growth rate (FCGR) results for Ti 29 1G/PA gas tungsten arc welding (GTAW) specimens in air, seawater under cathodic potential and sour brine environments under galvanic potentials are presented and compared to vendor recommended design curves.
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Qualification Testing of Titanium Stress Joints Designed for Galvanic Hydrogen Mitigation Conveying Hot, Sour Well Fluids
Volume 5: Pipelines Risers and Subsea Systems, 2018Co-Authors: Ronald W. Schutz, Gabriel Rombado, Heath W. Walker, David A. Baker, Christopher S. CaldwellAbstract:A three-phase laboratory test qualification program for Titanium Stress Joint (TSJ) use in an offshore steel catenary riser (SCR) system handling hot, marginally sour well brine fluid offers guidance for expanded, safe TSJ use in hot sour well service. Phase 1 results indicated a reasonable concern and risk for long-term excessive hydrogen uptake and damage to the TSJ when directly coupled with the steel riser and steel topside piping. An alternative TSJ design, incorporating an Alloy 625 cathode buffer transition between adjoining steel tubulars, was proposed for mitigation of galvanic hydrogen charging uptake and damage prevention for hot sour fluid service. This “Tri-Metal couple” design was modeled in Phase 2 using polarization curves as input, and simulations projected insignificant hydrogen charging on TSJ bore surfaces exposed to “Worst-Case Sour” brine fluid at 250°F (121°C). Phase 3 aimed at qualifying the TSJ welds for even more severe and acidic sour well fluid service conditions up to 275°F (135°C), via fatigue crack growth rate (FCGR) and J-R fracture toughness testing of weld metal, and S-N fatigue and slow strain rate (SSR) tensile testing of cross-welds. These tests confirmed the high degree of hot sour environmental resistance for Grade 29 Titanium welded Joints, and reasonable compatibility with TSJ design requirements.
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Verification of Fracture and Fatigue Performance of Titanium Gr. 29 Welds in Tapered Stress Joints
Volume 6: Materials Technology; Polar and Arctic Sciences and Technology; Petroleum Technology Symposium, 2012Co-Authors: Jaime Buitrago, Nathan A. Nissley, Gabriel RombadoAbstract:Design of a Steel Catenary Riser (SCR) requires the use of connection hardware to accommodate the bending moment that arises from the abrupt change in stiffness at the floater hang-off. Reliability of this connection hardware is of paramount importance in ultra deepwater applications (up to 3000m), especially those involving high pressure and temperature fluids. One type of such connection hardware is a metallic tapered Stress Joint. Because of its inherent density, strength, and stiffness, steel is not well suited for these applications due to the length and weight constraints. Titanium Gr. 29 (Ti), which is as strong as steel but lighter and more flexible, has been identified as a good material candidate for a tapered Stress Joint.The required length (∼40ft) and thickness (∼3.5in.) of the Titanium Stress Joint (TSJ) cannot be fabricated as a single piece due to forging size limitations. Thus, an intermediate girth weld becomes necessary. The fracture and fatigue performances in the presence of the external seawater and cathodic protection (CP) and the internal sour production with galvanic effects between the Ti and steel must be assessed to verify the service life of the Stress Joint. ExxonMobil has developed and initiated a Joint Industry Project to fully address the fracture and fatigue qualification of titanium welds. In particular, the project plans to establish a robust methodology for the future qualification of TSJs that parallels, to the extent possible, the qualification process currently used for SCRs.This paper discusses the primary aspects of the titanium weld qualification: (1) selection of test specimens, (2) load frequency effects on initiation and propagation lives, (3) environmental assisted cracking due to hydride formation under cathodic and galvanic conditions, (4) full-thickness small-scale fatigue, (5) size effect on fatigue, and (6) weld inspection.Copyright © 2012 by ASME
Stephen J. Hudak - One of the best experts on this subject based on the ideXlab platform.
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Corrosion-Fatigue Crack Growth Performance of Titanium Grade 29 Welds In Tapered Stress Joints
Journal of Offshore Mechanics and Arctic Engineering, 2021Co-Authors: Gabriel Rombado, David A. Baker, Lars M. Haldorsen, Pedro Craidy, Jim Feiger, Stephen J. HudakAbstract:Abstract Design of a steel catenary riser requires the use of connection hardware to decouple the large bending moments induced by the host floater at the hang-off location. Reliability of this connection hardware is essential, particularly in applications involving high pressure and high temperature fluids. One option for this connection hardware is the metallic tapered Stress Joint. Titanium (Ti) Grade 29 has been identified as an attractive material candidate for demanding Stress Joint applications due to its “high strength, low weight, superior fatigue performance and innate corrosion resistance”.2 Titanium Stress Joints for deepwater applications are typically not fabricated as a single piece due to titanium ingot volume limitations, thus making an intermediate girth weld necessary to satisfy length requirements. As with steel, the potential effect of hydrogen embrittlement induced by cathodic and galvanic potentials must be assessed to ensure long-term weld integrity. This paper describes testing from a Joint industry project (JIP) conducted to qualify titanium Stress Joint (TSJ) welds for ultra-deepwater applications under harsh service and environmental conditions. Corrosion-fatigue crack growth rate (CFCGR) results for Ti Grade 29 flat welding-groove weld (1G/PA) gas tungsten arc welding (GTAW) specimens in seawater under cathodic potential and sour brine under galvanic potential are presented and compared to vendor recommended design curves.
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Corrosion-Fatigue Crack Growth Performance of Titanium Grade 29 Welds in Tapered Stress Joints
Volume 5B: Pipelines Risers and Subsea Systems, 2019Co-Authors: Gabriel Rombado, David A. Baker, Lars M. Haldorsen, Pedro Craidy, Jim Feiger, Stephen J. HudakAbstract:Abstract Design of steel catenary risers (SCRs) requires the use of connection hardware to decouple the large bending moments induced by the host floater at the hang-off location. Reliability of this connection hardware is imperative, especially in those applications involving high pressure and temperature fluids. One option for connection hardware is the metallic tapered Stress Joint. Because of its inherent density, strength and stiffness, steel is not well suited for these applications as it would result it excessive length and weight for deepwater applications. Titanium grade 29 (Ti 29) has been identified as an attractive material candidate for demanding Stress Joint applications due to its unique mechanical properties including greater flexibility, excellent fatigue performance, and high resistance to sour fluids. Industry has successfully used this technology in over 60 SCR applications. Titanium Stress Joints (TSJs) for deep-water applications are typically not fabricated as a single piece due to titanium ingot/billet volume limitations, thus making an intermediate girth weld necessary to satisfy length requirements. Fracture and fatigue performance of these welds in the presence of cathodic potential in seawater and galvanic potentials in sour production fluids that may produce hydrogen embrittlement effects must be assessed to ensure long term weld integrity. This paper describes a Joint industry project (JIP) performed to qualify titanium Stress Joints welds for ultra-deep water applications under harsh service and environmental conditions. Fatigue crack growth rate (FCGR) results for Ti 29 1G/PA gas tungsten arc welding (GTAW) specimens in air, seawater under cathodic potential and sour brine environments under galvanic potentials are presented and compared to vendor recommended design curves.
David A. Baker - One of the best experts on this subject based on the ideXlab platform.
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Corrosion-Fatigue Crack Growth Performance of Titanium Grade 29 Welds In Tapered Stress Joints
Journal of Offshore Mechanics and Arctic Engineering, 2021Co-Authors: Gabriel Rombado, David A. Baker, Lars M. Haldorsen, Pedro Craidy, Jim Feiger, Stephen J. HudakAbstract:Abstract Design of a steel catenary riser requires the use of connection hardware to decouple the large bending moments induced by the host floater at the hang-off location. Reliability of this connection hardware is essential, particularly in applications involving high pressure and high temperature fluids. One option for this connection hardware is the metallic tapered Stress Joint. Titanium (Ti) Grade 29 has been identified as an attractive material candidate for demanding Stress Joint applications due to its “high strength, low weight, superior fatigue performance and innate corrosion resistance”.2 Titanium Stress Joints for deepwater applications are typically not fabricated as a single piece due to titanium ingot volume limitations, thus making an intermediate girth weld necessary to satisfy length requirements. As with steel, the potential effect of hydrogen embrittlement induced by cathodic and galvanic potentials must be assessed to ensure long-term weld integrity. This paper describes testing from a Joint industry project (JIP) conducted to qualify titanium Stress Joint (TSJ) welds for ultra-deepwater applications under harsh service and environmental conditions. Corrosion-fatigue crack growth rate (CFCGR) results for Ti Grade 29 flat welding-groove weld (1G/PA) gas tungsten arc welding (GTAW) specimens in seawater under cathodic potential and sour brine under galvanic potential are presented and compared to vendor recommended design curves.
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Fatigue Performance of Thick Section Titanium Grade 29 Girth Welds
Volume 3: Materials Technology, 2020Co-Authors: Gabriel Rombado, Heath W. Walker, David A. Baker, Lars M. Haldorsen, Kenneth Macdonald, Chris Caldwell, Carol JohnstonAbstract:Abstract Design of Steel Catenary Risers (SCRs) requires the use of specialized connection hardware to mitigate the high dynamic bending moments at the hang-off location induced by host floater motion. Reliability of this connection hardware is imperative, especially in those applications involving high tension loads, high pressure and elevated fluid temperature. One option for connection hardware is a monolithic, metallic tapered Stress Joint. Because of its inherent density, strength, and stiffness properties, steel is not well suited for these applications due to excessive Stress Joint length and weight requirements. Titanium Grade 29 has been identified as an attractive material candidate for demanding service applications due to its unique mechanical properties including increased flexibility, excellent fatigue performance and corrosion resistance to sour fluids. This technology is well established in the offshore industry and utilized in over 60 SCR installations with operating lives exceeding 20 years of continuous subsea operation. Large titanium Stress Joints (TSJs) for deep-water applications are typically not fabricated as a single piece due to titanium ingot volume limitations thus making one or more intermediate girth weld(s) necessary to satisfy the overall length requirements. Fatigue testing of 38 mm (1.5-in) wall thickness girth welds, utilizing an optimized GTAW welding procedure to limit defect sizes to sub-millimeter, has previously been performed in seawater (OD exposure) under cathodic protection potentials and sour service (ID exposure) under galvanic potentials. Fatigue testing results fully verified the vendor S-N fatigue design curve, in addition, no appreciable differences in fatigue performance in environments were observed allowing project-specific testing to be limited to in-air testing. This paper presents in-air fatigue testing results of 51 mm (2.0-in) wall thickness Grade 29 girth welds, using the same optimized welding procedure, to assess thickness size effect on the vendor S-N fatigue design curve. Verification of the vendor fatigue design curve was demonstrated by testing curved dog-bone specimens, extracted longitudinally across the girth weld, with production level surface finishes on inner and outer surfaces in-air up to a predefined S-N fatigue target curve with 95% confidence level.
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Corrosion-Fatigue Crack Growth Performance of Titanium Grade 29 Welds in Tapered Stress Joints
Volume 5B: Pipelines Risers and Subsea Systems, 2019Co-Authors: Gabriel Rombado, David A. Baker, Lars M. Haldorsen, Pedro Craidy, Jim Feiger, Stephen J. HudakAbstract:Abstract Design of steel catenary risers (SCRs) requires the use of connection hardware to decouple the large bending moments induced by the host floater at the hang-off location. Reliability of this connection hardware is imperative, especially in those applications involving high pressure and temperature fluids. One option for connection hardware is the metallic tapered Stress Joint. Because of its inherent density, strength and stiffness, steel is not well suited for these applications as it would result it excessive length and weight for deepwater applications. Titanium grade 29 (Ti 29) has been identified as an attractive material candidate for demanding Stress Joint applications due to its unique mechanical properties including greater flexibility, excellent fatigue performance, and high resistance to sour fluids. Industry has successfully used this technology in over 60 SCR applications. Titanium Stress Joints (TSJs) for deep-water applications are typically not fabricated as a single piece due to titanium ingot/billet volume limitations, thus making an intermediate girth weld necessary to satisfy length requirements. Fracture and fatigue performance of these welds in the presence of cathodic potential in seawater and galvanic potentials in sour production fluids that may produce hydrogen embrittlement effects must be assessed to ensure long term weld integrity. This paper describes a Joint industry project (JIP) performed to qualify titanium Stress Joints welds for ultra-deep water applications under harsh service and environmental conditions. Fatigue crack growth rate (FCGR) results for Ti 29 1G/PA gas tungsten arc welding (GTAW) specimens in air, seawater under cathodic potential and sour brine environments under galvanic potentials are presented and compared to vendor recommended design curves.
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Qualification Testing of Titanium Stress Joints Designed for Galvanic Hydrogen Mitigation Conveying Hot, Sour Well Fluids
Volume 5: Pipelines Risers and Subsea Systems, 2018Co-Authors: Ronald W. Schutz, Gabriel Rombado, Heath W. Walker, David A. Baker, Christopher S. CaldwellAbstract:A three-phase laboratory test qualification program for Titanium Stress Joint (TSJ) use in an offshore steel catenary riser (SCR) system handling hot, marginally sour well brine fluid offers guidance for expanded, safe TSJ use in hot sour well service. Phase 1 results indicated a reasonable concern and risk for long-term excessive hydrogen uptake and damage to the TSJ when directly coupled with the steel riser and steel topside piping. An alternative TSJ design, incorporating an Alloy 625 cathode buffer transition between adjoining steel tubulars, was proposed for mitigation of galvanic hydrogen charging uptake and damage prevention for hot sour fluid service. This “Tri-Metal couple” design was modeled in Phase 2 using polarization curves as input, and simulations projected insignificant hydrogen charging on TSJ bore surfaces exposed to “Worst-Case Sour” brine fluid at 250°F (121°C). Phase 3 aimed at qualifying the TSJ welds for even more severe and acidic sour well fluid service conditions up to 275°F (135°C), via fatigue crack growth rate (FCGR) and J-R fracture toughness testing of weld metal, and S-N fatigue and slow strain rate (SSR) tensile testing of cross-welds. These tests confirmed the high degree of hot sour environmental resistance for Grade 29 Titanium welded Joints, and reasonable compatibility with TSJ design requirements.
Lars M. Haldorsen - One of the best experts on this subject based on the ideXlab platform.
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Corrosion-Fatigue Crack Growth Performance of Titanium Grade 29 Welds In Tapered Stress Joints
Journal of Offshore Mechanics and Arctic Engineering, 2021Co-Authors: Gabriel Rombado, David A. Baker, Lars M. Haldorsen, Pedro Craidy, Jim Feiger, Stephen J. HudakAbstract:Abstract Design of a steel catenary riser requires the use of connection hardware to decouple the large bending moments induced by the host floater at the hang-off location. Reliability of this connection hardware is essential, particularly in applications involving high pressure and high temperature fluids. One option for this connection hardware is the metallic tapered Stress Joint. Titanium (Ti) Grade 29 has been identified as an attractive material candidate for demanding Stress Joint applications due to its “high strength, low weight, superior fatigue performance and innate corrosion resistance”.2 Titanium Stress Joints for deepwater applications are typically not fabricated as a single piece due to titanium ingot volume limitations, thus making an intermediate girth weld necessary to satisfy length requirements. As with steel, the potential effect of hydrogen embrittlement induced by cathodic and galvanic potentials must be assessed to ensure long-term weld integrity. This paper describes testing from a Joint industry project (JIP) conducted to qualify titanium Stress Joint (TSJ) welds for ultra-deepwater applications under harsh service and environmental conditions. Corrosion-fatigue crack growth rate (CFCGR) results for Ti Grade 29 flat welding-groove weld (1G/PA) gas tungsten arc welding (GTAW) specimens in seawater under cathodic potential and sour brine under galvanic potential are presented and compared to vendor recommended design curves.
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Fatigue Performance of Thick Section Titanium Grade 29 Girth Welds
Volume 3: Materials Technology, 2020Co-Authors: Gabriel Rombado, Heath W. Walker, David A. Baker, Lars M. Haldorsen, Kenneth Macdonald, Chris Caldwell, Carol JohnstonAbstract:Abstract Design of Steel Catenary Risers (SCRs) requires the use of specialized connection hardware to mitigate the high dynamic bending moments at the hang-off location induced by host floater motion. Reliability of this connection hardware is imperative, especially in those applications involving high tension loads, high pressure and elevated fluid temperature. One option for connection hardware is a monolithic, metallic tapered Stress Joint. Because of its inherent density, strength, and stiffness properties, steel is not well suited for these applications due to excessive Stress Joint length and weight requirements. Titanium Grade 29 has been identified as an attractive material candidate for demanding service applications due to its unique mechanical properties including increased flexibility, excellent fatigue performance and corrosion resistance to sour fluids. This technology is well established in the offshore industry and utilized in over 60 SCR installations with operating lives exceeding 20 years of continuous subsea operation. Large titanium Stress Joints (TSJs) for deep-water applications are typically not fabricated as a single piece due to titanium ingot volume limitations thus making one or more intermediate girth weld(s) necessary to satisfy the overall length requirements. Fatigue testing of 38 mm (1.5-in) wall thickness girth welds, utilizing an optimized GTAW welding procedure to limit defect sizes to sub-millimeter, has previously been performed in seawater (OD exposure) under cathodic protection potentials and sour service (ID exposure) under galvanic potentials. Fatigue testing results fully verified the vendor S-N fatigue design curve, in addition, no appreciable differences in fatigue performance in environments were observed allowing project-specific testing to be limited to in-air testing. This paper presents in-air fatigue testing results of 51 mm (2.0-in) wall thickness Grade 29 girth welds, using the same optimized welding procedure, to assess thickness size effect on the vendor S-N fatigue design curve. Verification of the vendor fatigue design curve was demonstrated by testing curved dog-bone specimens, extracted longitudinally across the girth weld, with production level surface finishes on inner and outer surfaces in-air up to a predefined S-N fatigue target curve with 95% confidence level.
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Corrosion-Fatigue Crack Growth Performance of Titanium Grade 29 Welds in Tapered Stress Joints
Volume 5B: Pipelines Risers and Subsea Systems, 2019Co-Authors: Gabriel Rombado, David A. Baker, Lars M. Haldorsen, Pedro Craidy, Jim Feiger, Stephen J. HudakAbstract:Abstract Design of steel catenary risers (SCRs) requires the use of connection hardware to decouple the large bending moments induced by the host floater at the hang-off location. Reliability of this connection hardware is imperative, especially in those applications involving high pressure and temperature fluids. One option for connection hardware is the metallic tapered Stress Joint. Because of its inherent density, strength and stiffness, steel is not well suited for these applications as it would result it excessive length and weight for deepwater applications. Titanium grade 29 (Ti 29) has been identified as an attractive material candidate for demanding Stress Joint applications due to its unique mechanical properties including greater flexibility, excellent fatigue performance, and high resistance to sour fluids. Industry has successfully used this technology in over 60 SCR applications. Titanium Stress Joints (TSJs) for deep-water applications are typically not fabricated as a single piece due to titanium ingot/billet volume limitations, thus making an intermediate girth weld necessary to satisfy length requirements. Fracture and fatigue performance of these welds in the presence of cathodic potential in seawater and galvanic potentials in sour production fluids that may produce hydrogen embrittlement effects must be assessed to ensure long term weld integrity. This paper describes a Joint industry project (JIP) performed to qualify titanium Stress Joints welds for ultra-deep water applications under harsh service and environmental conditions. Fatigue crack growth rate (FCGR) results for Ti 29 1G/PA gas tungsten arc welding (GTAW) specimens in air, seawater under cathodic potential and sour brine environments under galvanic potentials are presented and compared to vendor recommended design curves.
Hugh Thompson - One of the best experts on this subject based on the ideXlab platform.
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Sleeved Stress Joint for Steel Catenary Riser Application
29th International Conference on Ocean Offshore and Arctic Engineering: Volume 5 Parts A and B, 2010Co-Authors: S.-h. Mark Chang, Sunil Kuriakose, Paul Stanton, Hugh ThompsonAbstract:Steel catenary risers (SCRs) have been widely used for oil/gas/water transport on floating platforms for the last fifteen years. Flex Joints and tapered Stress Joints are often used for interface between the SCR and platform. Flex Joints and tapered Stress Joints need to be designed to meet both the stiffness and flexibility requirements. A Stress Joint requires high stiffness to withstand the bending moment induced by the SCR and at the same time needs to be sufficiently flexible so as not to overStress the SCR. To achieve these complex requirements, a sleeved Stress Joint (SSJ) provides a sound technical and economical alternative for the interface between the SCR and platform. A sleeved Stress Joint utilizes multiple pipes to provide variable stiffness and to meet the strength and flexibility requirements. In the design of a SSJ, the number of sleeves, and the outer diameters and wall thicknesses of the sleeved pipes can be adjusted to achieve the design requirements. In addition, the locations of welds in the sleeved pipes can be placed to achieve the high fatigue performance that is important in Stress Joint design. Feasibility of the SSJ design is verified through state-of-the-art computer modeling. Generic cases of SSJ design applied to the porch and pull tube of a floating platform are presented. The design concept is compared with traditional flex Joint and tapered Stress Joint designs. The technical and economic advantages of such a design are discussed. © 2010 by ASME.
