Development and Qualification of Alternative Solutions for Improved Fatigue Performance of Deepwater Steel Catenary Risers

2007 ◽  
Author(s):  
Rajiv K. Aggarwal ◽  
Marcio M. Mourelle ◽  
Steinar Kristoffersen ◽  
Henri Godinot ◽  
Pedro Vargas ◽  
...  
Keyword(s):  
Laboratory Testing ◽  
Fatigue Testing ◽  
High Strength ◽  
Operating Conditions ◽  
Fatigue Performance ◽  
Steel Catenary Riser ◽  
Regulatory Bodies ◽  
Steel Catenary Risers ◽  
Floating Platforms ◽  
Floating Systems

Several initiatives have been undertaken by the operators, engineering companies, product manufacturers, and regulatory bodies to enable increased use of steel catenary riser (SCR) design in development of deepwater and ultra-deepwater fields. Some of these efforts focus on improvement in understanding of soil-structure interaction at SCR touch down zone (TDZ) and its impact on fatigue damage estimates through analytical studies, laboratory testing, or in-field monitoring of SCR behavior. Through recent studies and laboratory testing work for floating platforms with SCR, the need for significant enhancement of SCR design at TDZ through implementation of alternate solutions has been identified. This paper presents a summary of the work undertaken in a Joint Industry Project (JIP) during 2004 to 2007 [1, 2] to develop solutions and undertake qualification tasks for four alternatives with potential to improve fatigue performance at TDZ by factor of up to 10 or more. The solutions considered at SCR TDZ include: thick light-weight coating over steel riser sections; steel riser sections with upset ends; high strength steel riser sections with integral connectors; and a titanium segment. The major qualification tasks undertaken for each solution will be identified and discussed. The qualification program undertaken for each solution varied and in some cases, it also included manufacturing of samples, laboratory and full-scale fatigue testing, and post-failure evaluation. Through significant qualification activities undertaken in this JIP, progress has been made to bring these solutions to project ready state for their consideration at the frond end engineering design (FEED) stage. Such design enhancements would enable increase in selection of SCR design for production and export riser applications under severe operating conditions, harsh environment, and floating systems with high motions.

Process-Structure-Property Fatigue Characterisation for Welding of X100 Steel Catenary Risers

2019 ◽  
Author(s):  
Ronan J. Devaney ◽  
Adrian Connaire ◽  
Padraic E. O’Donoghue ◽  
Sean B. Leen
Keyword(s):  
Weld Metal ◽  
Fatigue Testing ◽  
Weld Zone ◽  
Parent Material ◽  
Strain History ◽  
Structure Property ◽  
Steel Catenary Riser ◽  
Thermomechanical Simulation ◽  
Steel Catenary Risers ◽  
Process Structure

Abstract Welded connections are a fatigue sensitive location for offshore steel catenary risers. The susceptibility to fatigue is due to the notch effect of the weld and the gradient in microstructure and material properties across the weld which result from welding thermal cycles and differences in the composition of the parent material and weld metal. In this work, a representative full-scale steel catenary riser girth weld is conducted using X100Q steel. The thermal and strain history in the weld zone are captured using a thermocouple and strain gauge array. A parallel programme of Gleeble thermomechanical simulation is implemented to develop microstructurally uniform heat affected zone (HAZ) test specimens. The parent material, weld metal, simulated HAZ and a cross-weld sample are characterised using a programme of nanoindentation, tensile and fatigue testing. A softened region with microstructure corresponding to intercritical HAZ (ICHAZ) is identified in the girth weld. Tensile and fatigue failures are shown to occur in a representative microstructural region for simulated HAZ specimens, indicating a susceptibility to failure in the ICHAZ for matched or over-matched X100Q welds.

Steel Lazy Wave Riser Optimization Using Artificial Intelligence Tool

2020 ◽  
Author(s):  
Mayank Lal ◽  
Abhilash Sebastian ◽  
Feng Wang ◽  
Xiaohua Lu
Keyword(s):  
Artificial Intelligence ◽  
Genetic Algorithm ◽  
Design Process ◽  
Oil And Gas ◽  
Time Domain Analysis ◽  
Fatigue Performance ◽  
Wave Form ◽  
Steel Catenary Risers ◽  
Performance Drivers ◽  
Floating Platforms

Abstract Use of steel lazy wave risers has increased as oil and gas developments are happening in deeper waters or in parts of the world with no pipeline infrastructure. These developments utilize FPSO’s with offloading capabilities necessary for these developments. However, due to more severe motions compared to other floating platforms, traditional catenary form of risers are unsuitable for such developments and this is the reason Steel lazy wave risers (SLWR) are required. SLWRs have shown to have better strength and fatigue performance and lower tensions at the hang-off compared to steel catenary risers. A suitable Lazy-Wave form of the catenary riser is achieved by targeted placement of a custom configured buoyancy section. The strength and fatigue performance of steel lazy wave risers are governed by parameters such as length to start of this buoyancy section, length of the buoyancy section, hang-off angle and the buoyancy factor. Achieving these key performance drivers for a SLWR takes several iterations throughout the design process. In this paper, genetic algorithm which is an artificial intelligence optimization tool has been used to automate the generation of an optimized configuration of a steel lazy wave riser. This will enable the riser designer to speed up the riser design process to achieve the best location, coverage and size of the buoyancy section. The results that the genetic algorithm routine produces is compared to a parametric study of steel lazy wave risers varying the key performance drivers. The parametric analysis uses a regular wave time domain analysis and captures trends of change in strength and fatigue performance with change in steel lazy wave parameters.

Sleeved Stress Joint for Steel Catenary Riser Application

2010 ◽  
Author(s):  
S.-H. Mark Chang ◽  
Paul Stanton ◽  
Sunil Kuriakose ◽  
Hugh Thompson
Keyword(s):  
Bending Moment ◽  
Variable Stiffness ◽  
Floating Platform ◽  
Steel Catenary Riser ◽  
High Fatigue ◽  
Steel Catenary Risers ◽  
Design Requirements ◽  
Floating Platforms ◽  
Oil Gas ◽  
Economical Alternative

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.

scholarly journals Electrochemical treatment of high strength chrome bathwater: A comparative study for best-operating conditions

2021 ◽  
pp. 100093
Author(s):  
Vishakha Gilhotra ◽  
Rekha Yadav ◽  
Aditi Sugha ◽  
Laxmi Das ◽  
Ashutosh Vashisht ◽  
...  
Keyword(s):  
Comparative Study ◽  
High Strength ◽  
Electrochemical Treatment ◽  
Operating Conditions

Dynamic Optimization of Steel Catenary Risers Based on Reliability Using Metamodel

2010 ◽  
Author(s):  
Wenqing Zheng ◽  
Hezhen Yang
Keyword(s):  
Dynamic Optimization ◽  
Computational Cost ◽  
Minimum Cost ◽  
Probabilistic Constraints ◽  
Optimization Approach ◽  
Element Analysis ◽  
Steel Catenary Riser ◽  
Reliability Based Design ◽  
Minimum Cost Design ◽  
Steel Catenary Risers

Reliability based design optimization (RBDO) of a steel catenary riser (SCR) using metamodel is investigated. The purpose of the optimization is to find the minimum-cost design subjecting to probabilistic constraints. To reduce the computational cost of the traditional double-loop RBDO, a single-loop RBDO approach is employed. The performance function is approximated by using metamodel to avoid time consuming finite element analysis during the dynamic optimization. The metamodel is constructed though design of experiments (DOE) sampling. In addition, the reliability assessment is carried out by Monte Carlo simulations. The result shows that the RBDO of SCR is a more rational optimization approach compared with traditional deterministic optimization, and using metamodel technique during the dynamic optimization process can significantly decrease the computational expense without sacrificing accuracy.

The Motion of Floating Systems: Nonlinear Dynamics in Periodic and Random Waves

2009 ◽  
Vol 131 (4) ◽  
Author(s):  
Katrin Ellermann
Keyword(s):  
Dynamical Behavior ◽  
Nonlinear Behavior ◽  
Operating Conditions ◽  
Random Waves ◽  
Multiple Components ◽  
Random Disturbances ◽  
Restoring Forces ◽  
Steady State Responses ◽  
External Forces ◽  
Floating Systems

Floating systems, such as ships, barges, or semisubmersibles, show a dynamical behavior, which is determined by their internal structure and the operating conditions caused by external forces e.g., due to waves and wind. Due to the complexity of the system, which commonly includes coupling of multiple components or nonlinear restoring forces, the response can exhibit inherently nonlinear characteristics. In this paper different models of floating systems are considered. For the idealized case of purely harmonic forcing they all show nonlinear behavior such as subharmonic motion or different steady-state responses at constant operating conditions. The introduction of random disturbances leads to deviations from the idealized case, which may change the overall response significantly. Advantages and limitations of the different mathematical models and the applied numerical techniques are discussed.

Use of DNVGL-RP-C203 for Determining the Fatigue Capacity of Connectors

2021 ◽  
Author(s):  
Anthony Muff ◽  
Anders Wormsen ◽  
Torfinn Hørte ◽  
Arne Fjeldstad ◽  
Per Osen ◽  
...  
Keyword(s):  
Finite Element ◽  
Fatigue Testing ◽  
Experimental Testing ◽  
High Strength ◽  
Element Model ◽  
Fatigue Analysis ◽  
Full Scale ◽  
The Finite Element Model

Abstract Guidance for determining a S-N based fatigue capacity (safe life design) for preloaded connectors is included in Section 5.4 of the 2019 edition of DNVGL-RP-C203 (C203-2019). This section includes guidance on the finite element model representation, finite element based fatigue analysis and determination of the connector design fatigue capacity by use of one of the following methods: Method 1 by FEA based fatigue analysis, Method 2 by FEA based fatigue analysis and experimental testing and Method 3 by full-scale connector fatigue testing. The FEA based fatigue analysis makes use of Appendix D.2 in C203-2019 (“S-N curves for high strength steel applications for subsea”). Practical use of Section 5.4 is illustrated with a case study of a fatigue tested wellhead profile connector segment test. Further developments of Section 5.4 of C203-2019 are proposed. This included acceptance criteria for use of a segment test to validate the FEA based fatigue analysis of a full-scale preloaded connector.

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