scholarly journals Re-Evaluation of Fatigue Thickness Effect Based on Fatigue Test Database

2020 ◽  
Vol 8 (11) ◽  
pp. 895 ◽  
Author(s):  
Wangwen Zhao ◽  
Wei-Ting Hsu
Keyword(s):  
Fatigue Strength ◽  
Oil And Gas ◽  
Offshore Wind ◽  
Thickness Effect ◽  
Research Programmes ◽  
Offshore Oil And Gas ◽  
Corrosive Environments ◽  
Steel Joints ◽  
Test Database ◽  
Current Standards

This paper reassesses the detrimental effect on fatigue performance of welded structural steel joints due to thicker sections based on an extensive fatigue strength test database, taken from research programmes worldwide over the past half century, mostly from the offshore oil and gas and marine industries. The data entries in the database were evaluated to ensure its data integrity. Statistical analyses on these S-N data were performed with or without the thickness correction at different exposure levels to a corrosive environment, in order to re-evaluate the suitability of current standards in regard to the thickness effect. The study concentrated on T-joints, transverse butt-welded joints and tubular joints, as these are the most commonly used joint types in the offshore wind industry. The analysis indicates a general agreement of fatigue strength with the thickness effects in current standards for in-air conditions, but great conservatism for corrosive environments. In addition, the statistical models determined in this study can be used for a broader range of studies, such as probabilistic fatigue analysis.

scholarly journals Revaluation of Fatigue Thickness Effect Based on Fatigue Test Database

2020 ◽  
Author(s):  
Wangwen Zhao ◽  
Wei-Ting Hsu
Keyword(s):  
Fatigue Strength ◽  
Offshore Wind ◽  
Thickness Effect ◽  
Exposure Level ◽  
Corrosive Environment ◽  
Current Standard ◽  
Tubular Joint ◽  
Offshore Oil ◽  
Test Database ◽  
Offshore Wind Industry

This paper reassesses the detrimental effect on fatigue performance due to thicker sections based on extensive fatigue strength test database, taken from research program worldwide over the past half of a century in offshore oil & gas and renewable industry. The data entries in the database have been evaluated to ensure its data integrity. Statistical analyses on these S-N data are performed with or without the thickness correction at different exposure level to corrosive environment, in order to re-evaluate the suitability of current standards in regard to the thickness effect. The study has concentrated on T-joint, transverse butt welded joint and tubular joint as these are the most commonly used joint types in the offshore wind industry. The analysis indicates general agreement of fatigue strength with the thickness effects in current standard for in air conditions but great conservatism for corrosive environment.

scholarly journals Calibration of Design Fatigue Factors for Offshore Wind Turbine Support Structure Based on Fatigue Test Database

2020 ◽  
Author(s):  
Wangwen Zhao ◽  
Wei-Ting Hsu
Keyword(s):  
Probabilistic Models ◽  
Offshore Wind ◽  
Offshore Wind Turbine ◽  
Corrosion Condition ◽  
Structural Fatigue ◽  
Multiple Factors ◽  
Fatigue Design ◽  
Test Database ◽  
Current Standards ◽  
Offshore Wind Industry

The concept of Design Fatigue Factors (DFFs) was introduced for providing desired level of safety in structural fatigue design, often associated with damage calculated from S-N curves. Calculation of fatigue damage from S-N curves can be affected by multiple factors, e.g. types of weld class, corrosion condition, loading conditions, stress concentration on different geometries etc. Each of them can be subject to different level of uncertainties. This study intends to recalibrate the DFFs from a detailed reliability analysis by investigating the probabilistic models derived from the database of S-N curves that has been most frequently used in offshore wind industry. The results of such study indicate that the DFFs can be reduced substantially for the corrosive environmental fatigue models from current standards to the same level of target reliability.

Revision of DNV Design Standard for Offshore Wind Turbine Structures

2007 ◽  
Author(s):  
Jakob Wedel-Heinen ◽  
Knut O. Ronold ◽  
Peter Hauge Madsen
Keyword(s):  
Wind Turbine ◽  
Oil And Gas ◽  
Oil And Gas Industry ◽  
Offshore Wind ◽  
Offshore Wind Turbine ◽  
Wave Loads ◽  
Gas Industry ◽  
Standard Design ◽  
Practical Guidelines ◽  
Offshore Oil And Gas

The first DNV-OS-J101 standard “Design of Offshore Wind Turbine Structures” [1] was issued in June 2004. The standard represented a condensation of all relevant requirements in DNV standards for the offshore oil and gas industry which were considered relevant also for offshore wind turbine structures, supplemented by necessary adaptation to the wind turbine application. Det Norske Veritas (DNV) plans to issue the next revision of DNV-OS-J101 [2] in 2007. The DNV revised standard now implements the requirements of the coming IEC 61400-3 standard [11], which was presented as a committee draft in 2006. Numerous practical guidelines have been included to help designers of offshore wind turbine structures to develop cost optimal designs. The present paper summarises the proposed revisions of DNV-OS-J101 [2]. The most important revisions cover new formulations for design load cases, modified partial safety factors, exclusion of transformer platforms, more information on wave loads in shallow water and a revised chapter for design of concrete structures.

scholarly journals A Review of Life Extension Strategies for Offshore Wind Farms Using Techno-Economic Assessments

Energies ◽  
2021 ◽  
Vol 14 (7) ◽  
pp. 1936
Author(s):  
Benjamin Pakenham ◽  
Anna Ermakova ◽  
Ali Mehmanparast
Keyword(s):  
Wind Farm ◽  
Oil And Gas ◽  
Wind Farms ◽  
Offshore Wind ◽  
Life Extension ◽  
Financial Model ◽  
Offshore Wind Farms ◽  
Advantages And Disadvantages ◽  
Course Of Action ◽  
Offshore Oil And Gas

The aim of this study is to look into the current information surrounding decommissioning and life extension strategies in the offshore wind sector and critically assess them to make informed decisions upon completion of the initial design life in offshore wind farms. This was done through a two-pronged approach by looking into the technical aspects through comprehensive discussions with industrial specialists in the field and also looking into similar but more mature industries such as the Offshore Oil and Gas sector. For the financial side of the assessment, a financial model was constructed to help portray a possible outcome to extend the life for a current offshore wind farm, using the existing data. By employing a techno-economic approach for critical assessment of life extension strategies, this study demonstrates the advantages and disadvantages of each strategy and looks to inform the offshore wind industry the best course of action for current wind farms, depending on their size and age.

Girth Weld Joints From Long Upset Pipe Ends for Improving Fatigue Strength of Offshore Oil and Gas Pipelines

2019 ◽  
Author(s):  
Israel Marines-Garcia ◽  
Aarón Aguilar ◽  
Ramón Aguilar ◽  
Mauricio Pelcastre ◽  
Philippe Darcis
Keyword(s):  
Mechanical Properties ◽  
Fatigue Strength ◽  
Structural Integrity ◽  
Oil And Gas ◽  
Numerical Comparison ◽  
Entire Line ◽  
Girth Welding ◽  
Production Stages ◽  
Offshore Oil And Gas ◽  
Girth Welds

Abstract For special high dynamic loading applications, the structural integrity of the girth welds shall withstand stress levels that might be on the limits of the permissible defect tolerances for current production welding standards for plain pipe ends. In addition, unexpected loading conditions might take the stress limits out of safe operation, which can compromise the entire line. As a solution, the cross section of the girth weld may be increased for ensuring the strength and fatigue resistance under any loading circumstances, including strain cycles of reeling installation technique. The employment of pipes with upset ends is an excellent option for those cases. To propose this option as an alternative to current offshore solution for a Major O&G company, Tenaris developed a long upset pipe end with enhanced fatigue life. The challenges of this work included the manufacturing of very long upset ends from a medium wall thickness pipe, very tight mechanical properties difference between pipe and upset material properties, and finally a welding qualification program. The improvement of the fatigue strength of this product was highly expected. In order to achieve all requirements, especial arrangements were performed on the upsetter machine for achieving the target upset geometry; which was previously obtained by a design of experiments technique. Then the heat treatment of the pipes was designed for obtaining the tight mechanical properties difference between pipe body and upset sections. The main outcomes of the whole development are described within this paper; which include key information of how to overcome issues that might arise during the development and production stages of upsetted line pipes. The upset ends undertake a cylindrical machining; this process provides the advantage of achieving tight dimensional tolerances in the high-low girth welding alignment. The fatigue endurance data after full scale reeling experimental test are included, as well as the numerical comparison between the strain fields of plain pipe and upset girth weld unions. The welding procedure qualified during this work is described. The results of the whole development were very satisfactory and, as expected, the fatigue strength of upset ends was higher than the plain pipe.

scholarly journals Environmental Permitting and Compliance Cost Reduction Strategies for the MHK Industry: Lessons Learned from Other Industries

2020 ◽  
Vol 8 (8) ◽  
pp. 554
Author(s):  
Sharon Kramer ◽  
Craig Jones ◽  
Geoffrey Klise ◽  
Jesse Roberts ◽  
Anna West ◽  
...  
Keyword(s):  
Wind Energy ◽  
Oil And Gas ◽  
Clean Energy ◽  
Vital Role ◽  
Lessons Learned ◽  
Offshore Wind ◽  
Compliance Cost ◽  
Offshore Oil And Gas ◽  
Environmental Permitting ◽  
The U.S

The marine and hydrokinetic (MHK) industry plays a vital role in the U.S. clean energy strategy by providing a renewable, domestic energy source that may offset the need for traditional energy sources. The first MHK deployments in the U.S. have incurred very high permitting costs and long timelines for deploying projects, which increases project risk and discourages investment. A key challenge to advancing an economically competitive U.S. MHK industry is reducing the time and cost required for environmental permitting and compliance with government regulations. Other industries such as offshore oil and gas, offshore wind energy, subsea power and data cables, onshore wind energy, and solar energy facilities have all developed more robust permitting and compliance pathways that provide lessons for the MHK industry in the U.S. and may help inform the global consenting process. Based on in-depth review and research into each of the other industries, we describe the environmental permitting pathways, the main environmental concerns and types of monitoring typically associated with them, and factors that appear to have eased environmental permitting and compliance issues.

Offshore Wind Turbine and Substructure Modelling for a Float Over Installation Design

2009 ◽  
Author(s):  
Jean-Marc Cholley ◽  
M. Cahay
Keyword(s):  
Wind Turbine ◽  
Wind Turbines ◽  
Wind Farm ◽  
Oil And Gas ◽  
Cost Effective ◽  
Offshore Wind ◽  
Offshore Wind Turbine ◽  
Heavy Lift ◽  
Offshore Oil And Gas ◽  
Turbine Installation

We can learn from the offshore oil and gas experience for the future offshore wind turbine installation. For the offshore ‘wind farm’ developments, the installation of wind turbines onto preinstalled foundations using the heavy lift vessel method or stabilized vessel is now well established, though, for large units, this requires multiple lifts and hence extensive offshore assembling. As demand for lift vessels increases, their availability to match a future large specific project’s schedule cannot be guaranteed. Consequently, an alternative wind turbine installation vessel design has been developed for not only installing simultaneously two wind turbines in a single piece, but also with a high air gap (up to 70 ft). This paper presents this new design. The new vessel design consists of a catamaran shaped vessel with dimensions that permit it to go around variety of substructures (piles foundation, tripod, concrete foundation or floating substructure) for float-over installation of wind turbines. For the float-over operation, a thorough understanding of dynamic behavior and environmental conditions are necessary to allow the design load to be assessed, with the objective to minimize the risk and maximize the operating sea states. This paper gives a description of how the substructure / Wind turbine / transition piece / floating unit can be modeled. This new vessel design greatly extends the geographical range for offshore wind turbine installation using the float-over method and offers a cost effective alternative to relying on crane vessels.

scholarly journals Case Study of Integrating an Offshore Wind Farm with Offshore Oil and Gas Platforms and with an Onshore Electrical Grid

2013 ◽  
Vol 2013 ◽  
pp. 1-10 ◽  
Author(s):  
Wei He ◽  
Kjetil Uhlen ◽  
Mahesh Hadiya ◽  
Zhe Chen ◽  
Gang Shi ◽  
...  
Keyword(s):  
Wind Farm ◽  
Oil And Gas ◽  
Wind Farms ◽  
Offshore Wind ◽  
Offshore Wind Farm ◽  
Electrical Grid ◽  
Economical Analysis ◽  
Electrical Grids ◽  
Offshore Oil And Gas ◽  
Offshore Oil

This research project explored the technical feasibility of utilizing an offshore wind farm as a supplementary power source to several electrical grids of offshore oil and gas platforms and providing surplus power to an onshore grid. Three case studies comprising wind farms rated at 20 MW, 100 MW, and 1000 MW have been studied with the focus on (i) the operation benefits of CO2/NOxemission reduction, (ii) the electrical grid stability, and (iii) the technical implementation feasibility. The proposed 20 MW, 100 MW, and 1000 MW wind farm cases are theoretically feasible in terms of the selected technical criteria, although further detailed design operational studies, and economical analysis are required.

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