Free Span Design Development: Experience With the New Revision of DNVGL-RP-F105

2018 ◽  
Author(s):  
Knut Vedeld ◽  
Håvar Sollund ◽  
Olav Fyrileiv
Keyword(s):  
Operations Management ◽  
Combined Loading ◽  
Recent Experience ◽  
Design Development ◽  
Direct Wave ◽  
Vortex Induced Vibrations ◽  
Waves And Currents ◽  
Environmental Events ◽  
Pipeline Design ◽  
Wave Induced

Free spans constitute a threat to the integrity of offshore pipelines. Ocean currents and wave induced flow near the seabed can cause excitation of vortex induced vibrations (VIV), exposing the pipeline to cyclic loading which may result in fatigue failure. In extreme environmental events, waves and currents may cause significant bending moments due to VIV or direct wave loading, which may cause unacceptably high combined loading potentially resulting in pipeline failure. Safe and reliable free span design is therefore a key aspect of pipeline design in general. When free spans are located in close proximity to each other, modal response may cause span interaction, effectively coupling potential VIV or direct wave action response of two or more spans. Such spans configurations are called multi-spans. Treatment, and particularly identification of multi-span configurations has long been a challenge in the pipeline industry. In 2017, a new revision of the DNV GL recommended practice for free span pipeline design DNVGL-RP-F105 was issued. Among other subjects, the new revision provides significantly improved guidance on identification and classification of multi-span free spanning pipelines. The new guidance facilitates the option of automating identification, modal analysis and ultimately fatigue analysis of multi-span configurations. This paper demonstrates background for and benefits with01 the new revision of DNVGL-RP-F105 in systematic and automated treatment of multi-span identification, fatigue and extreme loading assessments based on recent experience from a selection of pipeline design and operations management case studies.

Recent Advances in Pipeline Free Span Design: A New Revision of DNV-RP-F105

2016 ◽  
Author(s):  
Knut Vedeld ◽  
Håvar Sollund ◽  
Olav Fyrileiv
Keyword(s):  
Dynamic Response ◽  
Limit State ◽  
Cross Flow ◽  
Ease Of Use ◽  
Direct Result ◽  
Ultimate Limit State ◽  
Vortex Induced Vibrations ◽  
Load Effects ◽  
Pipeline Design ◽  
Wave Induced

Pipeline free span design has evolved from basic avoidance criteria in the DNV ’76 rules [1], to fatigue and ultimate limit state considerations in Guideline no. 14 [2]. Modern multimode, multi-span free span design is predominantly performed according to DNV-RP-F105 [3]. In 2006, the latest revision of DNV-RP-F105 [3] was written as a direct result of extensive research, performed due to significant free span challenges in the Ormen Lange pipeline project. DNV-RP-F105 was at the time, and still is, the only pipeline design code giving contemporary design guidance for vortex induced vibrations (VIV) and direct wave loading design for pipelines in free spans. The last revision of DNV-RP-F105 included a few, but highly important advances, particularly the consideration for multi-mode and multi-span pipeline dynamic response behavior. In the 10 years that have followed, no breakthroughs of similar magnitude have been achieved for pipeline free spans, but a large number of incremental improvements to existing calculation methods, and some novel advances in less critical aspects of VIV understanding have been made. As a result, DNV-RP-F105 has recently been revised to account for these advances, which include improved frequency-domain analyses of wave-induced fatigue, a new response model for cross-flow VIV in low Keulegan-Carpenter (KC) regimes in pure waves, new analytical methods for dynamic response calculations of short spans in harsh conditions, and extensive guidance on how to apply the recommended practice for assessment of fatigue and extreme environmental load effects on curved structural members such as spools, jumpers and manifold flexloops. This paper gives an overview of most of the important changes and updates to the new revision of DNV-RP-F105. Case studies are used to demonstrate the importance and effects of the changes made, and to some extent how the revision of DNV-RP-F105 can enhance its applicability and ease of use.

Loads on Ships and Offshore Structures

2007 ◽  
Author(s):  
P. Temarel
Keyword(s):  
State Of The Art ◽  
Fatigue Loading ◽  
Rogue Waves ◽  
Offshore Structures ◽  
Green Water ◽  
Vortex Induced Vibrations ◽  
Ice Loads ◽  
Offshore Industry ◽  
Multi Body ◽  
Wave Induced

The Loads Committee of the International Ship and Offshore Structures Congress (ISSC) critically reviews the state of the art of environmental and operational loads. Amongst these, elements more relevant to the offshore industry will be presented in this paper. These comprise wave-induced loads, including linear and nonlinear methods, multi-body interactions, slamming, green water, sloshing and rogue waves, cables and risers, vortex-induced vibrations, ice loads, fatigue loading and, verification and validation.

Calibration of Safety Factors for DNV RP-F105 Free Spanning Pipelines

2006 ◽  
Author(s):  
Gudfinnur Sigurdsson ◽  
Kim Mo̸rk ◽  
Olav Fyrileiv
Keyword(s):  
Fatigue Damage ◽  
Structural Reliability ◽  
Uncertainty Modeling ◽  
Submarine Pipeline ◽  
Safety Factors ◽  
Sources Of Uncertainty ◽  
Fatigue Design ◽  
Vortex Induced Vibrations ◽  
Stochastic Parameters ◽  
Pipeline Design

Free spans often become a significant challenge in pipeline design and operation due to uneven seabed or seabed scouring effects. The trend towards deeper waters, harsher environment and installation of pipelines at very uneven seabed often implies a high number of free spans. High costs related to span intervention puts focus on minimizing these costs and still ensure integrity of the pipeline with respect to vortex induced vibrations (VIV) and associated fatigue damage. On the other hand the potential costs related to fatigue failure of a pipeline (recovery costs and economical loss) are enormous. Therefore it is essential to ensure that the probability of failure for free spans is within acceptable limits, e.g. as required by DNV-OS-F101 “Submarine Pipeline Systems”. This paper describes the structural reliability analysis performed to obtain the safety factors for free span fatigue design. Accumulation of fatigue damage due to VIV of free spans is associated with various sources of uncertainty. The important stochastic parameters are described, and the basis for the uncertainty modeling given. The calibration scope defined from a set of different pipeline cases, span scenarios, and environmental conditions is presented from which calibration results and sensitivities will be discussed.

Fatigue Design and Analysis of Offshore Pipelines and Risers Subjected to Waves and Currents

2017 ◽  
Vol 140 (2) ◽  
Author(s):  
M. Liu ◽  
C. Cross
Keyword(s):  
Fatigue Damage ◽  
Damage Accumulation ◽  
Coupling Effect ◽  
Limit State ◽  
Ultimate Limit State ◽  
Offshore Pipelines ◽  
Fatigue Design ◽  
Fatigue Damage Accumulation ◽  
Waves And Currents ◽  
Wave Induced

The industry consensus would appear that the effect of currents on wave-induced fatigue damage accumulation is assumed as insignificant and can be ignored. Only when dealing with stability, ultimate limit state design, and vortex-induced vibration (VIV), is the recommended industry practice to consider both currents and waves simultaneously, except for fatigue design. This paper presents a study on how environmental loads should be considered in terms of currents and waves for the fatigue life design of offshore pipelines and risers. The study is intended as a spur to redress the misapprehension by focusing on the coupling effect of direct waves and currents in the context of fatigue damage assessment. It is demonstrated unequivocally that waves and currents cannot be decoupled for fatigue design assessments. Wave-induced fatigue with the inclusion of currents is manifested twofold, not only the increased mean stress correction effect but also higher total damage accumulation due to elevated stress ranges. The practice of using wave histograms while ignoring currents is shown to result in an unacceptable nonconservative fatigue design. Both effects should be accounted for in the engineering assessment. A first-order correction factor involving the ratio of current and wave velocities is introduced to evaluating the environmental load coupling effect. It is recognized that fatigue associated specifically with VIV phenomena is well understood and documented elsewhere, its discussion is thus out with the aims of this paper.

Metocean Criteria for the Fatigue Analysis of Subsea Pipelines

2019 ◽  
Author(s):  
Richard Gibson ◽  
Marios Christou
Keyword(s):  
Fatigue Damage ◽  
Clustering Algorithms ◽  
Statistical Dependence ◽  
The Caspian Sea ◽  
Vortex Induced Vibrations ◽  
Waves And Currents ◽  
Order Of Magnitude ◽  
Extreme Value Model ◽  
Current Loading ◽  
Subsea Pipelines

Abstract This paper is concerned with a methodology for defining metocean criteria for the analysis of subsea pipelines. The approach that has been developed incorporates the statistical dependence between wave and current loading. The method achieves this through a combination of the application of the conditional extreme value model of Heffernan and Tawn (2004) and clustering algorithms. This is particularly important in regions where the currents are largely wind driven as there can be a strong correlation between the two. The results can be used to assess fatigue damage from vortex-induced-vibrations and wave loading. The same model can be used to derive deterministic design events. The method is applied to a pipeline in the Caspian Sea. The results are compared to models that assume either independence or a perfect correlation between waves and currents. It is shown that simpler models that do not accurately model the dependence between the waves and the currents can provide estimates of fatigue damage that are an order of magnitude too high or too low.

A suppressor to prevent direct wave-induced cavitation in shock wave therapy devices

2005 ◽  
Vol 118 (1) ◽  
pp. 178-185 ◽  
Author(s):  
Thomas J. Matula ◽  
Paul R. Hilmo ◽  
Michael R. Bailey
Keyword(s):  
Shock Wave ◽  
Shock Wave Therapy ◽  
Direct Wave ◽  
Wave Induced

Philosophy of Architecture Design in Web Information Systems

2011 ◽  
pp. 443-461
Author(s):  
Tony C. Shan ◽  
Winnie W. Hua
Keyword(s):  
Information Systems ◽  
Operations Management ◽  
System Analysis ◽  
Architecture Design ◽  
Design Development ◽  
Web Based ◽  
Web Information ◽  
Service Oriented ◽  
Web Information Systems ◽  
Guiding Principles

This article defines a comprehensive set of guiding principles, called philosophy of architecture design (PAD), as a means of coping with the architecture design complexity and managing the architectural assets of Web information systems in a service-oriented paradigm. This coherent model comprises a multidimensional collection of key guiding principles and criteria in system analysis, modeling, design, development, testing, deployment, operations, management, and governance. The systematic framework provides a multidisciplinary view of the design tenets, idioms, principles, and styles (TIPS) in the IT architecting practices for engineering process and quality assurance. There are 26 constituent elements defined in the scheme, the names of which form an array of A-Z using the first letter. The characteristics and applicability of all 26 dimensions in the PAD model are articulated in detail. Recommendations and future trends are also presented in the context. This overarching model has been extensively leveraged in one format or another to design a wide range of Web-based systems in various industry sectors.

Metocean Design Criteria for Pipeline On-Bottom Stability

2011 ◽  
Author(s):  
Richard Gibson
Keyword(s):  
Parametric Representation ◽  
Extreme Value Analysis ◽  
Design Criteria ◽  
Value Analysis ◽  
Reliability Method ◽  
Extreme Response ◽  
Wave Cycle ◽  
Induced Velocity ◽  
Pipeline Design ◽  
Wave Induced

This paper is concerned with a response based method for determining metocean design criteria for offshore pipelines. The method determines a set of metocean parameters that are consistent with the extreme response of the pipeline, and hence, incorporates the dependence between them implicitly. However, there are a number of challenges in its application. Firstly, the loading on a pipeline is dependent on the previous wave cycle, and hence, the drag and inertia coefficients vary within a sea-state. Secondly, along many pipeline routes the waves are depth limited and the short-term distribution of wave induced velocity and pipeline response can be difficult to define. These challenges are overcome through a number of approaches that include a parametric representation of the distribution of the response and the application of multivariate extreme value analysis. Furthermore, the sensitivity of the method to assumptions about the pipeline design is examined, and the problems with using the combined wave and current induced velocity as a proxy for the response are discussed. The method is applied to a site in the Mediterranean Sea and the results are compared to those from the application of the first order reliability method.

scholarly journals Characterizing Wave Shape Evolution on an Ebb-Tidal Shoal

2019 ◽  
Vol 7 (10) ◽  
pp. 367 ◽  
Author(s):  
Floris de Wit ◽  
Marion Tissier ◽  
Ad Reniers
Keyword(s):  
Wave Breaking ◽  
Field Measurements ◽  
Tidal Currents ◽  
Wave Shape ◽  
Spatial Gradients ◽  
Nonlinear Energy Transfer ◽  
Waves And Currents ◽  
Wave Induced ◽  
Local Parameters ◽  
Nonlinear Energy

Field measurements of waves and currents were obtained at ten locations on an ebb-tidal shoal seaward of Ameland Inlet for a six-week period. These measurements were used to investigate the evolution of the near-bed velocity skewness and asymmetry, as these are important drivers for wave-induced sediment tranport. Wave shape parameters were compared to traditionally used parameterizations to quantify their performance in a dynamic area with waves and tidal currents coming in from different directions over a highly variable bathymetry. Spatially and temporally averaged, these parameterizations compared very well to observed wave shape. However, significant scatter was observed. The largest deviations from the parameterization were observed at the shallowest locations, where the contribution of wave-induced sediment transport was expected to be the largest. This paper shows that this scatter was caused by differences in wave-breaking, nonlinear energy transfer rate, and spatial gradients in tidal currents. Therefore, it is proposed to include the prior evolution of the wave before reaching a location in future parameterizations in numerical modeling instead of only using local parameters to predict wave shape.

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