bluuebunny/crossref_metadata_2025_split huggingface dataset:
Taking Further the Domain of Use of Low Plasticized High Molecular Weight PVDF for Monolayer Dynamic Application in Flexible Pipe
Authors: Epsztein Thomas , Demanze Frederic 
Published: October 2016

Flexible pipes have been used to transport oil and gas in subsea applications for more than 40 years. Since 2010, and following a significant qualification work performed within Technip flexible pipe technology center, it has been possible to use a low plasticized high molecular weight PVDF with enhanced mechanical properties as monolayer pressure sheath in flexible pipe applications. This qualification work covered both static and dynamic applications. A large number of projects have already taken advantage of the monolayer design for high temperature applications. Indeed, more than 80km of flexible pipe with this PVDF grade have already been manufactured.
This paper will present the work that has been carried out during the last 5 years in order to extend the qualified domain of use of this PVDF grade:
-Maximum design temperature extended from 130°C to 150°C,
-Minimum design temperature extended from −20°C to −30°C,
-Design pressure extended up to 17.5kPsi.
A specific focus will be made on the results obtained on several tests performed at lab scale and on full scale flexible pipes and which have been used to support this extension of the domain of use.
Such tests include the verification of the PVDF grade to sustain rapid gas decompression after exposure to gas medium at high pressure (> 17.5kPsi) and high temperature (150°C). Permeation tests have also been performed at 150°C.
Four full scale tests have been performed on a 6″ flexible pipe with design pressure equal to 17.5kPsi. The first test was performed on a flexible pipe sample submitted to a hydrostatic pressure test at a pressure reaching 27.5kPsi. The second test was performed on a flexible subjected to a fatigue test (tension and angle variation) simulating flexible pipe loading in operating conditions. A burst test was performed on a third flexible pipe sample. During this test, a burst pressure equal to 37.9kPsi was reached. Finally, a fourth flexible pipe sample was tested through the realization of a large number of large bending cycles while keeping the flexible under internal pressure.
The possibility to use this PVDF grade with enhanced mechanical properties down to −30°C has been demonstrated through the realization of thermal cycles between 150°C and −30°C on two flexible pipe samples. This test is realized in order to confirm sealing efficiency towards thermal stresses which occur during shutdowns. The result of a specific full scale test performed, after ageing at 150°C, in extreme conditions of bending and temperature (lower than −30°C) will also be presented.
This extension of the qualified domain of use enables the use of flexible pipes in harsher applications, and also further substantiates the robustness for the use of this grade within the initial qualification domain.
Flow-Induced Vibrations of Riser Array System
Authors: Joshi Vaibhav , Liu Bin , Jaiman Rajeev K. 
Published: October 2016

When a riser array system is subjected to a uniform flow, an unstable flow-induced vibration commonly occurs among cylinders, generally called fluid-elastic instability. It can cause long-term or short-term damage to the riser array system. A numerical investigation has been performed in the present study. Generally, flow-induced vibrations include vortex-induced vibration (VIV), wake-induced vibration (WIV), jet switching, turbulent buffeting and fluid-elastic instability. The dynamic interactions among the fluid-induced vibrations, wake interference and proximity interference pose difficulties in the design and operation of the riser array system. The dynamics of a riser array system is very different from that of basic canonical configurations such as side-by-side, tandem and staggered arrangements. In a riser array system, the interferences come from all possible nearby constituent risers. There is a synchronization phenomenon among the cylinders, which may lead to detrimental collisions and short-term failures. It is known that the vortex-induced vibration (VIV) of an isolated circular cylinder is self-limiting. An extensive vibration occurs in the lock-in region within which the frequency of the vortex shedding matches the structural frequency of the immersed structure. In a riser array system, there is a point at which the vibration of cylinder suddenly increases. The vibration of the constituent risers increases without bound with the increment of the free-stream velocity. This free-stream velocity is defined as the critical velocity. The interference not only comes from the inline and cross-flow directions, but also the wake interference from the diagonal upstream risers. In a riser array system, each riser vibrates independently. However, there is symmetry of frequency spectrum observed about the inline direction along the middle row of the risers.
In this study, the dynamic response of the different risers in the array system is investigated with the help of the amplitude response results from the canonical arrangements (side-by-side and tandem) and wake flow structures. The long top-tensioned riser system can be idealized by two-dimensional elastically mounted cylinders to solve the complex fluid-structure interaction problem. The dynamic response of a typical riser array system has been analyzed at low and high Reynolds number. It is encouraging to see that the results reported in the present investigation can provide useful insight and suggestions in the design and optimization of riser systems to avoid collisions and various long-or short-term failures.
A Preliminary Investigation on the Risk Arising From the Use of HP FGS System in LNGC by Analyzing Risk Contributors Comparatively
Authors: Yoon Joon Young , Park Sung-In , Lee Jae Bong , Kwon Seungmin , Hwang Yoonsik 
Published: October 2016

This work is motivated by the need to identify the fire and explosion risk on LNGCs developed by Daewoo Shipbuilding & Marine Engineering Co., Ltd. (DSME) because the main engines are designed to use highly pressurized natural gas (about 300 bar), which has caused vague fears of fire and explosion risks.
In this context, to identify the risk of fires and explosions quantitatively caused by ignitions of unintended leaked gas from fuel gas lines, a FERA was carried out for the LNGCs [1]. This paper, as a part of the FERA, presents the results of a preliminary investigation on the effect of introducing the highly pressured fuel gas system into LNGCs on the fire and explosion risk especially in the cargo compressor room. This study is conducted in a comparative way considering the risk contribution of each parameter that could impact on the fire and explosion risk in LNGCs. The effect of the highly pressured fuel gas is indirectly taken into account by the change of the initial leak rate in the system. To identify effects of the considered parameters quantitatively, dozens of simulations for the selected gas dispersion, explosion and fire scenarios were carried out using FLACS and KFX. Based on the results from the simulations, it is concluded that, in case of the LNGCs, the effects of the initial large leak rate due to the high pressure in the fuel gas pipes on fire and explosion risk are not significant compared with the other parameters’ effects.
A System for Measuring Ice-Induced Accelerations and Identifying Ice Actions on the CCGS Amundsen and a Swedish Atle-Class Icebreaker
Authors: Heyn Hans-Martin , Skjetne Roger 
Published: October 2016

When ships operate in the Arctic, sea-ice induce an additional environmental load on the vessel. The ice load can vary significantly depending on the dominating ice-breaking failure mode.
In this work a sensor system for measuring ice induced accelerations on the Canadian icebreaker CCGS Amundsen and a Swedish Atle-class icebreaker is presented. The sensor system consists of low-cost inertial measurement units. Ship-ice interaction data has been collected during expeditions along the coast of Labrador in Canada and in the Greenland Sea north of the Norwegian Svalbard archipelago. Depending on the failure mechanism of the interacting ice, vibrations at different frequencies are induced into the icebreaker ship. A time-frequency decomposition based on the Wigner-Ville distribution has been modified such that it is applicable to analysis of ice-load induced acceleration signals. Based on the frequency pattern of the induced vibrations, this novel method allows for evaluation of the intensity of the ice-loads and identification of the dominating ice failure mechanism, which is demonstrated for several ship-ice interaction events.
The presented novel time-frequency decomposition for ice induced accelerations is a powerful tool for the identification of the threat imposed by sea-ice to a structure. In further work the time-frequency decomposition will be used as feedback in ice-capable control and monitoring systems for Arctic offshore operations.
The Relationship Between the Shape of Freak Waves and Nonlinear Wave Interactions
Authors: Fujimoto Wataru , Waseda Takuji 
Published: October 2016

The local shapes of freak waves are essential to estimate responses of ships or offshore structures by freak waves for limit state design or maritime accident survey. It is known that freak waves deform like a crescent and their trough depth become asymmetric in directional and irregular wave fields. Meanwhile, Class I & II instabilities also affect wave shape.
We discussed how those instabilities affect the geometry of freak waves, using Higher Order Spectrum Method (HOSM) which is a fast simulator of water wave. This paper investigated the relationship between Class I & II instabilities and the nonlinear order of HOSM to separate the effects of the different order nonlinear instabilities on freak waves. This investigation and freak wave simulations by HOSM clarified that four-wave Class I instability with finite width wave spectra affected both the crescent deformation and the asymmetry. The results showed that Class II instability effects to the freak wave shapes were not significant.
A Methodology to Assess the Downtime of a Multi-Phase Offshore Floating Bulk Transshipment Operation
Authors: Wang Yijun , van Deyzen Alex , Pauw Willemijn , Huijsmans René 
Published: October 2016

Operators who want to im- or export bulk (coal, iron ore, scrap, etc.) by means of offshore bulk transshipment often want to determine the operability of their bulk transshipment configuration in an early stage to assess if offshore floating bulk transshipment is a feasible option for im- or export of the commodity. The downtime of such offshore (un)loading operations may be unacceptably large. The operational windows may become limited. This implies insufficient im- or export volumes, which may result in large and expensive storage capacity onshore.
In this paper a methodology is proposed to assess the operability of offshore floating bulk transshipment. Offshore bulk transshipment is a multi-phase operation. For offshore operations consisting of multiple phases, persistency of the environmental conditions has to be considered. Persistency analysis allows for multiple operational phases, individual phase duration and shift of sea states during the operation.
The proposed methodology shows that using persistency data of the waves (wind and current are not considered yet), the downtime of an offshore floating bulk transshipment operation can be estimated more accurately. Compared to persistency analysis, scatter analysis (using wave scatter diagrams) resulted in an optimistic estimate of the downtime. Persistency analysis is better in demonstrating the influence due to each consecutive step on the total operability. This methodology could be further extended to other multi-phase offshore operations.
Model Test Investigation of the Influence of Damping on the Vortex Induced Motions of Deep Draft Semi-Submersibles Using a Novel Active Damping Device
Authors: Sterenborg Joost , Koop Arjen , de Wilde Jaap , Vinayan Vimal , Antony Arun , Halkyard John 
Published: October 2016

Vortex Induced Motions (VIM) of semi-submersibles occur when the vortex shedding frequency is close to the natural frequency of the semi-submersible in the direction transverse to the current. Recent studies suggest that the magnitude of VIM predicted during model tests is higher than that observed in the field. Among others, the damping effect provided by the risers and mooring lines is regarded as one of the reasons for this difference. In this paper the setup and results are presented for model tests to investigate the influence of damping on VIM.
For these model tests an active damping system was developed, which introduces an actively controlled external force mimicking a damping force. This applied damping force is based on the floater sway motion and sway velocity. With this system the introduced damping level can easily be controlled and verified without changing the stiffness of the system. In this paper the advantages and disadvantages of this active damping system are presented.
The VIM tests were conducted for two semi-submersibles: a paired-column semi with eight columns and a four column semi. Reduced velocities ranged from Ur=3 to Ur=10 and different levels of additional linear damping were applied to the floaters in the direction transverse to the current direction. Damping was found to reduce the VIM motions significantly: reductions of more than 60% were observed in the nominal A/D response for 25% equivalent linear damping. This indicates that damping has a significant effect on the global VIM response and thus should be considered in the design phase of the risers and mooring lines of the semi-submersibles.
To improve the understanding of the driving mechanism of VIM and also to provide validation data for CFD analyses, forces were measured on each column of the four column semi. Column force measurements indicate that for the four column semi for 45 degrees heading, i.e. the heading with largest VIM responses, the upstream, the portside and the starboard side columns are exciting the VIM motions. For 22.5 degrees, the downstream, the portside and the starboard side columns excite the VIM motions. For all tested headings the pontoon always damps the VIM response.
A Procedure to Include Slip Damping in a VIV Analysis of an Umbilical
Authors: Passano Elizabeth , Abtahi Shahriar , Ottesen Torfinn 
Published: October 2016

Ocean currents may cause vortex induced vibrations (VIV) of deep-water umbilicals. The VIV response may give significant contributions to the total fatigue damage. Good estimations of the VIV response and damage are therefore important for the design of deep-water umbilicals. As VIV response is very sensitive to the structural damping, good response and fatigue estimates will be dependent on good estimates of the damping and that they are included in the VIV response analysis in a consistent way.
A complex cross section such as an umbilical or a flexible riser will have two sources of structural damping; damping due to the strain variation in the individual materials that make up the cross sections, and damping due to the different layers slipping against one another. The first may be denoted material damping and is present at all response levels, and will be particularly important at low response levels. The second may be denoted slip damping and will contribute when the curvature exceeds the initial slip curvature.
Ideally, accurate data for both the material and the slip damping are available. Unfortunately, this is not always the case and the damping parameters must then be estimated. The material damping may be estimated from the material properties of the various layers in the cross section, taking operating conditions such as temperature into account. The slip damping may be estimated from detailed cross-sectional analyses.
As the slip damping is dependent on the curvature, iterations are needed to ensure that the applied damping and the calculated response are consistent with each other. A procedure to include these iterations within a VIV response calculation is proposed.
A case study is presented demonstrating the use of the proposed procedure for a deep-water umbilical in a lazy wave configuration. For the case studied, the maximum curvatures caused by VIV are significantly reduced.
Verifying Production Losses due to Petroleum Flow Improving Well Intervention and Design
Authors: Coca Suaznabar Paola Adriana , Miura Kazuo , Morooka Celso Kazuyuki 
Published: October 2016

The purpose of this research is to identify in the literature: causes, factors, case study descriptions and adopted solutions for production losses regarding the petroleum flow in offshore oil wells. Those facts will be organized and structured to identify potential zones of intervention for planning the well maintenance during well design phase to avoid production losses.
This paper focuses on four offshore regions: Campos Basin, Gulf of Mexico, North Sea, and West Africa. These regions represent the most significant share of offshore oil production in the world.
Data set available in the last thirty five years through academic, technical and governmental reports in the literature were the basis of this study. The procedure was accomplished in three steps: (1) data research (2) analysis of the data (3) guidelines establishment.
The main cause of production loss regarding the petroleum flow is the solids deposition in the well/line system, such as hydrates, asphaltenes, wax, scales (barium sulfate, strontium sulfate, calcium sulfate, calcium carbonate, and naturally occurrence radioactive material), and calcium naphthenates.
In this work the superposition of graphics (hydrate curve, wax appearance temperature, asphaltene onset pressure, and saturation index) resulted in a region free of solids deposition, denominated as “flow assurance envelope”.
The main expected result is to propose a guideline to be used during the well design phase in order to minimize and facilitate the well intervention.
The main contributions of this paper to the oil industry are the identification of potential zones of intervention due to solids deposition in the well/line system, the foresight of well intervention before the beginning of the oilfield production, and finally, possibilities to improve the well or intervention design.
A French Application Case of Tidal Turbine Certification
Authors: Paboeuf Stéphane , Macadré Laura-Mae , Yen Kai Sun Pascal 
Published: October 2016

Tidal turbines are emerging technologies offering great potential for the harnessing of a renewable and predictable oceanic resource. However, exploitation at sea comes with significant design, installation, grid connection, and maintenance operations challenges. Consequently, guidelines and standards are required to ensure safety, quality, performance and accelerate tidal turbines development and commercialisation. Standardisation is also a necessity to support and improve safety and confidence of a wide range of Marine Renewable Energy (MRE) stakeholders such as designers, project operators, investors, insurers or final users.
There are undergoing developments on guidelines, standards and certification systems within the International Electrotechnical Commission (IEC) Technical Committee TC 114 “Marine energy - Wave, tidal and other water current converters” and the IEC Renewable Energy “Marine Energy - Operational Management Committee” (IECRE ME – OMC). However, as the tidal energy concepts are only at the demonstration stage, only few guidelines and no dedicated certification scheme has been published so far within this organization, which guarantee an international, independent, non-governmental and consensus-based elaboration process.
The aim of this paper is to present a proposal of certification methodology, developed by Bureau Veritas for the design assessment of current and tidal turbines, and its application to a French case study. This certification procedure was developed within the French research project Sabella D10 funded by ADEME and is published in the Bureau Veritas guideline NI603 “Current & Tidal Turbines”.
The suggested certification procedure addresses prototype, component, type and project certification. Main objective, scope, intermediary steps to be completed and resulting certificates will be detailed for each certification scheme, as well as their interactions.
This methodology will be illustrated by the case study on the Sabella D10 prototype, a French tidal turbine installed in 2015 in the Fromveur Passage, off Ushant Island. Sabella D10 is a 1 MW tidal turbine fully submerged laid on the seabed with a horizontal axis and 6 blades. It is the first French tidal turbine producing electricity and connected to the electrical network.
The Sabella D10 case study will focus on prototype certification and computations performed for support structure and blades. The paper will describe the load cases that have been considered, the review procedure for the support structure and the blades design assessment, including description of a streamlined method for basic design and a detailed method for final design. In conclusion, the next steps will be introduced to continue the certification developments of tidal and current turbines.
Marine Operation Windows Offshore Norway
Authors: Kvamme Bjarte O. , Orimolade Adekunle P. , Haver Sverre K. , Gudmestad Ove T. 
Published: October 2016

A study of the wave conditions in the North Sea, the Norwegian Sea and the Barents Sea is presented in this paper. For each region, one reference location for which there are buoy measurements is selected. For the selected locations, WAM10 hindcast data are obtained from the Norwegian Meteorological Institute (MET Norway). The hindcast data for each location cover the period from 1957 to 2014.
First, the hindcast datasets were validated against available buoy measurements — both for extreme value predictions and for application of hindcast data for planning of marine operations. The validation was carried out considering the winter season and the summer season separately. For each season, the datasets for two consecutive months were used. A comparison of the time-series of the hindcast datasets against the buoy measurements showed that the hindcast datasets compared relatively well with the buoy measurements.
However, a comparison of the statistical parameters of the hindcast datasets against the buoy measurements showed that the hindcast datasets are slightly conservative in the estimate of the significant wave height for the Barents Sea and the Norwegian Sea. Overall, the data compared well, and the hindcast datasets are therefore considered in the following analysis.
Hindcast data from these 57 years show that the wave conditions in the selected Norwegian Sea location is harsher than the wave conditions in both the North Sea and the Barents Sea locations. This is in agreement with the general expected spatial trend in the wave climate on the Norwegian Continental Shelf (NCS). It was also observed that the wave conditions in the selected Barents Sea location are harsher than the wave conditions in the North Sea. These findings are also reflected in the NORSOK N-003 standard on “Actions and Action effects” (NORSOK, 2015).
The weather windows for weather-sensitive marine operations, that is, operations with operational reference period not exceeding 72 hours, were established from the hindcast dataset for each of the locations. It was observed that the Norwegian Sea has shorter weather windows, especially in the winter seasons, compared to both the Barents Sea and the North Sea. It was expected that the operational windows would be shorter in the winter seasons in the Barents Sea, due to the occurrence of polar lows. However, the polar lows are few and cause more concern related to forecasting of the weather conditions to start actual marine operations. Generally, the month with the highest probability of weather windows exceeding 72 hours was found to be July for all three locations.