bluuebunny/crossref_metadata_2025_split huggingface dataset:
Vortex Induced Motion of TLP With Consideration of Appurtenances
Authors: Tan Jaime Hui Choo , Teng Yih Jeng , Magee Allan , Ly Benedict Toong Heng , Bhat Aramanadka Shankar 
Published: September 2014

Offshore floating platform configurations often consist of geometrically simple and symmetrical shapes which are made complicated by the presence of appurtenances such as helical strakes, tendon porches, steel catenary riser (SCR) porches, pipes, chains, fairleads and anodes on the surface of the hull. Previous studies mainly on spars show that these hull external features affect the Vortex Induced Motion (VIM) performance of the platform significantly. This is to be expected since VIM is controlled by the flow separation on the hull surface and the resulting vortex shedding patterns. Scale effects may also play a role in model tests for bare cylinders or hulls with bare cylindrical columns, whereas previous studies have shown less Reynolds dependence when appurtenances are modelled.
This study investigates the effect of hull appurtenances on VIM of a multi-column floating platform, i.e. a Tension Leg Platform (TLP) designed for Southeast Asian environment. Significant difference in VIM behaviors is expected between spars and TLPs since the column aspect ratios are very different and TLPs do not have helical strakes that are commonly fitted on spars. Model testing and Computational Fluid Dynamics (CFD) simulation are used in this VIM study, with the former being the emphasis of this paper. Descriptions of the respective experimental and numerical methodologies are presented and the comparison of the results is made. Further work required to improve the model test set-up and the CFD simulation are suggested. From this study, it is shown that the effect of appurtenances on TLP VIM simulation is important and must be taken into account to obtain realistic results.
Safety of LNG Transportation in Arctic Conditions When Using Systems of Various Types
Authors: Shaposhnikov Valery M. , Nesterov Alexander B. , Aleksandrov Anatoly V. , Vasilik Evgeniia G. 
Published: September 2014

Possible expansion of the LNG sea transportation region to the Russian Arctic makes topical the issue on feasibility of using various types of cargo containment systems for large ice LNG carriers of higher ice class notations.
When analyzing safety of LNG transportation in the Arctic conditions in case of using cargo containment systems of various types, both fatigue issues adjusted for ice effects (this is especially topically for membrane containment systems) and consequences of emergency situations shall be studied.
To evaluate fatigue of membrane cargo containment systems, a special finite element analysis was performed; at that ice effects on the hull were considered together with vibration caused by screws and engines for the purpose of determining maximum possible excitations occurring during the ice navigation. Static, dynamic and life tests, that permitted to estimate experimentally the fatigue margin of membrane containment system elements’ attachment to the vessel hull, were conducted as well.. The study results permit to conclude that the fatigue of CCS NO96 membrane cargo containment system is quite sufficient for resisting vibration loads, which occur during 40-year service life of large Arctic LNG carriers in severe ice conditions.
Another important aspect of LNG transportation safety in Arctic conditions consists in accidental load problems. The following types of emergency situations were considered:
• accident collision of vessels (LNG carrier ramming by another vessel);
• landing on rock (bottom collision with rock in sea conditions);
• hull side impact against an iceberg fragment during turning.
Consequences of vessels’ collision and impacts against an iceberg were evaluated with the use of software LS-DYNA. It was ascertained based on the performed analysis that the feasibility of LNG carriers with membrane containment systems is minimal; the feasibility of LNG carriers with SPB containment systems is slightly higher, and the feasibility of LNG carriers with MOSS containment systems is essentially higher than that of LNG carriers with membrane containment systems. It could be explained physically by the fact that MOSS cargo containers approach the outer shell plating near the centerline plane (for the bottom) and in the compartment middle (for the side and bottom) only; when moving off from the centerline plane and the compartment middle the distance between cargo containers and the outer shell plating essentially grows.
Nevertheless, development of large Arctic LNG carriers having sufficient accidental load levels is possible on application of any containment system type.
Fatigue Evaluation Procedures for Multiaxial Loading in Welded Structures Using Battelle Structural Stress Approach
Authors: Hong Jeong K. , Forte Thomas P. 
Published: September 2014

The Battelle structural stress method is examined for the evaluation of multiaxial loading fatigue behavior in welded structures. Even though the structural stress and its master S-N curve approach have been mainly focused on normal loading dominant (Mode I) failure cases, the evaluations on multiaxial loading weld fatigue using structural stress parameters have been relatively recently performed such as using the modified Gough ellipse [1] and the path-dependent maximum range (PDMR) cycle counting procedure [2].
In this article, in order to evaluate the multiaxial fatigue behavior, an effective equivalent structural stress range (EESS) parameter is defined as a von Mises form of combined normal and in-plane shear equivalent structural stress ranges. The newly developed in-plane shear equivalent structural stress range for in-plane shear dominant loading (Mode III) is introduced. This in-plane shear equivalent structural stress range parameter has been formulated based on the evaluation of fatigue behavior under in-plane shear loading. Also, the EESS parameter is a function of damage parameter based on the PDMR procedure.
In this article, the procedure employing the EESS parameter is evaluated and validated using published weld fatigue data. The multiaxial fatigue date is consolidated within a small scatter band regardless of in-phase, out-of-phase, and non-proportional loading as well as torsional loading. Finally, the design master S-N curve is proposed for multiaxial loading weld fatigue.
It is found that the dimensionless bend ratio parameter, Iτ (rτ)1/mτ for in-plane shear loading is a much more significant correction than that for normal loading when the ratio of bending structural stress to the total structural stress, rτ increases. This procedure will be beneficial for fatigue design with preventing over-conservatism.
Analytical Prediction of Progressive Structural Failure of a Damaged Ship for Rapid Response Damage Assessment
Authors: Bardetsky Alexander , Lee AiKuo 
Published: September 2014

The assessment of the residual strength of a damaged ship is a key element of ABS’ Rapid Response Damage Assessment (RRDA) program. When determining the residual strength, it is important to understand how the initial structural damage can spread in response to sea wave dynamic loads and can lead to a gradual reduction of the ship’s residual strength. This progressive, time-dependent structural failure caused by cracks emanating from the damaged area could eventually lead to total hull girder collapse. This is why it is important to quantify the progressive structural failure over time when assessing the residual strength of the damaged ship. Until now, progressive structural failure analysis has been conducted numerically using the Finite Element (FE) modeling approach. While this approach is accurate, it is extremely time-consuming, which makes it inappropriate for incident response, where time for decision-making is very limited. In order to overcome this limitation, an alternative analytical modeling approach for assessing the progressive structural failure of a damaged ship is proposed.
This paper presents a new comprehensive procedure for analytical prediction of crack propagation under sea wave loading using spectral fatigue analysis, beam theory, fracture mechanics and an equivalent stress intensity factor (SIF) range concept. The SIF range obtained analytically is validated by FE modeling of a damaged ship subjected to sea wave dynamic loading. The procedure for analytical prediction of the crack propagation is demonstrated for a typical, modern 170,000 DWT bulk carrier in a full load condition. The results of this research can be used to support informed decision-making when analyzing a vessel’s residual strength for the transit voyage from the accident location to a repair facility.
Study of Slug Control Techniques in Pipeline Systems
Authors: Monteiro P. C. C. , Loureiro Silva L. , Vidal J. L. A. , Netto Theodoro A. 
Published: September 2014

Severe slugging may occur at low flow rate conditions when a downward inclined pipeline is followed by a vertical riser. This phenomenon is undesirable for offshore oil and gas production due to large pressure and flow rate fluctuations. It is of great technological relevance to develop reliable and economical means of severe slugging mitigation. This study aims to develop an automated control system to detect and mitigate the formation of severe slugging through a choke valve and a series of sensors. As a first step, an overall flow map is generated to indicate the region within which severe slugging may occur based on Boe’s criterion [1] and Taitel’s model [2, 3]. It was possible to obtain different flow patterns by controlling the rate of water and gas injection.
The aim of this paper is, however, the formation of severe slugs and study of mitigation techniques. In the control part, we used a choke valve controlled by software which is in feedback with data from a system with pressure, temperature, flow, which are able to measure even small changes in the relevant parameters to the model. A two-phase flow loop was built for the study of severe slugging in pipeline-riser system with air and water as work fluids. The inner diameter of riser and flowline is 76.2 mm. The riser is 20 meters high and the flowline is 15 meters long and could be inclined upward or downward up to 8-degree. It has been shown by experiments how riser slugging can be controlled by automated control system.
Revisiting the Dimensional Analysis of Pipeline Embedment During Installation
Authors: Carneiro Daniel 
Published: September 2014

In deep water, pipelines are usually laid directly onto the seabed, in which they embed becoming partially buried. The depth a pipe will embed during installation depends on its weight and on the soil strength, but also on many other features of the lay process. The embedment along the pipeline length will govern many aspects of its behavior, for example the axial and lateral stiffness in thermo-mechanical expansion process. Despite its importance, foreseeing this penetration in design stage is still a difficult task, for which many models have been proposed over the years.
Verley & Sotberg [1] and Verley & Lund [2] have presented a thorough dimensional analysis of the pipe-soil interaction, as part of a broad study on the lateral stability of pipelines. Their equations for the initial embedment (in particular the last for embedment in undrained conditions) have been often used in design, but usually receiving additional correction factors to account for aspects not originally considered by the authors. Unlike the original dimensional analysis, the calibration of these correction factors has been done in trial and error basis, often leading to unreasonable results.
This paper revisits the dimensional analysis of the pipeline embedment during installation, aiming at widening the set of variables involved. The objective is to put together a dimensionally consistent framework in which additional aspects of the embedment process can be included in a rational way.
The paper is limited to the desktop study of selecting a new set of dimensionless groups. This might be later used for deriving a new, more accurate, model for foreseeing pipeline embedment levels in design stage. This would though require extensive testing. Which is beyond the scope of the current work.
Microstructure Identification for X80 Plates/Pipes With Low Temperature Toughness and Enhanced Strain Capacity
Authors: Di Schino Andrea , Zheng Lei , Zhang Chuanguo , Porcu Giorgio 
Published: September 2014

Due to the increasing demand for natural gas, the construction of long-distance pipelines through seismically active regions or arctic regions with ground movement caused by permafrost phenomena will become more and more necessary. To guarantee the safe operation of those pipelines, the pipe material has to fulfil strain-based design requirements. Hence in longitudinal direction low yield-to-tensile ratios, high uniform elongation values and a roundhouse shape of the stress-strain curve combined with sufficient strength values in transverse direction are essential. Moreover, a satisfactory low temperature toughness has to be guaranteed.
An adequate plate metallurgical design is fundamental for appropriate pipe properties achievement. As far as concerns the plate design the understanding and the control of microstructure are the key factors, achieved by an adequate steel chemical composition and proper process parameters.
In the framework of a co-operation between Baosteel and Centro Sviluppo Materiali (CSM), a project has been started aimed at manufacturing X80 strain based designed pipes. As a starting point pilot trials have been carried out at Baosteel Research Center in order to produce different microstructures. Besides the steel chemical composition, the cooling process has the most significant influence on the formation of the microstructure: in order to assess the effect of the cooling process, the same rolling schedule was adopted for producing the different test materials, obtained varying the start cooling and finish cooling temperatures.
The microstructure and mechanical properties of the different test materials were assessed and the best microstructure for the plates for X80 pipes with enhanced strain capacity has been identified.
Load Response and Finite Element Modelling of Bonded Loading Hoses
Authors: Lassen Tom , Lem Andreas Istad , Imingen Geir 
Published: September 2014

Steel reinforced bonded vulcanized rubber loading hoses are frequently used in offshore oil loading systems. The hoses are used as offloading system between platforms and shuttle tankers and represent a flexible economical feasible solution for hydrocarbon transfer. The reliability of these hoses throughout the service life is an important issue both with respect to operational availability and with respect to environmental safety. Hence, the load bearing capacity of these hoses and the fatigue endurance become matters of concern and important design topics. Due to the large deformation of these hoses and the complicated composite structure in the hose wall, the hoses are difficult to analyze with respect to the strain and stress response when subjected to the various load cases.
The present paper presents extreme load capacity assessments and a fatigue life prediction methodology for bonded loading hoses subjected to high pressure, tension and bending in a catenary configuration and in repeated reeling under high hose tension. The load effects on the hose during the reeling operations and the fatigue life predictions methodology for both steel components and rubber are emphasized in the present work. A combination of advanced finite element modeling and full scale testing to corroborate the analyses results has been carried out to qualify the hoses to be fit for service and to fulfill the API17K requirements. The present paper presents results from advanced finite element models and full scale testing for a 20″ bonded hose with steel end fittings. The investigation brings new knowledge in the field of hose design methodology and the results are discussed in light of current requirements and regulations such as OCIMF and API 17K.
A consequence of the comprehensive testing and analysis work is that the requirement for testing in future projects is reduced, and calibrated analysis models can be used to predict hose capacities.
Northern Sea Route: Modern State and Challenges
Authors: Marchenko Nataliya 
Published: September 2014

It is well-known that navigating the waterway from the primary trade hubs in northern Europe to the Asia-Pacific ports and contrariwise along the Russian Arctic Coast (Northern Sea Route - NSR) is much shorter and faster, than southern ways via Suez or around Africa. The NSR can significantly save costs (through saving time and fuel) and avoids the risk of attack by pirates. In addition, an increase in oil and gas activity in the North, forecasts of global warming and an ice-free Arctic have stimulated interest in Arctic navigation. However, Arctic transportation poses significant challenges because of the heavy ice conditions that exist during both the winter and summer. The profitability of using the NSR is called into question if possible high tariffs are included in the cost estimates.
For many years, the NSR was principally used for internal Russian transport and since the end of the 1980s up until 2010, it was in stagnation with total amount of cargo transported annually stood at less than two million tons. Important political decisions in the 90s and increased economic feasibility intensified traffic and freight turnover. In 2013, the NSR Administration (NSRA) was established, new rules for navigation were approved and tariff policies were modified. In 2013, the NSRA issued 635 permits to sail in NSR waters, and 71 transit voyages have since been completed. The total amount of transit cargo was 1.36 million tons. More than 40% of the total number of permits were issued to vessels without ice class [1] according to the Russian Maritime Register of Shipping [2]. There are strong technical requirements for vessels attempting to sail the NSR; regardless, several accidents occurred in 2012–2013. Two vessels were dented by ice in the Chukchi Sea in 2012. A tanker was holed in September 2013 and created a real danger of an ecological disaster from fuel leakage for several days. Despite the expectation of an ice-free Arctic, the ice conditions in 2013 were rather difficult, and the Vilkitsky Strait (a key strait in the NSR between the Kara and Laptev seas) was closed by ice for almost the entire navigation period.
In this paper, we review the current situation in the Russian Arctic, including political and administrative actions, recent accidents and the associated conditions and lessons learned.
Model Test of a 1:8 Scale Floating Wind Turbine Offshore in the Gulf of Maine
Authors: Viselli Anthony M. , Goupee Andrew J. , Dagher Habib J. 
Published: September 2014

A new floating wind turbine platform design called VolturnUS developed by the University of Maine uses innovations in materials, construction, and deployment technologies such as a concrete semi-submersible hull and a composite tower to reduce the costs of offshore wind. These novel characteristics require research and development prior to full-scale construction. This paper presents a unique offshore model testing effort aimed at de-risking full-scale commercial projects by providing properly scaled global motion data, allowing for implementation of full-scale structural materials, and demonstrating full-scale construction and deployment methods. The model is a 1:8-scale model of a 6MW semi-submersible floating wind turbine and was deployed offshore Castine, Maine, USA in June, 2013. The model uses a fully operational turbine and was the first grid connected offshore wind turbine in the Americas.
The testing effort includes careful treatment of the offshore test site, scaling methods, model design, and construction. A suitable test site was identified that provides the correct proportions of wind and wave loading in order to simulate design load cases prescribed by the American Bureau of Shipping Standard for Building and Classing Floating Offshore Wind Turbines.
Sample model test data is provided. Model test data is directly compared to full-scale design predictions made using coupled aeroelastic/ hydrodynamic software. VolturnUS performance data from scaled extreme sea states show excellent agreement with predictive models. Model test data are also compared to a numerical representation of the physical model for the purposes of numerical code validation. The numerical model results compare very favorably with data collected from the physical model.
Design of Novel Solution of Flexible Pipe for Offshore Oil Offloading Transfer
Authors: Do A. T. , Legeay S. , Charliac D. , Pere J. M. , Roques J. P. , Karnikian A. 
Published: September 2014

Spread moored FPSO (Floating Production and Storage Offloading) vessels are generally used for the large West African oil fields. The oil is transferred from the FPSO to shuttle tankers via an Oil Loading Terminal (OLT). 2 to 3 large diameter flexible lines are connecting the FPSO to the OLT. The final connection between the OLT and the shuttle tanker is made by floating hoses.
The single length of each flexible pipe can be typically 2,300 meters or higher, and the internal diameter is generally very large in the order of 15_23″ to minimize the pressure drop and the offloading time.
Conventional flexible pipe is the most suitable solution for this application. However, its long length and large diameter require a large number of buoyancy modules which are necessary to support the substantial weight generated by the steel armor wires.
An alternative to steel is Carbon Fiber Composite (CFC). This material is not only twice as strong and five times lighter than a high strength steel but it is also characterized by its exceptional performance in fatigue. As the weight of the composite armor flexible pipe is significantly reduced, the use of buoyancy is no longer necessary. The pipe can also be manufactured in a single length without intermediate connection.
A qualification program based on a 19″ internal diameter prototype has been launched. This is the first time that a large internal prototype with Carbon Fiber Composite Armor (CFA) and end-fittings have been designed and manufactured. The main goals are to confirm the suitability of the CFA flexible pipe for oil offloading application in accordance with the design tools. The mechanical behavior responses of the CFA are monitored by strain gages when the flexible pipe is in straight and curved positions under internal pressure and bending cycles.
The paper will present the main mechanical properties and the overall performance of the flexible pipe designed and tested.
The economic viability will be demonstrated by showing how the CFC material cost is positively offset by the removal of the buoyancy modules and a faster offshore installation.