Time filter

Source Type

Pesce C.P.,University of Sao Paulo | Ramos Jr. R.,University of Sao Paulo | Da Silveira L.M.Y.,Prysmian Cables and Systems | Tanaka R.L.,Prysmian Cables and Systems | And 4 more authors.
Proceedings of the International Conference on Offshore Mechanics and Arctic Engineering - OMAE | Year: 2010

Umbilicals for offshore application are very complex, since they combine elements of different mechanical behavior, such as steel tubes, thermoplastic hoses and power cores in a single structure, not to mention helically laid-up armouring layers and polymeric sheathes. This motivates continuous research on their mechanical modeling. This paper presents research undertaken in the structural behavior of umbilicals and focus on the mathematical modeling of the elements, which are gathered into concentric layers. Interaction between layers is included as well as helical lay-up of elements. The model here presented will be compared to a set of experimental results in a separate paper (Part II). An analytical model was developed combining equilibrium equations, geometric compatibility and constitutive relations to obtain a set of equations that describe the umbilical behavior under external loads. This set of equations is numerically solved to obtain contact pressures (or gaps) among layers, radial variations and strains in the elements (used to calculate the stresses). The model was built to be general in order to be able to cope with complex cross-sections designs often encountered. It was then implemented in a tailor made local analysis software, called UTILFLEX®. Both modeling and software resulted from a development program partnership between Prysmian Cables & Systems and University of São Paulo. The paper will present modeling hypotheses and structural models that were used for steel tubes, hoses (thermoplastic and reinforced) and power cables and how the interaction among them has been treated. © 2010 by ASME.

Neto A.G.,University of Sao Paulo | Martins C.A.,University of Sao Paulo | Malta E.R.,University of Sao Paulo | Tanaka R.L.,Prysmian Cables and Systems | Godinho C.A.F.,Prysmian Cables and Systems
Journal of Offshore Mechanics and Arctic Engineering | Year: 2016

Dry collapse is one of the possible failure modes of flexible pipes. It refers to the situation in which no damage occurs in the flexible pipe external sheath. In this scenario, all layers of the pipe withstand the external pressure loading in a deep-water application. Such a situation is addressed in this work, which proposes some simplified modeling techniques to represent straight and curved flexible pipes subjected to external pressure, undergoing dry collapse during simulation procedure. The results of the proposed models are compared to other reference results, from a fully three-dimensional (3D) finite element model. Good agreement has been got, even with the proposed simplifications with a large reduction in computational cost when compared to full 3D model. © 2016 by ASME.

Fujarra A.L.C.,University of Sao Paulo | Goncalves R.T.,University of Sao Paulo | Pesce C.P.,University of Sao Paulo | Silva M.R.,Prysmian Cables and Systems | Godinho C.A.F.,Prysmian Cables and Systems
Proceedings of the International Conference on Offshore Mechanics and Arctic Engineering - OMAE | Year: 2010

New optical measurement approach for crushing tests of flow lines internal layers is detailed, based on an accurate tracking of the deformed carcass section through image processing. The results are compared to those from standard procedures based on discrete measurements using calipers. The new approach shows to be not only appropriate for the standard measurement requirements but also enables a comprehensive understanding of the crushing behavior. © 2010 by ASME.

Neto A.G.,University of Sao Paulo | Martins C.D.A.,University of Sao Paulo | Malta E.R.,University of Sao Paulo | Godinho C.A.F.,Prysmian Cables and Systems | And 2 more authors.
Proceedings of the International Offshore and Polar Engineering Conference | Year: 2012

Flexible pipes for offshore applications can operate in deep water. In this situation the pipe must resist to the external pressure without collapse. Two different failure modes must be analyzed: the dry and the wet collapse. The first is possible to occur when the external polymeric layer of the flexible pipe has no damages. In the wet collapse scenario the external polymeric layer is damaged, permitting that the water floods the annulus. So, the internal polymeric layer receives the external pressure. In this case the limit external pressure to that the pipe can resist is usually smaller than in the former one. This work deals with both the failure modes, comparing their characteristics and collapse pressure values. For that purpose, a full 3D finite element model was constructed, including the interlocked carcass, the internal polymeric layer, the pressure armor and the external polymeric layer. The model considers all the cross section details of the pressure armor and interlocked carcass and contemplates self-contacts and interactions between layers. The length of pipe simulated corresponds to dozens of pitches of the interlocked carcass. The developed model can deal with a straight or curved flexible pipe to study the effect of curvature in the collapse pressure limit. Case studies are presented, compared and discussed. Copyright © 2012 by the International Society of Offshore and Polar Engineers (ISOPE).

Neto A.G.,University of Sao Paulo | Martins C.D.A.,University of Sao Paulo | Pesce C.P.,University of Sao Paulo | Meirelles C.O.C.,University of Sao Paulo | And 3 more authors.
Journal of Offshore Mechanics and Arctic Engineering | Year: 2013

Usually when a large internal fluid pressure acts on the inner walls of flexible pipes, the carcass layer is not loaded, as the first internal pressure resistance is given by the internal polymeric layer that transmits almost all the loading to the metallic pressure armor layer. The last one must be designed to ensure that the flexible pipe will not fail when loaded by a defined value of internal pressure. This paper presents three different numerical models and an analytical nonlinear model for determining the maximum internal pressure loading withstood by a flexible pipe without burst. The first of the numerical models is a ring approximation for the helically rolled pressure layer, considering its actual cross section profile. The second one is a full model for the same structure, considering the pressure layer laying angle and the cross section as built. The last numerical model is a two-dimensional (2D) simplified version, considering the pressure layer as an equivalent ring. The first two numerical models consider contact nonlinearities and a nonlinear elastic-plastic material model for the pressure layer. The analytical model considers the pressure armor layer as an equivalent ring, taking into account geometrical and material nonlinear behaviors. Assumptions and results for each model are compared and discussed. The failure event and the corresponding stress state are commented. © 2013 American Society of Mechanical Engineers.

Connaire A.,MCS Kenny | Smyth J.,MCS Kenny | Nestor R.,MCS Kenny | Tanaka R.,Prysmian Cables and Systems | Albuquerque E.,Prysmian Cables and Systems
Proceedings of the International Conference on Offshore Mechanics and Arctic Engineering - OMAE | Year: 2013

Accurate prediction of the load capacity of the constituent components of flexible risers and flowline structures is critical in demonstrating fitness for purpose, particularly as the envelope of application of flexible pipe is being extended to incorporate higher flow rates, greater water depths, more aggressive fluid contents and challenging installation conditions. Analytical techniques and numerical solid modelling methods have evolved significantly in recent years as a means of improving the ability to accurately predict flexible pipe load capacity. Due to the complexity of the flexible pipe structure and the load sources and load paths to which it can be subjected, different analysis methods are required, depending on the type of response being evaluated. Specific effects can be difficult to simulate using analytical approaches and require local stress analysis using numerical techniques. This paper presents numerical approaches to two such effects, the extreme loading of tensile armour wires within a flexible pipe end fitting and the stability of tensile armour wires in axial compression. Copyright © 2013 by ASME.

Mansoldo A.,Eirgrid Plc | Rivera A.,Eirgrid Plc | Norton M.,Eirgrid Plc | Zaccone E.,Prysmian Cables and Systems | Barry V.,Prysmian Cables and Systems
CIGRE 2011 Bologna Symposium - The Electric Power System of the Future: Integrating Supergrids and Microgrids | Year: 2011

The directive on the promotion of the use of renewable energy resources published by the European Commission in 2008 has given further impetus to the development of Europe's wind energy resources. As at the end of 2010, approximately 1400 MW of wind generation had been installed in the Republic of Ireland, roughly 25 MW of which comes in the form of off-shore plant. Given that Ireland has some of the most favourable wind conditions in the whole of Europe, wind farm development in and off the coast is expected to grow rapidly over the coming years, as evidenced by the fact that some 6,000 MW of wind generation is currently awaiting connection to the grid. Furthermore recent Government Targets in the framework of "20-20-20" EU initiative, set for ROI a challenging 40% of Renewable Energy for 2020. This large amount and nature of Wind Resources is challenging the Transmission System Operator, Eirgrid, as to how to guarantee the connection and to integrate the incoming vast Wind resources in the present Transmission Grid. Large investments have already been planned onshore to accommodate some 5000 MW of wind farms, in the framework of the strategic development plan GDS 25. Recent advancements in the strategic plan have drawn attention to the offshore landscape, where some stakeholders have already obtained rights to installation tens of kilometres off the east coast of the country. Eirgrid is therefore undertaking a thorough and comprehensive investigation into how an offshore grid must be designed and which Transmission technologies are available today and in the future for the overall strategic deployment plan. The paper describes to which extent technology could provide the TSO flexibility in the decision making process to the ultimate objective of a technical efficient and cost effective designed solution. In particular the potential of a mixed AC/DC network structure may impose decision at the very beginning of the investment plan which may turn out in different results in the long term perspectives. At this stage, the selection of the proper Transmission Technology may mitigate the planner dilemma of large initial investment in the long term versus small investments in a shorter term Results of a study case of the Irish transmission network in the North-Sea context, showing Offshore Grid results and comparison of system performances are shown.

Risch B.G.,Prysmian Cables and Systems
Proceedings of SPIE - The International Society for Optical Engineering | Year: 2015

Since the first commercial introduction in the 1980s, optical fiber technology has undergone an almost exponential growth. Currently over 2 billion fiber kilometers are deployed globally with 2014 global optical fiber production exceeding 300 million fiber kilometers. 1 Along with the staggering growth in optical fiber production and deployment, an increase in optical fiber technologies and applications has also followed. Although the main use of optical fibers by far has been for traditional data transmission and communications, numerous new applications are introduced each year. Initially the practical application of optical fibers was limited by cost and sensitivity of the optical fibers to stress, radiation, and other environmental factors. Tremendous advances have taken place in optical fiber design and materials allowing optical fibers to be deployed in increasingly harsh environments with exposure to increased mechanical and environmental stresses while maintaining high reliability. With the increased reliability, lower cost, and greatly expanded range of optical fiber types now available, new optical fiber deployments in harsh and high radiation environments is seeing a tremendous increase for data, communications, and sensing applications. An overview of key optical fiber applications in data, communications, and sensing for harsh environments in industrial, energy exploration, energy generation, energy transmission, and high radiation applications will be presented. Specific recent advances in new radiation resistant optical fiber types, other specialty optical fibers, optical fiber coatings, and optical fiber cable materials will be discussed to illustrate long term reliability for deployment of optical fibers in harsh and high radiation environments. © 2015 SPIE.

Risen B.G.,Prysmian Cables and Systems
9th International Topical Meeting on Nuclear Plant Instrumentation, Control, and Human-Machine Interface Technologies, NPIC and HMIT 2015 | Year: 2015

Cables deployed within nuclear power plants must be able to maintain their functionality throughout very long lifetimes even with high levels of cumulative radiation exposure. With requirements for qualified lifetimes being 60 years or more, large acceleration factors are often required for Arrhenius lifetime simulations. When comparing test data from accelerated aging studies to actual in-service conditions, it is important to ensure that the fundamental mechanisms of changes induced in the materials during the accelerated aging conditions are the same as those that would be experienced in service. Traditional room temperature mechanical characterization as well as rheological analysis, thermal analysis, and vibrational spectroscopy are used to characterize various cable materials under different thermal and radiation histories. From the combined data, clear mechanisms of the physical and chemical changes in each cable materials as well as relative rates of change can be determined. For thermoplastic compounds melt or solution viscosity measurements can provide rheological information about changes in polymer structure. These traditional viscosity measurements, however, are not possible on crosslinked materials. Dynamic Thermal Mechanical Analysis is be used to present a detailed picture of the structural changes which take place as a function of material as these materials are exposed to radiation and subsequent thermal aging. Changes in temperature dependent dynamic modulus and complex viscosity in various materials show that crosslinking is the dominating mechanism of chemical change in the cable materials studied.

Da Silveira L.M.Y.,Prysmian Cables and Systems | Tanaka R.L.,Prysmian Cables and Systems | Novaes J.P.Z.,Prysmian Cables and Systems
Proceedings of the International Conference on Offshore Mechanics and Arctic Engineering - OMAE | Year: 2011

Despite global analysis of umbilicals is a well-known area in the offshore systems design, some topics are still opened for discussions. One of these topics refers to the structural damping. Obviously, the viscous damping caused by hydrodynamic drag forces is the major source of damping to the whole system. However, in some severe load cases, the host vessel dynamics may induce high snatch loads to the umbilical top end and these loads are more related to structural damping, specifically in tension - elongation hysteresis, than to viscous damping. The snatch loads must be taken into account in the whole design process, which leads to an umbilical designed to resist to higher tension loads and implies also, in most cases, in overdimensioned accessories, such as the bending limiters. Actually, due to the high level of friction between layers, the umbilical presents some level of structural damping which is, in fact, related to hysteretic moment-curvature and tensionelongation relations. This intrinsic structural damping may in fact contribute to the reduction of the snatch loads and considering it may reduce the level of conservatism in the design. However, due to the complexity and diversity of umbilical designs, it is not straightforward to come up with general-use hysteretic curves. A simplification then is to apply classic Rayleigh damping. Typically, damping levels of 5% are accepted in the offshore industry when using stiffness-proportional Rayleigh damping (the 5% damping is a percentage of the critical damping and is accounted for at the regular wave period or irregular wave spectral peak period). The problem here is that stiffness-proportional Rayleigh damping increases linearly with the frequency and the damping level at 1Hz, for example, may get to 60%. This fact indicates that the high-frequency part of the response may be simply discarded from the results, which in turn may lead to an incorrect, over-damped analysis. The present work aims tackling the Rayleigh damping issue, evaluating its effects on tension levels and spectral density of the tension time history. A recommendation of how to apply Rayleigh damping is proposed. Copyright © 2011 by ASME.

Loading Prysmian Cables and Systems collaborators
Loading Prysmian Cables and Systems collaborators