Characterisation of the Wave Environment in the Fatigue Analysis of Flexible Risers

2005 ◽  
Author(s):  
John M. Sheehan ◽  
Frank W. Grealish ◽  
Russell J. Smith ◽  
Annette M. Harte
Keyword(s):  
Cost Effective ◽  
Critical Issue ◽  
Fatigue Analysis ◽  
Harsh Environments ◽  
Flexible Pipes ◽  
Water Developments ◽  
Key Issues ◽  
Flexible Risers ◽  
Offshore Industry ◽  
Unbonded Flexible Pipes

As the offshore industry moves towards deeper water developments and continues to embrace harsh environments, unbonded flexible pipes are increasingly being utilised as a cost effective riser solution. Furthermore, with the advent of issues such as non-pristine annuli environments, the fatigue performance of these flexible risers is becoming a critical issue. This paper presents an overview of the comparisons between deterministic and stochastic global fatigue analysis techniques. Methods used to perform both deterministic and stochastic analyses are outlined, from performing the global analyses to using local models to generate armour wire stresses and subsequent fatigue damage. The paper identifies the key issues in the analysis performed and presents key results and conclusions with regard to the characterisation of the wave environment in the global fatigue analysis of flexible risers.

Characterizing the Wave Environment in the Fatigue Analysis of Flexible Risers

2005 ◽  
Vol 128 (2) ◽  
pp. 108-118 ◽  
Author(s):  
John M. Sheehan ◽  
Frank W. Grealish ◽  
Annette M. Harte ◽  
Russell J. Smith
Keyword(s):  
Cost Effective ◽  
Critical Issue ◽  
Fatigue Analysis ◽  
Flexible Pipes ◽  
Water Developments ◽  
Key Issues ◽  
Flexible Risers ◽  
Offshore Industry ◽  
Unbonded Flexible Pipes

As the offshore industry moves towards deeper water developments and continues to embrace harsh environments, unbonded flexible pipes are increasingly being utilized as a cost effective riser solution. Furthermore, with the advent of issues such as nonpristine annuli environments, the fatigue performance of these flexible risers is becoming a critical issue. This paper presents an overview of the comparisons between deterministic and stochastic global fatigue analysis techniques. Methods used to perform both deterministic and stochastic analyses are outlined, from performing the global analyses to using local models to generate armor wire stresses and subsequent fatigue damage. The paper identifies the key issues in the analysis performed and presents key results and conclusions with regard to the characterization of the wave environment in the global fatigue analysis of flexible risers.

Numerical investigation of friction joint between Basalt Fiber Reinforced Composites and aluminum

2016 ◽  
Vol 231 (5) ◽  
pp. 543-551
Author(s):  
Andrei Costache ◽  
Christian Berggreen ◽  
Ion Marius Sivebæk ◽  
Kristian Glejbøl
Keyword(s):  
Finite Element ◽  
Basalt Fiber ◽  
Element Model ◽  
Fiber Reinforced ◽  
Pullout Force ◽  
Flexible Pipes ◽  
The Coefficient Of Friction ◽  
Flexible Risers ◽  
Offshore Oil Industry ◽  
Unbonded Flexible Pipes

Flexible risers are used in the offshore oil industry for exporting hydrocarbons from subsea equipment to floating production and storage vessels. The latest research in unbonded flexible pipes aims to reduce weight by replacing metal components with composite materials. This would result in lighter and stiffer flexible risers, which would be well suited for ultra deep water applications. This paper develops a new finite element model used for evaluating the efficiency of anchoring flat unidirectional fiber reinforced tendons in a mechanical grip. It consists two flat grips with the fiber reinforced tendon in between. The grips are pressed against the composite and the pullout force is ensured through friction. The novelty of the paper is represented by the detailed investigation of the influence between the coefficient of friction and the pullout force. By comparing numerical and experimentally obtained results, it is possible to show the importance of friction decay in the grip. Improper contact between the grips and composite is also taken into account and leads to good agreement between numerical and experimental results. This study shows how to avoid over-estimating the efficiency of such grip by using dry friction in finite element models.

Global Dynamic Performance of Flexible Risers Employing Coupled Analysis

2015 ◽  
Author(s):  
Sigve Orheim Drabløs ◽  
Katharina Haakenstad ◽  
Nils Sødahl ◽  
Kjell Herfjord ◽  
Oddrun Steinkjer
Keyword(s):  
Material Behavior ◽  
Harsh Environments ◽  
Coupled Analysis ◽  
Flexible Pipes ◽  
Analysis Scheme ◽  
Global Performance ◽  
Flexible Risers ◽  
Current Loading ◽  
Platform Motions ◽  
Slender Structures

Flexible risers are inevitable in the operation of floating production units in intermediate water depths in harsh environments. The operation of flexible pipes under these conditions is challenging, and reliable and accurate analysis of the global performance of risers is vital. The main purpose of this paper is to describe an analysis method for the global performance of flexible risers taking advantages from advanced floater motion modelling and comprehensive modelling of the risers. The analysis scheme has been employed on a semi-submersible platform, operated in harsh environments in the North Sea and all its flexible risers and umbilicals have been analyzed. The platform motions are generated by means of a coupled vessel/slender structure model in which the vessel force model is introduced into a finite element model of the slender structures including the mooring lines and all its flexible risers. In this way all relevant coupling effects from damping, restoring and current loading on the slender structures are consistently included in the platform motion predictions. Subsequently each riser is analyzed in separate models with high element mesh resolution. The platform motions, in terms of low frequency and wave frequency motions obtained from the coupled model, are applied consistently with wave and current loading in the detailed riser model. In the detailed riser models, bending stiffeners are modelled with non-linear material behavior. The diffracted wave field is included in the wave loading of the risers. The stick-slip bending of the flexible pipes have been modelled for a selection of risers and the effect of this on the riser hang off loads and the curvature in the bend stiffener region is discussed. The main responses looked into have been the curvature in the bend stiffener region, the hang off loads and interference between risers and platform pontoons. The riser responses obtained from the coupled analysis scheme performed in the present work is compared to more standard analysis schemes where extreme offsets and transfer functions are used to generate platform motions.

Safety Factors for Fatigue Analysis of Flexible Pipes Based on Structural Reliability

2012 ◽  
Author(s):  
Fernando dos Santos Loureiro Filho ◽  
Edison Castro Prates de Lima ◽  
Luís Volnei Sudati Sagrilo ◽  
Fernando Jorge Mendes de Sousa ◽  
Carlos Alberto Duarte de Lemos
Keyword(s):  
Reliability Analysis ◽  
Structural Reliability ◽  
Fatigue Analysis ◽  
Design Criterion ◽  
Flexible Riser ◽  
Safety Factors ◽  
Common Procedure ◽  
Flexible Pipes ◽  
Campos Basin ◽  
Flexible Risers

Structural reliability–based methodology [1,2] has been proposed for fatigue analysis of flexible pipes tension armours. In this methodology a design criterion is verified using a standard reliability analysis approach and checking if the fatigue failure probability is equal to or less than a target value. The use of reliability analysis in the every day design practice is not yet a common procedure. Hence, in this paper we present the calibration of safety factors for Brazilian environmental conditions to be used in the standard fatigue analysis of flexible riser tension armours. The calibration is performed in order to guarantee the same target probability of failure. The safety factors are calibrated considering four flexible risers, two connected to FPSOs and the other two to semi-submersibles located in different water depths in Campos Basin offshore Brazil.

A Collaborative Approach to Upgrading to Limits of Technology at the York River Treatment Plant

2009 ◽  
Vol 4 (3) ◽  
Author(s):  
I. Venner ◽  
J. Husband ◽  
J. Noonan ◽  
A. Nelson ◽  
D. Waltrip
Keyword(s):  
Chesapeake Bay ◽  
Phase 1 ◽  
Treatment Plant ◽  
Cost Effective ◽  
Design Flow ◽  
Nutrient Reduction ◽  
York River ◽  
Hampton Roads ◽  
Key Issues ◽  
Virginia Department

In response to rapid population growth as well as to address the nutrient reduction goals for the Chesapeake Bay established by the Virginia Department of Environmental Quality (VDEQ), the Hampton Roads Sanitation District (HRSD) initiated the York River Treatment Plant (YRTP) Expansion Phase 1 project. The existing YRTP is a conventional step-feed activated sludge plant and is rated for an average daily design flow of 57 million liters per day (MLD). This project proposes to expand the existing treatment capacity to 114 MLD and to reduce the nutrients discharged to the York River, a tributary for the Chesapeake Bay. In order to meet the effluent limits set by the VDEQ, a treatment upgrade to limit of technology (LOT) or enhanced nutrient removal (ENR) was required. Malcolm Pirnie worked with HRSD and the VDEQ to develop and evaluate ENR process alternatives to achieve the required effluent limits with the goal of determining the most reliable and cost effective alternative to achieve the aggressive nutrient reduction goals. This paper will highlight the key issues in determining the most desirable treatment process considering both economic and non-economic factors.

scholarly journals Electrochemical Biosensors in Food Safety: Challenges and Perspectives

Molecules ◽  
2021 ◽  
Vol 26 (10) ◽  
pp. 2940
Author(s):  
Antonella Curulli
Keyword(s):  
Food Industry ◽  
Electrochemical Sensors ◽  
Cost Effective ◽  
Electrochemical Biosensors ◽  
Food Chains ◽  
Sensing Systems ◽  
Highly Sensitive ◽  
Skilled Personnel ◽  
Recent Developments ◽  
Key Issues

Safety and quality are key issues for the food industry. Consequently, there is growing demand to preserve the food chain and products against substances toxic, harmful to human health, such as contaminants, allergens, toxins, or pathogens. For this reason, it is mandatory to develop highly sensitive, reliable, rapid, and cost-effective sensing systems/devices, such as electrochemical sensors/biosensors. Generally, conventional techniques are limited by long analyses, expensive and complex procedures, and skilled personnel. Therefore, developing performant electrochemical biosensors can significantly support the screening of food chains and products. Here, we report some of the recent developments in this area and analyze the contributions produced by electrochemical biosensors in food screening and their challenges.

Cathodic Protection Design Consideration for an Offshore Flexible Riser Connected to an Impressed Current System

2021 ◽  
Author(s):  
Thierry Dequin ◽  
Clark Weldon ◽  
Matthew Hense
Keyword(s):  
Cathodic Protection ◽  
Sacrificial Anode ◽  
Flexible Riser ◽  
Flexible Pipe ◽  
Linear Resistance ◽  
Flexible Pipes ◽  
Flexible Risers ◽  
Impressed Current ◽  
Host Structure ◽  
Impressed Current Cathodic Protection

Abstract Flexible risers are regularly used to produce oil and gas in subsea production systems and by nature interconnect the subsea production system to the floating or fixed host facilities. Unbonded flexible pipes are made of a combination of metallic and non-metallic layers, each layer being individually terminated at each extremity by complex end fittings. Mostly submerged in seawater, the metallic parts require careful material selection and cathodic protection (CP) to survive the expected service life. Design engineers must determine whether the flexible pipe risers should be electrically connected to the host in order to receive cathodic protection current or be electrically isolated. If the host structure is equipped with a sacrificial anode system, then electrical continuity between the riser and the host structure is generally preferred. The exception is often when the riser and host structure are operated by separate organizations, in which case electrical isolation may be preferred simply to provide delineation of ownership between the two CP systems. The paper discusses these interface issues between hull and subsea where the hull is equipped with an impressed current cathodic protection (ICCP) system, and provides guidance for addressing them during flexible pipe CP design, operation, and monitoring. Specifically, CP design philosophies for flexible risers will be addressed with respect to manufacturing, installation and interface with the host structure’s Impressed Current Cathodic Protection (ICCP) system. The discussion will emphasize the importance of early coordination between the host structure ICCP system designers and the subsea SACP system designers, and will include recommendations for CP system computer modeling, CP system design operation and CP system monitoring. One of the challenges is to understand what to consider for the exposed surfaces in the flexible pipes and its multiple layers, and also the evaluation of the linear resistance of each riser segment. The linear resistance of the riser is a major determinant with respect to potential attenuation, which in turn largely determines the extent of current drain between the subsea sacrificial anode system and the hull ICCP system. To model the flexible riser CP system behavior for self-protection, linear resistance may be maximized, however the use of a realistic linear resistance is recommended for evaluation of the interaction between the host structure and subsea system. Realistic flexible linear resistance would also reduce conservatism in the CP design, potentially save time during the offshore campaign by reducing anode quantities, and also providing correct evaluation of drain current and stray currents.

Data Collection and Analysis for the Creation of a Digital Shadow During the Production of Thermoplastic Composite Layers in Unbonded Flexible Pipes

2018 ◽  
Author(s):  
Martin Schäkel ◽  
John McNab ◽  
Neville Dodds ◽  
Tido Peters ◽  
Henning Janssen ◽  
...  
Keyword(s):  
External Pressure ◽  
Thermoplastic Composite ◽  
Sensor Data ◽  
Consolidation Process ◽  
Specific Strength ◽  
Additional Information ◽  
Flexible Pipes ◽  
Potential Part ◽  
Path Dependent ◽  
Unbonded Flexible Pipes

Unbonded flexible pipes present a mature technology for the efficient recovery and transport of hydrocarbons offshore. The substitution of metallic reinforcement layers in the multi-layered structure by thermoplastic fiber-reinforced polymer (FRP) presents a solution for self-weight issues of especially long pipes, as FRP materials display high specific strength and modulus while being resistant to external pressure and corrosion. The production of these layers is automated by the laser-assisted tape winding process without the need of additional curing steps. During the manufacturing process, several data like process temperature and consolidation pressure are continuously monitored by non-contact sensors to ensure process stability without interfering in the consolidation process. To gain additional information about the temperature distribution within the multi-layered laminate, contact temperature sensors were introduced in the tape winding process. By this method the temperature of subjacent tapes can be assessed during the continued winding process. Additionally, this paper features a new approach of utilizing winding path data for relating the time-dependent sensor data to the exact position on the produced part. The visualization of path-dependent sensor data opens up possibilities of linking quality monitoring results to manufacturing insufficiencies and potential part defects.

scholarly journals Research Progress and Key Issues of Hydrodebenzylation of Hexabenzylhexaazaisowurtzitane (HBIW) in the Synthesis of High Energy Density Material Hexanitrohexaazaisowurtzitane (HNIW)

Materials ◽  
2022 ◽  
Vol 15 (2) ◽  
pp. 409
Author(s):  
Xiaofei Tang ◽  
Rui Zhu ◽  
Tianjing Shi ◽  
Yu Wang ◽  
Xiaochen Niu ◽  
...  
Keyword(s):  
Energy Density ◽  
High Performance ◽  
Research Effort ◽  
Specific Impulse ◽  
Cost Effective ◽  
High Energy ◽  
High Energy Density ◽  
Research Progress ◽  
Fourth Generation ◽  
Key Issues

High energy density materials (HEDM) are the subject of an extensive research effort in relation to the use of these compounds as components of rocket propellants, powders, and formulations of high-performance explosives. Hexanitrohexaazaisowurtzitane (HNIW, i.e., CL-20) has received much attention in these research fields for its specific impulse, burning rate, ballistics, and detonation velocity. In this paper, the development and performances of the explosives from the first to the fourth generation are briefly summarized, and the synthesis status of the fourth-generation explosive, HNIW, is reviewed. The key issues that restrict the development of industrial amplification synthesis of HNIW are analyzed, and the potential directions of development are proposed. It is pointed out that to synthesize new and efficient catalysts is the key to making the cost-effective manufacturing of CL-20 a reality.

scholarly journals POST DISASTER WASTE MANAGEMENT STRATEGIES IN DEVELOPING COUNTRIES: CASE OF SRI LANKA

2009 ◽  
Vol 13 (2) ◽  
pp. 171-190 ◽  
Author(s):  
Gayani Karunasena ◽  
Dilanthi Amaratunga ◽  
Richard Haigh ◽  
Irene Lill
Keyword(s):  
Developing Countries ◽  
Sri Lanka ◽  
Waste Management ◽  
Management Strategies ◽  
National Level ◽  
Critical Issue ◽  
Structured Interviews ◽  
Key Issues ◽  
Communication And Coordination ◽  
Post Disaster

Disasters cause substantial damage around the world. This causes serious environmental and economic burden on normal living conditions, reconstruction and general waste collection processes. Within this context, waste management has emerged as a critical issue in responding to a disaster. Thus, this paper addresses post disaster waste management strategies adopted in developing countries and applicability of best global practices in respect of challenges encountered. Comprehensive literature review and field survey among national level institutes in Sri Lanka were conducted to gather information and semi‐structured interviews were used as a method of data collection. The findings revealed that strategies, issues and challenges are varying according to type of disaster, magnitude, location, country etc. Further, poor implementation of prevailing rules and regulations; poor standards of local expertise and capacities, inadequate funds, lack of communication and coordination are identified as key issues encountered. Santruka Stichines nelaimes visame pasaulyje pridaro daug žalos. Tai labai pasunkina aplinkosaugine ir ekonomine situacija iprastomis gyvenimo salygomis, atstatant aplinka ir vykdant bendruosius atlieku rinkimo procesus. Šiame kontekste atlieku tvarkymas išryškejo kaip esmine problema, reaguojant i stichine nelaime. Taigi šiame darbe nagrinejamos atlieku tvarkymo po stichiniu nelaimiu strategijos, taikomos besivystančiose šalyse, ir geriausiu pasauliniu praktiku taikymas, imantis kilusiu iššūkiu. Siekiant surinkti informacija, išsamiai apžvelgta literatūra ir tiesiogiai ištirtos Šri Lankos valstybines institucijos, o duomenims rinkti pasitelktas pusiau struktūriniu interviu metodas. Iš rezultatu aišku, kad strategijos, problemos ir iššūkiai skiriasi priklausomai nuo stichines nelaimes pobūdžio, masto, vietos, valstybes ir pan. Be to, nustatyta, kad pagrindines problemos yra prastas visuotiniu taisykliu ir reglamentu taikymas, prasti vietines patirties standartai ir menkos galimybes, lešu trūkumas, komunikacijos ir koordinavimo trūkumas.

Sign in / Sign up

Export Citation Format

Share Document