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Keywords: effective tension
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Proceedings Papers

Paper presented at the The 29th International Ocean and Polar Engineering Conference, June 16–21, 2019
Paper Number: ISOPE-I-19-242
... aero-hydroservo-elastic model is established in AQWA-OrcaFlex-FAST. The effects of uniform and dynamic winds on platform motions, effective tension of mooring system, blade deformation and force on tower are analyzed and compared. In addition, in order to validate the feasibility and safety of the...
Proceedings Papers

Paper presented at the The 29th International Ocean and Polar Engineering Conference, June 16–21, 2019
Paper Number: ISOPE-I-19-179
... efficiently design of riser systems have been continued. configuration vms maximum value dynamic simulation internal flow condition effective tension specification slug flow condition riser flow condition catenary equation dynamic analysis upstream oil & gas slug flow load case...
Proceedings Papers

Paper presented at the The 29th International Ocean and Polar Engineering Conference, June 16–21, 2019
Paper Number: ISOPE-I-19-189
... aroused the interests of numerous scholars. fairlead axial stiffness calculation mooring system upstream oil & gas equation equilibrium equation subsea system node response estimation cable relation catenary equation rod theory consideration effective tension strain relation...
Proceedings Papers

Paper presented at the The 28th International Ocean and Polar Engineering Conference, June 10–15, 2018
Paper Number: ISOPE-I-18-043
... turbine system has better stability, but the mooring system affords a much more serious effective tension problem. Then to take blades loads into consideration, a twin counter-rotating turbine system, with specific-sized rotor, was modelled in Orcaflex. Different hydrofoils from NACA 63XXX foil family are...
Proceedings Papers

Paper presented at the The 28th International Ocean and Polar Engineering Conference, June 10–15, 2018
Paper Number: ISOPE-I-18-158
... riser is studied, the result shows that the influence of internal flow on the static response of a catenary flexible riser is not obvious, however, it can change the effective tension of a moving catenary flexible riser in three dimensions, the amplitude of a flexible riser's effective tension increases...
Proceedings Papers

Paper presented at the The 28th International Ocean and Polar Engineering Conference, June 10–15, 2018
Paper Number: ISOPE-I-18-638
... stress curvature nonlinear effective tension cross-section tensile armor layer Global Analysis of Flexible Riser with Internal and External Pressure Load Effects Jeong Du Kim1, Beom-Seon Jang2, Lan Hee Yoon1 1Department of Naval Architecture and Ocean Engineering, Seoul National University Seoul...
Proceedings Papers

Paper presented at the The 26th International Ocean and Polar Engineering Conference, June 26–July 2, 2016
Paper Number: ISOPE-I-16-062
... configuration, either SCR or flexible riser, is not a consideration. fpso effective tension flexible riser riser system maximum effective tension configuration load case buoyancy module screening result max curvature environmental condition curvature riser coefficient dynamic analysis...
Proceedings Papers

Paper presented at the The Twenty-fourth International Ocean and Polar Engineering Conference, June 15–20, 2014
Paper Number: ISOPE-I-14-209
... from the stress pattern of the fatigue life which meets the fatigue service life. upstream oil & gas department of the interior stress pattern effective tension boundary condition riser typhoon calculation platform fatigue life liwan gasfield deepwater riser elastomer flexible...
Proceedings Papers

Paper presented at the The Twenty-first International Offshore and Polar Engineering Conference, June 19–24, 2011
Paper Number: ISOPE-I-11-252
... jumper viv simulation chen modal shape huang effective tension shear 7 Flexible Jumper VIV Simulation in Uniform Current Kevin Huang, Hamn-Ching Chen Ocean Engineering Program, Department of Civil Engineering Texas A&M University, College Station, Texas, USA Chia-Rong Chen Department of...
Proceedings Papers

Paper presented at the The Eleventh International Offshore and Polar Engineering Conference, June 17–22, 2001
Paper Number: ISOPE-I-01-137
... effective tension wall thickness application diameter upstream oil & gas plastic thickness deformation pipe Proceedings of the Eleventh (2001) International Offshore and Polar Engineering Conference Stavanger, Norway, June 17-22, 2001 Copyright © 2001 by Tile International Society of Offshore...
Proceedings Papers

Paper presented at the The Eleventh International Offshore and Polar Engineering Conference, June 17–22, 2001
Paper Number: ISOPE-I-01-133
... pipeline. However, with spans up to 200 m as in the present study for a 20-inch pipeline, the major stiffness contribution becomes the cable effect in which the effective tension is the primary parameter. The static configuration over the free span is given as the equilibrium pattern between the net weight...
Proceedings Papers

Paper presented at the The Ninth International Offshore and Polar Engineering Conference, May 30–June 4, 1999
Paper Number: ISOPE-I-99-153
... and the effective tension at the bottom, are presented. Several boundary conditions at the end of the riser are examined. The influence of the low bending stiffness of the structure is discussed and closed form asymptotic formulae are derived for this case. These results are compared against...
Proceedings Papers

Paper presented at the The Ninth International Offshore and Polar Engineering Conference, May 30–June 4, 1999
Paper Number: ISOPE-I-99-152
... < H + l (3) where Psmin is a minimum surface pressure. The riser should be checked for various combinations of internal and external pressures to determine the appropriate design cases. In addition to these terms the guideline includes incidental pressure and system test pressure, which also varies along the riser. Characteristic functional load effect The following apply when the characteristic values of the F-loads shall be determined: - In the case of constant functional loads, the expected value of the load effect shall be used. Examples are accurate data of the riser weight, buoyancy, contents and applied tension; - In the case of variable functional loads, the specified highest or lowest values shall be used. Example is corrosion allowance. - In the case of functional oad effects caused by deformation, the extreme value shall be used. Example is intended vessel offset. Characteristic extreme environmental load effect The characteristic value for ULS, SLS and ALS is the maximum or minimum value (whichever is the most unfavourable) corresponding to a load effect. Examples of environmental load effects are load effects due wave, current and vessel motions. The characteristic environmental load effect to be applied in the limit state design checks should reflect the most probable extreme response over a specified time period. The characteristic environmental load effect during temporary conditions hould be taken as the most probable extreme load effect in a given sea-state (defined by the significant wave height, H and the spectral peak period, Tp), and appropriate current and associated vessel offset. For other (permanent) conditions, the most probable extreme response during D years is commonly also denoted the D-year return period value, e.g. 100 year return period for load effect for permanent risers in operation. A D-year return period value corresponds to an annual exceedance probability of 1/D. Two fundamentally different methods for assessment of the characteristic load effect can be applied. The fundamental requirement based on response statistics is the preferred one. However, design based on environmental statistics may be applied provided that a critical evaluation of the design criteria is conducted. Characteristic environmental load effects are normally established by global riser system analysis. One or a combination of the following methods may be applied to establish extreme load effects: - Regular (design) wave analysis in time domain - Irregular wave analysis in frequency domain - Irregular wave analysis in time domain The irregular wave analysis term refers to modelling of water particle kinematics as vessel motions. If regular wave analysis or frequency domain analysis is used, validation against irregular wave should be performed. Characteristic fatigue environmental load effect For FLS the characteristic load effect is defined as the expected load history. Expected values should also be applied for the other loads. The main environmental contributors to fatigue damage are as follows: - First order wave effects (direct wave loads and associated vessel motions) - Second order slow drift motions - Vortex induced vibrations (VIV) The total fatigue damage from each contributor can be taken as the sum of the damage due to each of the effects if no more accurate methods are available. The balance between theses damage contributions i clearly site and configuration dependent. The fatigue response due to the first two contributors may be calculated with the same methods as for extreme response calculation. If frequency domain analysis is used, validation against irregular time domain should be performed The fatigue analysis shall cover all relevant sea states. Suitable blocking of the sea scatter diagram shall be applied. In the case of wide band load effects, a rainflow counting approach should be applied. VIV may be a contributor to fatigue damage, especially for deepwater isers. Several approaches are proposed to predict VIV response of tensioned risers spanning from semi-empirical methodologies based on measurements to numerical calculation of the viscous flow around the riser preferable supported by model testing. Predictions of vortex induced vibrations causing fatigue damages in risers are normally associated with significant uncertainties. However, assessment should be performed to investigate the possible susceptibility for vortex induced vibrations. The possibility for VIV may be reduced by modifying the properties of the riser by increased tension or by introduction of vortex suppression devices. If VIV is expected to cause significant fatigue damage, monitoring of the riser during operation should be considered. Characteristic accidental load effects Relevant accidental loads and their magnitude shall be determined on the basis of risk analyses and relevant accumulated experience. Examples of accidental load effect cases are tensioner failure, vessel drive-off or drift-off, impact, explosion and fire. Accidental oads should be determined with due account of the factors of influence. Such factors may be personnel qualifications, operational procedures, the arrangement of the installation, equipment, safety systems and control procedures. DES IGN LOADS AND LOAD EFFECT FACTORS Design load effects are obtained by multiplying the characteristic load effect of each category by their corresponding load effect factor. Specific examples are given below for bending moment, effective tension, internal overpressure and external overpressure. Design bending moment: mSd F "MF +YE'ME Design effective tension: Te,Sd = ~F " L ,F at- 7E " T¢.E Design internal overpressure (> 0): Pi,sd = "YP" Pli Design external overpressure 0): Po,Sd = YP " Plo where MF Me T,.F T~,e (4) (5) (6) (7) = characteristic bending moment from functional loads - characteristic bending moment from environmental loads = characteristic effective tension from functional loads - characteristic...
Proceedings Papers

Paper presented at the The Eighth International Offshore and Polar Engineering Conference, May 24–29, 1998
Paper Number: ISOPE-I-98-132
... oftloading) vessel. By global analysis is meant that riser response in terms of minimum radius of curvature and minimum (at touch down point region) and maximum (at top) effective tension will be of primary interest. Loads taken into account are weight, buoyancy, current, vessel static offset and vessel...

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