Coupled Analysis of SCR and Flowline Under High Pressure and High Temperature

Author(s):  
C. H. Luk ◽  
Xinhai Qi ◽  
Jianxia Zhong

This paper presents a coupled design analysis for a Pipe-in-Pipe (PIP) Steel Catenary Riser (SCR) and Flowline (FL) system in 5000ft of water under high pressure and high temperature (HP/HT) conditions in the Gulf of Mexico (GOM). The finite element program ABAQUS is used to model the inner and outer pipes of the PIP system, the centralizer, the SCR hangoff, the flowline lateral and end supports, and pipe-soil interactions on the seabed. Thermal stresses and stress ranges caused by repeated temperature transients, axial and lateral displacements of SCR and flowline, as well as by the dynamic responses of the coupled riser and flowline system, are presented. Comparisons are also made with results by ABAQUS models with beam and pipe elements, and results obtained by coupled and de-coupled analysis. The sample vessel motion was obtained for an example Spar platform in GOM.

Author(s):  
Juntao Bao ◽  
Jianming Gong ◽  
Shantung Tu ◽  
Yuesheng Li ◽  
Yanfei Qiu

Tapered pipe used in the main steam pipelines, which operated at high temperature and high pressure, including concentric tapered pipe and eccentric tapered pipe, they are sources of weakness in the piping system serviced in the power stations and the chemical plants, and creep is the significant reason that caused their failure. Creep damage analyses are carried out for these two kinds of tapered pipes by introducing user subroutine based on the modified Karchanov-Rabotnov constitutive equations into finite element program ABAQUS, then the effects of bending moments and internal pressure to the serviced life of the components are investigated by comparing four group of calculated results under different loads, the results indicated that eccentric tapered pipe is more inclinable to broken than concentric tapered pipe under the same conditions, so it is not recommended to use the eccentric tapered pipe in the piping system. The bending moments will accelerate the components’ failure, so it is necessary to take some advantages to reduce the bending moments near the tapered pipe, on the other hand, the life of the tapered pipe will decrease quickly with the internal pressure increasing, so the control of the operated pressure is important to ensure the serviced life of the pipelines.


2012 ◽  
Vol 246-247 ◽  
pp. 3-6
Author(s):  
Xiu Ying Yang ◽  
Qiang Qin ◽  
Yang Yang Cui

To study the performance of steel at elevated temperatures, the stress and deformation of steel beam were analyzed under high temperature in this paper. During the analysis, the properties of steel material must be defined firstly, which are the decisive factor affecting the carrying capacity of steel beam. The mechanical and physical properties of steel at high temperatures were accessed accordance to the provisions of the European specification in analysis. The finite element program ANSYS was used to analyze the constraints steel beam, which subjected to the uniformly line loads, then the steel beam was heated up continuously, and the mechanical properties and deformation of the steel beam was analyzed at different temperatures. The regularity of mid-span deflection changing with temperature was concluded, so as the variation of axial stress at both ends of the steel beam.


Author(s):  
Lun Qiu ◽  
Li Lee

The method of pulling a steel catenary riser (SCR) through a steel tube (termed as a pull tube) is common practice for deepwater riser tie back applications. Vortex-induced vibration (VIV) of such a system is complex. VIV analysis programs, such as Shear7 [1], are suitable only for a single, chain-like structure. The application of such a software tool in VIV design of the SCR-pull tube system requires careful consideration of a number of structural and hydrodynamic factors. This paper presents a methodology for VIV analysis of the combined structural system of the SCR with the pull tube. Firstly, the entire SCR-pull tube system is modeled with the finite element program Flexcom [2]. The modes are then calculated for the entire structure with program Modes [3]. Afterwards, the structural nodes are rearranged for VIV analysis with Shear7. The pull tube is secured on the platform through a number of guides on the truss structure of the hull. The diameter of the pull tube is much larger than that of the SCR, and the pull tube is much stiffer in bending than the SCR is. If the entire structure is analyzed with Shear7, the mode for the pull tube (a mode involving a large motion of the pull tube section), which is very high in order, would be embedded in the analysis. It makes sense to single out the pull tube mode for study as if it is the first mode. A computer program, named as V-Span [4] for subsea span VIV analysis, is used to analyze both in-line and cross-flow VIV of the pull tube. A numerical example is presented to demonstrate this methodology. This is a deepwater SCR, which has a diameter of 9 inches. The water depth is 6,300 ft. The pull tube is 640 feet long and 20 inch in diameter. Both the loop-eddy and background currents are analyzed. The fatigue damage resulted from both in-line and cross-flow VIV is estimated.


2011 ◽  
Vol 368-373 ◽  
pp. 1961-1964
Author(s):  
Jin Xia Kang

In this paper, the models of traditional anti-seismic and base-isolated masonry and concrete frame composite structures were created by the three-dimensional finite element program and their time history responses were analyzed under the actions of different seismic waves. The results show that whether they were under the action of frequently occurred earthquake or rarely occurred earthquake, the story shears of base-isolated structure are far less than those of traditional anti-seismic structure; the lateral displacements of the former are nearly translational, while those of the latter are approximately parabolic; and the fundamental period of the former is much longer than the counterpart. In conclusion, the seismic fortification intensity of base-isolated structure is one or two degree less than that of traditional anti-seismic structure, and adopting the base-isolated structure will protect the life-safety and property of people and achieve good economic benefits as well.


2012 ◽  
Vol 461 ◽  
pp. 93-96
Author(s):  
Xiao Jun Yuan ◽  
Li Chen ◽  
Jian Hua Wu ◽  
Jing Xin Tang

Much effort has been devoted to studying the blast properties of masonry infilled panels due to recent increasing accidental blast events. In this paper, the blast properties of the masonry infilled walls were analyzed with the finite element program LS-DYNA by the way of distinctive consideration of the bricks and mortar material in contrast to the experimental data. The numerical results have a good agreement with experimental data. The reliability and efficiency of this method in predicting the dynamic responses of masonry walls to blast loads was proven.


Author(s):  
J. S. Sandman ◽  
B. R. Tittmann

The focus of this paper is an Ultrasonic Position Indication System (UPIS) that is capable of determining one-dimensional target location in a high temperature steel-container with gaseous medium. The combination of the very high acoustical impedance of steel (45.4MRayl) and the very low impedance of air (0.0004MRayl) causes extremely high-energy losses upon transmission. In addition to the energy loss, propagation through a steel plate produces many internal reflections in the plate. The strategy of this investigation was to develop a self-contained ultrasonic transducer that is capable of replacing a small portion of a high temperature-pressure boundary. In building such a transducer, sufficient acoustic matching layers for the steel-gas interface, a mechanically and acoustically competent housing, a sufficient piezoelectric element, and backing materials are all developed and tested. The results include a successful housing design, high-temperature acoustic matching layers, and subsequent successful waveforms. Target location through 9.6” (24.5cm) of ambient air was successful, with a steel pressure boundary 0.4566” (1.1598cm) thick, and using one matching layer. In addition to the experimental results, this investigation includes numerical simulations. Sample waveforms were predicted one-dimensionally with the Mason model using MatLab, and two-dimensionally with a Coupled Acoustic Piezoelectric Finite Element Method (CAPA) program. The Mason model program predicts waveform changes as the wave travels through various interfaces. CAPA is a finite element program that predicts waveforms based on the equations for ultrasonic wave propagation.


Author(s):  
Mahdi Mirzaei ◽  
Mehdi Shafieefar ◽  
Mohammad Reza Moharrami

This paper contains the results of mooring analyses of two side-by-side operating crane barges in the installation procedure of a jacket type platform in an oil-gas field in the Persian Gulf. Since the vessels are proposed to operate next to a fixed structure, making sure about their displacements and a convenient clearance between them and the jacket is a highly important aspect of the design process. In essence, the analyses consist of setting an appropriate configuration and positioning of the vessels relative to each other, considering a reasonable gap between vessels and the jacket, connecting the vessels together, and studding the behavior of the moored system when it is subjected to a set of environments. In particular, an equilibrium configuration is found when the system is subjected to the mean force of the environment which consists of waves, wind gusts and currents. Then the dynamics of the system about the mean position is investigated. In order to study the influence of a dynamic mooring analysis, two cases are compared; one considering weight and buoyancy as the only forces acting on the lines and carrying out a quasi-static mooring analysis, and the other taking into account the hydrodynamic forces from the mooring lines. An accurate and efficient finite element program for the coupled analysis of the hull-mooring system is used and two types of modeling the connected vessels are compared; one using joints with restraints for all relative motions but in relative roll, and the other using slings and fenders. In all cases, the results of time domain analyses consisting of mooring line loads and motion responses of the vessels are presented in time histories and the statistics are studied.


2000 ◽  
Vol 27 (4) ◽  
pp. 655-670
Author(s):  
Chuen-Shii Chou ◽  
Shou-Chih Lou

The deformation of a high-pressure sluice gate under an orthogonal water pressure load of 0.539 MPa (i.e., 55 m water height), acting upon the upstream side of a gate leaf, was studied numerically and experimentally. The sluice gate was installed at the end of a water-release tunnel in the Nan-Hwa Reservoir, Nan-Hwa, Taiwan, R.O.C. The numerical results obtained using the ANSYS 5.5.2 finite element program agreed reasonably well with the experimental data. The deformation of this high-pressure sluice gate under water pressure loads of 0.736 MPa (i.e., 75 m water height) and 0.931 MPa (i.e., 95 m water height) was predicted by ANSYS 5.5.2. The research reported here may provide a method for establishing a safety monitoring system for any high-pressure gate and provide engineers with useful information to evaluate the possibility of increasing the capacity of an existing reservoir.Key words: sluice gate leaf, finite element method (FEM), strain gauge, water pressure.


2011 ◽  
Vol 94-96 ◽  
pp. 81-85
Author(s):  
Qiao Yan Li ◽  
Gai Hua Yu ◽  
Xiao Yun Guo

The impact of blast load is always taken into consideration in significant building and protective construction. In order to study the mechanical behavior of the concrete slab under blast load, the dynamic responses of a square concrete slab under surface explosion are simulated by the nonlinear finite element program ANSYS/LS-DYNA. The JOHNSON_HOLMQUIST_CONCRETE model is used for concrete material and the damage and strain rate effect are considered in this mode1. The simplified exponential load is used as blast load. The Z-displacement,Mises effective stress and damage state of concrete slab under different blast load of corresponding scaled distance are investigated and discussed. It can be found from the results that the influence of blast pressure can be neglected when scaled distance is around 2.0 and the damage of slab is beginning from the edge.


Author(s):  
Ki-Du Kim ◽  
Sorrasak Vachirapanyakun ◽  
Pasin Plodpradit ◽  
Van Nguyen Dinh ◽  
Jin-Ho Park

Abstract Coupled analysis of offshore structures is currently challenging. The 3D finite element analysis software X-SEA coupled with FAST 8 program is therefore developed and discussed in this paper. The current version of X-SEA includes the results of extensive research and development based on finite element program XFINAS, which was originally developed in Imperial College London. The solution of the X-SEA ranges from the simple static to highly advanced dynamic analysis applied to the offshore structures. GID is used as pre- and post processor of X-SEA. The brief theoretical background of X-SEA software is summarized. Numerical examples of offshore monopile, wind turbine jackets, pile super element and fatigue analysis verified with SACS software in terms of reactions, displacements and member forces are investigated.


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