Analysis Of Piping Systems Research Articles

Research on digital vibration model of typical components in pipe system

The spatial distribution of pipe system is complex, long span and multi-point elastic support, so vibration analysis of pipe system is required in the pipeline design. This paper takes the pipe system as a typical component, based on the Timoshenko beam model, establishes a dynamic procedure for straight pipe elements that considers the axial flow rate of fluid, the pressure on the pipe wall, the Poisson coupling effect of fluid and pipeline structure, and the axial, transverse and torsional vibration. Through Laplace transform, the frequency simplified dynamic model is established. And the frequency transfer matrix model of straight pipe elements and the boundary constraint matrix of common boundary (such as fixed support) is established. Finally, the frequency domain transfer matrix model of different pipeline elements are set to the overall transfer matrix of the flow pipe system, providing a convenient means for rapid optimization of pipe system vibration.

Vibration analysis of piping system coupled with conical-cylindrical combined shells

Fluid-filled piping system are widely used in power cooling, fuel transportation and underwater vessel, which not only produce vibration along the system, but also transmit to the connecting structure to generate noise in ambient environment. Most investigations have concentrated on either the vibration characteristics of piping systems or of combined shells separately. In this work, an analytical impedance synthesis method (ISM) is proposed to analyze the vibration characteristics of a pipe-hull coupled system, in which the hull can be simplified to a combined conical-stiffened cylindrical-hemisphere shell. The piping system is modeled by fluid-filled beams in three-dimensional configuration. Wave function and power series solution are used to describe the displacements of cylindrical and conical shell respectively. Based on exact analytical solutions, the impedance matrix of each segment is established separately and assembled in the global coordinate by displacement continuity and force balance boundary conditions. Forced responses are compared with the experimental results to verify the correctness of the method.

STRESS ANALYSIS EVALUATION AND PIPE SUPPORT TYPE ON HIGH-PRESSURE AND TEMPERATURE STEAM PIPE

The design and analysis of piping systems are critical in the power and process industries. The steam pipe is one of the main requirements for the plant to be installed. High-pressure and high-temperature steam pipes in the piping system are critical lines that need to be subjected to stress analysis. This study aims to evaluate the stress and the effect of using pipe supports on the stress in the piping system. Stress analysis is needed to ensure that the piping system that is designed is safe and does not exceed the allowable stress under operating conditions. Data analysis used ASTM A335-P11 as a pipe material with a design pressure of 65 bars and a design temperature of 480 °C. Stress analysis was carried out using CAESAR II software, which refers to ASME B31.3 process piping standards and codes. The findings revealed that the type of support chosen, such as the gap and distance of pipe support, has a significant impact on the stress value in the piping system. The results of the analysis are carried out several times to get the stress value so that it does not exceed the allowable stress. The greatest stress value occurs at the expansion load condition in the steam pipe system design. The chosen piping system design has a ratio of 93.6%, which is located at node 220 with a stress value of 35889.1 psi and an allowable stress of 38327.2 psi. Because the stress value that occurs is below the allowable stress, the steam pipe system is safe to be installed and operated.

Determination of Fourier expansion number for elasto-plastic analysis of piping systems using flexibility factor

Determination of Fourier expansion number for elasto-plastic analysis of piping systems using flexibility factor

Advanced elasto-plastic response analysis model for piping systems with tees

Finite element analyses were conducted to improve the elasto-plastic response analysis of piping systems with tees, taking into account the actual geometry and material properties, and comparing the results with the design analysis. The tee geometry was converted from point cloud data to CAD data and applied to vibration mode analysis and elasto-plastic response analysis. Values obtained from tensile test specimens cut from actual tee pipes were used to consider the effect on mechanical properties during forming. In piping systems where the tee section is the damaged location, the stiffness of the tee section has a significant effect on the modal deformation, and it was confirmed that the tee section with small elongation requires appropriate damage evaluation.

Theoretical vibration analysis for piping system including elbow and concentrated mass

Theoretical vibration analysis for piping system including elbow and concentrated mass

Pressure-Dependent Models in Ship Piping Systems

This paper aims to evaluate the feasibility of pressure-dependent models in the design of ship piping systems. For this purpose, a complex ship piping system is designed to operate in firefighting and bilge services through jet pumps. The system is solved as pressure-dependent model by the piping system analysis software EPANET and by a mathematical approach involving a piping network model. This results in a functional system that guarantees the recommendable ranges of hydraulic state variables (flow and pressure) and compliance with the rules of ship classification societies. Through this research, the suitability and viability of pressure-dependent models in the simulation of a ship piping system are proven.

내부 유체에 의한 고유진동수 분리 효과를 고려한 배관계의 적절한 시간이력 해석 방법론

In this study, the natural frequency separation phenomena found in the dynamic analysis of piping systems with internal fluids were identified, and methods for efficient seismic time history analysis were studied. We conducted a dynamic analysis of a piping system with consideration for the effect of its internal fluids using the coupled model, which incorporates the fluid-structure interaction effect. Owing to the mode separation effect, modes were divided into the fluid mass added (FMA) mode, generated by the added mass effect of the fluid, and coupled mode, which is created by the resonance of the internal fluid. The response contribution of the FMA and coupled modes was confirmed to be effective for efficient seismic time history analysis.

Analysis of Pipe System with Passive Vibration Absorber

The Vibration problem is the main cause of pipeline accidents. Passive vibration absorber is widely used in pipeline vibration absorption which has small environmental dependence and high engineering applicability. The free vibration of pipeline system is analyzed by transfer matrix method. The vibration absorber is introduced in the second kind of Lagrange equation. The damping term is introduced into the equation in the form of damping viscous force. The forced vibration of pipeline is analyzed by solving the vibration equation. The correctness of this method is verified by comparing with the finite element method. A three-section pipeline model with vibration absorber is analyzed in this paper. The results show that when a large mass absorber is divided into two small mass absorbers, the effect of vibration absorption will be improved.

Application of pipestress and ansys in stress analysis of nuclear pipe support – case study

A power uprate of the nuclear power plant will affect some systems, which will be exposed to new loads, transients and operating parameters. After defining of new loads, transients and operating conditions, work to qualify a system begins with modelling of this pipe system as well as modelling of supports which are active in the system. Pipe supports in pipe model are defined depending on the supports function and also their correct stiffness. After analysis is done, reaction forces are obtained in points where pipe supports are defined in the pipe model. Reaction forces from pipestress analysis, in the points where pipe supports are defined, becomes attacking forces in pipe supports analysis. A complete calculation of support is explained as well as the way to use required standard. The calculation includes stiffness calculation, calculation of membrane stress and membrane plus bending stress. In order to qualify the support a limit load analysis is performed. Finally, it is showed that pipe support could be qualified according to the standard ASME NF-3200. This paper describes use of software Pipestress and Ansys in stress analysis of piping systems and pipe supports.

Numerical Analysis of Pipe System with Elbow by Transfer Function Matrix Method

Numerical Analysis of Pipe System with Elbow by Transfer Function Matrix Method

A study on seismic response analysis of piping systems excited by multiple support motion

A study on seismic response analysis of piping systems excited by multiple support motion

Vibration Control of Nuclear Power Plant Piping System Using Stockbridge Damper under Earthquakes

Generally the piping system of a nuclear power plant (NPP) has to be designed for normal loads such as dead weight, internal pressure, temperature, and accidental loads such as earthquake. In the proposed paper, effect of Stockbridge damper to mitigate the response of piping system of NPP subjected to earthquake is studied. Finite element analysis of piping system with and without Stockbridge damper using commercial software SAP2000 is performed. Vertical and horizontal components of earthquakes such as El Centro, California, and Northridge are used in the piping analysis. A sine sweep wave is also used to investigate the control effects on the piping system under wide frequency range. It is found that the proposed Stockbridge damper can reduce the seismic response of piping system subjected to earthquake loading.

Finite Element Analysis of Pipe Systems Connected by Bellows Based on APDL Customizing

This study performed a finite element stress analysis of pipe system connected by bellows based on APDL(ANSYS Parametric Design Language) customizing. The effects of different shapes of developed pipes for various parameters are studied using the finite element commercial package for this study. The structural behavior of complex pipe structures with bellows was also investigated to study the interactions between bellows and other parts. Based on the ANSYS APDL, the effect of initial axial and lateral displacements, and internal temperature and pressure on the Von Mises stress distribution is also analyzed.

J1240404 配管系の弾塑性解析手法の検討 : ベンチマーク解析

This paper provides method of an elasto-plastic analysis for practical seismic design of nuclear piping system. JSME started up the task to establish method of an elasto-plastic analysis for nuclear piping system. The benchmark analyses have been performed in the task to investigate on method of an elasto-plastic analysis. And our company has participated in the benchmark analyses. As a result, we have settled on the method which simulates the result of piping exciting test accurately. Therefore the recommended method of an elasto-plastic analysis is shown as follows; 1) An elasto-plastic analysis is composed of dynamic analysis of piping system modeled by using beam elements and static analysis of deformed elbow modeled by using shell elements. 2) Bi-linear is applied as an elasto-plastic property. Yield point is standardized yield point multiplied by 1.2 times, and second gradient is 1/100 young's modulus.Kinematic hardening is used as a hardening rule. 3) The fatigue life is evaluated on strain ranges obtained by elasto-plastic analysis, by using the rain flow method and the fatigue curve of previous studies.

Failure Analysis of Piping Systems With Thinned Elbows on Tri-Axial Shake Table Tests

This paper presents a computational failure analysis of piping systems with and without thinned elbows on tri-axial shake table tests. In a previous experimental study, two piping models, a sound piping system and a degraded piping system with thinned elbows, were assessed. The sound piping system was found to fail at the elbow flank due to in-plane cyclic bending, whereas the degraded system failed at the end of the elbow due to excessive pipe ovalization. In the present study, finite element (FE) models of elbows were developed in order to carry out fracture analysis. The measured displacements of seismic motions were used as the boundary conditions for FE models. In the sound piping system, plastic strain concentrated at the flank of the elbow due to in-plane bending. The cumulative damage factor was calculated from the fatigue curve and Miner's rule. The effect of ratcheting was also considered. In the failed elbow, the calculated cumulative damage factor showed good agreement with experimental results. On the other hand, for the fracture analysis of the thinned elbow, the entire seismic loading history on the tri-axial shake table was considered, since the effect of pipe ovalization depends on loading history. The ovalization occurred at the elbow due to cumulative seismic loading. Consequently, the principal plastic strain began to concentrate at the end of the elbow. These FE results offer quantitative explanation for the observed failure modes in the degraded piping system.

면진 원전 면진-비면진구간 연결 배관의 내진성능 평가

A methodology to evaluate the seismic performance of interface piping systems that cross the isolation interface in the seismically isolated nuclear power plant (NPP) was developed. The developed methodology was applied to the safety-related interface piping system to demonstrate the seismic performance of the target piping system. Not only the seismic performance for the design level earthquakes but also the performance for the beyond design level earthquakes were evaluated. Two artificial seismic ground input motions which were matched to the design response spectra and two historical earthquake ground motions were used for the seismic analysis of piping system. The preliminary performance evaluation results show that the excessive relative displacements can occur in the seismically isolated piping system. If the input ground motion contained relatively high energy in the low frequency region, we could find that the stress response of the piping system exceed the allowable stress level even though the intensity of the input ground motion is equal to the design level earthquake. The structural responses and seismic performances of piping system were varied sensitively with respect to the intensities and frequency contents of input ground motions. Therefore, for the application of isolation system to NPPs and the verification of the safety of piping system, the seismic performance of the piping system subjected to the earthquake at the target NPP site should be evaluated firstly.

Pressure Drop Predictions for Laminar Fully-Developed Flows of Purely-Viscous Non-Newtonian Fluids in Circular Ducts

This paper provides the results of numerical calculations of pressure drops and centerline velocities for laminar fully-developed flows of non-Newtonian fluids in circular ducts. The particular non-Newtonian fluid model considered is the Cross model, which has shown the ability to model the behavior of time-independent purely-viscous fluids over a wide range of shear rates. It is shown that the Cross model is equivalent to the more recently proposed extended modified power law (EMPL) model, and an alternative formulation of the nondimensional parameters arising from the use of these models is explored. Results are presented for friction factors and nondimensional centerline velocities over a wide range of fluid and flow conditions, and it is shown that simpler constitutive models can be used in cases where the ratios of the limiting Newtonian viscosities are extreme. The implications of the results to the design and analysis of piping systems is considered, and simple and accurate correlations are provided for engineering calculations.

Vibrational characteristics of piping system in air conditioning outdoor unit

The modal analysis of piping system in air conditioner (AC) outdoor unit is essential to investigate the vibration properties of the system. In view of the growing significance of numerical finite element (FE) model for vibration behaviour prediction, the AC piping elastic end support characterization has been explored. The axial and radial stiffness variables (k a , k r1, k r2) of the compressor-piping mounting are obtained and represented by dynamic stiffness of compressor grommet. They are obtained from dynamic load deflection test based on compressor operating condition such as excitation frequency and amplitude. The unknown stiffness variables of the other tube end (chassis-piping mounting) are determined by parameter fine tuning. An experimental modal analysis using impact hammer test has also been employed to determine the vibration properties such as natural frequencies, mode shapes and damping ratio of the piping structures. The modal parameters acquisition using SCADAS mobile acquisition system and LMS Impact Testing software is compared with the corresponding simulated modal properties using Abaqus. Most of the simulated natural frequencies achieve good correlation with the measured frequencies and it is reasonably a good prediction model to predict vibration behaviour of AC piping structures.

Response of piping system on friction support to bi-directional excitation

Installation of friction devices between a piping system and its supporting medium is an effective way of energy dissipation in the piping systems. In this paper, seismic effectiveness of friction type support for a piping system subjected to two horizontal components of earthquake motion is investigated. The interaction between the mobilized restoring forces of the friction support is duly considered. The non-linear behavior of the restoring forces of the support is modeled as an elastic-perfectly plastic system with a very high value of initial stiffness. Such an idealization avoids keeping track of transitional rules (as required in conventional modeling of friction systems) under arbitrary dynamic loading. The frictional forces mobilized at the friction support are assumed to be dependent on the sliding velocity and instantaneous normal force acting on the support. A detailed systematic procedure for analysis of piping systems supported on friction support considering the effects of bi-directional interaction of the frictional forces is presented. The proposed procedure is validated by comparing the analytical seismic responses of a spatial piping system supported on a friction support with the corresponding experimental results. The responses of the piping system and the frictional forces of the support are observed to be in close agreement with the experimental results validating the proposed analysis procedure. It was also observed that the friction supports are very effective in reducing the seismic response of piping systems. In order to investigate the effects of bi-directional interaction of the frictional forces, the seismic responses of the piping system are compared by considering and ignoring the interaction under few narrow-band and broad-band (real earthquake) ground motions. The bi-directional interaction of the frictional forces has significant effects on the response of piping system and should be included in the analysis of piping systems supported on friction supports. Further, it was also observed that the velocity dependence of the friction coefficient does not have noticeable effects on the peak responses of the piping system.