Pipeline Vibration Research Articles

Experimental Study on the Performance of Ship Pipeline Coated Vibration Isolator

In order to improve the efficiency of ship pipeline vibration isolation, an optimized design scheme of coated rubber vibration isolator was proposed. The natural frequency was calculated and a test bench was established for vibration isolation performance test. The results show that the dynamic and static stiffness of the optimized vibration isolator is significantly lower than the traditional design value at the natural frequency. The natural frequency of the vibration isolator is reduced from about 35Hz to about 9.7Hz from the initial design scheme, and the vibration isolation efficiency is increased from about 20dB to about 33dB as well.

Стохастизация колебаний трубопровода в условиях динамического внутреннего давления

Рассматриваются колебания заполненного жидкостью трубопровода относительно горизонтальной оси, опирающегося на две опоры - одна из которых неподвижна, другая может смещаться в горизонтальном направлении. Начальное движение трубы характеризуется её изгибным отклонением в вертикальной плоскости, угловым во вращательном движении вокруг горизонтальной оси и гидравлическим ударом, при действии которого внутреннее давление на стенки трубы приобретает вид δ -толчков. Исходная система уравнений колебаний трубопровода приводится к уравнению Дуффинга. В переменных «действие-угол» получена граница стохастичности, которая отделяет детерминированную область решения от стохастической. Получено диффузионное уравнение типа Фоккера-Планка-Колмогорова, решение которого определяет функцию плотности вероятности, с помощью которой можно находить случайные параметры колебаний трубы для оценки её движения. Vibrations of a liquid-filled pipeline relative to the horizontal axis are considered. The pipe is supported by two supports - a movable and a fixed one. The initial movement of the pipe is characterized by is bending, angular deflection and hydraulic shok, after which the internal pressure on the pipe walls takes the form of δ -shoks. The system of equations for pipeline vibrations is reduced to the Duffing equation. A stochasticity boundary is obtained that divides the deterministic domain of the solution from the stochastic one. The Fokker-Plank-Kolmogorov diffusion equation is obtained, which makes it possible to determine the standard deviation of the bending vibrations of the pipe.

Алгоритм и программа расчета параметров вибрации трубопровода с учетом протекания жидкости

This paper discusses the development of calculation complex (model, algorithm and software) needed to investigate vibration parameters (amplitudes of displacements, internal forces and support responses) of a constant cross-section pipeline with a perfect incompressible fluid flowing inside it. This paper presents a pipeline model as quasi-monomeric finite-element system. Presently, the study discusses vibration of a straight constant cross-section pipeline resting on two elastic supports. Calculation algorithm is based on the discrete variant of partial-response method. The effect of fluid flow is taken into account as an additional inertial load incorporated, in its turn, by means of corrections and modifications of inertia & stiffness parameters of pipeline model. The study gives calculation expressions for partial responses and partial parameters, needed to implement the algorithm suggested by the authors. The problem formulated in this paper was solved as per specially developed mathematical model taking into account the forces due to the flow in the pipe. The paper also suggests calculation algorithm for vibration parameters of the adopted model. These vibration parameters were obtained in specially developed Koriolis software. The study also investigated the effect of additional inertial load components upon vibration parameters and natural frequencies of the structure at question. All these activities made it possible to accomplish the task of the whole study, i.e. to develop the calculation complex for determination of pipeline vibration parameters.

Analysis and Research on Pipeline Vibration of a Natural Gas Compressor Station and Vibration Reduction Measures

The abnormal vibration of natural gas station pipelines seriously threatens the safety of pipeline transportation, and improper handling will cause huge economic losses. For the abnormal vibration of the pipeline, reasonable treatment must be carried out. The Yongchang gas station belongs to the west–east gas pipeline system in China. Since its production, abnormal vibration has often occurred in the west-third outbound pipeline of the Yongchang gas station, and the vibration changes according to the different gas transport volumes. In this paper, the outbound pipeline of the Yongchang pressure station is taken as the research object, and the vibration analysis of the station yard pipeline is carried out. The numerical model of the station yard pipeline is established, and the correctness of the model is verified by the field vibration test. The fluid–solid coupling method is used to analyze pipeline vibration under different working conditions. Then, three kinds of vibration reduction schemes are proposed and verified by simulation. The main conclusions are as follows: (1) The fluid pressure fluctuation in the pipeline is the root cause of abnormal vibration in the station. (2) When the gas transmission volume is large, the vibration of the pipeline system will become more severe. (3) The scheme of increasing pipe diameter and adding appropriate constraints has the best vibration reduction effect.

Method for vibration measurement in pipelines of residential buildings

The article is devoted to the problem of insufficiency and incompleteness of existing methods for measuring vibration in pipelines of residential buildings. Existing methods for measuring vibrations in pipelines are considered and their effectiveness is analyzed. The assessment of complexity, cost efficiency and accuracy of the existing vibration measurement methods is made. An improved method for measuring the vibration of a pipeline section with a tap based on the analysis of the trace of blurring a circular mark and the Doppler Effect is proposed.

Vortex-induced vibrations of piggyback pipelines near the horizontal plane wall in the upper transition regime

Slender subsea structures like pipelines, jumpers and umbilicals when exposed to currents may experience vortex-induced vibrations (VIV), which can shorten their fatigue life and increase the risk of structural failure. In the present study, flow around different configurations of a piggyback pipeline close to a flat seabed has been investigated using the two-dimensional (2D) Unsteady Reynolds-Averaged Navier Stokes (URANS) equations with the k − ω Shear Stress Transport (SST) turbulence model. The Reynolds number (based on the free stream velocity and large cylinder diameter) is equal 3.6 × 106 corresponding to upper-transition regime. The drag forces acting on the cylinders and base pressure coefficient value are well predicted by the present simulations, while the other hydrodynamic quantities (root-mean-square lift coefficient, Strouhal number) are predicted reasonably well as compared to published experimental data. The piggyback pipeline in the present study is modeled as two circular cylinders with a diameter ratio d/D = 0.2 (D denoting diameter of the large cylinder, d is diameter of the small cylinder). These two cylinders are clamped together at a distance G/D = 0.2. The two rigidly coupled cylinders are elastically supported and free to vibrate in two degrees of freedom. The effects on the vibration amplitudes and hydrodynamic forces are analyzed. The flow structures around the cylinders are investigated to explain the variations in observed structural responses. Depending on the angular position (α) of the small cylinder, the lock-in regime is narrower (α = 0°) or significantly wider (α = 180°) when compared to that of a single cylinder.

Reliability assessment of pitting corrosion of pipeline under spatiotemporal earthquake including spatial-dependent corrosion growth

The pitting corrosion of pipelines subjected to the spatio-temporal earthquake was evaluated to illustrate the failure probability of multiple loading conditions. The pipeline vibration was modeled as a coupled 3D vibration equation considering the uncertain soil parameters. Using a combination of the Gamma process and Gaussian copula function implemented time-dependent corroded growth of single defect as well as the spatial-dependent between corroded depth growths of different defects. All modeling was embedded in a frame of Bayesian inference and Markov chain Monte Carlo (MCMC) simulation techniques to predict the future corroded growth by reported in-line inspections (ILIs). Moreover, the Monte Carlo simulation (MC) technique was used to evaluate the reliability of the pipeline system, including multiple corroded defects. A case study was employed to prove the application of all proposed models. The results indicate that the reliability analysis of pipelines under the earthquake considering pitting corrosion growth is of considerable significance to the accuracy of the evaluation, which can inform operators from process industry to mitigate the risk of pipeline failure.

Assessment of the technical condition of pipelines in polyurethane insulation

The paper considers issues of improving the reliability of operation of pipelines of heating networks. A description of the created diagnostic complex is given, with the help of which it is possible to determine the technical condition of pipelines in polyurethane foam insulation. Finite-element models were constructed and modal calculations of defective and defect-free pipelines in polyurethane foam insulation were carried out. The analysis of the received acoustic signals was carried out using neural network algorithms. The results of processing acoustic vibrations of pipelines by a neural network showed a high efficiency in identifying pipelines by their state (defective / defect-free).

Multi-modal identification of leakage-induced acoustic vibration in gas-filled pipelines by selection of coherent frequency band

Leak location using correlation-based acoustic method is a common practice in gas-filled pipelines, which will be extremely effective when the leakage-induced acoustic wave has a constant propagation speed. This premise is often not satisfied as result of multi-modal and dispersive nature which will cause acoustic speed to vary with frequency and modal type. In this work, the multi-modal identification based on selection of coherent frequency band is proposed for improving leak location in gas pipelines. The dispersive and multi-modal characteristics are studied by theory analysis and experimental validation to give understanding of the reason that correlation-based leak location has a larger error at times. The results demonstrate that the multi-modal type can be identified from law of acoustic speed variation by selection of coherent frequency band and multi-modal and dispersive characteristics are the main cause of a larger leak location error.

Energy Dissipation Characteristics and Parameter Identification of Symmetrically Coated Damping Structure of Pipelines under Different Temperature Environment

In this paper, a symmetrically coated damping structure for entangled metallic wire materials (EMWM) of pipelines was designed to reduce the vibration of high temperature (300 °C) pipeline. A series of energy dissipation tests were carried out on the symmetrically coated damping structure at 20–300 °C. Based on the energy dissipation test results, the hysteresis loop was drawn. The effects of temperature, vibration amplitude, frequency, and density of EMWM on the energy dissipation characteristics of coated damping structures were investigated. A nonlinear energy dissipation model of the symmetrically coated damping structure with temperature parameters was established through the accurate decomposition of the hysteresis loop. The parameters of the nonlinear model were identified by the least square method. The energy dissipation test results show that the symmetrically coated damping structure for EMWM of pipelines had excellent and stable damping properties, and the established model could well describe the changing law of the restoring force and displacement of the symmetrically coated damping structure with amplitude, frequency, density, and ambient temperature. It is possible to reduce the vibration of pipelines in a wider temperature range by replacing different metal wires.

Vibration Characteristic Analysis of Pressure Fluctuating Attenuator with Circular Elastic Sheets for Linear-Driving Pump

Aiming at the problem of pipeline vibration caused by fluids in linear-driving pump pipeline system, this paper proposed a vibration reduction method based on a pressure-fluctuating attenuator with circular elastic sheets. Firstly, a new type of pressure-fluctuating attenuator was proposed, and its working principle and frequency characteristics were analyzed. Secondly, the mathematical model of the developed attenuator was established in combination with the dynamic characteristic equations of the pipeline. Besides, the effect of relevant parameters on attenuation performance was investigated through simulation. The size and material of the circular elastic sheet were screened according to the pressure fluctuating frequency of the linear-driving pump under the rated conditions. The prototype of the pressure-fluctuating attenuator was fabricated, and the performance of the prototype in the pipeline was tested. The experimental results show that the pressure-fluctuating attenuator with circular elastic sheets has a good suppression effect on the pulsating pressure of the linear-driving pump under the rated conditions.

Anti-strong pipeline vibration method combining frequency variance and amplitude feature for vortex flowmeter

In order to eliminate vibration harmonic interference and solve the measurement problem of the co-frequency signal that the flow signal and vibration interference are at the same or similar frequency, a signal processing method combining frequency variance with amplitude feature is proposed for the vortex flowmeter with a single piezoelectric sensor. The method uses multiple peak frequencies to calculate the frequency variance, and then rapidly outputs the frequency of the flow signal. The ratio of the spectral amplitude to the dynamic cut-off amplitude is used as an auxiliary criterion to eliminate vibration harmonic interference. The maximum difference among spectral amplitudes of the co-frequency signal is used to solve the measurement problem of the co-frequency signal. A low-power and two-wire vortex flowmeter system was developed, and the gas calibration experiment and anti-vibration experiment were performed to validate the effectiveness and measurement accuracy of the anti-vibration method.

Construction of a mathematical model of the vibrational process of pipelines under internal and external loads

The article proposes a modal analysis of the natural vibrations of polyethylene pipelines, which is a calculation of the vertical and lateral pressure exerted by the soil on the pipelines, on the basis of which an oscillation study was conducted in the Ansys software package. The results of modal analysis for polyethylene pipes are presented for a laying scheme with inclined walls and various soils.

Numerical study of the effect of viscoelastic properties of the material and bases on vibration fatigue of pipelines conveying pulsating fluid flow

The article presents the results of mathematical and computer modeling of the oscillatory processes of viscoelastic pipelines considering stationary external loads. A mathematical model of viscoelastic pipeline vibrations based on the theory of beams was developed when a pulsating fluid flows through it. Using the Bubnov-Galerkin method, based on a polynomial approximation of deflections, the problem was reduced to the study of a system of ordinary integro-differential equations, the solution of which was found numerically. A computational algorithm has been developed to solve vibration problems of composite pipelines conveying pulsating fluid. Stability and amplitude-time characteristics of vibrations of composite pipelines conveying pulsating fluid were studied at wide range of parameters variation of deformable systems and fluid flow. Critical fluid flow rates were found at which a viscoelastic pipe lost its rectilinear equilibrium shape. A singularity effect in hereditary kernels on vibrations of structures with viscoelastic properties was numerically studied. It was shown that with an increase in viscosity parameter of the pipeline material, the critical flow rate decreases. It was revealed that an increase in fluid pulsation frequency and excitation coefficient led to a decrease in the fluid flow critical rate. It was stated that an increase in Winkler bases parameters and the rigidity parameter of a continuous layer led to an increase in the critical flow rate.

Numerical modeling of vibration fatigue of viscoelastic pipelines conveying pulsating fluid flow

The effect of investigation results on viscoelastic properties of the material and bases on vibration fatigue of a pipeline conveying pulsating fluid flow is given in the paper. A mathematical model of viscoelastic pipeline vibrations based on the theory of beams was developed when a pulsating fluid flows through it. A computational algorithm has been developed to solve vibration problems of composite pipelines conveying pulsating fluid. Stability and amplitude-time characteristics of vibrations of composite pipelines conveying pulsating fluid were studied at wide range of parameters variation of deformable systems and fluid flow.

Моделирование вибрации трубопровода на основе теории балки Тимошенко

Моделирование вибрации трубопровода на основе теории балки Тимошенко

Behaviour and Calculation of Polymer Pipelines Under Real Earthquake Records

The effect of real records of several earthquakes on polymer pipeline vibrations are studied and analyzed in the paper. Longitudinal vibrations of straight end section of the underground pipeline are considered using the Kelvin-Voigt model. To solve the equation, the method of finite differences of the second order of accuracy is used. An algorithm has been compiled and on its basis a software product has been developed for the numerical calculation of an underground polymer pipeline under the effect of real seismograms recorded in different cities of the world. The stress-strain state (SSS) of polymer pipelines is determined under various boundary conditions.

Research on Semi-Active Vibration Control of Pipeline Based on Magneto-Rheological Damper

This paper proposes a scheme to control the low-frequency vibration of pipelines by using magneto-rheological (MR) vibration reduction technology. The state equation and the transfer function of the pipeline system are established, and its stability and the sinusoidal excitation response are analyzed. The prototype of MR damper is developed. The dynamic characteristics of MR damper are tested and the double-sigmoid model of MR damper is established. The two-state control, Proportion Integration Differentiation (PID) control and sliding-mode-variable-structure (SMVS) control methods of pipeline vibration using MR damper are analyzed comparatively, and the vibration control laws are deduced. The simulation analyses are carried out to predict the control effect of different pipeline vibration control algorithms. The verification tests through a semi-active measurement and control platform are carried out, and the feasibility and applicability of different pipeline vibration control strategies are analyzed. The test results show that the three kinds of pipeline vibration control methods based on MR damper can effectively control the pipeline vibration. Especially, SMVS control has the best vibration control effect, the pipeline amplitude drop and the acceleration drop can reach 22.31 dB and 16.34 dB respectively, while the amplitude attenuation rate and the acceleration attenuation rate can reach 92.34% and 84.77%, respectively.

Sealing failure and fretting fatigue behavior of fittings induced by pipeline vibration

Pipeline fittings containing ferrules are used to connect sections of aircraft hydraulic pipelines. Therefore, their reliability and stability are essential. The purpose of this investigation is to better understand and analyze the sealing failure mechanism of pipeline fittings produced by pipeline vibration. Based on accelerated tests, the sealing failure mechanism and fatigue life of fittings are discussed. The influences of stress and pre-tightening torque on fretting fatigue behavior are also considered. Results from tests using an electromagnetic shaker apparatus indicate that sealing failure in pipeline fittings is caused by fretting fatigue of the front ferrule. Moreover, the decrease of pre-tightening torque will lead to more serious fretting fatigue.

Prediction Method of Cavitation Jet Wave Attenuation Based on Five-Equation Two-Fluid Model

In this paper, the seven-equation two-fluid flow model is streamlined to a five-equation numerical calculation method. This method is applied to predict the wave attenuation of the cavitation jet. Compared with 9 different experimental schemes in two separate laboratories, it is found that the velocity flow characteristics are different from normal transient flow when the cavitation jet is formed in the pipeline. Such a difference in velocity flow characteristics will cause changes in the prediction deviation of pressure response time and amplitude. A numerical method for predicting the attenuation of pressure fluctuation with the cavitation jet is presented taken into account these flow characteristics. In this method, the unsteady friction model is opened after the jet wave transmits 3–5 cycles, and the cavitation jet wave attenuation is well simulated. This calculation method could provide a research basis for pipeline leakage, vibration, noise, and other fields that need accurate pressure signals.