A Calculation Model for Leak Detection and Location of Single Pipeline With Two Leaks

2018 ◽  
Author(s):  
Xu Diao ◽  
Juncheng Jiang ◽  
Lei Ni ◽  
Yong Pan ◽  
Qiang Chen
Keyword(s):  
Linear Equations ◽  
Time Domain Analysis ◽  
Economic Loss ◽  
Calculation Model ◽  
Pressure Waves ◽  
Transient Pressure ◽  
Transient Event ◽  
Leak Location ◽  
Pipeline Valve ◽  
Transportation Modes

Pipeline, as one of the transportation modes, is playing an increasingly important role in national economy. But leakages in pipelines may cause severe problems, such as environmental damages and economic loss. Therefore, how to calculate the leak location and leak size has been investigated for last decades. This paper presents a calculation model based on time-domain analysis solution for detecting and locating two leaks in the pipeline. The model is based on a transient event that is generated by fast closure of the valve at the end of a reservoir-pipeline-valve (RPV) system. The presence of leak causes continuous drops in pressure waves and leak information can be revealed by analyzed the leak transient pressure waves. The time of reflection wave represents the leak location and the magnitude of the piezometric head represents the leak size. The governing equations for calculating the leak size are derived as a system of linear equations based on the Method of Characteristics (MOC). The first transient pressure wave was analyzed to obtain the calculation parameters. Then the applicability of this method is verified on simulated pressure data. The results indicate that this model can perfectly solve two leaks problem in a single pipeline.

Transient Impact of Valve Closure Times: Disagreements Between Design and Application

2017 ◽  
Author(s):  
Ilker T. Telci ◽  
Shesh R. Koirala
Keyword(s):  
Transient Analysis ◽  
Lag Time ◽  
Field Conditions ◽  
Dynamic Loads ◽  
Design Stage ◽  
Pressure Waves ◽  
Valve Closure ◽  
Pipe Network ◽  
Transient Pressure ◽  
Transient Event

Many pressurized liquid systems require emergency shut down procedures in order to prevent damage to the piping and components, environmental contamination and fire hazard. The emergency shutdowns (ESDs) are facilitated by fast closing on-off valves installed at various locations along the piping system. When these valves close they create transient pressure waves traveling through the pipe network. These waves can be reflected at the dead-ends or closed valves. At locations where the pressure decreases below the vapor pressure, liquid column separation followed by a rejoining can cause creation of new transient pressure waves. As these waves travel, they may meet and superpose. These complex surge pressure wave behaviors require modeling of the pipe network and simulation of the transient event as the first step of a transient analysis. The second step of the transient analysis is to pin point the problems such as excessive surge pressures and dynamic loads that may occur in the system. The third step is to provide recommendations to prevent undesired transient consequences. One of the most important components of these recommendations include valve closure times during ESDs. Recent field measurements on the valve closure rates showed that the valve closure times recommended by the transient analysis were not accurately implemented. One reason for this disagreement between the designed closure rates and the applied closure rates is that the actuators of the valves introduce a time lag between the shutdown signal and start of valve closure. Another reason comes from the decision taken by the operator adjusting the actuator timing. Some operators may adjust the actuators such that the valves close within the prescribed time including the lag time which may result in very fast valve closures depending on the lag of the actuators. Other operators may choose to close the valves within the prescribed time including the lag time or even slower than the recommended rates. This may impair the orchestrate of the valve closure events designed in the transient analysis resulting in excessive surge pressures or dynamic loads. This study investigates (i) the discrepancies between the recommendations from transient study made early in the design stage and (ii) the transient impact due to the deviation and/or misinterpretation of those recommendations. Specifically, in this study, these problems are demonstrated in a case study from LNG - Ship loading systems. The results indicated that transient analysis is the essential tool in finding critical components of the system in the field conditions providing a variety of solutions such as valve closure rate adjustments, flow rate reduction at the beginning of ESDs via pump trips and pipe size increase at dead legs. This study showed that the pressure piping systems can deviate from initial design under dynamic field conditions and frequent inspections of the ESD valves are crucial for safe operations of these systems.

New Leak Location Approaches for Gas Pipelines Using Acoustic Waves

2018 ◽  
Author(s):  
Cuiwei Liu ◽  
Yuxing Li ◽  
Qihui Hu ◽  
Wuchang Wang ◽  
Yazhen Wang ◽  
...  
Keyword(s):  
Natural Gas ◽  
Acoustic Waves ◽  
Economic Loss ◽  
Transportation Systems ◽  
Gas Pipelines ◽  
Natural Gas Pipelines ◽  
New Methods ◽  
Leak Location ◽  
Localization Errors ◽  
Leak Localization

Natural gas is a vital energy carrier which can serve as an energy source, which is extremely vulnerable to leakages from pipeline transportation systems. The required ignition energy is low. Although the safety of natural gas pipelines has been improved, the average economic loss of natural gas accidents, including leaks, is large. To solve these problems, an acoustic leak localization system is designed and researched for gas pipelines using experiments with methods proposed according to different application situations. The traditional method with two sensors installed at both ends can be improved by a newly proposed combined signal-processing method, which is applied for the case that it is necessary to calculate the time differences with data synchronicity. When the time differences cannot be calculated accurately, a new method based on the amplitude attenuation model is proposed. Using these methods, the system can be applied to most situations. Next, an experimental facility at the laboratory scale is established, and experiments are carried out. Finally, the methods are verified and applied for leak localization. The results show that this research can provide a foundation for the proposed methods. The maximum experimental leak localization errors for the methods are −0.592%, and −7.62%. It is concluded that the system with the new methods can be applied to protect and monitor natural gas pipelines.

scholarly journals Dynamic Stability of Cylindrical Shells under Moving Loads by Applying Advanced Controlling Techniques Part I—Using Periodic Stiffeners

2009 ◽  
Vol 2009 ◽  
pp. 1-17
Author(s):  
Khaled M. Saadeldin Eldalil ◽  
Amr M. S. Baz
Keyword(s):  
Critical Frequency ◽  
Detection System ◽  
Velocity Ratio ◽  
Time Domain Analysis ◽  
Transient Pressure ◽  
Bending Vibrations ◽  
Time Resolved ◽  
Before And After ◽  
Pointing Precision ◽  
The Time Domain

The load acting on a cylindrical shell, with added periodic stiffeners, under a transient pressure pulse propelling a pullet (gun case) has been experimentally studied. This study is based on two modes of velocities, the first is subcritical mode and the second is supercritical mode. The stiffeners are added to the gun tube of an experimental gun facility, of 14 mm bore diameter. The radial strains are measured by using high-frequency strain gage system in phase with a laser beam detection system. Time-resolved strain measurement of the wall response is obtained and both precursor and transverse hoop strains have been resolved. The time domain analysis has been done using “wavelet transform package” in order to determine the frequency domain modes of vibrations and detect the critical frequency mode. A complete comparison of the dynamic behavior of the shell tube before and after adding periodic stiffeners has been done, which indicated that a significant damping effect reaches values between 61.5 and 38% for subcritical and critical modes. The critical frequency of the stiffened shell is increased, so the supercritical mode is changed to subcritical mode. The amplification and dispersion factors are determined and constructed; there is a reduction in the corresponding speed frequencies by about 10%. Also the radial-bending vibrations and tube muzzle motions are detected at muzzle velocity ratio of 0.99%, the results indicated that there is a significant improvement in increasing the number of rounds per second by about 36% and increasing the pointing precision by about 47%.

Estimation of Location and Discharge of Water Leak from Transient Pressure Waves in Pipelines

2018 ◽  
Vol 74 (4) ◽  
pp. I_613-I_618 ◽  
Author(s):  
Yohei ASADA ◽  
Masaomi KIMURA ◽  
Issaku AZECHI ◽  
Toshiaki IIDA ◽  
Naritaka KUBO
Keyword(s):  
Pressure Waves ◽  
Transient Pressure ◽  
Water Leak

Experimental investigation on multi-cycle two-phase spiral pulse detonation tube of two configurations

2018 ◽  
Vol 233 (11) ◽  
pp. 4166-4175
Author(s):  
Hua Qiu ◽  
Zheng Su ◽  
Cha Xiong
Keyword(s):  
Pressure Waves ◽  
Propagation Characteristics ◽  
Transient Pressure ◽  
Two Phase ◽  
Pulse Detonation ◽  
Compression Waves ◽  
Detonation Tube ◽  
Deflagration To Detonation Transition ◽  
Pulsed Detonation ◽  
Detonation Transition

The spiral tube structure is an effective method to shorten the axial length of the pulse detonation chamber. In this article, spiral pulsed detonation tube with two kinds of spiral configuration was experimentally investigated. Liquid gasoline and air were used as fuel and oxidant, respectively, and equivalence ratios were controlled to about 1.0. Based on the transient pressure along the tube, the propagation characteristics of the pressure waves in the multi-cycle spiral pulsed detonation tubes, such as pressure peaks, wave velocities and propagation process, were analyzed. Results showed that propagation of double compression waves was the common feature during the process of deflagration to detonation transition in the presented spiral tubes, and the onset of detonation was initiated by a local explosion in the second compression wave. The deflagration to detonation transition characteristics with detonation initiation and combustion characteristics without initiation in the spiral sections were both related to the dimensionless distance. Propagation characteristics of the pressure waves were influenced by the use of different spiral configuration. And some interesting phenomena were also found.

A one-dimensional model for the propagation of transient pressure waves through the lung

2002 ◽  
Vol 35 (8) ◽  
pp. 1081-1089 ◽  
Author(s):  
Quentin Grimal ◽  
Alexandre Watzky ◽  
Salah Naili
Keyword(s):  
Pressure Waves ◽  
Dimensional Model ◽  
Transient Pressure ◽  
One Dimensional

scholarly journals Pressure Wave Transmission in a Fluid Contained in a Plastically Deforming Pipe

1974 ◽  
Vol 96 (4) ◽  
pp. 258-262 ◽  
Author(s):  
G. L. Fox ◽  
D. D. Stepnewski
Keyword(s):  
Plastic Deformation ◽  
Pressure Wave ◽  
Pipe Wall ◽  
Experimental Tests ◽  
Elastic Wave Velocity ◽  
Wave Transmission ◽  
Pressure Waves ◽  
Transient Pressure ◽  
Cooling Systems ◽  
Wall Deformation

The transmission of high pressure pulses through piping loops such as reactor cooling systems is usually studied with water hammer analysis techniques. Conventional wave analysis includes only elastic pipe wall deformation. However, plastic deformation of the pipe wall is effective in reducing the magnitude of transmitted pressure waves if the pressure is of sufficient magnitude to cause plastic yielding. This effect can be treated using a one-dimensional dynamic analysis by noting the similarity between the equations describing pressure wave induced plastic deformation in a solid bar and wave transmission causing plastic strain in a fluid filled pipe. The results of the analysis show that at fluid pressures less than the pipe yield pressure, waves are transmitted at elastic wave velocity; however, at pressures which exceed the pipe yield point, wave velocities are substantially reduced and the waves are dispersed. These results demonstrate that plastic deformation from transient pressure loading is limited to a relatively short length of piping near the source of the pressure pulse. The significance of this behavior with respect to reactor cooling systems is that pressures above those causing yield are not transmitted to primary loop components such as pumps and heat exchangers. The theoretical results are compared with experimental tests and show reasonable agreement.

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