Development of instrumentation for acoustic monitoring

This thesis describes a source/sink flow acoustic wave sensor for the identification of leaks in gas pipelines. One of the many type of signals associated with the high velocity gas flowing out of a hole in the pipeline is the ramp or step pressure drop.;A large 3-inch diameter diaphragm was installed in an attempt to detect the low frequency waves associated with a leak. This diaphragm with source or sink flow through a 17mm internal diameter pipe acts as a pressure signal amplifier.;The deflection of the diaphragm due to the amplified force can be measured with a strain gage whose voltage is proportional to this deflection. A microphone should be used to record high frequency sound generated by the fluid inside the transmission line. (Abstract shortened by UMI.)

Water and Wastewater Pipe Nondestructive Evaluation and Health Monitoring: A Review

Civil infrastructures such as bridges, buildings, and pipelines ensure society's economic and industrial prosperity. Specifically, pipe networks assure the transportation of primary commodities such as water, oil, and natural gas. The quantitative and early detection of defects in pipes is critical in order to avoid severe consequences. As a result of high-profile accidents and economic downturn, research and development in the area of pipeline inspection has focused mainly on gas and oil pipelines. Due to the low cost of water, the development of nondestructive inspection (NDI) and structural health monitoring (SHM) technologies for fresh water mains and sewers has received the least attention. Moreover, the technical challenges associated with the practical deployment of monitoring system demand synergistic interaction across several disciplines, which may limit the transition from laboratory to real structures. This paper presents an overview of the most used NDI/SHM technologies for freshwater pipes and sewers. The challenges that said infrastructures pose with respect to oil and natural gas pipeline networks will be discussed. Finally, the methodologies that can be translated into SHM approaches are highlighted

Gas Pipeline Leak Detection Using Differential Pressure Method and Acoustic Emission Method

This report essentially discusses the work on the project entitled Gas Pipeline Leak Detection Using Differential Pressure Method and Acoustic Emission method. The objective of this project is to implement leak detection using differential pressure method and acoustic emission method and also to determine the ability of these methods to estimate size and location of the leak. In order to carry on experiment on these method, a differential pressure flow meters test rig need to be designed and constructed. The theory part explains in details about principle and mechanism of component related to differential pressure, flow measurement and acoustic emission. The methodology explains about the development of the test rig, hardware and software used in this project and experimental procedure to acquire differential pressure, flow rate and acoustic emission signal. Chapter 4 shows results obtained from experiment and analysis part of the results. The analysis part will verify the theory and hypothesis made before doing experiment. Throughout the project, there are some difficulty face such as lack of hardware and instrument needed for the project and also time constrains as a final year students. However, all these difficulties have been overcome in order to complete the project at the time given. The outcome of this project would be very useful in the industry as leak detection is very crucial in a process plant which can save lives and cost for early detection

Acoustic noise characterization for leak detection in water mains

Acoustic emission (AE) method is becoming popular for leak detection in municipal water mains where leaks are identified and the locations are determined through interpretation of measured acoustic signals without any excavation or disruption of services. For the interpretation of signals, several parameters such as frequency band of signals, coherence between signals, and cross-correlation between signals are employed. However, published literature lack data on applicability of the AE method under various field conditions. This research presents field investigation of leak detection using AE method, identification of leak noise source, leak noise attenuation characteristics and finite element (FE) simulation of acoustic wave propagation through fluid filled pipe. The field application of the AE method was performed through measuring acoustic noise at two points bracketing the leak along the pipe length in the City of Mount Pearl in Newfoundland and Labrador, Canada. For a better understanding of the source of leak noise, a preliminary laboratory investigation was conducted under a controlled environment. At low flow rates, it was found that water (escaping from the leak) hits surrounding obstacles and generates the leak noise. To explore the characteristics of leak noise, a new laboratory facility was developed and the attenuation characteristics of the leak noise was investigated. Leak noise attenuation was found to depend on the flow rate of the water. Finally, finite element (FE) method was used for modelling of acoustic wave propagation and attenuation characteristics. A commercially available FE software “ABAQUS” was used. FE analysis reveals that acoustic leak noise can propagate up to 150 m before attenuating to the ambient noise level in water mains

Magnetic Flux Leakage techniques for detecting corrosion of pipes

Oil and gas pipelines are subjected to corrosion due to harsh environmental conditions as in refinery and thermal power plants. Interesting problems such as internal and external corrosion, emerging from the increasing demand for pipeline protection have prompted this study. Thus, early detection of faults in pipes is essential to avoid disastrous outcomes. The research work presented in this thesis comprises investigations into the use of magnetic flux leakage (MFL) testing for pipe in extreme (underwater and high temperature) conditions. The design of a coil sensor (ferrite core with coil) with a magnetic circuit is carried out for high temperature conditions. The sensor thus developed lays the ground for non-destructive evaluation (NDE) of flaws in pipes through the MFL technique. The research focusses on the detection and characterization of MFL distribution caused by the loss of metal in ferromagnetic steel pipes. Experimental verifications are initially conducted with deeply rusted pipe samples of varying thicknesses in air. AlNiCo magnets are used along with Giant Magneto Resistance (GMR) sensor (AA002-02). The experiment is further repeated for saltwater conditions in relation to varying electrical conductivity with radio frequency identification (RFID) technique. A further study carried out in the research is the correlation between magnetic and underwater data communication. The study has resulted in the development and experimental evaluation of a coil sensor with its magnetic response at room and high temperatures. This makes the system effective under high temperature conditions where corrosion metal loss needs to be determined

Magnetic Flux Leakage techniques for detecting corrosion of pipes

Oil and gas pipelines are subjected to corrosion due to harsh environmental conditions as in refinery and thermal power plants. Interesting problems such as internal and external corrosion, emerging from the increasing demand for pipeline protection have prompted this study. Thus, early detection of faults in pipes is essential to avoid disastrous outcomes. The research work presented in this thesis comprises investigations into the use of magnetic flux leakage (MFL) testing for pipe in extreme (underwater and high temperature) conditions. The design of a coil sensor (ferrite core with coil) with a magnetic circuit is carried out for high temperature conditions. The sensor thus developed lays the ground for non-destructive evaluation (NDE) of flaws in pipes through the MFL technique. The research focusses on the detection and characterization of MFL distribution caused by the loss of metal in ferromagnetic steel pipes. Experimental verifications are initially conducted with deeply rusted pipe samples of varying thicknesses in air. AlNiCo magnets are used along with Giant Magneto Resistance (GMR) sensor (AA002-02). The experiment is further repeated for saltwater conditions in relation to varying electrical conductivity with radio frequency identification (RFID) technique. A further study carried out in the research is the correlation between magnetic and underwater data communication. The study has resulted in the development and experimental evaluation of a coil sensor with its magnetic response at room and high temperatures. This makes the system effective under high temperature conditions where corrosion metal loss needs to be determined

Monitoring of long steel pipes using acoustic emission

This thesis relates to the condition monitoring of long steel pipes using acoustic emission (AE). A number of experiments were carried out on pipes with a range of internal and external environments using a linear axial array of sensors with the ultimate aim of locating and reconstituting the time-domain and frequency-domain signatures of AE sources. The AE waves were generated from simulated, discontinuous, continuous, and semi-continuous sources and from real sources generated by impacts and crack propagation. The simulated source work in different internal and external environments was carried out to develop a generic empirical approach to AE propagation in long steel pipes which acknowledges the distortion of a source disturbance in the time and frequency domains. Generally, the acquired signals have two identifiable components and methods are developed for separating these components automatically and determining their group velocities. A simple model for attenuation is also developed which includes effects brought about by burial of the pipe and /or the nature of the fluid transported (liquid or gas). In the impact and crack extension tests a variety of intensities were simulated and the effect of type and intensity on time- and frequency-domain characteristics of the source was determined. The overall outcome is the demonstration of the potential of AE for identifying the nature, intensity and location of damaging events, such as crack growth and denting, and for the location and intensity assessment of leaks