Study on Damage Mechanism of Pipe Using Ultrasonic Wave and Acoustic Emission Technique

2007 ◽  
Vol 353-358 ◽  
pp. 2415-2418
Author(s):  
Jin Kyung Lee ◽  
Sang Ll Lee ◽  
Joon Hyun Lee
Keyword(s):  
Acoustic Emission ◽  
Carbon Steel ◽  
Ultrasonic Wave ◽  
Guided Waves ◽  
Damage Mechanism ◽  
Ultrasonic Waves ◽  
Steel Pipe ◽  
Thin Wall ◽  
Acoustic Emission Technique ◽  
Velocity Transmission

A study on corrosion evaluation by using ultrasonic waves and acoustic emission technique is presented. The experimental equipment was established to improve the corrosion process of carbon steel pipe. The carbon steel pipe was under 473K temperatures and 10Mpa pressure conditions, and ultrasonic wave and acoustic emission techniques were used to inspect the degree of corrosion after a certain period of time. Ultrasonic bulk waves are limited by the poor time resolution when used in the measurement of corrosion depth in thin wall structures because the corroded surfaces cause unclear echo signal edges. Therefore, in this study, the ultrasonic guided waves were generated on the pipe because the thickness of pipe was thin. Various wave modes were subsequently generated on the pipe to evaluate the implications of corrosion thinning on group velocity, transmission and reflection amplitudes. The amplitudes of the transmitted and the reflected waves are influenced by couplent material. In order to reduce the effect of coupling acoustic emission sensor was used. Acoustic emission technique has lots of parameters to evaluate the corrosion besides amplitude parameter. Among parameters energy, count, and frequency were useful parameters to measure the degree of corrosion inside the carbon steel pipe under 473K temperatures.

An Evaluation on Corrosion Effect of Carbon Steel Using the NDT

2007 ◽  
Vol 353-358 ◽  
pp. 2411-2414
Author(s):  
Sang Ll Lee ◽  
Jin Kyung Lee ◽  
Joon Hyun Lee
Keyword(s):  
Acoustic Emission ◽  
Carbon Steel ◽  
Power Plant ◽  
Failure Mechanism ◽  
Attenuation Factor ◽  
Ultrasonic Test ◽  
Carbon Steels ◽  
Secondary Circuit ◽  
Acoustic Emission Technique ◽  
Corrosion Effect

The nuclear power plant has lots of pipes that the fluid of high temperature and high pressure flows. Among the pipe materials used at secondary circuit of the power plant the carbon steels are sensitive to corrosion due to their material properties. In this study, both ultrasonic test and acoustic emission test were used to study the corrosion effect for the carbon steel pipe nondestructively. The carbon steel specimens were in the pipe under 473K temperatures and 10MPa pressure conditions for corrosion processing. According to the degree of corrosion the strength of the specimen was evaluated, and the thickness of the corrosion specimens was also measured by using the ultrasonic wave. The experimental results showed that the attenuation factor was also increased as a depth of corrosion increased. The measured depth of the real corrosion by ultrasonic test shows the good agreement with that by an optical microscope. In order to understand the corrosion effect for the failure mechanism of carbon steel, a failure test on the specimen with various corrosion conditions was performed. An acoustic emission technique was also used to evaluate the degree of damage of corrosion specimen in real time. Acoustic emission technique is proved a useful method for on-line monitoring the microscopic failure mechanism and the damage location for the structures.

An Online Monitoring Technique for Long-Term Operation Using Guided Waves Propagating in Steel Pipe

2017 ◽  
Vol 3 (4) ◽  
Author(s):  
Francesco Bertoncini ◽  
Mauro Cappelli ◽  
Francesco Cordella ◽  
Marco Raugi
Keyword(s):  
Power Plants ◽  
Guided Waves ◽  
Variable Temperature ◽  
Complex Structure ◽  
Guided Wave ◽  
Ultrasonic Waves ◽  
Nuclear Industry ◽  
Steel Pipe ◽  
Primary Circuit ◽  
Term Operation

Nondestructive testing (NDT) techniques are widely used as a reliable way for preventing failures and helping in the maintenance design and operation of critical infrastructures and complex industrial plants as nuclear power plants (NPPs). Among the NDT techniques, guided waves (GWs) are a very promising technology for such applications. GWs are structure-borne ultrasonic waves propagating along the structure confined and guided by its geometric boundaries. Testing using GWs is able to find defect locations through long-range screening using low-frequency waves (from 5 to 250 kHz). The technology is regularly used for pipe testing in the oil and gas industry. In the nuclear industry, regulators are working to standardize monitoring and inspection procedures. To use the technology inside an active plant, operators must solve issues like high temperatures (up to more than 300 °C inside a light-water reactor's primary piping), high wall thickness of components in the primary circuit, and characteristic defect typologies. Magnetostrictive sensors are expected to overcome such issues due to their physical properties, namely, robust constitution and simplicity. Recent experimental results have demonstrated that magnetostrictive transducers can withstand temperatures close to 300 °C. In this paper, the GW technology will be introduced in the context of NPPs. Some experimental tests conducted using such a methodology for steel pipe having a complex structure will be described, and open issues related to high-temperature guided wave applications (e.g., wave velocity or amplitude fluctuations during propagation in variable temperature components) will be discussed.

Evaluation of Wall-Thinning in Pipes Using Laser-Generated Guided Waves

2006 ◽  
Vol 326-328 ◽  
pp. 705-708
Author(s):  
Jong Ho Park ◽  
Joon Hyun Lee ◽  
Min Rae Lee
Keyword(s):  
Carbon Steel ◽  
Nuclear Power ◽  
Power Plants ◽  
Nuclear Power Plants ◽  
Guided Waves ◽  
Single Mode ◽  
Steel Pipe ◽  
Wall Thinning ◽  
Structural Fracture ◽  
Local Wall Thinning

Local wall thinning is one of the major causes for the structural fracture of pipes of nuclear power plants. Therefore, assessment of local wall thinning due to corrosion is an important issue in nondestructive evaluation for the integrity of nuclear power plants. In this study, lasergenerated guided waves were used for pipe inspection, where a laser beam illuminated through linear slit array was used as the transmitter and the air-coupled transducer was used as the receiver. Slits was used in order to enhance the mode-selectivity of guided waves, since the space of slits is equal to the wavelength of the generated wave. The air-coupled transducer detected the selected single mode by turning its detection angle that was calculated from the relations between the wave propagation velocity in air and the phase velocity in dispersion curves. Experimental results for a 4- mm thick carbon steel pipe showed that the detection of the specific mode was useful in the distinction of the wall-thinning thickness in the carbon steel pipe.

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