The Analysis of Guided Wave Propagating on Elbow Pipe Shiuh-Kuang Yang 1,a , Hong-Yi Chen 1 , Jyin-Wen Cheng 2 , Ping-Hung Lee 3 , Jin-Jhy Jeng 4 and Chi-Jen Huang 3 1 Department of Mechanical and Electro-Mechanical Engineering, National Sun Yat-sen University, Kaohsiung, 80424, Taiwan 2 Cepstrum Technology Corporation, Kaohsiung, 80245, Taiwan 3 Taiwan Metal Quality Control Corporation, Kaohsiung, 81256, Taiwan 4 CPC Corporation, Kaohsiung, 81126, Taiwan a email: [email protected]Keywords: Guided Wave, Elbow, Interference, ANSYS Abstract. Guided wave technique is widely used in the petrochemical plant for pipes inspection. The technique detects corrosion and defects on straight pipes easily. However, pipe bends or elbows are known to distort the guided waves due to its anti-symmetric natures in geometry. The interference of the propagating guided waves occurred inside and beyond the elbow could lead to complicated signals from features reflection. It may cause missing detections or fault calls of flaws on and beyond the elbow pipe. This paper focuses on the above-mentioned interference phenomena through pipeline with elbows. A finite element method, ANSYS, was used to obtain the transient solution for the travelling guided waves along a pipe elbow without defect. The reflection signals of the guided wave mode T(0,1) and its converted modes were analyzed. The results were also verified with experiments by a commercial guided wave system on a 6-inch diameter, schedule 40 steel pipe. The comparisons between the simulated and experimental results were in good agreement. Introduction The advantage of using guided wave method for pipelines inspection lies in its short testing time and long-rang detection ability. Pipes are commonly nested in the field of refinery and petrochemical plants. The pipe elbows are usually used to change the path of the pipeline for manufacturing process and space requirements. However, the geometry of elbow makes the guided wave path is no longer completely axially symmetry and the mode conversion of the guided wave occured. Results of the mode conversion also cause the signal of guided waves become more complex and difficult to identify for analysis. It may also lead to missing detections or fault calls of flaws on and beyond the elbow pipe. For guided waves used in the field, Rose et al. [1-6], Alleyne et al. [7-12] published a number of researchs in recent years to study the feasibility of guided waves used in pipeline detection technology. In 2001, Rose et al. [13] excited the high-order and non-axisymmetrical modes propogating on the straight tube to find defects 360 。 around the circumferences. In 2005, Hayashi et al. [14] used simulation method to excite a point source on a straight pipe to discuss its wave propagation and interference behavior. Sun et al. [15] generated a flexural torsional guided wave on the straight pipe in experiments to study its wave propagation and interference status. At the year of 2005, Rose et al. [16] reported an automatic interference low frequency guided wave experiment for the detection of defects beyond elbows. In 2011, Nishino et al. [17] studied the ring-shaped array on an aluminum pipe to analyze the transmission signal after elbow by pitch and catch method. The transducers were fixed before and after elbow and generated 30 to 80 kHz frequency range in experiment. The time-domain signals were received to identify varity modes by phase characteristic analysis. They successfully More Info at Open Access Database www.ndt.net/?id=15064
8
Embed
The Analysis of Guided Wave Propagating on Elbow Pipe
This document is posted to help you gain knowledge. Please leave a comment to let me know what you think about it! Share it to your friends and learn new things together.
Transcript
The Analysis of Guided Wave Propagating on Elbow Pipe
Shiuh-Kuang Yang 1,a
, Hong-Yi Chen 1, Jyin-Wen Cheng
2, Ping-Hung Lee
3, Jin-Jhy
Jeng 4 and Chi-Jen Huang
3
1Department of Mechanical and Electro-Mechanical Engineering, National Sun Yat-sen University,