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强磁性體 小口徑配管 檢査用 보빈形 자기카메라에 관한 硏究

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Author(s)
서종현
Issued Date
2016
Keyword
MFLT, ECT, PSECT, Ferromagnetic Small Bore-Piping, Inspecting
Abstract
Small-bore pipes (smaller than tens of mm) made of Cr-Mo base low alloy steel are usually used in boiler and heat exchanger piping systems in thermal power plants because they have excellent high-temperature steel, oxidation-resistance and hydrogen embrittlement resistance and are able to withstand high pressure and temperature. However, those pipes are subject to fretting wear and sliding wear since they are used in high temperature, high-pressure, floating environment, and vibration contact with tube support plates, for a prolonged time. Therefore, it is necessary to develop non-destructive test and evaluation system to detect and evaluate shape and sizes of those wear defects.
In this paper, an inspection system will be developed to inspect the wear defects that occur in the small-bore pipes using in boiler and heat exchanger piping systems of thermal power plants. The system has 22 magnetic sensors circumferentially arrayed with interval 16.4° (1.2 mm) in a sensor probe to measure electromagnetic field distribution around the defects and then the defect could be inspected and evaluated. To verify the effectiveness of the inspection system, artificial Short circumferential groove, Wear scar, and Sliding wear on outer diameter of a small-bore pipe will be examined.
The magnetic source of the inspection system has three types that using: a permanent magnet, an alternating bobbin coil and combined a permanent magnet with an alternating bobbin coil. By using only a permanent magnet, the system works based on magnetic flux leakage testing (MFLT) principle, and it can detect a minimum depth of 0.46 mm, 0.23 mm, and 0.92 mm (20%, 10%, and 40% of pipe wall thickness) for wear scar, short circumferential groove, and sliding wear, respectively. By using only a alternating bobbin coil (320 mA – 600 Hz input current), the system works based on eddy current testing (ECT) principle, and it can detect a minimum depth of 0.46 mm, 0.46 mm, and 0.92 mm (20%, 20%, and 40% of pipe wall thickness) for wear scar, short circumferential groove, and sliding wear, respectively. However, by using combined a permanent magnet and alternating bobbin coil (320 mA – 600 Hz input current), the system works based on partial saturation eddy current testing (PSECT), the system can detect a minimum depth of 0.46 mm, 0.46 mm, and 0.69 mm (20%, 10%, and 30% of pipe wall thickness) for Wear scar, Short circumferential groove, and Sliding wear, respectively. It shows that the PSECT method provides better results than the MFLT and ECT methods. In addition, the quantitative evaluation algorithm of defect depth will be proposed. The depth evaluation average errors are 18.14% for the depth of Wear scar, Short circumferential groove and Sliding wear.
Alternative Title
A Study of Bobbin-type Magnetic Camera for Inspecting the Ferromagnetic Small Bore-Piping System
Alternative Author(s)
JONGHYUN SEO
Affiliation
朝鮮大學校 大學院 制御計測工學科
Department
일반대학원 제어계측공학과
Advisor
이진이
Awarded Date
2016-08
Table Of Contents
ABSTRACT viii
제1장 서 론 1
제2장 이론적 배경 7
제1절 누설자속탐상법 8
1. 원리 8
2. 유한요소해석에 의한 원통좌표계 누설자속 분포 11
제2절 와전류탐상법 14
1. 원리 14
2. 유한요소해석에 의한 원통좌표계 와전류 분포 17
제3절 부분포화 와전류탐상법 22
제3장 실험장치 23
제1절 보빈형 자기카메라 23
1. 보빈형 여자기 23
2. 환형배열 자기센서 25
3. 신호처리회로 27
4. 보빈형 자기카메라 시스템 29
제2절 자동이송장치 및 시험편 고정장치 30
제3절 소프트웨어 32
1. 설정모드 32
2. 측정모드 34
3. 해석모드 36
제4장 실험결과 및 고찰 38
제1절 시험편 38
제2절 부분마모 시험편 실험결과 40
1. 누설자속탐상 실험결과 40
2. 와전류탐상 실험결과 41
3. 부분포화 와전류탐상 실험결과 43
4. 히스토그램 해석 45
5. 결함 자동판별 알고리즘 47
제3절 원주그루브 시험편 실험결과 49
1. 누설자속탐상 실험결과 49
2. 와전류탐상 실혐결과 50
3. 부분포화 와전류탐상 실험결과 52
4. 히스토그램 해석 54
5. 결함 자동판별 알고리즘 55
제4절 슬라이딩마모 시험편 실험결과 57
1. 누설자속탐상 실험결과 57
2. 와전류탐상 실험결과 58
3. 부분포화 와전류탐상 실험결과 60
4. 히스토그램 해석 62
5. 결함 자동판별 알고리즘 63
제5절 정량평가 알고리즘 65
제5장 결 론 68
REFERENCE 69
Degree
Master
Publisher
朝鮮大學校 大學院
Citation
서종현. (2016). 强磁性體 小口徑配管 檢査用 보빈形 자기카메라에 관한 硏究.
Type
Dissertation
URI
https://oak.chosun.ac.kr/handle/2020.oak/12874
http://chosun.dcollection.net/common/orgView/200000265636
Appears in Collections:
General Graduate School > 3. Theses(Master)
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