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Guided Wave Testing on Insulated Overhead Pipeline Corrosion
Lee Ping Hung
Taiwan Metal Quality Control Co. LtdTel. 07-8019312, 8019340 Fax. 07-8063017
WEB: www.tmqc.com.tw
1 2016/10TMQC in CNDT2016
Guided Wave Testing, GWT
GWT Ring
Pipe corrosion
Guided wave
2016/10TMQC in CNDT20162
Local Corrosion
General Corrosion
Guided Wave Propagation Beyond Elbow
2016/10TMQC in CNDT20163
T(0,1)Incident
T(0,1)Focusing
T(0,1)Reflection
T(0,1)Transmission
T(0,1)Reflection
T(0,1)Mode Conversion
Guided Wave Testing on Insulated Overhead Pipeline Corrosion
2016/10TMQC in CNDT20164
Testing on both vertical section
Testing on Horizontal section
GWT signals of pipe support beyond the elbow on overhead pipeline
2016/10TMQC in CNDT20165
Wave Propagation at Pipe Support and Elbow
2016/10TMQC in CNDT20166
Reflection
Transmission
Wave Leakage
Pipe Support Pipe Elbow
Wave Natural Focusing
Research in 2012 CNDT conference
2016/10TMQC in CNDT20167
Frequency: 20~30kHz-Guided Wave Focusing-Sensitivity higher than 2~3 times
Easy to misscorrosion detection Natural focusing is depended on
the wave mode, frequency and location
According to the difference of the sensitivity, it needs modify the severity of the GWT signal.
Next Step: How to get a reliable analysis beyond elbow
2014Guided wave natural focus map at elbow
2016/10TMQC in CNDT20168
Intrado
Extrado
2014Guided wave natural focus map beyond elbow
2016/10TMQC in CNDT20169
Extrado
Intrado3 o’clock
9 o’clock
2014Guided wave natural focus map beyond elbow
2016/10TMQC in CNDT201610
3 o’clock
9 o’clock
GWT signal of Overhead Pipeline without Corrosion
2016/10TMQC in CNDT201611
-25.0 -20.0 -15.0 -10.0 -5.0 0.00.0
0.5
1.0
1.5
2.0
2.5
G3-1
12#5
974
(Lin
ear)
-25.0 -20.0 -15.0 -10.0 -5.0 0.00.0
0.5
1.0
1.5
2.0
2.5
Distance (m)
G3-1
12#5
981
(Lin
ear)
B3W2S1W1B2B1
B4B3W2S1W1B2
GWT signal of Overhead Pipeline with Corrosion
2016/10TMQC in CNDT201612
-20.0 -15.0 -10.0 -5.0 0.00.0
1.0
2.0
3.0
G3-1
12#6
209
(Lin
ear)
-20.0 -15.0 -10.0 -5.0 0.00.0
1.0
2.0
3.0
Distance (m)
G3-1
12#5
990
(Lin
ear)
-F1B5 B6X1 W3
B8-F1B7X2X3W3B6
Multi-frequency Analysis: GWT signal of Overhead Pipeline with Severe Corrosion
2016/10TMQC in CNDT201613
-12d
B
-14.0 -12.0 -10.0 -8.012
9
6
3
12
Cloc
k
-14.0 -12.0 -10.0 -8.00.0
0.2
0.4
0.6
0.8
1.0
1.2
Distance (m)
Amp (L
inea
r)
B6 X1 W3
-12d
B
-14.0 -12.0 -10.0 -8.012
9
6
3
12
Cloc
k
-14.0 -12.0 -10.0 -8.00.0
1.0
2.0
3.0
Distance (m)
Amp (L
inea
r)
B6 X1 W3
45kHz 30kHz
GWT signal collected from the ring location on horizontal section
2016/10TMQC in CNDT201614
-18d
B
-4.0 -2.0 0.0 2.0 4.0 6.012
9
6
3
12
Cloc
k
-4.0 -2.0 0.0 2.0 4.0 6.00.0
2.0
4.0
6.0
8.0
10.0
12.0
Distance (m)
Amp
(Lin
ear)
B7X2X3W3X1B6
Bottom Corrosion
Corrosion X1,X2 surface VT after polishing
2016/10TMQC in CNDT201615
X1Multiple holes
X2Multiple severe corrosion
Conclusion
Pipeline Type
Simple support √ x
Welded support √ √
Clamp support √ √
Simple support √ x
Welded support √ √
Clamp support √ ∆
2016/10TMQC in CNDT201616
√: Need GWT, x: No need GWT,∆ : Depend on contact conditionPS. If testing results on vertical section show obvious corrosion signal, another testing location should be done in the overhead pipeline inspection results
Bare OverheadPipeline
Insulated OverheadPipeline
Pipe Support Type Testing on both vertical section
Testing on Horizontal section