4. Guided Wave Testing on Insulated Overhead
Pipeline Corrosion
2016/10TMQC in CNDT20164
Testing on both vertical
section
Testing on Horizontal section
5. GWT signals of pipe support beyond the
elbow on overhead pipeline
2016/10TMQC in CNDT20165
6. Wave Propagation at Pipe Support and Elbow
2016/10TMQC in CNDT20166
Reflection
Transmission
Wave Leakage
Pipe Support Pipe Elbow
Wave Natural Focusing
7. Research in 2012 CNDT conference
2016/10TMQC in CNDT20167
Frequency: 20~30kHz
-Guided Wave Focusing
-Sensitivity higher than 2~3 times
Easy to miss
corrosion 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
14. GWT signal collected from the ring location
on horizontal section
2016/10TMQC in CNDT201614
-18dB
-4.0 -2.0 0.0 2.0 4.0 6.0
12
9
6
3
12
Clock
-4.0 -2.0 0.0 2.0 4.0 6.0
0.0
2.0
4.0
6.0
8.0
10.0
12.0
Distance (m)
Amp(Linear)
B7X2X3W3X1B6
Bottom
Corrosion
15. Corrosion X1,X2 surface VT after polishing
2016/10TMQC in CNDT201615
X1
Multiple holes
X2
Multiple severe corrosion
16. 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 condition
PS. If testing results on vertical section show obvious corrosion signal, another testing
location should be done in the overhead pipeline inspection results
Bare
Overhead
Pipeline
Insulated
Overhead
Pipeline
Pipe Support Type
Testing on both
vertical section
Testing on
Horizontal section