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

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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

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Wave Propagation at Pipe Support and Elbow

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Reflection

Transmission

Wave Leakage

Pipe Support Pipe Elbow

Wave Natural Focusing

Research in 2012 CNDT conference

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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

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Intrado

Extrado

2014Guided wave natural focus map beyond elbow

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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

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-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

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-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

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-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

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-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

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X1Multiple holes

X2Multiple severe corrosion

Conclusion

Pipeline Type

Simple support √ x

Welded support √ √

Clamp support √ √

Simple support √ x

Welded support √ √

Clamp support √ ∆

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√: 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