GWUT for IM

GUWT for Integrity Management

Larry WeigelStructural Integrity Associates, Inc.

Whittier, Ca

(562) 944-8210lweigel@structint.com

Pipeline R &D Forum

-20 0 20 40.0

0.5

1.0

1.5

2.0

Distance (ft)

Amp

(mV)

90 E

lbow

90 E

lbow

90 E

lbowWal

l

-F1

-F2

-F3

-F4

GWUT for IM

Our Experience with GWUT

• Started utilizing technology 2000• Utilized both Teletest and GUL systems• Provided inspection services with Unitek until

2004• Joined Structural Integrity Associates in 2004• Over 40,000 shots on above and below ground

piping, 950 miles of piping

GWUT for IM

When we joined SIThe Questions Came Quickly:What can it detect? What will it not detect?• How can it be used in a integrity management

process?• How can we prioritize the indications?• How well does it measure the depth and axial

length of metal loss?

GWUT for IMOver time the answers

became apparent• Developed software models to estimate flaw

size and predict detectable feature sizes

GWUT for IM

16-inch x 0.281-inch Pipe GScan Flaw Detection Limits at Indicated % Sensitivity

0.000

0.020

0.040

0.060

0.080

0.100

0.120

0.140

0.160

0.180

0.200

0.220

0.240

0.260

0.280

0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40 42 44 46 48 50

Flaw Width (inch)

Flaw

Dep

th (i

nch)

3%6%9%

Example of expected detectable flaw sizes

GWUT for IM

GWUT for IM

• Developed the concept that GWUT is similar to a pressure test AND developed procedures that specify the sensitivity that is needed for pressure test equivalency

Over time the answers became apparent (cont.)

GWUT for IM

Example how SI Calculates required sensitivitiesailure Plot

Corrosion Dimensions vs. Failure at Factored Pressure

3%

ACE

10%

6.8% GWUT Sen

Fail Pressure Flaw

Min Pit Limit

0.00

0.05

0.10

0.15

0.20

0.25

0.30

0.35

0 10 20 30 40 50 60 70Length (in): Circumferential (GWUT) or Axial (Failure Curve)

Pit D

epth

(in)

Factored Pressure (Failure Test Pressure) = 562.5 psi.

GWUT for IM

• Developed procedures to measure the sensitivity of the actual shot

Over time the answers became apparent (cont.)

GWUT for IM

GWUT for IMOver time the answers

became apparent (cont.)• Have shot numerous test loops • While the test loops are challenging they are

not realistic♦ Machined flaws rather than natural♦ Density and physical orientation of flaws♦ Flaws are much smaller than pressure test would

detect♦ Intact coating fills or covers external flaws♦ Limited feedback♦ Tend to compare operators instead of

establishing GWUT as an equal to pressure testing

GWUT for IM

Going ForwardChallenges we continue to see:• Unpredictable Attenuation• Industry understanding of the technology• Qualification of operators• indications• Pattern recognition• Inaccurate or misleading preassessment data

GWUT for IM

AttenuationConduct research on the measurement and

reduction of attenuation• Attenuation measurements on coatings, soils

and corrosion damage• Research on new technology approaches i.e.

Through Transmission

GWUT for IM

Qualifications • A Learning Loop

♦ A test loop with natural defects that inspectors can learn from

♦ Inspectors can see the defect and compare to GWUT response

• A certification body that certifies GWUT technicians consisting of:♦ Education♦ Training♦ Experience♦ Demonstrated capabilities

GWUT for IM

Indication Prioritization• Data analysis: SI has thousands of shots with

prove-up BScan data. Compare prove-up with GWUT signature

• Develop industry accepted methodology on prioritizing indications