distance (ft) management - dot
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GWUT for IM
GUWT for Integrity Management
Larry WeigelStructural Integrity Associates, Inc.
Whittier, Ca
(562) [email protected]
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
• 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 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