surface open corrosive wall thinning effects · • 2d simulation is accurate enough to interpret...
TRANSCRIPT
Surface Open Corrosive Wall Thinning Effects
Isabel Cristina Pérez Blanco Gerd Dobmann
Research Institute of Corrosion (Colombia)
Fraunhofer Institute of Nondestructive Testing (Germany)
1
• MFL Principle and In-Line Tools
• Corrosive defects Approximation
• Comparison between 3D and 2D Simulation Results
• Conclusions
2
Outline
3
MFL Principle
N
S
S
N
Test specimen Test specimen
with flaw
Magnets
Magnetizing yoke
Sensor N
S
S
N Sensor
Magnetic Flux
Magnetic
Leakage Flux
4
MFL Principle
Hn Ht
Normal and tangential magnetic field components of the leakage signal
Hinc
5
In‐Line Inspection Tools
MFL Tools (axial)
High Resolution MFL-tool
from C-Pig
(Foto C-Pig)
High Resolution
MFL-tool from GE-PII
(Foto GE-PII)
6
In‐Line Inspection Tools
Design of intelligent pigs
Propulsion
Sensor carrier
Data Recording IDOD-Sensors
Battery section
Odometer-wheels
7
Corrosive Defects Approximation
Name Defects depth [%]
Plate height [mm]
Plate width [mm]
Plate length [mm]
TK 10-05 0.5
10
120 500
TK 10-30 30
TK 10-70 70
TK 15-05 0.5
15 TK 15-30 30
TK 15-70 70
TK 20-05 0.5
20 TK 20-30 30
TK 20-70 70
Specimen TK 10-70
10 mm thick
70% defect depth
Set of specimens
8
Corrosive Defects Approximation
Magnetic field components at 1 mm lift-off in TK 10-70:
Tangential Circumferential Normal
9
Corrosive Defects Approximation
TK 10-70
External defects
Simulation Experiment
TK 10-70
Internal defects
10
Corrosive Defects Approximation
0
0.5
1
1.5
2
2.5
3
0 5 10 15 20 25
Hz
p-p
no
rm.
[A/m
]
Defect Radius [mm]
Simulation
Experiment
Linear (Simulation)
Linear (Experiment)
Comparison between simulated and experiment results
for specimen TK 10-70
11
Corrosive Defects Approximation
D1
D2
Distance between defects in
test specimen
-1500
-1000
-500
0
500
1000
1500
-200 -150 -100 -50 0 50 100 150 200
Hz
[A/m
] Position [mm]
D1=50mm D1=100mm
12
Corrosive Defects Approximation
Influence of adjacent defects (D > 2L)
3D Simulation
0
500
1000
1500
2000
2500
3000
0 20 40 60 80 100
Hz
p-p
[A
/m]
Distance between defects [mm] -1500
-1000
-500
0
500
1000
1500
-200 -100 0 100 200 Hz
[A/m
]
Position [mm]
D=20mm
R= 5 mm
R= 7.5 mm
R= 15 mm
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Corrosive Defects Approximation
Defect Radius = 3 mm
3D simulation
0
200
400
600
800
1000
1200
1400
1600
1800
2000
0 20 40 60 80 100
Hz
p-p
[A
/m]
Defect Depth [%]
14
Corrosive Defects Approximation
Analysed parameters:
• Magnetic field signal components
• Intern and extern signals
• Influence of adjacent defects
• Radius vs. depth in defect
15
Comparison between 3D and 2D simulation
Tangential
component
Normal
component
16
Comparison between 3D and 2D simulation
External defects Internal defects
2D simulation
17
Comparison between 3D and 2D simulation
0
500
1000
1500
2000
2500
3000
3500
4000
0 20 40 60 80 100
Hz
p-p
[A
/m]
Distance between defects [mm]
R= 5 mm
R= 7.5 mm
R= 15 mm
Influence of adjacent defects (D > 2L)
2D simulation
18
Comparison between 3D and 2D simulation
Defect
Superposition
D = 10 mm
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Comparison between 3D and 2D simulation
Defect Radius = 3 mm
2D simulation
0
500
1000
1500
2000
2500
3000
3500
4000
4500
5000
0 20 40 60 80 100
Hz
p-p
[A
/m]
Defect depth [%]
20
Conclusions
• 2D simulation is accurate enough to interpret MFL signals obtained from corrosion defects and subsequently allow the defect reconstruction.
• Selection of an ideal mesh resolution and suitable boundary conditions are essential to guarantee accurate numerical results.
• Besides time and computational cost savings, obtained signals in 2D are smoother as 3D signals.
• A mathematical model should be develop to take into account the influence of the third component in the signal amplitude of the results in 2D.
• Further research is needed for irregular defects.
21
Thank you for your attention !
Questions?