Predicting Corrosion Rates and Future Corrosion Severity From in-line Inspection Data
BASF-DR Techniques for Corrosion Inspection
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Transcript of BASF-DR Techniques for Corrosion Inspection
DR techniques for corrosion inspection
Zscherpel, Alekseychuk, Ewert, BAM VIII.3Rost, BASF AG, DWF/FZ
NDT 2003, BINDT, September 2003, Worcester, U.K.1
application „on stream“application „on stream“
contents:- basic principles- software for evaluation and documentation
- corrosion depth evaluation- „corrosion mapping“
contents:- basic principles- software for evaluation and documentation
- corrosion depth evaluation- „corrosion mapping“
common research projectBASF and BAM :
computer based radiographic wall thickness measurement
common research projectBASF and BAM :
computer based radiographic wall thickness measurement
Projection Radiography
DR techniques for corrosion inspection
Zscherpel, Alekseychuk, Ewert, BAM VIII.3Rost, BASF AG, DWF/FZ
NDT 2003, BINDT, September 2003, Worcester, U.K.2
Corrosion ErosionCorrosion and Seads
Projection Radiography Examples on Corrosion and Erosion
DR techniques for corrosion inspection
Zscherpel, Alekseychuk, Ewert, BAM VIII.3Rost, BASF AG, DWF/FZ
NDT 2003, BINDT, September 2003, Worcester, U.K.3
History: radiographic wall thickness evaluation
BASF drawing from 1954• applied since ca.
1950• nearly no literature
until 1980• growing importance
in chemical industrycaused by on-stream application
• since 1996 projectsBASF und BAM forphysical studies
• standardizationopen (IAEA Draft)
DR techniques for corrosion inspection
Zscherpel, Alekseychuk, Ewert, BAM VIII.3Rost, BASF AG, DWF/FZ
NDT 2003, BINDT, September 2003, Worcester, U.K.4
classical set-up:classical set-up: film,imagingplate,orflatpanel
pipeline
radiation source, Ir 192
insulationtypical exposure:typical exposure:
profile line
DR techniques for corrosion inspection
Zscherpel, Alekseychuk, Ewert, BAM VIII.3Rost, BASF AG, DWF/FZ
NDT 2003, BINDT, September 2003, Worcester, U.K.5
Projection Radiography
on-site exposure, Ir 192 radiograph
sourcefilm
Example : distribution station
DR techniques for corrosion inspection
Zscherpel, Alekseychuk, Ewert, BAM VIII.3Rost, BASF AG, DWF/FZ
NDT 2003, BINDT, September 2003, Worcester, U.K.6
visual evaluation of wall thickness
error sources:- wrong density range - inaccurate edge detection (unsharpness)- wrong magnification factor
w
Projection Radiography
DR techniques for corrosion inspection
Zscherpel, Alekseychuk, Ewert, BAM VIII.3Rost, BASF AG, DWF/FZ
NDT 2003, BINDT, September 2003, Worcester, U.K.7
Principle of projection radiography
w` measured on film
tangential penetration of pipe wall
pipe
insulation
f - film focus distancer - outer pipe radiusR - outer radius of insulationw‘ - wall thickness projection
on detector plane
DR techniques for corrosion inspection
Zscherpel, Alekseychuk, Ewert, BAM VIII.3Rost, BASF AG, DWF/FZ
NDT 2003, BINDT, September 2003, Worcester, U.K.8
0
1
2
3
4
2 4 6 8 10
f/2r
erro
r [%
]
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⎝
⎛−
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−=
fw
rRfr
fw
rRfrRf
rw
exact magnificationcorrection :
practicalapproximation :
program :
DR techniques for corrosion inspection
Zscherpel, Alekseychuk, Ewert, BAM VIII.3Rost, BASF AG, DWF/FZ
NDT 2003, BINDT, September 2003, Worcester, U.K.9
film digitisation flat panelimaging plate
PC based wall thickness measurement
• single program for evalution of all digital images, no size limitation• support for all detectors by external 16 bit LUT tables for lineari-
sation (gray value proportional to radiation intensity)
Projection Radiography
DR techniques for corrosion inspection
Zscherpel, Alekseychuk, Ewert, BAM VIII.3Rost, BASF AG, DWF/FZ
NDT 2003, BINDT, September 2003, Worcester, U.K.10
overview of measurement equipment at BASF :
RT exposure scanner PC
protocol
data basefilm digitisation(16 bit, 300 dpi)
software for measurement
(algorithms) anddocumentation
screen/film :RCF + F8 (7% of exposuretime of Pb+D7)
Projection Radiography PC based wall thickness measurement
DR techniques for corrosion inspection
Zscherpel, Alekseychuk, Ewert, BAM VIII.3Rost, BASF AG, DWF/FZ
NDT 2003, BINDT, September 2003, Worcester, U.K.11
16 bit software platform
transfer of image processing know-how to Windows PC(ScanManager 1992 -1995, SUN workstations) :- fully 16 bit data depth for evaluation and display - unlimited image sizes, limited only by main memory (>512 MByte)- all detectors (digitized film, imaging plates, flat panel detectors)via external 16 bit Lookup Tables (LUT) linearizable, ASCII text
- fast rekursive moving average filtering for arbitrary sizes of high andlow pass filters, convolution with variable kernels (ASCII text)
- sub-sampling for image display with true averaging- error estimation for measured values and „simple“ geometric correction- quick documentation of measurements by protocol generation andtransfer to Word- protection of application by individual encrypted license keys
transfer of image processing know-how to Windows PC(ScanManager 1992 -1995, SUN workstations) :- fully 16 bit data depth for evaluation and display - unlimited image sizes, limited only by main memory (>512 MByte)- all detectors (digitized film, imaging plates, flat panel detectors)via external 16 bit Lookup Tables (LUT) linearizable, ASCII text
- fast rekursive moving average filtering for arbitrary sizes of high andlow pass filters, convolution with variable kernels (ASCII text)
- sub-sampling for image display with true averaging- error estimation for measured values and „simple“ geometric correction- quick documentation of measurements by protocol generation andtransfer to Word- protection of application by individual encrypted license keys
wtScope.exe
DR techniques for corrosion inspection
Zscherpel, Alekseychuk, Ewert, BAM VIII.3Rost, BASF AG, DWF/FZ
NDT 2003, BINDT, September 2003, Worcester, U.K.12
tangential wall thicknessalgorithm
wall thickness result
table with mea-surement regions
wall thickness deviation in mea-surement region
input exposureparameters
Projection Radiography PC based wall thickness measurement
DR techniques for corrosion inspection
Zscherpel, Alekseychuk, Ewert, BAM VIII.3Rost, BASF AG, DWF/FZ
NDT 2003, BINDT, September 2003, Worcester, U.K.13
synchronous display of positions in profile and image !
position correction by hand, if algorithm fails !
DR techniques for corrosion inspection
Zscherpel, Alekseychuk, Ewert, BAM VIII.3Rost, BASF AG, DWF/FZ
NDT 2003, BINDT, September 2003, Worcester, U.K.14
PC generated measurement protocolProjection Radiography
DR techniques for corrosion inspection
Zscherpel, Alekseychuk, Ewert, BAM VIII.3Rost, BASF AG, DWF/FZ
NDT 2003, BINDT, September 2003, Worcester, U.K.15
PC based wall thickness measurementProjection Radiography Algorithms : problem: correct detection of wall positions
characteristic points, curve fitting, CT reconstr.inner wall of pipe
outer wall of pipemax.
projectedwall thickness w‘
DR techniques for corrosion inspection
Zscherpel, Alekseychuk, Ewert, BAM VIII.3Rost, BASF AG, DWF/FZ
NDT 2003, BINDT, September 2003, Worcester, U.K.16
Accuracy DN 150 steel test pipe
-0,8
-0,6
-0,4
-0,2
0
0,2
0,4
0,6
0 2 4 6 8 10 12
wall thickness / mm
Abw
eich
ung
/ mm
BASF altBASF neuCTPWT
new wall thickness algorithm with adaptive smoothingfor improved detection of inner wall position :
Accuracy DN 200 steel test pipe
-0,8
-0,6
-0,4
-0,2
0
0,2
0,4
0,6
0 2 4 6 8 10
wall thickness / mm
Abw
eich
ung
/ mm
BASF altBASF neuCTPWT
Comparison of accuracy of PC based algorithms
DR techniques for corrosion inspection
Zscherpel, Alekseychuk, Ewert, BAM VIII.3Rost, BASF AG, DWF/FZ
NDT 2003, BINDT, September 2003, Worcester, U.K.17
Ir 192, DN200:6 11 mm
Co 60, DN300:14 24 mm
algorithm detects edges, visual not seeable in image :
extension ofapplicationrange in com-parison tovisual evalu-ation
DR techniques for corrosion inspection
Zscherpel, Alekseychuk, Ewert, BAM VIII.3Rost, BASF AG, DWF/FZ
NDT 2003, BINDT, September 2003, Worcester, U.K.18
erosionw-Δw
intensity change, ΔI
detector
pipesource
absorption law : µ-effective absorption coefficientIw = I0 e -µw
local corrosion : wall thickness differences inpenetration direction
relative measurement :relative measurement : 2 step algorithm
1. Calibration :2. Measurement :
µeff = ln ( DREF / DIQI ) / ΔwIQI
Δw = ln ( DREF / DMESS ) / µeff
DR techniques for corrosion inspection
Zscherpel, Alekseychuk, Ewert, BAM VIII.3Rost, BASF AG, DWF/FZ
NDT 2003, BINDT, September 2003, Worcester, U.K.19
digitized film, step wedge, 160 kV:digitized film, step wedge, 160 kV: imaging plate, pipe (DN 150), Ir :imaging plate, pipe (DN 150), Ir :
Projection Radiography PC based wall thickness measurement
linearization of film curve and (log.) imaging plate scanner by external 16 bit LUT [Log(gray value proportional to radiation dose)]
DR techniques for corrosion inspection
Zscherpel, Alekseychuk, Ewert, BAM VIII.3Rost, BASF AG, DWF/FZ
NDT 2003, BINDT, September 2003, Worcester, U.K.20
test pipe DN 100 x 5,6 mmpit 1 Ø R3 x 1mm (Tool-Ø / depth)
pit 2 Ø R3 x 2 mm
pit 3 Ø R3 x 3 mm
Measurement of local corrosion1. Calibration (µ-eff estimation)
reference point
measure point
LUT for linearisation
known wall thicknessat reference point
known wall thicknessat measurement point
DR techniques for corrosion inspection
Zscherpel, Alekseychuk, Ewert, BAM VIII.3Rost, BASF AG, DWF/FZ
NDT 2003, BINDT, September 2003, Worcester, U.K.21
Measurement of local corrosion
2. depth measurement
reference point
measure point
known wall thicknessat reference point (un-changed)
result : local penetratedwall thickness in mm(error ca. 0.2 mm)
pitting depth: 3mm
DR techniques for corrosion inspection
Zscherpel, Alekseychuk, Ewert, BAM VIII.3Rost, BASF AG, DWF/FZ
NDT 2003, BINDT, September 2003, Worcester, U.K.22
Projection Radiography evaluation of corrosion depth ininner third of pipe diameter possible
error < 0,5 mm
DR techniques for corrosion inspection
Zscherpel, Alekseychuk, Ewert, BAM VIII.3Rost, BASF AG, DWF/FZ
NDT 2003, BINDT, September 2003, Worcester, U.K.23
simulation
separable investigations on influence of :• wall thickness• radiation source
• scattered radiation
• unsharpness
Projection Radiography
G.-R.Tillack,C. Bellon
DR techniques for corrosion inspection
Zscherpel, Alekseychuk, Ewert, BAM VIII.3Rost, BASF AG, DWF/FZ
NDT 2003, BINDT, September 2003, Worcester, U.K.24
Simulation: visual position of edge in image and profile differ !
DR techniques for corrosion inspection
Zscherpel, Alekseychuk, Ewert, BAM VIII.3Rost, BASF AG, DWF/FZ
NDT 2003, BINDT, September 2003, Worcester, U.K.25
problem :
simulation
local corrosionin wall, tangentialprojection
wall thickness on bothsides of pipe 5 mm, only profile form differ !
DR techniques for corrosion inspection
Zscherpel, Alekseychuk, Ewert, BAM VIII.3Rost, BASF AG, DWF/FZ
NDT 2003, BINDT, September 2003, Worcester, U.K.26
median filtering indirection of symmetry :
measurement after mapping :
corrosion 5 mm -> complete wall !
corrosion pit
median filterperpenticular(1x49) >2x flaw size
difference imagepseudo colorrepresentation
DR techniques for corrosion inspection
Zscherpel, Alekseychuk, Ewert, BAM VIII.3Rost, BASF AG, DWF/FZ
NDT 2003, BINDT, September 2003, Worcester, U.K.27
- 0 mm
+ 10 mm
- 5 mm
real pipe, innercorrosion, insulated
corrosion mappingafter median high pass(gray value prop. penetratedwall thickness, 1x300 points) :
DR techniques for corrosion inspection
Zscherpel, Alekseychuk, Ewert, BAM VIII.3Rost, BASF AG, DWF/FZ
NDT 2003, BINDT, September 2003, Worcester, U.K.28
corroded pipewith weld
+ 5 mm
- 0 mm
- 5 mm
corrosion mappingafter median high pass(gray value prop. topenetrated wall thickness1x200 points) :
DR techniques for corrosion inspection
Zscherpel, Alekseychuk, Ewert, BAM VIII.3Rost, BASF AG, DWF/FZ
NDT 2003, BINDT, September 2003, Worcester, U.K.29
validation
L
w
application range, limits for pipe inspection
material: steelEwert, Onel BAM VIII.3 wall thickness
DR techniques for corrosion inspection
Zscherpel, Alekseychuk, Ewert, BAM VIII.3Rost, BASF AG, DWF/FZ
NDT 2003, BINDT, September 2003, Worcester, U.K.30
SummaryProjection Radiography
inspection technique not standardised, written practice necessary !
• program for PC based routine measurements on images from all radiographic detectors, tangential wall thickness measurement and local corrosion, simple documentation
• wall thickness range enlarged compared with visual evaluation in projection radiography
• measurement of corrosion depth (in centre of pipe)• 3D simulation tool for case studies on recognibility• Corrosion mapping with median high pass along
symmetry axis of the pipe allows presentation of wall thickness differences relative to the nominal wall thickness of the pipe
standard development will be started in 2004
DR techniques for corrosion inspection
Zscherpel, Alekseychuk, Ewert, BAM VIII.3Rost, BASF AG, DWF/FZ
NDT 2003, BINDT, September 2003, Worcester, U.K.31
The END
contact : [email protected]