projection radiography application „on stream“application ... · principle of projection...
TRANSCRIPT
Corrosion and Wall Thickness Measurement
U. Zscherpel, O. Alekseychuk, S. Bär, BAM VIII.3P. Rost, BASF AG, DWF/FZ
Imaging NDE 2007, April 2007, Kalpakkam, India1
application „on stream“application „on stream“
contents:- basic principles- software for evaluationand documentation
- corrosion depth evaluation- validation of methods
contents:- basic principles- software for evaluationand documentation
- corrosion depth evaluation- validation of methods
common research projectBASF and BAM, later withAGFA/GE IT, IAEA:computer based radiographicwall thickness measurement
common research projectBASF and BAM, later withAGFA/GE IT, IAEA:computer based radiographicwall thickness measurement
Projection Radiography
Corrosion and Wall Thickness Measurement
U. Zscherpel, O. Alekseychuk, S. Bär, BAM VIII.3P. Rost, BASF AG, DWF/FZ
Imaging NDE 2007, April 2007, Kalpakkam, India2
Corrosion ErosionCorrosion and Seads
Projection Radiography Examples on Corrosion and Erosion
Corrosion and Wall Thickness Measurement
U. Zscherpel, O. Alekseychuk, S. Bär, BAM VIII.3P. Rost, BASF AG, DWF/FZ
Imaging NDE 2007, April 2007, Kalpakkam, India3
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)
Corrosion and Wall Thickness Measurement
U. Zscherpel, O. Alekseychuk, S. Bär, BAM VIII.3P. Rost, BASF AG, DWF/FZ
Imaging NDE 2007, April 2007, Kalpakkam, India4
classical set-up:classical set-up: film,imagingplate,orflatpanel
pipeline
radiation source, Ir 192
insulationtypical exposure:typical exposure:
profile line
Corrosion and Wall Thickness Measurement
U. Zscherpel, O. Alekseychuk, S. Bär, BAM VIII.3P. Rost, BASF AG, DWF/FZ
Imaging NDE 2007, April 2007, Kalpakkam, India5
Projection Radiography
on-site exposure, Ir 192 radiograph
sourcefilm
Example : distribution station
Corrosion and Wall Thickness Measurement
U. Zscherpel, O. Alekseychuk, S. Bär, BAM VIII.3P. Rost, BASF AG, DWF/FZ
Imaging NDE 2007, April 2007, Kalpakkam, India6
visual evaluation of wall thickness
error sources:- wrong density range - inaccurate edge detection (unsharpness)- wrong magnification factor
w
Projection Radiography
Corrosion and Wall Thickness Measurement
U. Zscherpel, O. Alekseychuk, S. Bär, BAM VIII.3P. Rost, BASF AG, DWF/FZ
Imaging NDE 2007, April 2007, Kalpakkam, India7
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
Corrosion and Wall Thickness Measurement
U. Zscherpel, O. Alekseychuk, S. Bär, BAM VIII.3P. Rost, BASF AG, DWF/FZ
Imaging NDE 2007, April 2007, Kalpakkam, India8
overview of measurement equipment (BASF at 2000, before CR):
RT exposure scanner PC
protocol
data basefilm digitisation(16 bit, 300 dpi)
software formeasurement
(algorithms) anddocumentation
screen/film :RCF + F8 (7% of exposuretime of Pb+D7)
Projection Radiography PC based wall thickness measurement
Corrosion and Wall Thickness Measurement
U. Zscherpel, O. Alekseychuk, S. Bär, BAM VIII.3P. Rost, BASF AG, DWF/FZ
Imaging NDE 2007, April 2007, Kalpakkam, India9
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
Corrosion and Wall Thickness Measurement
U. Zscherpel, O. Alekseychuk, S. Bär, BAM VIII.3P. Rost, BASF AG, DWF/FZ
Imaging NDE 2007, April 2007, Kalpakkam, India10
16 bit software platform
image processing know-how on Windows PC:(ISee!, see http://www.kb.bam.de/~alex/ic.html)- fully 16 bit data depth for evaluation and display- unlimited image sizes, limited only by main memory (>1 GByte)- 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 geometric correction- quick documentation of measurements by protocol generation andtransfer to Word- protection of application by individual encrypted license keys
image processing know-how on Windows PC:(ISee!, see http://www.kb.bam.de/~alex/ic.html)- fully 16 bit data depth for evaluation and display- unlimited image sizes, limited only by main memory (>1 GByte)- 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 geometric correction- quick documentation of measurements by protocol generation andtransfer to Word- protection of application by individual encrypted license keys
wtScope.exe
Corrosion and Wall Thickness Measurement
U. Zscherpel, O. Alekseychuk, S. Bär, BAM VIII.3P. Rost, BASF AG, DWF/FZ
Imaging NDE 2007, April 2007, Kalpakkam, India11
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
Corrosion and Wall Thickness Measurement
U. Zscherpel, O. Alekseychuk, S. Bär, BAM VIII.3P. Rost, BASF AG, DWF/FZ
Imaging NDE 2007, April 2007, Kalpakkam, India12
synchronous display of positions in profile and image !
position correction by hand, if algorithm fails !
Corrosion and Wall Thickness Measurement
U. Zscherpel, O. Alekseychuk, S. Bär, BAM VIII.3P. Rost, BASF AG, DWF/FZ
Imaging NDE 2007, April 2007, Kalpakkam, India13
PC generated measurement protocolProjection Radiography
Corrosion and Wall Thickness Measurement
U. Zscherpel, O. Alekseychuk, S. Bär, BAM VIII.3P. Rost, BASF AG, DWF/FZ
Imaging NDE 2007, April 2007, Kalpakkam, India14
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‘
Corrosion and Wall Thickness Measurement
U. Zscherpel, O. Alekseychuk, S. Bär, BAM VIII.3P. Rost, BASF AG, DWF/FZ
Imaging NDE 2007, April 2007, Kalpakkam, India15
Limits of Tangential Radiography (TRT):Limits of Tangential Radiography (TRT):
Energy: Lmax100 kV : 10 mm200 kV : 30 mm300 kV : 40 mm400 kV : 50 mmSe-75 : 60 mmIr-192 : 75 mmCo-60 : 120 mm
L max
W
Lmax = 2W sqrt(Da/W –1)
200 kV
300 kV
Corrosion and Wall Thickness Measurement
U. Zscherpel, O. Alekseychuk, S. Bär, BAM VIII.3P. Rost, BASF AG, DWF/FZ
Imaging NDE 2007, April 2007, Kalpakkam, India16
2003 2004 2005
Algeria Hungary Romania Iran Pakistan Germany Uruguay Syria India Turkey Malaysia Canada
Radiographic Evaluation of Corrosion and Deposits in Pipelines:
Results of an IAEA Co-ordinated Research Programme
Steel pipes up to 20” with NDT film and X-ray, Ir-192, Co-60Steel pipes up to 20” with NDT film and X-ray, Ir-192, Co-60
Corrosion and Wall Thickness Measurement
U. Zscherpel, O. Alekseychuk, S. Bär, BAM VIII.3P. Rost, BASF AG, DWF/FZ
Imaging NDE 2007, April 2007, Kalpakkam, India17
Fabricated Reference Blocks with Steps and Holes:Fabricated Reference Blocks with Steps and Holes:
Iran
Idea:explore inspection methods with known wall thicknessesIdea:explore inspection methods with known wall thicknesses
Corrosion and Wall Thickness Measurement
U. Zscherpel, O. Alekseychuk, S. Bär, BAM VIII.3P. Rost, BASF AG, DWF/FZ
Imaging NDE 2007, April 2007, Kalpakkam, India18
Corrosion and Wall Thickness Measurement
U. Zscherpel, O. Alekseychuk, S. Bär, BAM VIII.3P. Rost, BASF AG, DWF/FZ
Imaging NDE 2007, April 2007, Kalpakkam, India19
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
Corrosion and Wall Thickness Measurement
U. Zscherpel, O. Alekseychuk, S. Bär, BAM VIII.3P. Rost, BASF AG, DWF/FZ
Imaging NDE 2007, April 2007, Kalpakkam, India20
2005: Validation of wtScope, CR-Tower and Ir-192 2005: Validation of wtScope, CR-Tower and Ir-192
BAMBASFGE IT
Corrosion and Wall Thickness Measurement
U. Zscherpel, O. Alekseychuk, S. Bär, BAM VIII.3P. Rost, BASF AG, DWF/FZ
Imaging NDE 2007, April 2007, Kalpakkam, India21
Validation as measurement method according to ISO 17025: Validation as measurement method according to ISO 17025:
Steel pipes 50 – 300 mm dia, empty, water filled, w/o insulation
Corrosion and Wall Thickness Measurement
U. Zscherpel, O. Alekseychuk, S. Bär, BAM VIII.3P. Rost, BASF AG, DWF/FZ
Imaging NDE 2007, April 2007, Kalpakkam, India22
Two inspection techniques possible :
2. Corrosion assessment from local film density changes (Double Wall Technique, DWT)
Radiographic Corrosion InspectionRadiographic Corrosion Inspection
Corrosion and Wall Thickness Measurement
U. Zscherpel, O. Alekseychuk, S. Bär, BAM VIII.3P. Rost, BASF AG, DWF/FZ
Imaging NDE 2007, April 2007, Kalpakkam, India23
erosionw-Δw
intensity change, ΔI
detector
pipesource
attenuation law: µeff - effective attenuation coefficientIw = I0 e -µeff w
local corrosion : wall thickness differences in penetration direction (DWT)
relative measurement:relative measurement: 2 step algorithm
1. Calibration:2. Measurement:
µeff = ln ( DREF / DIQI ) / ΔwIQI
Δw = ln ( DREF / DMEAS ) / µeff
Corrosion and Wall Thickness Measurement
U. Zscherpel, O. Alekseychuk, S. Bär, BAM VIII.3P. Rost, BASF AG, DWF/FZ
Imaging NDE 2007, April 2007, Kalpakkam, India24
1. Calculation of effectiveattenuation coefficient µeff
signal atreference point
signal atmeasurement point
known pipe wall thicknessw at reference point
known hole depth
DWT for localcorrosionDWT for localcorrosion
Result: µeff = f(w)dep. on radiation energy andwall thickness differences
Result: µeff = f(w)dep. on radiation energy andwall thickness differences
Corrosion and Wall Thickness Measurement
U. Zscherpel, O. Alekseychuk, S. Bär, BAM VIII.3P. Rost, BASF AG, DWF/FZ
Imaging NDE 2007, April 2007, Kalpakkam, India25
Double wall technique 6" and 8", 100 kV, with and without insulation
y = 0,6689x-0,3385
R2 = 0,7316
y = 0,5039x-0,3927
R2 = 0,3817
0,00
0,05
0,10
0,15
0,20
0,25
0,30
0,35
0,40
0,45
0,50
0 2 4 6 8 10 12 14 16 18
Penetrated steel wall thickness (mm)
Cal
cula
ted
atte
nuat
ion
coef
ficie
nt
(1/m
m)
insulation
decreasing µeff with penetrated wall and insulationdecreasing µeff with penetrated wall and insulation
Iran, UruguayIAEA CRP, filmIAEA CRP, film
Corrosion and Wall Thickness Measurement
U. Zscherpel, O. Alekseychuk, S. Bär, BAM VIII.3P. Rost, BASF AG, DWF/FZ
Imaging NDE 2007, April 2007, Kalpakkam, India26
Double wall technique, Ir 192
0,00
0,01
0,02
0,03
0,04
0,05
0,06
0,07
0,08
0,09
0,10
0 10 20 30 40 50 60
Penetrated steel wall thickness (mm)
Cal
cula
ted
atte
nuat
ion
coef
ficie
nt
(1/m
m)
Uruguay Iran
Uruguay with Insulation Iran with Insulation
80 % of all measurements: µeff = 0.046 +/- 0.005 mm-180 % of all measurements: µeff = 0.046 +/- 0.005 mm-1
IAEA CRP, filmIAEA CRP, film Ir-192
Corrosion and Wall Thickness Measurement
U. Zscherpel, O. Alekseychuk, S. Bär, BAM VIII.3P. Rost, BASF AG, DWF/FZ
Imaging NDE 2007, April 2007, Kalpakkam, India27
Double wall technique
0,000
0,005
0,010
0,015
0,020
0,025
0,030
0,035
0,040
0,045
0 10 20 30 40 50 60
Penetrated steel wall thickenss [mm]
Cal
cula
ted
atte
nuat
ion
coef
ficie
nt [1
/mm
]
12" pipe8" pipemean µeff
75 % of all measurements: µeff = 0.028 +/- 0.004 mm-175 % of all measurements: µeff = 0.028 +/- 0.004 mm-1
IAEA CRP, filmIAEA CRP, film Co-60
Corrosion and Wall Thickness Measurement
U. Zscherpel, O. Alekseychuk, S. Bär, BAM VIII.3P. Rost, BASF AG, DWF/FZ
Imaging NDE 2007, April 2007, Kalpakkam, India28
Computer based evaluationwith wtScope/ISee! software:accuracy 0.5 mm, µeff=0.028/mm
Computer based evaluationwith wtScope/ISee! software:accuracy 0.5 mm, µeff=0.028/mm
Corrosion and Wall Thickness Measurement
U. Zscherpel, O. Alekseychuk, S. Bär, BAM VIII.3P. Rost, BASF AG, DWF/FZ
Imaging NDE 2007, April 2007, Kalpakkam, India29
Comparison Film / CRComparison Film / CR
DWT with Ir-192:DWT with Ir-192:
reason: scatter sensitivity!reason: scatter sensitivity!0
0,01
0,02
0,03
0,04
0,05
0,06
0 2 4 6 8 10 12 14
pipe wall thickness [mm]
effe
ctiv
e at
tenu
atio
n co
effic
ient
[1/m
m]
CR
Film
Result of wtScopevalidation forCR Tower byBAM / BASF / GE IT
µeff
Corrosion and Wall Thickness Measurement
U. Zscherpel, O. Alekseychuk, S. Bär, BAM VIII.3P. Rost, BASF AG, DWF/FZ
Imaging NDE 2007, April 2007, Kalpakkam, India30
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)• validation as measurement methods acc. to ISO 17025• programs transfered to GE IT for worldwide marketing
(Rhythm Version 2 all methods implemented)• differences in sensitivity to scattered radiation between
film and imaging plates
standard development has to be started soon