Corrosion and Wall Thickness Measurement U. Zscherpel, O. Alekseychuk, S. Bär, BAM VIII.3 P. Rost, BASF AG, DWF/FZ Imaging NDE 2007, April 2007, Kalpakkam, India 1 application „on stream“ contents: - basic principles - software for evaluation and documentation - corrosion depth evaluation - validation of methods common research project BASF and BAM, later with AGFA/GE IT, IAEA: computer based radiographic wall thickness measurement Projection Radiography
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Projection Radiography application „on stream“application ... · Principle of projection radiography w` measured on film tangential penetration of pipe wall pipe insulation f
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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
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):
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
Corrosion and Wall Thickness Measurement
U. Zscherpel, O. Alekseychuk, S. Bär, BAM VIII.3P. Rost, BASF AG, DWF/FZ