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Wall Thickness Measurements
Under Welds
with CAPT and FAATS-COG
Wall Thickness Measurements
Under Welds
with CAPT and FAATS-COG
H. Hébert, G.C. Longhurst
and K.R. Chaplin
Presenter: Hélène Hébert
Outline
• Degradation mechanism under welds
• CAPT and FAATS-COG
–Description of these tools
–Advantages of the technique
• The path to CIQB qualification
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Degradation Mechanism Under
Feeder Welds
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• Destructive examination of removed Pickering A feeders revealed areas of localized thinning (also knows as blunt flaws) under weld caps
–Grayloc Hub welds
–Fitting-to-fitting welds
Picture of Reactor Face
Degradation Mechanism Under
Feeder Welds
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Grayloc
Hub
1st Fitting/
Bend
Grayloc Hub
Weld
FlangeBolt
1st Fitting-to-fitting
Weld
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Degradation Mechanism Under
Feeder Welds
• Characteristics of blunt flaws:
- Abrupt, localized wall thickness changes
• Over regions ~10-20 mm axially
• With various circumferential lengths
- Appearance of a ridge on the inside surface
Degradation Mechanism Under
Feeder Welds
• Localized thinning can be:
– Under weld cap
– Adjacent to weld
Example of localized thinning found at fitting-to-fitting welds
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Normal Blunt flaw1st fitting 2nd fitting
Cross Section
Degradation Mechanism Under
Feeder Welds
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View from inside of feeder pipes
Localized thinning in Feeder B12W Localized thinning in Feeder B09E
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Degradation Mechanism Under
Feeder Welds
• Causes of thinning:
- Variation of chromium content:
• High content in the Grayloc hub
• Medium content in the weld
• Low content in the feeder material
- Could have been exacerbated by grinding that took place during
fit-up and localized turbulence caused by the root geometry
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CAPT
• Composite Angle Profiling Tool (CAPT)
- Delivery tool developed for COG members
- Adapted from the Header Nozzle Weld Inspection Tool developed by AECL
- Wall thickness measurements under and adjacent to welds
- Based on Phased Array Ultrasonic Testing
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CAPT
• Composite Angle Profiling Tool (CAPT)
- Circumferential scanning
- Region covered:
- The entire circumference
- The entire weld
- At least 10 mm of feeder pipe
adjacent to the weld
Region at Grayloc Hub Weld
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CAPT
Region at Fitting-to-fitting Weld
• Composite Angle Profiling Tool (CAPT)
- Circumferential scanning
- Region covered:
- The entire circumference
- The entire weld
- At least 10 mm of feeder pipe
adjacent to the weld
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CAPT and FAATS-COG
*Patent Pending
CAPT (Mark 1)
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CAPT on Bruce “A” Mock-up
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CAPT
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Advantages of CAPT
• CAPT inspects the same region as 6-Probe/GAIT and the entire weld
• CAPT has found minimum thickness on feeder pipes in a region
that is not covered by METAR or 6-Probe/GAIT combined
• CAPT performs measurements every:
- 0.8 mm axially
- 1.5 to 1.9 mm circumferentially
• This measurement grid is adequate for detection of blunt flaws
under welds
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Advantages of CAPT
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• CAPT can detect 3 mm diameter flat bottom holes
The calibration specimen contains:- 3 flat bottom holes- 4 steps
WT and Sensitivity Calibration Specimen
Assembly
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Advantages of CAPT
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• Simple tool…the size of a small loaf of bread
• Easy and quick calibration checks
• Easy manipulation
• Measurements highly repeatable
• CAPT remains stable on the feeder
during use
Calibration Check with CAPT
Advantages of CAPT
• Portable acquisition station, small footprint
CAPTEntire Inspection System,
Including Acquisition Station
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Advantages of CAPT
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• Use a small amount of demineralized water as couplant
(reduces slipping hazards during inspections)
• Compatible with current data acquisition systems used for METAR,
6-Probe and GAIT inspection
• Maintains coupling over complex topography with weld cap,
even in the intrados of tight radius fittings/bends
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FAATS-COG
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• Software used to analyse CAPT data
- Measurement of minimum thickness on feeder pipe and under the weld
- Two-dimensional wall thickness maps
- Localized thinning patterns under welds (blunt flaws)
• Aid to the qualified data analyst
Advantages of FAATS-COG
• Quick calibration checks (performed under 1 min)
• High resolution (1 µm)
• Improved coverage using phased array
• Faster analysis using new software features
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Advantages of
CAPT and FAATS-COG
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• Improved coverage (even in the intrados of tight-radius bends)
• Detection of localized thinning under welds and on feeder pipes
Ex-service Feeder P1E19W
The Path to CIQB Qualification
Experience
• First field trial at Pickering A in 2009:
– Inspection procedure tested
–Areas of improvement identified for CAPT and FAATS-COG
• NRU Calandria vessel leak and repair:
–Extensive use of similar inspection technique and
software at NRU since 2009
–Continuous improvement of these tools
–CIQB qualified techniques
• CAPT Mark 1 and FAATS-COG 3.0 were produced for COG
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The Path to CIQB Qualification
ACQUISITION OF CAPT DATA
Inspection Procedure
Training Procedure
Training material
ANALYSIS OF CAPT DATA
Analysis Procedure
Training Procedure on Analysis
Training Material on Analysis
Technical Justification
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The Path to CIQB Qualification
ACQUISITION OF CAPT DATA
Inspection Procedure
Training Procedure
Training material
ANALYSIS OF CAPT DATA
Analysis Procedure
Training Procedure on Analysis
Training Material on Analysis
Technical Justification
Submitted to the CIQB
in 2011 March
Documents were reviewed
by an independent panel
of ultrasonic testing
experts
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The Path to CIQB Qualification
ACQUISITION OF CAPT DATA
Inspection Procedure
Training Procedure
Training material
ANALYSIS OF CAPT DATA
Analysis Procedure
Training Procedure on Analysis
Training Material on Analysis
Technical Justification
Submitted to the CIQB
in 2011 March
Documents were reviewed
by an independent panel
of ultrasonic testing
experts
Improved procedures
and training material
CAPT is the first COG thinning inspection
technique to undergo CIQB qualification!
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Acknowledgements
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• COG NDE Team and FIJP
• CIQB and their reviewers
• CAPT and FAATS-COG development teams
• B&W for use of their mock-up
• OPG for the first field trial
• Malcolm Clark for the pictures of blunt flaws
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QUESTIONS?
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