ut of pressure vessel construction welds
TRANSCRIPT
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Second level
Third level
Fourth level
Fifth level
1
Ultrasonic inspection of pressurevessel construction welds using
phased arrays
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Talk Outline
Weld inspections
Codes, including ASME Code Case 2235
Some dos and donts of phased arrays
AUT inspection instruments
Mechanics: some suggestionsSummary
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Weld inspections
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Linear Scanning Philosophy
Select arrays to give adequate coverage; need toensure HAZ and weld zone covered
Scan weld in parallel linear motion, or move weld past
stationary arrays -> much faster.
Left: raster scans Right: linear scans
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Electronic and Linear Scanning Typical weld inspection using combined
electronic and linear scanning. ASME-type 45oand 60oshear wave & TOFD
inspections; ~10x faster than raster scanning.
Need to cover weld, HAZ, any position errors
=> significant amount of coverage.
Works well for wide gap welds.
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Sample ResultsTop, side, end View
This image
shows weld
profile
superimposedon top, side,
end and
waveform
view.
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UT Zone Discrimination Weld is divided into many
Zones, each covering 2-3mm of weld wall
UT beams are focused to
~2 mm, and angled for
Lack of Fusion UT transducers are
designed and positioned
to inspect each zone
Scanner travels linearlyround pipe at high speed
Both sides of the weld
center line are inspected
independently
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Codes
ASME Code Case 2235 permits automatedultrasonic inspection of welds
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Advantages of AUT vs. RT
AUT does not disrupt production No safety hazard from AUT; no radiation
Immediate feedback on the weld quality
AUT can measure the defect height forFitness-For-Purpose analysis, => shouldreduce repairs and costs.
AUT inspections can be tailored to the weldprofile, vessel geometry and inspectionrequirements
Can maximize Probability of Detection
All data is stored, unlike manual UT
High production rates.
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Some Dos and Donts
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Dos and donts - calibration
DO
Calibrate array entire array for reproducible
and code-acceptable results
Best approach is to scan over calibrationreflectorthen compensate electronically
using software
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Dos and donts Weld overlays
DO
Add weld
overlay if
possible Helps locate
defects relative
to weld profile
and surface
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Dos and donts 3D images
MAYBE
Can do 3Dimaging withTomoView
Good pictures,
BUT needmaximum height,length etc.
ASME box more
useful for analysis Developmentdone with ZetecQuebec. Image courtesy of Zetec
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Dos and donts S-scans
DONT: perform single S-Scans on thick sections
Can calibrate S-scans at any angle on SDHS-scan does not necessarily give best angles for weld
inspections
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Inspection Systems
Instrumentation
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OmniScanPortable Phased Array
UnitBattery-powered/AC16/128 unit
Performs electronic
and sectorial scansPulse-echo, TOFD
etc.
Can operate withencoders or full
scanners
User-friendly software
With array and
encoder, OmniScan is a
complete system
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PV-100 System
Conventional multiprobe system with encodedhandscanner or automated scanner
Uses TOFD for weld midwall, and pulse-echo for
root and cap to give 100% coverage.
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PV-200
Uses full phased array units (Tomo III or FOCUS
LT) with automated scanners
Performs many different inspections, incl. TOFD
and top, side, end views
General purpose inspections.
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FOCUS LT
New instrumentreplaces FOCUS
As capable as
FOCUS, but
smaller, lighter,cheaper
Runs TomoView
Performs multiplescans
simultaneously
Good data
analysis
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PV-300Special ECA-Fitness
For Purposeapplications
200% NDE coverage
Multiple NDE
techniques
o Pulse-echo
o Tandem
o TOFD
o Eddy current
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Mechanics
From semi-automated to fully
automated
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Encoded ArraySimplest and
cheapest solutionWorks with
OmniScan
Can give top,side, end views
and TOFD
Limited byposition accuracy
and single
functionscans
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Handscanners
Low cost and easy to useCan use conventional or
phased arrays
Uses TOFD and pulse-echo
Good approach for very
thick wallsNeed allowance for
operator error
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Welding Bands
Good forpipes up to
~1.5 m
Quick, easy
and accurate
Routinely
used on
pipelineconstruction.
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Rotate the VesselGood for
fabricators, whorotate to weld
Simplest
mechanical solutionCan accommodate
position errors with
phased arrays
No safety hazard,
no delays
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Magnetic wheel scannersVariety of scanners
available from R/DTech and externally
Follows magnetic
strip, so can scan
nozzles, unusualgeometrys etc.
Can also use
joysticks, pre-
programming etc. forcontrol
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Robotics
Expensive, but very flexible solution
Robot can manipulate large probe pan with
many NDE devices.
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Advantages of Phased Arrays
Speed: scanning with phased arrays is much faster than single probeconventional mechanical systems, with better coverage;
Flexibility: set-ups can be changed in a few minutes, and typically alot more component dimensional flexibility is available;
Inspection angles: a wide variety of inspection angles can be used,depending on the requirements and the array;
Small footprint: small matrix arrays can give significantly moreflexibility for inspecting restricted areas than conventional probes
Imaging: showing a true depth image of defects is much easier tointerpret than a waveform. The data can be saved, analyzed and re-displayed as required.
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Conclusions
Many different PA & AUT systems can be used to
fulfill ASME 2235 and other weld inspection codes: portable phased arrays (OmniScan),
TOFD-based (PV-100)
more powerful phased arrays (PV-200 and FOCUS LT).
Many possibilities for delivery systems: handscanners,
welding bands,
magnetic wheel scanners,
rotate the vessel,
robotics. Choice is controlled by codes, component
requirements, budget and knowledge.