acoustic resonance
TRANSCRIPT
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ARTTM Acoustic Resonance Technology
Åshild Bergh – Technology ManagerJostein Jacobsen – Head of Section
© Det Norske Veritas AS. All rights reserved Slide 227 October 2008
What is ARTTM ?ARTTM is a more low frequency, wide-band method than traditional ultrasonics
ARTTM, or ”Acoustic Resonance Technology”, has been developed by DNV since1992. Basic technology principles have been known since 1946
Core technology patented by DNV
ARTTM utilizes half-wave frequency principles
ARTTM comprises <100 times more acoustic energy compared to traditionalultrasonics
Unique characterizing and penetration capabilities are offered through use of longer wavelengths as given by the lower frequency range
ARTTM – Acoustic Resonance Technology
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© Det Norske Veritas AS. All rights reserved Slide 327 October 2008
Acoustic Resonance Technology
Broad band, wide beam, low frequency (<2MHz) acoustic energy
Steel plateResonance modes
Transmitted andreflected energy
z1
z2
z3
22 fncd =
2ctd =
Traditional ultrasound echo method
ART method
Narrow band, narrow beam, high frequency (>2MHz) acoustic energy
12 fncd =
f1f2f f
Coating/concrete etc.
Steel
UTM ARTUTM ART
- Short wavelengths results in poor penetration.
- Increasing wavelengths enables increasing ability of penetration.
- In ART measurements, a ”footprint” of a certain area is insonified, and resonances created. The re-radiated energy spectra comprises all information of the area.
- Analysis of this resonant energy is basis for ART algorithms.
© Det Norske Veritas AS. All rights reserved Slide 427 October 2008
ARTTM – Thickness measurements
ART is capable of measuring thicknesses of solid materials, also through coating, corrosion products
marine growth etc. Pipe walls can be measured from outside or inside (pigging).
ART is capable of doing these measurements in air as well as in water/liquid
The pitting size possible to detect (area) is a function of the specific transducer system;
Increasing dynamic range results in increased capability of detecting, and measuring
small pittings
With existing laboratory equipment pitting/corrosion with diameter of about 1mm has been detected,
while pitting with diameter 4mm has been measured (pitting depth/remaining wall thickness).
Corresponding thickness resolution for steel is about 0.1mm with existing laboratory equipment.
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© Det Norske Veritas AS. All rights reserved Slide 527 October 2008
ART is very well suited for monitoring purposes with fixed sensors, since the ART algorithms are
extremely sensitive to changes in material parameters, corrosion and changes of the medium inside
the pipe (including delamination). Also each sensor could be designed to cover a relatively large area,
typically 20 – 100mm, which makes it possible to keep under surveillance large areas with a limited
number of sensors.
Examples of monitoring:
Corrosion
Delamination
Hydrate build up
Material deterioration
MEG concentration
Water ingress
ARTTM Monitoring
ART sensor system
© Det Norske Veritas AS. All rights reserved Slide 627 October 2008
ART MAIN APPLICATIONS
ART Storage Tank Scanner – In-service inspection of bottom plating through sludge
ART Riser Scanning – Inspection of neoprene / rubber coated risers in splash zone without need for coating removal
ART Freshwater piping scanner – Scanning of cast iron piping
ART Interactive 3D SW – on-line reporting
ART Hull scanning of e.g. FPSO / FSO
ART Hand held inspection tool (thickness, water in insulation, hydrate detection etc.)
ART Oil & Gas Pipeline scanning
Deepwater TLP tether / composite riser - Acoustic characterization of epoxy tether strand with embedded carbon fibres
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© Det Norske Veritas AS. All rights reserved Slide 727 October 2008
ART STORAGE TANK SCANNER
© Det Norske Veritas AS. All rights reserved Slide 827 October 2008
Acoustic positioning system
ART transducer array
ART STORAGE TANK SCANNER – system overview
Sludge
Oil
Operation container,
Zone 1
Operator Panel
Power unit Navigation
Computer
Nav. System
Amplifier
Umbilical
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© Det Norske Veritas AS. All rights reserved Slide 927 October 2008
ART STORAGE TANK SCANNER – Field test results
STATOIL KÅRSTØ FIELD TEST (SIT)SYSTEM INTEGRATION TEST
SCAN RESULTS
3D REPORTING SW
© Det Norske Veritas AS. All rights reserved Slide 1027 October 2008
ARTTM Freshwater PipescannerLicensed to Breivoll Inspection Technologies
In commercial operation since 2007
Documented capability of measuring through rust nodules & graphite
Capable of measuring thicknesses from 1.5mm and upwards
Thickness plot of a 6m pipe section
Distance plot of the same pipe section (shows rust nodules
and also the indicate how the skanner has moved through the pipe
Pitting indication plot of the same section, yellow means inside
pitting, light blue indicate outside pitting.
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© Det Norske Veritas AS. All rights reserved Slide 1127 October 2008
Acoustic transducer
Acoustic ’footprint’
ARTTM Measuring steel thicknesses through carbon-epoxycoating
Steel plate covered by a carbon-epoxy layer
(patch repaired)
Red, magenta and black line show half wave
resonances of the steel plate.
© Det Norske Veritas AS. All rights reserved Slide 1227 October 2008
Thickness measurements through 50mm, 3 layer coating
Outer: 3 layer coating 50 mm
Inner: Steel pipe, 13 mm
0 200 400 600 800 1000-4
-3
-2
-1
0
1
2
3
4
Time [uS]
Ampl
itude
[V]
Time response, shoot throug coating
160 180 200 220 240 260 280-4
-3
-2
-1
0
1
2
3
4
Time [uS]
Am
plitu
de [V
]
Time response, shoot throug coating
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© Det Norske Veritas AS. All rights reserved Slide 1327 October 2008
ARTTM – Characterization measurements
ART is capable of discriminating between media with different
acoustic impedance through a tank wall or pipe wall
Four different projects has been carried out:
1. Hydrate detection (Statoil). Field test has been carried out at Kårstø.
2. Oil detection.
3. Water ingress (Gassco). Two field tests have been carried out at Kårstø.
4. MEG detection (Statoil). The method has been qualified in the laboratory
for measuring the percentage MEG in a pipe with an accuracy of +/-2.5%
when sound velocity measurements have been combined with ART in the
range 0 – 40% MEG and with an accuracy of +/-10% if the MEG content
is higher than 40%.
© Det Norske Veritas AS. All rights reserved Slide 1427 October 2008
Water Ingress Detection Prototype
Hand-held sensor - sends and receives high frequency
acoustic signals
Electronics and Signal Processing- Analog and digital electronics achieve
high sensitivity and robustness- ARTTM signal processing compares
signal signature with reference signals
User interface- Water Ingress Detection result
displayed on PDA or laptop
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© Det Norske Veritas AS. All rights reserved Slide 1527 October 2008
ART Detection of Water Ingress in Pipe Insulation
Field tests at Kårstø- February 2008- July 2008- December 2008 (planned)
Focus of field tests- Improve sensitivity- Improve robustness- Fine-tuning of
algorithms/electronics- Human factors
© Det Norske Veritas AS. All rights reserved Slide 1627 October 2008
Field test Kårstø July 2008
Test of a variety of piping sheetings- Various diameters: 8”, 12”, 13”, 24”- Various thicknesses: sheetings with
resonance frequencies 5.5 - 6.7MHz
The majority of sheetingsencountered during test were outsidethe operating specifications of theWater Ingress Detector transducer –i.e. the sheetings were thinner thanspecifications
Nevertheless we were able to successfully detect water ingress
Evidence too that we can detectcorrosion arising from earlier water ingress
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© Det Norske Veritas AS. All rights reserved Slide 1727 October 2008
Field test Kårstø July 2008
Field test results indicate that ART is successful in detecting water ingress
Further development is underway to expand operating specifications ofthe detector to handle the majority ofsheetings found at Kårstø
”wet in places”
wet in places
12”
”dry”dry13”
Corrosion from water ingress
Corrosionon innersurface
8”
ART resultTrue stateof insulation
Sheeting
diameter
© Det Norske Veritas AS. All rights reserved Slide 1827 October 2008
DOCUMENTED PERFORMANCE:
Detects if water is present in piping insulation, and also water level through outersheathing.
If water level reaches up to inner piping, thickness of inner pipe is measured
Documented resolution for water pellet detection: >3-5mm dia. / water film thickness>0.2mm
Development of prototype system
ART successfully demonstrated in DNV laboratory on piping test pieces from Kårstø
Two field tests at Kårstø completed
Ongoing refinement of hardware/algorithms for increasing resolution
Water ingress performance
ART Water Ingress Detection
field test at Kårstø refinery
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© Det Norske Veritas AS. All rights reserved Slide 1927 October 2008