acoustic resonance

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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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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.


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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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


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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ART STORAGE TANK SCANNER


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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ART STORAGE TANK SCANNER – Field test results

STATOIL KÅRSTØ FIELD TEST (SIT)SYSTEM INTEGRATION TEST

SCAN RESULTS

3D REPORTING SW


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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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.


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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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%.


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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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


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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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


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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acoustic resonance

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