2010-11-17

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AKUSTISK EMISSIONTILLÄMPNINGAR FÖR MONITORING AV STRUKTURER

Leif NormanPhysical Acoustics ScandinaviaGöteborg

THE COMPLETE NDT SOLUTIONS COMPANY

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ACOUSTIC EMISSION PRODUCTS FROM PAC

Boards, online, wireless, custom, OEM, I.S., portable.

ACOUSTIC EMISSION & VIBRATION ACOUSTIC EMISSION & VIBRATION ACOUSTIC EMISSION & VIBRATION ACOUSTIC EMISSION & VIBRATION MONITORINGMONITORINGMONITORINGMONITORING AND AND AND AND

ANALYSISANALYSISANALYSISANALYSIS SYSTEMSYSTEMSYSTEMSYSTEM

The Sensor Highway II is a combined Acoustic Emission (AE) and Vibration monitoring system with up to 16 high speed (for AE, Vibration) monitoring channels and up to 32 additional parametric input channels (8 high speed).

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EN CODES AND STANDARDS

� EN 473 NDT personnel qualification and certification

� EN 1330 NDT terminology (AE in EN 1330-9)

� EN 13477 AE equipment characterisation

� EN 13554 AE general principles

� EN 14585 AE metal vessel proof testing with planar location

� EN 15495 AE metal vessel proof testing with zonal location

� EN 12817 to 12820 inspection and requalification LPG tanks above/under ground and under/over 13m3

� EN 15856 General principles of AE testing for the detection of corrosion within metallic surrounding filled with liquid

� EN 15857 AE -Testing of fibre-reinforced polymers. Specific methodology and general evaluation criteria

QUALITY CONTROL

• Operator certification:• ASNT level II acoustic emission (1yr./820 hours experience, AE general

training and examination.).

• ASNT procedure specific training and examination.

• ASNT procedure specific practical training and examination (e.g. MONPAC/TANKPAC/CARP).

• ISO 9002 controls include:• Documented procedures and worksheets.

• Data digitised and stored to disc, quality plan.

• Route to Level III.

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Physical Acoustics -Written PracticeMethod of Working

• Client provides information on test object of interest on the “background information form” e.g.

– MONPAC-pressure equipment and tank walls

– TANKPAC-tank floors

– PIPEWORK, GRP and other applications

– (Plus drawings where required)

• Physical Acoustics provide method statement and commercial proposal

• If contract awarded: job is scheduled

• Quality plan used for all work

TEKNIKEN

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WHAT IS ACOUSTIC EMISSION?

� Acoustic Emissions are transient elastic waves generated by the rapid release of the energy from localized sources within a material (from ASTM E610-82)

� AE sources could be: cracks, corrosion, leaks, delamination, impact and friction.

“Acoustic emissions are transient elastic waves generated by the rapid release of energy from localized sources within a material”

Acoustic Emission from a crack

Transient wave

Crack tip

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NATURE OF ACOUSTIC EMISSION

� Active cracks generate the acoustic emission by themselves under variable stresses.

� AE wave can propagate along all directions inside the material and can be detected by AE sensors installed some distance away from the AE source.

� Sensitive to relative movement, not geometry of the defects.

� No variable stresses, then no AE.

•AE is often used as a structure screening technique.

• AE is a real time condition monitoring techniquefor active material defects.

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DETECTION OF ACOUSTIC EMISSION

� AE signals travel as sound waves like an earthquake, but at higher frequencies.

� AE signals are detected using piezoelectric sensors mounted on the equipment under test.

• P. E. resonance sensors, 60 kHz, 150, kHz, 300 kHz

• Often used frequencies: from 60 - 600 kHz, sometimes from 20 kHz up to more than 1 MHz

• Typical sensor resonance forfor a majority of applications : 150 kHz

• AE is measured over a broadband, often 100 - >600 kHz.

The Acoustic Emission sensor

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Damage Mechanism and resulting Acoustic Emission

Energy ScaleA

E s

igna

l (ab

solu

te e

nerg

y)

1010

109

108

107

106

105

104

103

102Corrosion

Metal fatigue

Stress Corrosion cracking

Composite damage

Concrete fracture

Wire breaks

- Post tensioned concrete

- Suspension bridges

Sensor HN Source

5m

TransientAcoustic Emission

ContinuousAcousticEmission

Crack growth

Dislocation,delamination

Plasticdeformation

DischargeActive corrosion

Fracture

Cavitations

Leakage

Wear,ErosionFriction

Impacts

Flow noise

Process activity

AE Signal strength

Very high

High

Medium

Low

Small

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AeCORRTM – Active Corrosion Assessment (lab.test)AE and Visual Results of Corrosion Test

A beam with 20mm cover, 35MPa, T12 rebar

Current applied Start ofcorrosion

Termination

of test

•Early stage detection and assessment ofcorrosion

•Now used on motorway bridge joints, car parks, swimming pools, columns etc

VISUAL

BREAKOUT

SENSOR

SULPHUR TANK

CORROSION UNDER INSULATION

EMISSION OVER 20 SECOND PERIOD

20 seconds

Emission Amplitude

NumberofEmissions

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SULPHUR TANK

CORROSION UNDER INSULATION

EMISSION DURING ONE HOUR

Signal amplitude in dBAE

Timeseconds

Numberofemissions

SOURCE LOCATION

� Simple Linear location

� Planar Location� Uses Triangular to

locate source

3

2

1

d1 d2

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LINEAR SOURCE LOCATION

SPHERICAL LOCATION

•AE is also used spheres in refineries

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PLANER LOCATION

THREE DIMENSIONAL LOCATION

Five sensors or more are needed to locate

Z

X

Y

2

3

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THREE DIMENSIONAL LOCATION

DETECTION RANGE

� Examples:� Pigging operation in above ground pipeline > 6 kilometres� Leak detection in above ground pipe work ~ kilometres� Wire break in suspension bridge cable >100 metres.� Active corrosion of storage tank floor >50 metres.� Corrosion spalling - off-line vessel >5m.� Fatigue cracking - live traffic box girder >5 metres.� Stress-corrosion cracking -on-line vessel >3 metres.� Active corrosion - on-line pressure vessel <1m.� Fiber cracking - GRP tank < 1 m� Matrix cracking – GRP tank > 0.5 m

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PROJEKT I NORDEN

SAAB JAS-39 GRIPEN

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PROVING AV BETONGBALK

SP projektStudier av sprickbildning med Akustisk Emission,Optisk deformationsmätning och MikroskopiArtikel i Bygg & teknik nr 7 --2010

KAISER EFFECT ON CONCRETE BEAM

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Test of Stress Corrosion Cracking- gas cooler header

ACOUSTIC EMISSION FOR IN-SERVICE DETECTION

OF STRESS CORROSION CRACKING

� Operating 0.5 bar:� AE test 0.55 bar.� design 6 bar.� Nitrogen injection during

temporary process stop.� MONPAC “E” grade on top

heads of two reactors. (five tested at same time).

� At shutdown SCC from inside, 80% through wall, confirmed. Top heads were replaced.

� Advance warning saved >$2 million production.

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GRP TANKS TESTED IN NORWAY

33

300 m3

286 m3

645 m3

ASTM E1067-07 Standard Practice for Acoustic Emission Examination of Fiberglass Reinforced Plastic Resin (FRP)Tanks/Vessels

EN 15857 AE -Testing of fiber reinforced polymers

SENSOR INSTALLATION ON GRP TANK

Test according to ASTM E1067-07

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SVETSMASKIN STRUKTUR

SSAB BORLÄNGE -- BETSTRÄCKA

Monitoring av

sprickbildning/tillväxt med

Akustisk Emission

Mätning

under belastningsökning

Monitoring i ca 6 månader från

december 2010.

SVETSMASKIN STRUKTUR

SSAB BORLÄNGE--BETSTRÄCKA

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SVETSMASKIN STRUKTUR

SSAB BORLÄNGE--BETSTRÄCKA

SVETSMASKIN STRUKTUR

SSAB BORLÄNGE--BETSTRÄCKA

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In-Service Tank TestingMaintenance Planning for Tank Farms

FLOOR: TANKPAC™ Test

SHELL: LSI (UT) Corrosion Mapping

ANNULAR RING: TALRUT™

Long Range UT Mapping.

NOTE: If All Tests Show Good condition the Period In-Service is Extended, delaying costly cleaning for internal inspection.

Naptha Tank-Before: “E” grade,

and after repair: “A” grade

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Airborne Leak Detection in RBMK reactor

• Group Distribution headers have 800 valves in each of 2 rooms at 270 deg.C high radiation.

• Special Microphones suspended from ceiling have been proven in on-line tests at temperature with a leak at 30g/sec (after 12 months operation).

• Strictly 12 microphones required per room due to high background noise levels and sound absorption by the pipe-work and structure.

Fot note: RBMK means:

Реактор Большой

Мощности Канальный

“Reaktor Bolschoj Moshnosti Kanalnij

“Reactor (of) high power

(of the) channel (type)”

MARINA TILLÄMPNINGAR

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EUROPEISKA PROJEKT

ARIANE IV SPELDA UNDER TEST

� Structure:

� Thin CFRP skin.

� Aluminium Honeycombe.

� Bonded aluminium rings.

� 4 metres diameter, 4m high.

� Low safety margin on design.

� No way to prove joint strength by NDT so:

� Static test used.

� AE monitoring for insurance.

� AE monitoring to ensure survival flight cycle.

� 30 AE sensors, PAC system.

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Methanol Converter, continuous monitoring-10 years. Protects plant.

Fourteen Heat Exchangers (bolts) nine months monitoring. Identified

problem.

Platformer, shutdown monitoring and on-line for 12 months, identified

problem.

Nuclear power Plant, eight primary circuit exchangers-permanent since

2002, one of many nuclear installations, expanded 2008.

North Sea Platform, eight critical areas, continuous AE, 7 years

monitoring, 16 x strain.

risers, bearings, leaks etc.

AE, strain, displacement, vibration,…..

Remote and Continuous Monitoring by AE

Percentage of Total AE Signal Energy Per Half Joint Location

HJ B1 (2.4%)

HJ B6 (0.2%)

HJ B7 (2.8%)

HJ E1 (67.3%)

HJ E6 (4.8%)

HJ E7 (10.6%)

HJ F6 (10.1%)

HJ F7 (1.9%)

Percentage of cumulative energy released from each half joint nib.

Concrete bridges in the UK

Half Joint Location

Suspected

Condition

B1 Good

B6 Good

B7 Good

E1 Cracked, visbly corrodedE6 CrackedE7 CrackedF6 CrackedF7 Cracked

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Suspension bridgesMain cable wire break monitoring

Humber bridge UK Severn bridge UK

Continuous Post Tension Wire Break and Structural Monitoring of the A4 Hammersmith Flyover

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A4 HAMMERSMITH WIRE BREAK & STRUCTURAL

MONITORING

Project History

Contract award Autumn 2009 PAL 8 week installed April / May 2010

PAL successfully identify TfL blind wire break test 8th June 2010

System commissioned in early June 2010 - Initial monitoring for 5 years

Project Instrumentation

301 sensor Acoustic wire break system, 128 sensor Structural Monitoring System “SMS”

3 networked Total station system with 32 prisms

West side

East side

Underneath Viaduct

Sensors mounted on box girder around bearing

Bearing Monitoring

Emission located at bearing

WEST

Bearing position

Sensor locations

at girder end

Located noise source

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AE ON LOW SPEED BEARINGS

PAL ISO test procedure- multiple rotations at test - A-E gradingsA= no activityE= intensive activity

Platformer Reactor

• 48m high, 3m diameter.

• 3 vessels “stacked” on top of each other.

• Continuous process with recycled catalyst.

• Stainless internals and lining.

• 550 degrees C operation temp.

• High thermal stress at shutdown and start-up, results in high risk of cracking.

• 64 Welded wave-guides.

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AE-Storage Spheres and Bullets• Majority tested on-line using

MONPAC™ procedure (Monsanto licence based on >1000 tests).

• Pressure raised by product or gas injection.

• Abseilers used for sensor placement.

• 97% “good” resulting in continued operation.

• >1000 tests in Europe.

• Procedure adopted by ASME for new vessels.

STAINLESS PIPEWORK

Area with no SCC Area with SCC

Linear location along 110 metres of pipe

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TACK

Frågor?