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“Maximizing cylinder life cycle”
Avoiding hydrostatic testing and operating shutdowns using Acoustic Emission Testing.
Applications on spheres and underground tanks
Mehdi BATEL, Jean-Claude LENAIN (MISTRAS Group S.A), José LOPEZ GUERRA (REPSOL) & Pedro FERES (MISTRAS South America)
XXV Congresso da AIGLP28th September 2010
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Acoustic Emission (AE) Acoustic Emission (AE) Basic Process and Basic Process and
DefinitionDefinitionAcoustic Emissions are transient elastic waves generated by the rapid release of energy from localized sources within a material
AE detects GROWING defects and
ACTIVE damage within the material under
loading (mechanical, thermal) orenvironmental conditions
Real time method
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Defect geometriesDefect geometries
Most NDT techniques are sensitive to the orientation of defects: PT, MT, ET: surface defects UT: internal defects RT: need to be focused at the location
of the crack
AE does not depend on the orientation
AE is a volumetric, global technique for a control 100%
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Acoustic Emission sourcesAcoustic Emission sources
Plastic deformation
Failure mechanisms
Phase transformation
Hydrogen embrittlement
Corrosion
Fretting
Mechanical Impacts
Leaks
Cavitation
Partial Discharges,...
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AE source localizationAE source localization
Simple linear location
Planar locationUses triangular to locate source
t1 t2
32
1
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AE analysis vs loadingAE analysis vs loading
Stable trend versus pressureStable trend versus pressure
Linear trend versus pressure Linear trend versus pressure
Critical trend versus pressureCritical trend versus pressure
DangerDanger
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Acoustic Emission summaryAcoustic Emission summary
• Growing Defects, Real Time, • Early Detection, High Sensitivity,• Global Technique (100% volumetric)• Remote Detection,• No need to remove insulation,• Location of AE Sources,• Severity Diagnosis, • In service test, periodic or continuous,• Requalification Test (Regulations)
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AFIAP Reference document in AFIAP Reference document in FranceFrance
6 different sections: SpheresSmall buried gas vesselsCylindrical pressurized equipmentsReactorsAutoclaves
Stainless steel equipments (soon)Composite materials (soon)
AE recognized by the Administration as an inspection technique and requalification method (to avoid
hydrostatic tests)
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Example of applications on Example of applications on spheres and tanksspheres and tanks
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• Mounded Tanks
• Buried Tanks
• Aerial Tanks
Typical storage vessel applications
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Volume : 600 to 6 600 m3. More than 200 spheres ( aerial, insulated, fireproofed … ) tested by AE in France
Mounded Spheres and Vessels since 1995
Development Program to apply AE in the case of mounded vessels:
Data Base : Spheres
GOAL : Agreement from the French Department of Industry to replace the hydraulic re-test for the re-qualification of the LPG pressure equipment
Procedure for permanent installation of sensors
Design of a special AE sensor R15LPG (MISTRAS)
Test Procedure, criteria
AE testing on LPG storage tanks & AE testing on LPG storage tanks & vesselsvessels
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Pressure Cycle – AE intensity
Planar Location
AE SourceAE Source
(growing (growing defect)defect)
AE sensors AE sensors networknetwork
Sensor 26
AE testing on storage spheresAE testing on storage spheres
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Time
95 % MOP
105 % MOP
110 % MOP
Pressure
100 % OP
100 % MOP
98 % Pmax
30'30'
15'
10'
10'
10'
10'
10'
Pmax : Maximum Test Pressure
MOP : Maximum Operating Pressure
OP : Operating Pressure
10'
Pmax
10'
2nd Cycle
LOADING CYCLE Test Conditions : = 95 % liquid 110 % gas operating pressure
Test Conditions : = 95 % liquid 110 % gas operating pressure
AE : Typical requalification pressure cycleAE : Typical requalification pressure cycle
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Practical ConsiderationsPractical Considerations
Cannot monitor properly when raining: Insulated equipment is not a problem. Possible delay to pressurization, or sheet in.
Safe access needed for sensor placement: Scaffold, abseiler, aerial lift.
Minimize extraneous noise sources, e.g.: flow restrictions close to vessel. throttling and non-return valves. turbulence and impacts connected to vessel,
use rubber or long pipe to any pump.
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MONPAC procedure for spheres, MONPAC procedure for spheres, bullets, columns, etcbullets, columns, etc
• Developed by Monsanto Chemical Company in late 70’s 80’s
• Field-Proven in 1000’s of tests using follow-up NDT-(Experience based)
• Procedure adopted by ASME VIII art.12 for new vessels (without ZIP grading)
• Worldwide industry acceptance– “industry standard” per Institute Chemical Eng.
Intl. process safety working group publication
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MONPAC-Outline procedureMONPAC-Outline procedure
• Asses suitability against MONPAC scope:– vessel, material, attenuation, temp., noise level
• Install and test sensors.• Monitor change in stress.• Evaluate severity of emission:
– “A” very minor source No action– “B” minor source Visual external (corrosion)– “C” source Further evaluation– “D” active source Follow-up NDT, short term– “E” intense source Immediate NDT / shut
down
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CLASSE COULEUR INTERPRETATION RECOMMANDATIONS A
Green
Very minor source No action
B
Blue Minor source Visual inspection
C
Violet
Active AE source
Mid term examination with other NDT at location or other AE test
D Yellow
Intense AE source
Mid term examination with other NDT at location or other AE test Monitoring during critical service
E
Red
Critical AE sources
Assessment or shut down Inspection with other NDT technique Shut down or monitoring
Classification of zones and AE sourcesClassification of zones and AE sources
MONPAC criteriaMONPAC criteria
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Severity Diagram of AE zones Position of AE zones
Propane Spheres 500m3Propane Spheres 500m3
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A* : Very minor Source B* : Minor Source C* : Active Source D* : Intense Source E * : Critical Source
* IPAC Severity Grade- AE Diagnosis
AE Located Sources , Zones for recommended follow up inspection
AE Severity DiagnosisAE Severity Diagnosis
NDT Results NDT Results Ultrasonic Indications
AE Zones and Sources
180 mm Planar Defect to be repaired
PipingCorrosionVolumetric Indications
AE : a GLOBAL METHODAE : a GLOBAL METHODExample of STORAGE SPHEREExample of STORAGE SPHERE
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7000 m3 propane sphere REPSOL
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AE classification (bottom)AE classification (bottom)
North Sul
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AE classification (top)AE classification (top)
North North
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MONPAC Classification MONPAC Classification (bottom)(bottom)
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MONPAC Classification (top)MONPAC Classification (top)
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Conclusions of the AE test Conclusions of the AE test reportreport
During the test monitored with AE, till the maximum pressure:
Active sources of grade B have been detected, this means , no sources compromising the structural integrity of the equipment have been found.
This way the equipment is requalified for operations.
As per results of planar location, indications of the equipment where active sources have been located, which will have to be inspected through complementary non destructive testing.
The objective of this test is to control the integrity condition of the sphere and to orientate the operations management to define the inspection plan and the periodicity of future inspections.
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MONPAC StatisticsMONPAC Statistics
• On-line testing– Spheres:97% pass on-line test, left in-service– Stainless: 50% have SCC requiring repair
• Hydrotest monitoring (indicates also manufacturing defects due to high stress)
• 66% of new vessels pass, failures due to:– Welding after stress relief– Inadequate weld pre-heat (high residual stress)– Poor welding
• 84% of vessels pass re-qualification hydrotest
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Underground tanks Underground tanks
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Volume : 32 m3Material : A48P operating: 5 bar
NATURAL GAS INPUT
Buried LPG TankBuried LPG Tank
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PRESSURE LOADING CYCLEPRESSURE LOADING CYCLE(NATURAL GAS)
OP = 5 barMOP = 6 barDP = 14 barAE MaxP = 14 bar
90% Liquid LPG
Buried LPG TankBuried LPG Tank
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Buried LPG TankBuried LPG Tank
GLOBALGLOBALEMISSIVITYEMISSIVITY
Cycle
Amplitude
Intensity
Activity
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Underground Tank 30 MUnderground Tank 30 M33
Permanent installationof AE sensors
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AFIAP – GEA – Annex 4AFIAP – GEA – Annex 4
DOMESTIC LPG VESSELSDOMESTIC LPG VESSELS
- Buried- Carbon steel (A42, A48, A52)- Volume < 12 m3
50 2 cmentre-axe
pressurisation
capteur
capot
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AFIAP – GEA – Annex 4AFIAP – GEA – Annex 4
Pressurisation
2250 mm 2250 mm
Capteurs50 ± 2cm
Maille 1 Maille 2 Maille 3
Zone couverte par la maille n°1
Zone couverte par la maille n°2
Distances maximalessource-capteur 2400 mm
Zone couverte par la maille n°3
Distances maximalessource-capteur 2400 mm
Pressurisation
2250 mm 2250 mm
Capteurs50 ± 2cm
Maille 1 Maille 2 Maille 3
Zone couverte par la maille n°1
Zone couverte par la maille n°2
Distances maximalessource-capteur 2400 mm
Zone couverte par la maille n°3
Distances maximalessource-capteur 2400 mm
Dia : 1.2 mL : 7.2 mV : 7.3 m3
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AFIAP – GEA – Annex 4AFIAP – GEA – Annex 4
Capteur instrumenté
50 ± 2 cm 50 ± 2 cm
Zones couvertes parles mailles 1 et 2
Zones couvertes par lesmailles 3 et 4
Maille 1
Maille 3 Maille 4
Maille 2
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AFIAP – GEA – Annex 4AFIAP – GEA – Annex 4
PS
EXAMPLE OF PRESSURE CYCLE
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CONCLUSIONSCONCLUSIONS
• AE is the only global NDT method to control the integrity of pressurized equipment in service
• No stop of service, no loss of product• Several thousands of structures have been
tested, and the technique is clearly mature• Acoustic Emission Testing is recognized by
the authorities in many countries to re-qualify pressure equipments