keynote battelle nestleroth onmd3012006 · pdf filedeveloping an ultrasonic sensor system for...
TRANSCRIPT
Detection Keynote:Development of an Inspection Technology For Mechanical Damage
J. Bruce NestlerothBattelle
Testing of a tool in an operating pipelineDOT / PRCIPRCIMay
2008May2006
Design of a dual magnetization tool.Technology demonstration
DOT / PRCIBattelleMar
2005Sep2003
Summary of Research for Mechanical Damage That Included Battelle
Validation of decoupling and evaluation of circumferential MFL. Nonlinear harmonics and mechanical assessment.
GTI / DOTBattelle, SwRIJun
2003May2000
Magnetic properties of pipeline steels an Dual magnetization. Non linear harmonics and neural networks.
DOTBattelle, SwRI,Iowa State
Dec 1999
Sep1996
Feasibility of MFL to better characterize mechanical damage.GRIBattelle, SwRIMay
1996Oct
1994
OutcomesSponsorContractor(s)EndStart
Technology transferGTITuboscopeSep2003
Sep2001
Non Linear Harmonics (NLH)
• Developed by Southwest Research Institute SwRI®
• An electronic method for detecting surface stress/strain patterns
• Uses an alternating magnetic field (10kHz), making it sensitive to only surface strain changes
• Examines only a small area, requiring multiple sensors for complete coverage of pipe surface
• A current SwRI project with DOT is evaluating the ability of NLH to monitor changes in gouged dents as they are cyclically loaded to failure.
NLH signals reveal defect stress patterns on pipe inner surface
Defect stress pattern from FEA
Finite element stressanalysis confirms NLHsignals relate to stress
intense stress
intense signalNLH data from pressurized scan
Data Provided by SwRI
Technology demonstration at the Pipeline Simulation Facility
• DOT PHMSA and DOE NETL have conducted Technology Demonstrations in Sept 2004 and Jan 2006 examining:– Corrosion sensorsfor crawlers (3)– SCC (1) – MechanicalDamage (2)– Plastic pipe
• Blind tests• Industry observers
24” diameter mechanical
damagesamples
8” diameter corrosion samples
26”diameterSCC test samples
6”diameterplasticpipe
sample
Ultrasonic strain measurementsusing EMATs
• Pacific Northwest National Laboratory (PNNL) is developing an ultrasonic sensor system for detecting and characterizing pipeline stress and strain caused by denting and other deformation
• Ranks the severity of smooth dents based on ultrasonic measurements of the mechanical properties and the presence of plastic strain, rather than dent dimensions or wall thickness
• Strain is measurable for uniaxial deformation• Developing predictions of effective strain when the
damage is more complex than a simple uniaxialdeformation on deformed pipe
PNNL Ultrasonic strain measurements vs. effective strain from dimensional measurementsof deformed pipe
0%
1%
2%
3%
4%
5%
6%
7%
0% 1% 2% 3% 4% 5% 6% 7%Effective Strain (thickness ( L/L0 ) (%)
Ultr
ason
ic S
trai
n M
easu
rem
ent
(%)
EMAT Sensor
Motor for sensor rotation
Springs for smooth motion past dents
Dual Magnetization MFL Inspection for Mechanical Damage
• Inspection Goal:–Increase the probability of obtaining a measurable
signal from significant mechanical damage and properly differentiates these signals from other "anomalous" signals
–Function reliably under pipeline conditions
• Dual magnetization MFL technology–Can detect magnetic property variations due to
stress associated with dents and gouges–Is an extension of the most successfully used
pipeline inspection technology
Initial Result: Low magnetic fields are sensitive to stress and cold work
Magnetizing Field (H)
Mag
netiz
atio
n
Saturation, Ms
No Residual Stress
Compressive Residual StressPerpendicular to H-Field
-8 -6 -4 -2 0 2 4 6 8
Axi
al M
FL S
igna
l (G
auss
)
Distance (Inches)
-8 -6 -4 -2 0 2 4 6 8
Axi
al M
FL S
igna
l (G
auss
)
Distance (Inches)
9080
60
50
4030
70
70 Oersteds
110 Oersteds130120
100
90
80
110
70
Nominal MFL Tools
High Fields Mask Damage
Medium Fields Show Damage
Mechanical Damage MFL Tools
Data from the GRI Mechanical Damage Program
Dual Magnetization Approach
Dual magnetization level signal processing (decoupling)
1. MFL signals at high magnetization levels are almost entirely due to geometry changes (corrosion and removed metal)
2. MFL signals at low levels are due to both geometry and magnetic changes
3. The difference is due to magnetic changes - the most important components of mechanical damage
Extracting the Magnetic Component: Decoupling
Low MagnetizationSignal
Scaled Geometric Signal
SCALING FACTOR (SF)
MFL Signal due to Magnetic Changes
Only
High Magnetization Signal
Decoupling ExampleH
igh
Mag
netiz
atio
n
Low
Mag
netiz
atio
n
Dec
oupl
ed
ReroundHalo
Gouge Signal
• Extra metal near mechanical damage • A geometric change• Decoupling theory says that geometric changes cancel.
Concrete pier withConcrete pier withsteel plate on topsteel plate on top
Mechanical DamageMechanical DamageDefectsDefects
Demonstration that decoupling worksH
igh
Mag
netiz
atio
n
Low
Mag
netiz
atio
n
Mechanical Damage Revealed!!!
Dec
oupl
ed
ReroundHalo
Gouge Signal
Decoupling method was tested in a variety of pipe materials
High
Low Decoupled
The Most Recent Project:Design of a dual magnetization tool
• Prior projects established:– Theory– Signal processing– Functional in
pipeline materials
• Built and tested a prototype tool at the pipeline simulation facility
NSN
BrushesNS
Magnetic NullPivot point
-200
-150
-100
-50
0
50
100
-20 -15 -10 -5 0 5 10 15 20Axial Position (inches)
Mag
netiz
ing
Fiel
d (O
erst
ed)
HighLow
• Magnet bar split at the null point with a ball joint coupling for passing pipeline bends.
Articulating magnet bar
Prototype tool built and tested atBattelle’s Pipeline Simulation Facility
Dual Magnetization Summary
• Deformation tools have been used to assess dents in pipelines for years.
• Some newer commercial MFL tools incorporate deformation sensors to identify dents with missing metal.
• The dual field approach has the potential to augment current MFL technology to identify and provide additional information on dents that are the result of third party excavation.– The dual field method exposes areas of stress, re-
rounding and cold work.– In particular, the decoupled signal can expose a region of
cold work where the ductility of the steel has been exhausted and the re-rounding of the dent applies a tensile load to the anomaly.
Future project
• A PRCI project has been recommended for a DOT PHMSA award to start gaining field experience
• Pigging vendor will build a dual magnetization tool for use on an operating pipeline
• Pipelines have been designated for evaluation of dual magnetization technology
• Single magnetization MFL technology will be evaluated