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Fredrik Hagglund Channa Nageswaran Lu Zhao John Rudlin
Enhanced Inspection Capability for Specific Applications using phased array ultrasonics
Malaysia NDT Conference November 2015
Malaysia International NDT Conference & Exhibition 2015 (MINDTCE-15), Nov 22-24 - www.ndt.net/app.MINDTCE-15
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Plastic Pipe Weld Inspection
Weld Overlay cladding
Fatigue Crack monitoring
Aluminothermic rail weld inspection
Content
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>50% of gas distribution pipes in the US are made out of plastic
Failures can occur Improper welding
procedure
Poor workmanship
Contamination
Need for an NDT system
NDT of Plastic Pipe Joints
Plastics are increasingly being used in nuclear and utility sectors
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NDT of Plastic Pipe Joints
Flaws in PE pipe joints Joint misalignment
Axial/angular
Poor pipe preparation Uneven planing Poor/no scraping
Discrete planar flaws Fingerprints Oil/grease Rain droplets
Particulates Airborne dust Dirt/sand
Pipe under-penetration Cold fusions
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NDT of Plastic Pipe Joints
Phased Array Ultrasonic Testing of plastic PE joints
TWI’s PolyTest system
Full volumetric inspection
EF and BF joints
Thicknesses 8-65mm
OD 90-1000mm
Manufacturing or in-service
Locating/ sizing/
characterising defects
Validated through
mechanical testing
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NDT of Plastic Pipe Joints
Completed inspections for different industries across the world 30 days in South East Asia (270
joints in a 4km water pipeline) 20 days in the UK (130 joints in
fabricated pipework for water transportation)
10 days in Italy (50 joints for gas pipelines)
Good correlation with sectioned samples and mechanical tests
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Clad systems of interest:
Nickel Alloy 625 on X65 pipe
Stainless steel 316L on vessel steel
Inspection methods of interest:
PAUT
EMATs
(ET and DPI)
Flaw types of interest:
Fabrication – stop/start, dis-bonds, inclusions
Service - stress corrosion cracking
Weld Overlay Cladding and inspection issues
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Scattering, bending attenuation and reflection from coarse grains makes UT inspection difficult
Conventional UT inspection can be successful
using conventional shear wave probes with low frequencies
Compression wave probes can also show some improvements
TRL probes also assist with reduction of scattered reflections.
However sometimes these methods fail and further enhancement is needed
Weld Overlay Cladding
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Improved interpretation using commercial PA probes
Multiple PA probes to add information
Dual matrix array probes (Olympus) to improve focussing flexibility of TRL type probe
Improving techniques by modelling the grain structure and wave propagation through it
Improvements with PA
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Intermediate inspection of root and the hot pass in a Duplex 2209 girth weld with a metallurgical 316 SS cladding
Analysis of the microstructure indicated that conventional shear wave inspection was theoretically possible – according to the simple model presented earlier and on the analysis of the key parameters:
grain size vs. wavelength.
A case study
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Results verified by sectioning: root flaws
Through-wall sizing is possible …. in some cases
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Composite PAUT tool
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1mm FBH, 1mm through-wall
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Area with no known flaws (1)
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Signal-to-noise – how to optimise for a particular cladding system
Improve the confidence of the operator – training
Qualify statistically to establish PoD/PoR
TWI is active on three technology fronts
How to screen rapidly over large surface areas using automation during fabrication / installation
In-service application on pipelines and vessels (NII)
Model the cladding in order to help optimise the ultrasonic techniques
Influence welding in order to get the cladding suitable for inspection
Group 1 Group 2 Group 3
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TWI has been contracted by the Pipeline Research Council International (PRCI) to perform R&D in welding, fatigue failure and inspection of weld overlay cladding
Two phases have been completed to date, third phase will start in summer of 2015 focused on systematic qualification of the composite PAUT tool.
For further information please contact Max Toch ([email protected])
Work on finite element modelling of wave propagation in austenitic weld structure and its validation is ongoing in a TWI Core Research Project expected to end in late 2015 with submission of a report which will be available to Members in early 2016
Work on SCC in SS weld overlay cladding is part of an ongoing TWI Core Research Project expected to end in late 2015 with submission of a report which will be available to Members in early 2016
Current Projects
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Illustrates:
Real time imaging of a growing crack
Use of post-processed imaging methods (FMC/TFM)
Measuring the size – Engineering Critical Assessment
Instrumentation:
M2M GEKKO using real time FMC/TFM
Olympus 10MHz 32 element linear array probe
Component:
Standard notched specimen in carbon steel
Laboratory based fatigue testing machine
Fatigue Crack Monitoring
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Array ultrasonic concepts required
Focusing is essential to detect crack tip
Steering for coping with changing geometry and manipulating incidence angles
Electronic skewing using 2D arrays
Information presented here make use of commercially available probes, instrumentation and software
Ongoing developments are pushing boundaries of existing systems, leading to custom development of software in particular
Designing ultrasonic techniques
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The setup
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Processing the data in CIVA
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da/dt towards Paris’ Law
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Aluminothermic Welds in the Railway Industry
The majority of field welding is carried out using aluminothermic welding. This casting method is :
widely used for in-track welding during re-rail and defect replacement
an effective, highly mobile and cost effective
In the UK :
65,000 new welds per year produced by Network Rail and up to 2% rejection rate
1.5 million welds already on the main line railways
In Europe:
300,000 to 400,000 new welds made per year
11 million welds estimated to be on track
20% of all rail failures estimated to be caused
by weld failures
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Welding Defects
The most common volumetric defects for AT welding are:
These defects can cause welds to fail in months rather than years resulting in risk to safe operation and track closures for repairs
Porosity Shrinkage Lack of fusion
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Inspection Technique
Phased array techniques
To steer, focus and scan beams with a single transducer assembly, 32:128 multiplex
Focal laws were developed via modelling and trials
Hardware consists of :
8 phased array probes
Cables and connector box
Computerised instrument for data acquisition and display
Clamp on device, Railect system
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Deployment of Railect System
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Inspection of the Ankle of the Rail Foot
3 mm notch
2 mm
SDHs
Transducer and focal laws parameters: • 16 elements • 5 MHz • Sectorial scan 55- 75 • Step 0.5 degree
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Contacts
Plastic Pipe Weld Inspection [email protected]
Weld Overlay and
Fatigue Cracks-
Alumino-thermic welds-