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Transcript of Stress Corrosion Cracking Test Pieces for Inspection ... · Magnetic particle (MPI) Eddy current...
The Centre, Birchwood Park, WarringtonWednesday 17th April 2013
David Ludlow, AMECBINDT & ICORR Symposium on Inspection and Monitoring Techniques to Manage the Corrosion of Valuable Assets
Stress Corrosion Cracking Test Pieces for Inspection Qualification and NDT Development
2
Overview
What do we doStress corrosion cracking (SCC)InspectionNDT test piecesMISTIQ SCC test piecesNDT developmentsCase studyFuture developmentsConclusions
3
AMEC NDT Inspection Capability
Concept Development
Plant Implementation
Design
Problem Understanding
Inspection Techniques
Rigs and Test Pieces
Deployment
Training
Inspection Specification
Reliability Testing
Qualification Strategy
Procedure Development Data Analysis
Inspection AuditHuman Factors
Human Factors
Research
Modelling and Simulation
Training Audit
Monitoring & Inspection DesignInspection ValidationCentre
Independent Qualification Body
Qualification Consultancy
Technical Justifications
Site Support
Technology Transfer
4
Why Inspect?
Plant Failures:Flixborough explosion – SCC of chemical reactor, UK 1974Bhopal accident, India 1984Swiss swimming pool collapse caused by SCC, 1985Carlsbad pipeline explosion, New Mexico, 2000 El Al Boeing 747 crash caused by SCC, Amsterdam 1992
SCC is major degradation mechanism & difficult to
detect
6
SCC Initiation & Growth
Schematic diagram showing SCC initiation and growth(Ref. R. Staehle, “Predicting the SCC of Reactor Components from First Principles”, EUROCORR, 2009, Nice, France, Acropolis Palais de Congress, 6-10 September, 2009)
7
SCC 2-D Morphology
TGSCCChloride SCC in 304L ASS
Ref. Colorado Metallurgical Services
IGSCCLeft Ref. NACE (Inconel heat exchanger)
Right Ref. Okamura, Japan NPP
8
SCC 2-D Morphology
SKI Report 2006:24 Crack Characterisation for In-service Inspection Planning
Nearly 100 SCC defects characterised from plant, 77% IGSCC
10
Inspection
Asset ManagementPeriodic NDT during outageRisk based approach (RBI)NDT needs careful design
TechniqueEquipmentPersonnel
Design needs validationFormal Qualification
Holy Grail
Universal Technique
No Operational Interference
Early Warning
Future
Structural Health Monitoring
Now?
Targeted Online Monitoring
11
NDT Techniques
SCC SurfaceVisual Liquid dye penetrant (LPI)Magnetic particle (MPI)Eddy current (ECT)Electro-magnetic
VolumetricUltrasonicsRadiographyAcoustic emission
12
NDT Test Piece Development
Representative test pieces
–Material, geometry, defectsCrack defects
–EDM notches, fatigue cracks (smooth defects)
E.g. UT response weaker for SCC compared to fatigue cracks leading to SCC defects being missed / unreported during plant inspections
Requirement for realistic SCC defects
(rough defects)
13
AMEC MISTIQ SCC Process
Need for IGSCC in Inconel alloysControl over crack length & depthAccelerated processStainless steels & DM weldsStandard plate specimensBespoke specimensDedicated rigsFE analysis support
15
NDT Developments using SCC Test Pieces
Online data collectionGates & alarmsSignal processingEnhanced visual displayData analysisPhased array
– Total focussing method (TFM)
– Full matrix capture (FMC)
16
UT Online Monitoring
Pulse echo– SCC initiation – First stages of
growth
Time of flight diffraction (TOFD)
– SCC crack depth
19
Enhanced Visual Display
A-scan from Marker
3-D View Control
Rotatable
3-D View
Slider to Move
A-scan Marker
Prototype UT software with enhanced visualisation
20
UT Phased Array
Phased array TFM image superimposed on
MISTIQ SCC
(grade 304 plate)
FMC is data collection for every transmit-
receive combination.
21
Case Study
Objective– To deliver large DM weld
SCC specimen to Japan for round robin trials
Challenges–Largest SCC bespoke
specimen –DM weld composition–Rig design & loading
conditions–NDT–Delivery schedule–SCC target: 20mm wide &
20mm deep
22
Case Study
Weld metal trialsLoading conditions: FE analysisNDT
–UT specialised probes–DPI
Destructive Examination
Ref. E.Journal of Advanced Manufacturing, Vol.3 No.3 NT40 & Vol.2 No.2 NT24
162116232232729271
Depth mm
Lengthmm
Depth mm
Lengthmm
Specimen
Destructive Examination
NDT
weld
carbon steelstainless steel (304)
cladding
weld
carbon steelstainless steel (304)
cladding
23
Future Developments
SCC in ferritic steels & Al alloysTGSCC NDT specimensComplicated geometries e.g. full pipe sectionsDegradation mechanisms – pitting, general corrosionThermal fatigue & H cracking specimens
24
Conclusions
There is a real need for realistic SCC specimens to improve inspection systems for SCC detection & sizing
AMEC MISTIQ SCC test pieces offer a step improvement over conventional test pieces for SCC inspections
–Widely used in qualified inspections for NPP
Targeted NDT techniques can be adapted for online condition monitoring
25
Questions?
AcknowledgementsBINDT & ICORR
AMEC – Nick Smart, Bernard McGrath & MID Team
Contact:David LudlowT: 01925 254914E: [email protected]
AMEC Clean Energy- EuropeWalton House, Birchwood,Warrington, Cheshire, WA3 6GA