secondary surface preparation - montipower · date/reference/classification 24 acknowledgements . ....
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Date/reference/classification
Secondary Surface Preparation
Mark Lydon & Byron Williams
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Date/reference/classification 2
Secondary Surface Preparation
Secondary preparation used to prepare small areas of steel prior to the application of
coatings
Plethora of available techniques, range of preparation standards
Survey techniques to assess which is most suitable for use with performance coatings
exposed in a simulated aggressive environment
Measuring profiles produced on ground and polished steel panels
Corrosion testing of painted test panels
Influence of substrate properties on tool life
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Experimental procedure
Sa 2 ½ blast using G17/G24 chilled iron, 50-75mm profile – reference
2o Preparation Methods
Needle gun (Jasons pistol)
P60 emery hand preparation
Monti MBX bristle blaster
Ibix mini-blaster
Perago
P36 cubitron disc on grinder (used flat and with cross-hatch pattern)
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Experimental procedure
Measuring profiles using SEM generated 3d maps
Samples ground and polished flat prior to preparation
‘Background roughness’ <5mm
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3d surface map
Video
Insert your video here.
Make as large within boundaries
as your system performance will allow
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2d Line Profiles – from surface map (G17/G24 grit blast)
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Profile 1
Profile 5
Profile 9
Profile 10
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Experimental procedure
Measuring profiles using SEM generated 3d maps
Samples ground and polished flat prior to preparation
‘Background roughness’ <5mm
3d surface maps using SEM in backscatter
Generate line profiles from surface map
Estimate profile heights from 2d line profile and visual cue
Corrosion testing . . . . . . . . .
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Experimental procedure:- corrosion testing
Flat mild steel panels 3 x 100 x 200mm, taped around edges and “St Andrews cross”
prepared defect – painted with 2 pack epoxy barrier system
Sa 2 ½ blast prepared panels used as reference (G17 / G24 grit working mix, 50-75mm
profile)
Samples submitted in triplicate for
ASTM B117 salt spray (1000 hours)
BS3900 part F4 cyclic humidity testing (1000 hours)
Assessed iaw BS EN ISO 4628-8:2005
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Results:- SEM micrographs UTS 550 Steel
Blast (ref)
Bristle blaster
Hand prep
Needle gun (mild steel)
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Results:- SEM micrographs UTS 550 Steel
Ibix blaster
Grinder used flat
Perago
Grinder x-hatch pattern
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Date/reference/classification 11
Results:- SEM micrographs
Grinder x-hatch pattern – SE image showing ‘layered’ effect of repeated passes with grinder
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Results:- profile measurements from 3d surface map
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Grinder Cross-Hatch Pattern
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Results:- profile measurement on UTS 600
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Worn 1
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New 1
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Results:- correct use of MBX BB
Correctly used BB
Effect of repeated passes
Correctly used BB on UTS 600
Following preparation of
~0.5m2
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Results:- profile measurements from 3d surface map
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Hand Preparation
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Profile 2
Profile 3
Profile 6
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Date/reference/classification 16
Results:- profile measurements, comparative
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Profile Comparison, UTS 550 Steel
Perago
Hand Prep
Needle Gun
Grinder Flat
Clemco Blaster
Grinder x-hatch
Bristle Blaster
Grit Blast (Ref)
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Date/reference/classification 17
Profile measurements . . . .
SEM technique in good agreement with conformal tape measurements
Two techniques give profiles similar in complexity and depth to blast
reference
Majority of prep methods produce shallow / regular profiles
Conformal tape alone not suitable for assessing mechanical preparation
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Date/reference/classification 18
Results:- salt spray testing
Cubitron abrasive disc used to produce x-hatch pattern – 1000 hours B117 salt spray
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Date/reference/classification 19
Results:- salt spray testing
Cubitron abrasive disc used flat – 1000 hours B117 salt spray
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Date/reference/classification 20
Results:- BS3900 Cyclic humidity
Grinder x-hatch
Hand prep (P60) Bristle blaster
Grinder flat
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Date/reference/classification 21
Results:- corrosion testing, obs. 1000 hour salt spray
Preparation Method
Corroded area* Delamination
c-mm d-mm
Grinder x-hatch 0.6 0.4
Bristle Blaster 0.4 5.4
Clemco blaster 1 7.9
Needle gun 0.4 9.9
Grinder flat 0.8 Complete delamination
Hand abrade 1 Complete delamination
* Mean value measured from scribe mark
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Date/reference/classification 22
Results:- corrosion testing, summary
Test data are unequivocal and show very clear differences between techniques
Corrosion test data indicate that majority of secondary techniques assessed are
unsuitable either for wet or (nominally) dry spaces
Both Monti MBX bristle blaster and x-hatch grind pattern give comparable results with
blast reference in both test environments considered
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Date/reference/classification 23
Reliability and repeatability. . . . . . . ?
Preparation carried out by SQEP’d operators / downhand / lab etc
Results represent the best that can be achieved
Effective tool life dependent on material properties
Effective preparation dependent on operator
6 P rule – training and education?
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Date/reference/classification 24
Acknowledgements . . . .
Jamie Gallagher / Cactus Industrial
Marine Painting Forum
BAE Systems Marine
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