Coating Failure Analysis An overview © KTA-Tator, Inc.
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Coating Failure Coating Failure AnalysisAnalysis An overviewAn overview
© © KTA-Tator, Inc.KTA-Tator, Inc.
Coating Failure Coating Failure ConsequencesConsequences
Damage to substrateDamage to substrate
Costly reworkCostly rework
DowntimeDowntime
Product contaminationProduct contamination
Coating Failure Coating Failure Consequences : Consequences : Damage to SubstrateDamage to Substrate
Substrate repairSubstrate repair
Substrate replacement Substrate replacement
Pedestrian Pedestrian Bridge Bridge
Coating Failure Consequences:Coating Failure Consequences:Costly ReworkCostly Rework
Condition of the existing system?Condition of the existing system?
Field repairing a shop applied system Field repairing a shop applied system
Coating Failure Coating Failure Consequences: DowntimeConsequences: Downtime
Can cost more than the coating failureCan cost more than the coating failure
Examples areas where corrosion has developed Examples areas where corrosion has developed and may be difficult to address. and may be difficult to address. 5a– The surfaces above grating slots are below motor and lock pin assemblies. 5a– The surfaces above grating slots are below motor and lock pin assemblies. 5b– Grating strips and angle iron beneath sidewalk grating and curb. 5b– Grating strips and angle iron beneath sidewalk grating and curb. 5c– Corrosion above lift span girder below the steel curb over deck/sidewalk grating. 5c– Corrosion above lift span girder below the steel curb over deck/sidewalk grating. 5d- Back to back angles of a counterweight. 5d- Back to back angles of a counterweight. 5e– Rusted fasteners behind electric (latch pin) motor. 5e– Rusted fasteners behind electric (latch pin) motor. 5f– Steel above a lift span girder -the underside of various steel elements deck 5f– Steel above a lift span girder -the underside of various steel elements deck surface.surface.
SCRUB COLUMNSSCRUB COLUMNS
Coating Failure Coating Failure Consequences: Consequences: Product ContaminationProduct Contamination
Tanks, vessels, pipelinesTanks, vessels, pipelines
Product contact with disbonded coatingProduct contact with disbonded coating
Product contact with exposed substrate Product contact with exposed substrate
Coating Failure AnalysisCoating Failure Analysis
Receiving the “telephone call” Receiving the “telephone call” (Background)(Background)
Field InvestigationField Investigation
Laboratory analysisLaboratory analysis
Report and RecommendationsReport and Recommendations
BackgroundBackground
LocationLocation SubstrateSubstrate Age of Site and of CoatingAge of Site and of Coating Location,storage, or exposure of coatingLocation,storage, or exposure of coating Coating SpecificationCoating Specification Coating Product Data SheetsCoating Product Data Sheets Coating Inspection Coating Inspection
BackgroundBackground
Substrate preparationSubstrate preparation Environmental conditions during coating Environmental conditions during coating
applicationapplication Time reference between failure and Time reference between failure and
application of coatingsapplication of coatings Description of failure including any Description of failure including any
noticeable patternsnoticeable patterns
Field InvestigationField Investigation
View condition of the applied coatingsView condition of the applied coatings Investigate the nature of the failureInvestigate the nature of the failure Dry film thickness of the coatingDry film thickness of the coating Field testing of coating; physical parametersField testing of coating; physical parameters Condition of the substrateCondition of the substrate Obtain samples from “failing” areas that are Obtain samples from “failing” areas that are
representative of the failure representative of the failure
Field InvestigationField Investigation
Obtain samples from “non-failing” areas that Obtain samples from “non-failing” areas that are representativeare representative
Note any patterns Note any patterns
Laboratory Techniques Laboratory Techniques for Coatings Failure for Coatings Failure AnalysisAnalysis
Laboratory TestingLaboratory Testing Optical / Digital MicroscopyOptical / Digital Microscopy Infrared SpectroscopyInfrared Spectroscopy Gas Chromatography / Mass Spectroscopy / Gas Chromatography / Mass Spectroscopy /
PyrolysisPyrolysis High Performance Liquid ChromatographyHigh Performance Liquid Chromatography SEM / EDSSEM / EDS Atomic Absorption SpectroscopyAtomic Absorption Spectroscopy Differential Scanning CalorimetryDifferential Scanning Calorimetry Electrochemical Impedance SpectroscopyElectrochemical Impedance Spectroscopy
Optical / Digital MicroscopyOptical / Digital Microscopy
Visual examination of coating samplesVisual examination of coating samples
20X to 1000X magnification20X to 1000X magnification
Inexpensive, rapid gathering of informationInexpensive, rapid gathering of information
May change the course of a failure analysisMay change the course of a failure analysis
Cross-section Diamond Blade Cross-section Diamond Blade 50X50X
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Cross-section at Edge/CornerCross-section at Edge/Corner
Tank lining –cross-sectionTank lining –cross-section
Coating ThicknessCoating Thickness
Fourier Transform Infrared Fourier Transform Infrared Spectroscopy (the IR)Spectroscopy (the IR)
Produces a fingerprint of an individual paintProduces a fingerprint of an individual paint
Can determine if the paint specified was the Can determine if the paint specified was the
one actually applied one actually applied
How an IR WorksHow an IR Works
A spectrometer passes infrared light through A spectrometer passes infrared light through a coating samplea coating sample
Molecules absorb light at different ratesMolecules absorb light at different rates
An IR produces a spectrumAn IR produces a spectrum
Each coating type has its own spectrum Each coating type has its own spectrum
Amine Cured Epoxy Coating
Gas ChromatographyGas Chromatography
Detects the presence of solvents trapped in a Detects the presence of solvents trapped in a coatingcoating
Gas Chromatography works on the principle Gas Chromatography works on the principle of attractionof attraction
Each solvent eludes (comes out) at a Each solvent eludes (comes out) at a different rate different rate
Solvent EntrapmentSolvent Entrapment
Entrapped solvents can cause serious Entrapped solvents can cause serious problemsproblems
Solvent entrapment can be detected years Solvent entrapment can be detected years after applicationafter application
Pyrolysis / Gas Chromatography Pyrolysis / Gas Chromatography / Mass Spectroscopy/ Mass Spectroscopy
Pyrolysis- allows for vaporization of a solid Pyrolysis- allows for vaporization of a solid samplesample
Mass Spectroscopy- allows universal Mass Spectroscopy- allows universal identification of separated componentsidentification of separated components
Review-Gas Chromatography- allows for Review-Gas Chromatography- allows for separation of components within a mixture separation of components within a mixture
High Performance Liquid High Performance Liquid Chromatography (HPLC)Chromatography (HPLC)
Wide range of testingWide range of testing Employs a liquid, rather than a gas, to carry Employs a liquid, rather than a gas, to carry
a sample through the testing columnsa sample through the testing columns HPLC includes:HPLC includes:
Ion chromatographyIon chromatography Gel permeation chromatography Gel permeation chromatography
Ion ChromatographyIon Chromatography
Six salts can be identified through a single testSix salts can be identified through a single test
1.1. ChlorideChloride 4. Nitrite 4. Nitrite
2. Phosphate2. Phosphate 5. Nitrate 5. Nitrate
3. Sulfate3. Sulfate 6. Bromide 6. Bromide
Gel Permeation Gel Permeation ChromatographyChromatography
Looking for problems within a resin systemLooking for problems within a resin system
Allows separation of coating components by Allows separation of coating components by molecular weight molecular weight
SEM/EDSSEM/EDS
Uses magnification up to 5000X and beyond, Uses magnification up to 5000X and beyond, if necessaryif necessary
Examines defects in the coating surfaceExamines defects in the coating surface
Compares failing and non-failing areasCompares failing and non-failing areas
Provides Elemental Information Provides Elemental Information
SEM – EDS of Zinc Layer - Elemental Analysis of SEM – EDS of Zinc Layer - Elemental Analysis of FillerFiller
filler filler consisted consisted elementally elementally of calcium of calcium and and silicon……silicon……most likely most likely calcium calcium silicatesilicate
Differential Scanning Differential Scanning CalorimetryCalorimetry
Used to determine if a product has Used to determine if a product has properly curedproperly cured
Useful for product with high mix ratios Useful for product with high mix ratios
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Electrochemical Impedance Electrochemical Impedance SpectroscopySpectroscopy
AC (alternating current) electricity to measure AC (alternating current) electricity to measure electrical resistance (impedance)electrical resistance (impedance)
Impedance used to assess coating integrity Impedance used to assess coating integrity and to follow deteriorationand to follow deterioration
- -
Excellent
Results of Laboratory Results of Laboratory TechniquesTechniques
Optical Microscopy Starting point /Observation/ Determine Optical Microscopy Starting point /Observation/ Determine path of investigationpath of investigation
Infrared spectroscopy Resin types/mix ratiosInfrared spectroscopy Resin types/mix ratios Gas chromatography Solvent identificationGas chromatography Solvent identification Ion chromatography Salt identificationIon chromatography Salt identification GPC Separation / formulation discrepancyGPC Separation / formulation discrepancy SEM/EDS High magnification / elemental analysisSEM/EDS High magnification / elemental analysis AA spectroscopy Toxic Metals/ Environmental issues AA spectroscopy Toxic Metals/ Environmental issues DSC Degree of cure DSC Degree of cure EISEIS Barrier properties / track Barrier properties / track
degradationdegradation
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