Coating Failure Coating Failure AnalysisAnalysis An overviewAn overview

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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