jon r. cavallo, pe, pcs, cip level 3 senior consultant enercon services, inc. october 6, 2009nace...
DESCRIPTION
Step 1 – Define Failure The key to this step is to succinctly characterize the failure morphology of the coating system. The failure must be correctly and accurately described. The description of the failure must be made clear to others (use ASTM Standards, photos, etc.). October 6, 2009NACE Eastern Area Conference3TRANSCRIPT
Jon R. Cavallo, PE, PCS, CIP Level 3Senior Consultant
Enercon Services, Inc.
October 6, 2009 NACE Eastern Area Conference 1
Presentation ObjectivePresentation ObjectiveThis presentation outlines a structured protocol for performance of coating failure analysis.Thanks to Clive Hare for his past work
on this subject.
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Step 1 – Define FailureStep 1 – Define FailureThe key to this step is to succinctly characterize the failure morphology of the coating system.The failure must be correctly and
accurately described.The description of the failure must be
made clear to others (use ASTM Standards, photos, etc.).
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Step 2 – Interviews and Records Step 2 – Interviews and Records ExaminationExaminationTo understand the coating failure, it is
necessary to review all available records and, if possible, interview personnel who were originally involved with the selection and application of the coating system.
Interviews are particularly important where written documentation of coating work may not exist.
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Step 2 – Interviews and Records Step 2 – Interviews and Records Examination (continued)Examination (continued)Information to be assembled includes:
Product data sheets for coating materialsCoating work recordsNonconformance reportsStart and end dates of coating workTemperature, humidity and weather dataInformation from coating manufacturers
concerning formulation changes
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Step 3 – Specification ReviewStep 3 – Specification ReviewThis step involves the review of the coating material and application specifications for the coating system involved.Important – review documentation
contemporaneous with actual coating work! Coating formulations and coating application specifications change over time.
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Step 4 – Field ObservationsStep 4 – Field ObservationsThis step is the actual, close-up examination of the coating failure site(s).Carefully analyze the environment of the
failure site and determine effect on failure.Perform nondestructive and destructive
examinations as appropriate.Laboratory examinations may be required.
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Step 5 – Laboratory ExaminationsStep 5 – Laboratory ExaminationsThe laboratory techniques used are selected based upon the type of coating failure, and involve comparing selected properties of the failed coating with properly applied coating.“Failure Analysis of Paints and Coatings”
by Dwight Weldon is a good reference text.
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Step 6 – Examination of the Actual Step 6 – Examination of the Actual Coatings InvolvedCoatings InvolvedThis step is usually performed in two distinct parts:Review available data sheets and
batch tickets supplied by the coating manufacturer, and,
Review results of chemical analysis of the failed coating with chemical analysis of properly formulated, mixed and applied coating (data from Step 5).
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Step 7 – Literature SurveyStep 7 – Literature SurveyReview available technical literature to determine whether the failure being analyzed had been observed previously at the facility involved or at other facilities.
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Step 8 – The Hypothesized Failure Step 8 – The Hypothesized Failure MechanismMechanismIf possible, identify the failure mechanism(s) involved.
If not possible, postulate a failure mechanism(s) based on the results of Steps 1 through 7.
In both cases, vet your hypothesis – use independent third-party if required.
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Step 9 – Reconstruction and Step 9 – Reconstruction and TestingTestingIf necessary, prepare “bench batches” of the coatings involved in the failure and recreate the failure to validate the failure hypothesis.
This step is not always possible, usually because all variables connected with the failure may not be known.
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Questions?Questions?
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