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Quality Control of Industrial Painting Operations William D. Corbett KTA-Tator, Inc.

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Presentation on theme: "Quality Control of Industrial Painting Operations William D. Corbett KTA-Tator, Inc."— Presentation transcript:

1 Quality Control of Industrial Painting Operations William D. Corbett KTA-Tator, Inc.

2 Webinar Content Industry standards for coating application QC Developing a quality control plan for painting Navigating a Technical (Product) Data Sheet Measuring ambient conditions and surface temperature Witnessing mixing, thinning and application procedures Calculation and measurement of wet film thickness Dry film thickness measurement Post-application testing Cure/hardness Holiday/pinhole detection Adhesion Identifying application defects

3 Learning Objectives/Outcomes Completion of this webinar will enable the participant to: Describe the industry standards that pertain to coating application Prepare a Quality Control Plan for painting Describe the content of a Technical (Product) Data Sheet Measure environmental conditions and surface temperature prior to coating mixing Evaluate mixing, thinning and application procedures Calculate and measure wet film thickness Measure dry film thickness Perform post-application testing

4 Industry Standards for Coating Application SSPC-PA 1 Shop, Field and Maintenance Painting of Steel SSPC-PA 2 (frequency and tolerance of coating thickness measurements on steel) SSPC-PA 9 (frequency and tolerance of coating thickness measurements on concrete) ASTM E337 (use of whirling/aspirating psychrometers) ASTM D4414 (wet film thickness measurement) ASTM D7091/D6132 (dry film thickness measurement) ASTM D5402/D4752/D3363/D1640 (drying, curing, hardness) ASTM D5162/D4787 (holiday/pinhole detection) ASTM D3359/D6677/D4541/D7234 (adhesion)

5 SSPC Paint Application Specification No. 1 (PA 1) Shop, Field and Maintenance Painting of Steel Common specification reference Contains 14 Sections: 1.Scope 8. Shop Coating 2.Description 9. Field Coating 3.Referenced Standards 10. Repair of Damaged Coatings 4.Definitions 11. Appl. Proc. For Coatings 5.Pre-application Procedures 12. Curing & Handling 6.Factors Affecting Application 13. Inspection 7.Application Methods 14. Safety & Environmental

6 Purpose of a Quality Control Plan Provides QC Inspector with: A systematic inspection and testing plan that covers all phases of work in sequence A written document that lists what to inspect, how to inspect and the acceptance criteria A tool to enable an inspector to navigate through and extract inspection check points from the specification May be a required contract submittal

7 Benefits of a Quality Control Plan Coating specifications can be complex documents Specifications typically contain the quality requirements for a coatings project Good inspection doesnt happen by accident; it requires planning QC plans make specification compliance more streamlined and complete Provides a key communication tool between QA and QC inspection personnel

8 Inspection Item Technique/ Instrument Frequency of Tests Standard Test Method Reference Spec. Reference (mock) Acceptance Criteria (mock) Verify ambient conditions Electronic psychrometer Before mixing and every 4 hours; changing conditions SSPC-PA Air: °F Surface: °F RH: <85% ST > 5°F DP Verify installation of protective coverings VisualPrior to primer application SSPC-PA Properly installed & maintained Dry Film Thickness of Primer Calibrated Type 2 gage verified for accuracy Area coated during the previous work shift, per SSPC PA2 ASTM D 7091 SSPC-PA mils Holiday Detection Low voltage wet sponge detector After topcoat application ASTM D No pinholes or holidays Sample Quality Control Plan

9 Product Data Sheets Prepared by the coating manufacturer An instruction manual for the coating Technical & marketing information about the coating ASTM F 718 provides a standard specification for marine paints

10 Product Data Sheets, cont. Typically contain: Brand name of the product Generic type of the coating When/where the coating can be used Compatible coatings Product weight and volume solids content Theoretical coverage rate

11 Product Data Sheets, cont. Often contain: Recommended level(s) of surface preparation Recommended dry film thickness VOC content of the coating (as manufactured) Adjusted VOC content dependant on amount and type of thinner Performance data (adhesion, abrasion resistance, etc.) Recommended methods of application Mixing and thinning instructions Pot life, induction time Drying times (dry to handle, dry to recoat) Cure times Recoat times Method to verify cure

12 Product Data Sheets Vs. Specification Requirements Product data sheets contain recommendations When the PDS and the project specification differ, the specification is the governing document (contract) The specification may invoke the PDS QC inspector should note discrepancies/vague information and advise the owner at the bidding stage and at the pre-job meeting

13 Environmental Conditions for Coating Application Air Temperature (min. & max.) Relative Humidity (min. or max) Dew Point Temperature Surface Temperature [min. 5 °F (3°C)] above Dew Point Temperature Wind Speed (max.)

14 Significance of Conditions Air Temperature Too cold or too hot can affect coating application & curing Relative Humidity Too damp or too dry can affect coating application & curing Surface Temperature Too cold or too hot can affect application & curing Surface temperature at or below dew point temperature will result in condensation

15 Significance of Conditions, cont. Wind Speed Too windy can affect application (dry spray) and cause overspray damage Mixing/application of coatings under adverse weather conditions can void the manufacturers warranty and is considered a specification non- conformance

16 Ambient Conditions & Surface Temperature Measuring Instruments Sling Psychrometers* Battery-powered Psychrometers* Electronic Psychrometers Analog, Thermocouple- type & Non-contact Surface Thermometers * Used in conjunction with psychrometric charts or calculators

17 Sling Psychrometer

18 Using Sling Psychrometers ASTM E337 Verify wick cleanliness Saturate wick and/or fill reservoir with DI water Whirl second intervals until wet bulb stabilizes (2 readings within 0.5 o ) Record wet & dry bulb temperatures

19 Using Psychrometric Charts Locate Chart (relative humidity or dew point) Verify Barometric Pressure (e.g., 30.0 in.) Intersect air temperature with wet bulb depression (T a -T w ) Calculators (bottom image) can also be used

20 Electronic Psychrometers Measure/Record: Air Temperature Surface Temperature (ST) Relative Humidity Dew Point Temperature (DP) Spread between DP and ST Features Auto-logging allows for automatic data collection Magnetic surface probe Data graphing and Blue Tooth uploading Audio/visual alarm

21 Measuring Surface Temperature Dial-Type Thermometer Position & stabilize for minimum of 2 minutes Thermocouple-Type Thermometers Stabilize quickly Infrared (non-contact) thermometers Watch distance

22 Assessing Wind Speed Analog wind meters Digital wind meters Rotating Vane Anemometers Air flow inside containment Wind speed

23 Documenting Ambient Conditions and Surface Temperature ConditionData Date2/15/12 Time 0900 hours Dry Bulb Temperature (DB) 16 o C (60 o F) Wet Bulb Temperature (WB) 13 o C (55 o F) Depression (DB-WB) 3 o C (5 o F) Relative Humidity 73% Dew Point Temperature 11 o C (51 o F) Surface Temperature 15 o C (59 o F) Wind Speed 11 km/Hr (7 mph) Measurement Location West side of tank, ground level

24 Significance of 5°F (3°C) Theoretically, a small (<1°F) increase (surface temperature over dew point) will preclude moisture formation Minimum increase of 5°F (3°C) compensates for: Instrument tolerances Varying conditions Changing conditions

25 Location and Frequency of Data Acquisition Location Dictated by where the work is being performed (e.g., inside vs. outside of a containment; balcony of elevated storage tank vs. ground level) If interior, with ventilation in operation Shops: Blast or Paint bay area Frequency Prior to mixing of coatings Four-hour data collection intervals is common More frequent measurement if conditions are changing

26 Inspecting Mixing Procedures 1.Verify components are within the manufacturers shelf life (and stored properly) 2.Check PDS for mixing instructions 3.Measure coating temperature after all components are thoroughly blended 4.Straining required? 5.Thinning required/allowed? 6.Induction time required? 7.Pot life monitoring

27 Inspecting Thinning Procedures Verify: Correct type of thinner is used Calculation of thinner quantity is accurate Graduated containers are used to measure thinner Consider impact on local VOC regulations

28 Calculating the Target Wet Film Thickness Sometimes the wet film thickness will be listed on the PDS (many times it is not) Arriving at the target wet film thickness is necessary to arrive at the specified dry film thickness Must be adjusted based on the amount of thinner added

29 Calculating a Target Wet Film Thickness Calculating Target Wet Film Thickness WFT = Target DFT % solids by volume Example:5 mils DFT 68% solids by volume (0.68) Target wet film thickness: 7-8 mils

30 Calculating a Target Wet Film Thickness Effect of Thinner Addition on WFT Target WFT = Target DFT % solids by volume 100% + % thinner

31 Calculating a Target Wet Film Thickness Effect of Thinner Addition, continued WFT = 5 mils DFT % + 20% thinner 5 mils DFT 68 = 0.57= 9 mils WFT 120

32 Measuring Wet Film Thickness ASTM D 4414 – Practice for Measurement of Wet Film Thickness by Notch Gages Place gage into wet coating immediately Withdraw gage and read highest wetted step (e.g., 5 mils) Immediately clean coating from gage

33 Measuring Dry Film Thickness Three common standards that address the nondestructive measurement of coating thickness : Ferrous and nonferrous metals: ASTM D 7091 Steel only: SSPC-PA 2 (2004) 2012 version will address ferrous and nonferrous metals Non-metal surfaces ASTM D 6132 SSPC-PA 9

34 Measuring Dry Film Thickness Standards provide procedures for: Calibration (gage manufacturer/approved lab) Frequency of verifying gage accuracy (user) Frequency of measurements (number of measurements to obtain based on the size of the structure) SSPC-PA 2 places limits on spot and area readings vs. specified thickness

35 Measuring Dry Film Thickness (SSPC-PA 2) Requires calibration by manufacturer (typically annual) Certificate of calibration traceable to a National Metrology Institute required Verification of accuracy (by user) before and after each period of use Two types of nondestructive coating thickness gages Magnetic pull-off (Type 1) Electronic (Type 2)

36 Verifying Type 1 Gage Accuracy Use calibration blocks NIST Traceable Proprietary from gage manufacturers Verify accuracy: In range of use Before and after each period of use Must correct for surface roughness (BMR)

37 Verifying Type 2 Gage Accuracy Use calibration blocks or shims Verify accuracy in range of use Most can be adjusted Follow gage manufacturers instructions (vary)

38 Verification of Type 2 Gage Accuracy If smooth reference standards are used (A), user must correct* for surface roughness If shims (foils) are used (over the prepared steel; B), no correction is needed *Via Base Metal Reading (BMR) AB

39 Measurement Frequency Terminology: Gage Reading: A single reading at one location Spot Measurement: The average of at least 3 gage readings made within a 1.5 diameter circle Area Measurement: The average of 5 spot measurements made within a 100 square foot area

40 Measurement Frequency

41 Dividing Structures into Test Areas If the structure is less than 300 square feet, each 100 square feet is measured If the structure is between 300 and 1000 square feet, select 3 random 100 square foot test areas and measure For structures exceeding 1000 square feet, select 3 random 100 square feet testing areas for the first 1000 square feet, and select 1 random 100 square foot testing area for each additional 1000 square feet

42 Example: Structure Size:55,000 square feet No. of Areas: = 57 areas No. of Spots:57 Areas x 5 Spots/Area = 285 Spots No. of Gage Readings:285 Spots x 3 Readings/Spot = 855 Gage Readings

43 Coating Thickness Tolerance (SSPC-PA 2) Individual readings (averaged to create a spot measurement) are unrestricted Non-repeating low or high readings can be discarded The spot measurement (the average of 3) must be within 80% of the minimum thickness and 120% of the maximum Area measurement must be within specified range

44 Assessing Intercoat Cleanliness Airborne dust and/or abrasive may be deposited on coated surfaces Problematic if surface is to be recoated Requires visual or tactical (touch) examination of the surface

45 Verifying Recoat Times and Temperatures Coating materials may have a minimum and/or a maximum recoat time Verify: Coating has been allowed to dry or cure the minimum amount of time The next coat is applied before the maximum recoat time has been exceeded

46 Detecting Pinholes and Holidays Definitions: Holidays – skips or misses in the coating/lining system Pinholes – tiny voids in the coating or lining Standards: ASTM D5162 and D4787; NACE RP01-88 Conducted: After final coat has been applied, but before it has achieved complete cure (touch-up) Specifications may require holiday testing after the application of each coat May cause intercoat contamination

47 Rules for Holiday Detection Coating must be nonconductive Substrate must be conductive High voltage (spark) testing requires voltage setting 100 to 125 volts/mil of coating Obtain recommended test voltage from coating manufacturer Excessive voltage can damage coating film

48 Holiday Detectors Low voltage (wetted sponge) – coatings that are less than 20 mils thick High voltage (spark tester) – coatings that are greater than 20 mils thick Move wand/electrode maximum of one foot/second

49 Inspecting OAP Coating Systems Visual pinhole/holiday detection Optically Active Pigments (OAP) added to coatings during formulation Inspection performed using UVA-340 light Process described in SSPC TU 11 Inspector training recommended if inspections not previously performed

50 Assessing Coating Drying/Cure Pencil Hardness (ASTM D3363) Solvent Resistance (Solvent Rubs; ASTM D5402) for convertible coatings Solvent Resistance (Solvent Rubs; ASTM D4752) for ethyl silicate inorganic zinc primers Impressor Hardness Barcol Hardness (ASTM D2583) Durometer Hardness (ASTM D2240) Dry Time Testing (ASTM D1640)

51 Measuring Adhesion Adhesion is destructive testing Testing should not be conducted unless required Types of coating adhesion: The adhesion of the coating to the substrate The adhesion of the coating layers to each other The inner-strength of each coating layer (cohesion)

52 Adhesion Test Methods StandardTitle D 3359 A Adhesion by Tape Test (>5 mils DFT) D 3359 B Adhesion by Tape Test (5 mils DFT) D 6677 Knife Adhesion D 4541 D 7234 Pull-off Strength of Coatings Using Portable Adhesion Testers Pull-off Strength of Coatings on Concrete Using Portable Adhesion Testers


54 Tape Adhesion (D 3359) Method A (> 5 mils) RatingDescription 5ANo peeling or removal 4ATrace peeling or removal along the incisions 3AJagged removal along the incisions up to 1/16 on either side 2AJagged removal along the incisions up to 1/8 on either side 1ARemoval of most of the coating from the area of the X under the tape 0ARemoval of coating beyond the area of the X


56 Tape Adhesion (D 3359) Method B (< 5 mils) Ratin g %Description 5B0%Edges of cuts completely smooth 4B<5%Small flakes of coating detached at intersections 3B6- 15% Small flakes of coating detached along edges & at intersections 2B16- 35% Coating flaked along edges and parts of squares 1B36- 65% Coating flaked along edges in large ribbons and whole squares detached 0B>65%Flaking & detaching worse than 1B

57 Tensile (pull-off) Adhesion Testing ASTM D 4541 measures the resistance to a perpendicular pull Requires the attachment of loading fixtures Pulling mechanisms include: Spring Pneumatic Hydraulic (shown) Record psi (Mpa) and location of break

58 Illustrations of Various Locations of Break

59 Identifying Coating Application Defects Multitude of defect types Identifying type, causes and remedies is challenging Acquire a pictorial reference guide Sources: ASTM standards Fitzs Atlas 2 (shown)

60 Summary During this webinar, we have described : Industry standards for coating application Developing a quality control plan for painting Navigating a Technical (Product) Data Sheet Measuring ambient conditions and surface temperature Witnessing mixing, thinning and application procedures Calculating and measuring wet film thickness Dry film thickness measurement Post-application testing Identifying application defects

61 Quality Control of Industrial Painting Operations William D. Corbett KTA-Tator, Inc. THE END

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