Transcript Presentation Slides

Quality Control of Industrial
Painting Operations
William D. Corbett
KTA-Tator, Inc.
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
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
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)
SSPC Paint Application
Specification No. 1 (PA 1)
• Shop, Field and Maintenance Painting of Steel
• Common specification reference
• Contains 14 Sections:
1.
2.
3.
4.
5.
6.
7.
Scope
Description
Referenced Standards
Definitions
Pre-application Procedures
Factors Affecting Application
Application Methods
8. Shop Coating
9. Field Coating
10. Repair of Damaged Coatings
11. Appl. Proc. For Coatings
12. Curing & Handling
13. Inspection
14. Safety & Environmental
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
Benefits of a Quality Control Plan
 Coating specifications can be complex documents
 Specifications typically contain the quality
requirements for a coatings project
 Good inspection doesn’t 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
Sample Quality Control Plan
Inspection
Item
Technique/
Instrument
Frequency of
Tests
Standard
Test Method
Reference
Spec.
Reference
(mock)
Verify ambient
conditions
Electronic
psychrometer
Verify
installation of
protective
coverings
Acceptance
Criteria
(mock)
Before mixing
and every 4
hours; changing
conditions
SSPC-PA 1
3.4.1
Air: 50-100°F
Surface: 50-110°F
RH: <85%
ST > 5°F DP
Visual
Prior to primer
application
SSPC-PA 1
3.4.2
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-PA2
3.4.7
3-5 mils
Holiday
Detection
Low voltage
wet sponge
detector
After topcoat
application
ASTM D5162
3.4.10
No pinholes or
holidays
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
Product Data Sheets, con’t.
• 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
Product Data Sheets, con’t.
 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
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
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.)
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
Significance of Conditions, con’t.
• Wind Speed
Too windy can affect application (dry spray) and cause
overspray damage
• Mixing/application of coatings under adverse
weather conditions can void the manufacturer’s
warranty and is considered a specification nonconformance
Ambient Conditions & Surface
Temperature
• Measuring Instruments
Sling Psychrometers*
Battery-powered
Psychrometers*
Electronic Psychrometers
Analog, Thermocoupletype & Non-contact
Surface Thermometers
* Used in conjunction with
psychrometric charts or calculators
Sling Psychrometer
Using Sling Psychrometers
• ASTM E337
• Verify wick cleanliness
• Saturate wick and/or fill
reservoir with DI water
• Whirl 20-30 second
intervals until wet bulb
stabilizes (2 readings within
0.5o)
• Record wet & dry bulb
temperatures
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
(Ta-Tw)
• Calculators (bottom
image) can also be used
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
Measuring Surface Temperature
• Dial-Type Thermometer
 Position & stabilize for
minimum of 2 minutes
• Thermocouple-Type
Thermometers
 Stabilize quickly
• Infrared (non-contact)
thermometers
 Watch distance
Assessing Wind Speed
• Analog wind meters
• Digital wind meters
• Rotating Vane
Anemometers
 Air flow inside
containment
 Wind speed
Documenting Ambient Conditions and
Surface Temperature
Condition
Data
Date
2/15/12
Time
0900 hours
Dry Bulb Temperature (DB)
16oC (60oF)
Wet Bulb Temperature (WB)
13oC (55oF)
Depression (DB-WB)
Relative Humidity
3oC (5oF)
73%
Dew Point Temperature
11oC (51oF)
Surface Temperature
15oC (59oF)
Wind Speed
Measurement Location
11 km/Hr (7 mph)
West side of tank, ground level
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
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
Inspecting Mixing Procedures
1. Verify components are within
the manufacturer’s 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
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
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
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
Calculating a Target Wet Film
Thickness
• Effect of Thinner Addition on WFT Target
WFT =
Target DFT
% solids by volume
100% + % thinner
Calculating a Target Wet Film
Thickness
• Effect of Thinner Addition, continued
 WFT =
5 mils DFT
0.68
100% + 20% thinner
5 mils DFT
68
120
5 mils DFT
=
0.57
= 9 mils WFT
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
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
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
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)
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)
Verifying Type 2 Gage Accuracy
• Use calibration blocks
or shims
• Verify accuracy in
range of use
 Most can be adjusted
 Follow gage
manufacturer’s
instructions (vary)
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
A
*Via Base Metal Reading (BMR)
B
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
Measurement Frequency
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
Example:
Structure Size:
55,000 square feet
No. of Areas:
No. of Spots:
3 + 54 = 57 areas
57 Areas x 5 Spots/Area = 285
Spots
285 Spots x 3 Readings/Spot =
855 Gage Readings
No. of Gage Readings:
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
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
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
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
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
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
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
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)
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)
Adhesion Test Methods
Standard
Title
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
Pull-off Strength of Coatings Using Portable
Adhesion Testers
D 7234
Pull-off Strength of Coatings on Concrete
Using Portable Adhesion Testers
Tape Adhesion (D 3359) Method “A”
(> 5 mils)
SCRIBE AN “X”
INTO COATING
TO SUBSTRATE
APPLY TAPE AND
RUB ONTO SURFACE
REMOVE TAPE
QUICKLY
Tape Adhesion (D 3359) Method “A”
(> 5 mils)
Rating
Description
5A
No peeling or removal
4A
Trace peeling or removal along the incisions
3A
Jagged removal along the incisions up to 1/16” on either side
2A
Jagged removal along the incisions up to 1/8” on either side
1A
Removal of most of the coating from the area of the “X” under
the tape
0A
Removal of coating beyond the area of the “X”
Tape Adhesion (D 3359) Method “B”
(< 5 mils)
SCRIBE A CROSSCUT PATTERN
INTO COATING TO
SUBSTRATE
APPLY TAPE AND
RUB ONTO SURFACE
REMOVE TAPE
QUICKLY
Tape Adhesion (D 3359) Method “B”
(< 5 mils)
Ratin
g
%
5B
0%
4B
<5%
Small flakes of coating detached at
intersections
3B
615%
Small flakes of coating detached
along edges & at intersections
2B
1635%
Coating flaked along edges and
parts of squares
1B
3665%
Coating flaked along edges in
large ribbons and whole squares
detached
0B
Description
Edges of cuts completely smooth
>65% Flaking & detaching worse than 1B
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
Illustrations of Various Locations of
Break
1
2
3
4
5
Identifying Coating Application
Defects
• Multitude of defect types
• Identifying type, causes
and remedies is
challenging
• Acquire a pictorial
reference guide
• Sources:
 ASTM standards
 Fitz’s Atlas 2™ (shown)
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
Quality Control of Industrial
Painting Operations
THE END
William D. Corbett
KTA-Tator, Inc.