ASTM D7893-13
(Guide)Standard Guide for Corrosion Test Panel Preparation, Testing, and Rating of Coil-Coated Building Products
Standard Guide for Corrosion Test Panel Preparation, Testing, and Rating of Coil-Coated Building Products
SIGNIFICANCE AND USE
5.1 Coil-coated metals are subjected to a wide range of environmental stresses. Corrosion at cut edges, damage points, and fabricated areas can occur and lead to premature failure. Proper preparation and rating of test panels produces meaningful test results that allows comparisons between metal substrates and their pretreatments as well as between coating systems.
5.2 Laboratory-prepared test panels give a relative comparison of the substrates and coating systems under test, but may not duplicate all of the stresses imposed on manufactured components. Validation of results on a manufactured product is recommended.
5.3 Laboratory accelerated corrosion testing is useful in evaluating relative performance of new and existing metal coatings, pretreatments, and paints. It is up to the participating parties to agree on the significance of these tests to actual use.
SCOPE
1.1 This guide has been written specifically for coil-coated metal building products.
1.2 This guide applies to preparation, testing, and rating of line-coated and laboratory-coated test panels for the purpose of comparing and ranking the panels for corrosion resistance and other related properties.
1.3 Testing may include accelerated laboratory corrosion tests and outdoor exposure tests.
1.4 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.
1.5 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.
General Information
Relations
Standards Content (Sample)
NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
Contact ASTM International (www.astm.org) for the latest information
Designation: D7893 − 13
Standard Guide for
Corrosion Test Panel Preparation, Testing, and Rating of
Coil-Coated Building Products
This standard is issued under the fixed designation D7893; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope 100 % Relative Humidity
D2803 Guide for Testing Filiform Corrosion Resistance of
1.1 This guide has been written specifically for coil-coated
Organic Coatings on Metal
metal building products.
D3359 Test Methods for Measuring Adhesion by Tape Test
1.2 This guide applies to preparation, testing, and rating of
D4138 Practices for Measurement of Dry Film Thickness of
line-coated and laboratory-coated test panels for the purpose of
Protective Coating Systems by Destructive, Cross-
comparing and ranking the panels for corrosion resistance and
Sectioning Means
other related properties.
D4585 Practice for Testing Water Resistance of Coatings
1.3 Testing may include accelerated laboratory corrosion Using Controlled Condensation
D5796 TestMethodforMeasurementofDryFilmThickness
tests and outdoor exposure tests.
of Thin-Film Coil-Coated Systems by Destructive Means
1.4 The values stated in SI units are to be regarded as
Using a Boring Device
standard. No other units of measurement are included in this
D5894 Practice for Cyclic Salt Fog/UV Exposure of Painted
standard.
Metal, (Alternating Exposures in a Fog/Dry Cabinet and a
1.5 This standard does not purport to address all of the
UV/Condensation Cabinet)
safety concerns, if any, associated with its use. It is the
D7091 Practice for Nondestructive Measurement of Dry
responsibility of the user of this standard to establish appro-
Film Thickness of Nonmagnetic Coatings Applied to
priate safety and health practices and determine the applica-
Ferrous Metals and Nonmagnetic, Nonconductive Coat-
bility of regulatory limitations prior to use.
ings Applied to Non-Ferrous Metals
G7 Practice for Atmospheric Environmental Exposure Test-
2. Referenced Documents
ing of Nonmetallic Materials
2.1 ASTM Standards:
G85 Practice for Modified Salt Spray (Fog) Testing
B117 Practice for Operating Salt Spray (Fog) Apparatus
G87 Practice for Conducting Moist SO Tests
D610 Practice for Evaluating Degree of Rusting on Painted
G169 Guide for Application of Basic Statistical Methods to
Steel Surfaces
Weathering Tests
D714 Test Method for Evaluating Degree of Blistering of
2.2 SAE Standards:
Paints
J2334 Laboratory Cyclic Corrosion Test
D870 Practice for Testing Water Resistance of Coatings
Using Water Immersion 3. Terminology
D1654 Test Method for Evaluation of Painted or Coated
3.1 Definitions:
Specimens Subjected to Corrosive Environments
3.1.1 test panel, n—a representative specimen of metal
D1735 Practice for Testing Water Resistance of Coatings
substrate, coated with a coating system for evaluation, and
Using Water Fog Apparatus
prepared in a way that allows measurement of environmental
D2247 Practice for Testing Water Resistance of Coatings in
degradation, especially corrosion, for system performance
comparisons and ranking.
This guide is under the jurisdiction of ASTM Committee D01 on Paint and
4. Summary of Guide
Related Coatings, Materials, and Applications and is the direct responsibility of
Subcommittee D01.53 on Coil Coated Metal.
4.1 Test panels may be collected from coil line clips and
Current edition approved Nov. 1, 2013. Published November 2013. DOI:
formed building panels, or may be laboratory-prepared.
10.1520/D7893-13.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
Standards volume information, refer to the standard’s Document Summary page on Available from SAE International (SAE), 400 Commonwealth Dr.,Warrendale,
the ASTM website. PA 15096-0001, http://www.sae.org.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D7893 − 13
4.2 Test panels are prepared for testing in a specific con- 6.5 In addition to test panel configuration, the laboratory
figuration that simulates conditions on buildings. accelerated corrosion tests, exposure sites, and panel orienta-
tions should be considered. Exposure sites represent unique
4.3 Test panels are exposed to specific conditions in accor-
environments that cyclically expose the test panels to many
dance with standard practices and methods.
conditions such as temperature variation, moisture, salt
4.4 After testing, corrosion is measured in a way that relates
concentrations, industrial pollutants, and solar radiation. Expo-
to building performance and allows performance ranking
sure angles such as 1°, 5°, and 45° from horizontal might be
among samples, for example, by the corrosion creep distance
chosen for roof simulation, while vertical exposures would be
from test panel edges.
used for side walls. Exposure directions, north, south, east, or
west, can be chosen as can the degree of shade or shelter. A
5. Significance and Use
sheltered exposure may offer increased time of wetness for test
5.1 Coil-coated metals are subjected to a wide range of
panels.
environmental stresses. Corrosion at cut edges, damage points,
6.6 Use of coil line-coated test panels (line clips) is pre-
and fabricated areas can occur and lead to premature failure.
ferred to best represent the commercial product’s performance.
Proper preparation and rating of test panels produces meaning-
Often, however, where a number of variables are tested in a
ful test results that allows comparisons between metal sub-
screening experiment, it is not practical or economical to test
strates and their pretreatments as well as between coating
line clips. In such cases, laboratory test panels may be
systems.
prepared. For laboratory-prepared test panels, heating rate and
5.2 Laboratory-prepared test panels give a relative compari-
peak metal temperature should be as close as possible to coil
son of the substrates and coating systems under test, but may
line conditions.
not duplicate all of the stresses imposed on manufactured
6.7 Pretreatments are applied to a cleaned surface by
components.Validation of results on a manufactured product is
immersion, spray, drawdown, or rollcoater as appropriate in
recommended.
accordance with manufacturer specification.
5.3 Laboratory accelerated corrosion testing is useful in
6.8 For laboratory-prepared test panels, coil primers and
evaluating relative performance of new and existing metal
topcoats are typically applied to test panels by wire wound rod.
coatings, pretreatments, and paints. It is up to the participating
The wire number selected is critical for dry film thickness
parties to agree on the significance of these tests to actual use.
(DFT) accuracy. DFT must be established for each coating/rod
number combination because the same rod can produce differ-
6. Test Panel Preparation
ent DFTs with different coatings. Typical methods for measur-
6.1 An experiment is planned to evaluate the effects of
ing the dry film thickness of coil coatings include Practices
specific variables in the coated metal system on corrosion
D4138, D7091, and Test Method D5796.
performance.These variables typically include metal substrate,
6.9 For laboratory-prepared test panels, when the backside
cleaning, pretreatment, primer, topcoat, forming, and other
has not been line-primed or backed, a backer coating should be
appropriate stresses.
applied to test panels. This may be accomplished with room
6.2 The number of replicates in a test is determined by
temperature-cured coatings or tape.
availability of substrate, time, resource constraints, and statis-
6.10 The metal shear selection is important for consistent
tical methods for data analysis. Statistical methods require a
results and should be used consistently for all corrosion test
numberofreplicateswhichisdependentuponthevariabilityof
panels to be compared in an experiment if edge corrosion is to
the system under test and the measurement system itself.
be measured. The shear type and blade sharpness may influ-
Although not specific to corrosion testing, Guide G169 can
ence corrosion results.
serve as a reference for using statistical methods. Because of
test variations, a thorough experimental plan includes controls 6.11 For tests requ
...
Questions, Comments and Discussion
Ask us and Technical Secretary will try to provide an answer. You can facilitate discussion about the standard in here.