ASTM D4938-89(1996)
(Test Method)Standard Test Method for Erosion Testing of Antifouling Paints Using High Velocity Water
Standard Test Method for Erosion Testing of Antifouling Paints Using High Velocity Water
SCOPE
1.1 This test method covers the determination of erosion rates for marine antifouling paint systems immersed in flowing natural seawater.
1.2 This standard may involve hazardous materials, operations, and equipment. This standard does not purport to address all of the safety problems 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. For a specific hazard statement, see Section 7.
General Information
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Standards Content (Sample)
NOTICE: This standard has either been superseded and replaced by a new version or discontinued.
Contact ASTM International (www.astm.org) for the latest information.
Designation: D 4938 – 89 (Reapproved 1996)
AMERICAN SOCIETY FOR TESTING AND MATERIALS
100 Barr Harbor Dr., West Conshohocken, PA 19428
Reprinted from the Annual Book of ASTM Standards. Copyright ASTM
Standard Test Method for
Erosion Testing of Antifouling Paints Using High Velocity
Water
This standard is issued under the fixed designation D 4938; 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 (e) indicates an editorial change since the last revision or reapproval.
1. Scope pH. Additional velocities may be conducted at the discretion of
the customer.
1.1 This test method covers the determination of erosion
3.3 Color photographs and coating thickness measurements
rates for marine antifouling paint systems immersed in flowing
shall be taken prior to exposure, at specified time intervals, and
natural seawater.
repeated at the end of the test for comparison purposes.
1.2 This standard does not purport to address all of the
safety concerns, if any, associated with its use. It is the
4. Significance and Use
responsibility of the user of this standard to establish appro-
4.1 This test method is intended to measure the erosion rates
priate safety and health practices and determine the applica-
of ablative antifouling paint systems exposed to flowing water
bility of regulatory limitations prior to use. For a specific
at velocities designed to subject the paint system to shear
hazard statement, see Section 7.
stresses experienced in service.
2. Referenced Documents 4.2 Measurement of erosion rates are necessary to help in
the assessment of ablative antifouling paint film thicknesses
2.1 ASTM Standards:
required for fouling control between scheduled drydockings of
A 569/A 569M Specification for Steel, Carbon (0.15 Maxi-
ships, in the selection of materials, in producing quality
mum Percent), Hot-Rolled, Sheet and Strip, Commercial
assurance, and in understanding the performance mechanism.
Quality
4.3 The test data is intended to serve as a guide for
D 823 Practice for Producing Films of Uniform Thickness
predicting the service life of ablative antifouling paints in order
of Paint, Varnish, and Related Products on Test Panels
to calculate the necessary paint thickness to fit specified
D 1889 Test Methods for Turbidity of Water
deployment cycles. Erosion rates of antifouling paints in
D 2200 Pictorial Surface Preparation Standards for Painting
5 service will vary depending on such factors as: berthing
Steel Surfaces
location, geographic area of operation, salinity, pH, and tem-
2.2 U.S. Military Specifications:
perature of seawater. It should also be recognized that some
MIL-P-24441 Paint, Epoxy-Polyamide
areas of the ship are subject to different erosion rates.
DOD-P-24647 Paint, Antifouling, Ship Hull (Metric)
4.4 The degree of correlation between results obtained from
DOD-P-24655 Paint, Underwater Hull, Anticorrosion (Met-
this test method and shipboard service has not been deter-
ric)
mined.
3. Summary of Test Method
5. Apparatus
3.1 Steel panels coated with the antifouling paint system
5.1 Water Channel:
under evaluation are positioned in a high velocity water
5.1.1 High velocity flowing water in a contained channel,
channel, similar to the type shown in Figs. 1-3, parallel to the
similar to the type shown in Figs. 1-3, is used to induce
path of the flowing water.
hydrodynamic shear stresses on painted panels to determine
3.2 Exposure conditions shall include at least one series of
erosion rates of ablative antifouling paints.
test panels evaluated at the standard water velocity of 12 m/s
5.1.2 The basic apparatus consists of a four-walled channel,
and shall specify the length of time, temperature, salinity, and
rectangular in cross section, through which natural seawater
flows at varying linear velocities to simulate ships’ speeds.
This test method is under the jurisdiction of ASTM Committee D-1 on Paint
5.1.3 All wetted materials supplying seawater to and within
and Related Coatings, Materials, and Applications and is the direct responsibility of
the channel shall be nonmetallic with the following exceptions:
Subcommittee D01.45 on Marine Coatings.
Current edition approved April 28, 1989. Published June 1989.
5.1.3.1 Channel circulating pump impellers.
Annual Book of ASTM Standards, Vol 01.03.
5.1.3.2 Thermowells.
Annual Book of ASTM Standards, Vol 06.01.
4 5.1.3.3 Channel flow orifice plate.
Annual Book of ASTM Standards, Vol 11.01.
5.1.4 One section of the channel shall permit testing of the
Annual Book of ASTM Standards, Vol 06.02.
Available from Standardization Documents Order Desk, Bldg. 4 Section D, 700
panels at a standard test velocity of 12 m/s. All sections of the
Robbins Ave., Philadelphia, PA 19111-5094, Attn: NPODS.
NOTICE: This standard has either been superseded and replaced by a new version or discontinued.
Contact ASTM International (www.astm.org) for the latest information.
D 4938
FIG. 1 High Velocity Flow Channel
FIG. 2 Simplified Schematic of Flow Channel
W, mm Velocity, m/s
50 18
channel shall provide flow with fully formed turbulent charac-
60 15
teristics. A minimum Reynolds number of 1 000 000 shall be 75 12
100 9
achieved in each velocity test section. The Reynolds number,
150 6
R, is calculated as follows:
300 3
R 5 ~D 3 V 3 P!/U (1)
FIG. 3 Cross-Section View of Test Panel Mounted in Flow
Channel (Low Velocity Section)
where:
D 5 equivalent diameter 5 4 3 (area of flowing liquid/
For a channel with a rectangular cross section and a test
wetted perimeter), m,
V 5 velocity, in m/s, panel placed in the middle of the channel, the equivalent
P 5 density of medium, kg/m , and diameter would be calculated as follows:
U 5 viscosity, P/s.
4 3 @~A 3 B!/~2A 1 2B!# (2)
NOTICE: This standard has either been superseded and replaced by a new version or discontinued.
Contact ASTM International (www.astm.org) for the latest information.
D 4938
7. Hazards
where:
A 5 width of channel from side wall to panel face, m, and
7.1 Antifouling paints contain toxic materials that could
B 5 height of channel, m.
cause skin and eye irritation on contact and adverse physiologi-
5.2 Erosion Rate Determination—Erosion rates of ablative
cal effects if ingested or inhaled. In the preparation of panels
antifouling paints are determined by using noneroding refer-
and the application of various types of antifouling paints, the
ence points and measured in accordance with Section 8 with
use of appropriate protective clothing and equipment is re-
the following equipment:
quired consistent with local, state, and federal government
5.2.1 Microtome or encapsulating/polishing equipment. regulations and recognized industrial and technical standards.
Spills, overspray, and unused material shall not b
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