ASTM D4938-89(2002)
(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 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. For a specific hazard statement, see Section 7.
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Designation: D 4938 – 89 (Reapproved 2002)
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 and shall specify the length of time, temperature, salinity, and
pH.Additional velocities may be conducted at the discretion of
1.1 This test method covers the determination of erosion
the customer.
rates for marine antifouling paint systems immersed in flowing
3.3 Color photographs and coating thickness measurements
natural seawater.
shall be taken prior to exposure, at specified time intervals, and
1.2 This standard does not purport to address all of the
repeated at the end of the test for comparison purposes.
safety concerns, if any, associated with its use. It is the
responsibility of the user of this standard to establish appro-
4. Significance and Use
priate safety and health practices and determine the applica-
4.1 Thistestmethodisintendedtomeasuretheerosionrates
bility of regulatory limitations prior to use. For a specific
of ablative antifouling paint systems exposed to flowing water
hazard statement, see Section 7.
at velocities designed to subject the paint system to shear
2. Referenced Documents stresses experienced in service.
4.2 Measurement of erosion rates are necessary to help in
2.1 ASTM Standards:
the assessment of ablative antifouling paint film thicknesses
A 569/A 569M Specification for Steel, Carbon (0.15 Maxi-
required for fouling control between scheduled drydockings of
mum Percent), Hot-Rolled Sheet and Strip Commercial
ships, in the selection of materials, in producing quality
D 823 Practice for Producing Films of Uniform Thickness
assurance, and in understanding the performance mechanism.
of Paint, Varnish, and Related Products on Test Panels
4.3 The test data is intended to serve as a guide for
D 1889 Test Method for Turbidity of Water
predicting the service life of ablative antifouling paints in order
D 2200 Pictorial Surface Preparation Standards for Painting
to calculate the necessary paint thickness to fit specified
Steel Surfaces
deployment cycles. Erosion rates of antifouling paints in
2.2 U.S. Military Specifications:
service will vary depending on such factors as: berthing
MIL-P-24441 Paint, Epoxy-Polyamide
location, geographic area of operation, salinity, pH, and tem-
DOD-P-24647 Paint, Antifouling, Ship Hull (Metric)
perature of seawater. It should also be recognized that some
DOD-P-24655 Paint, Underwater Hull,Anticorrosion (Met-
areas of the ship are subject to different erosion rates.
ric)
4.4 The degree of correlation between results obtained from
3. Summary of Test Method
this test method and shipboard service has not been deter-
mined.
3.1 Steel panels coated with the antifouling paint system
under evaluation are positioned in a high velocity water
5. Apparatus
channel, similar to the type shown in Figs. 1-3, parallel to the
5.1 Water Channel:
path of the flowing water.
5.1.1 High velocity flowing water in a contained channel,
3.2 Exposure conditions shall include at least one series of
similar to the type shown in Figs. 1-3, is used to induce
test panels evaluated at the standard water velocity of 12 m/s
hydrodynamic shear stresses on painted panels to determine
erosion rates of ablative antifouling paints.
This test method is under the jurisdiction of ASTM Committee D01 on Paint
5.1.2 The basic apparatus consists of a four-walled channel,
and Related Coatings, Materials, andApplications and is the direct responsibility of
rectangular in cross section, through which natural seawater
Subcommittee D01.45 on Marine Coatings.
flows at varying linear velocities to simulate ships’ speeds.
Current edition approved April 28, 1989. Published June 1989.
5.1.3 All wetted materials supplying seawater to and within
Annual Book of ASTM Standards, Vol 01.03.
Annual Book of ASTM Standards, Vol 06.01.
the channel shall be nonmetallic with the following exceptions:
Annual Book of ASTM Standards, Vol 11.01.
5.1.3.1 Channel circulating pump impellers.
Annual Book of ASTM Standards, Vol 06.02.
6 5.1.3.2 Thermowells.
Available from Standardization Documents Order Desk, DODSSP, Bldg. 4,
Section D, 700 Robbins Ave., Philadelphia, PA 19111-5098. 5.1.3.3 Channel flow orifice plate.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
D 4938 – 89 (2002)
FIG. 1 High Velocity Flow Channel
FIG. 2 Simplified Schematic of Flow Channel
W, mm Velocity, m/s
50 18
60 15
5.1.4 One section of the channel shall permit testing of the
75 12
panels at a standard test velocity of 12 m/s. All sections of the 100 9
150 6
channel shall provide flow with fully formed turbulent charac-
300 3
teristics. A minimum Reynolds number of 1 000 000 shall be
FIG. 3 Cross-Section View of Test Panel Mounted in Flow
achieved in each velocity test section. The Reynolds number,
Channel (Low Velocity Section)
R, is calculated as follows:
R 5 ~D 3 V 3 P!/U (1)
where:
D 4938 – 89 (2002)
running time of the test is defined as the total hours of actual
D = equivalent diameter = 4 3 (area of flowing liquid/
channel operation under fully flowing conditions.
wetted perimeter), m,
V = velocity, in m/s,
P = density of medium, kg/m , and 6. Application of Paints
U = viscosity, P/s.
6.1 Antifouling paints under evaluation may be applied by
For a channel with a rectangular cross section and a test
spray over a primer from the same manufacturer in accordance
panel placed in the middle of the channel, the equivalent
with the manufacturer’s directions or over 9 mils of epoxy
diameter would be calculated as follows:
polyamide paint conforming to Military Specification MIL-P-
24441 with an appropriate tie-coat if necessary. Application
4 3 A 3 B!/ 2A 1 2B! (2)
@~ ~ #
shall be in accordance with Practice D 823.
where:
7. Hazards
A = width of channel from side wall to panel face, m, and
7.1 Antifouling paints contain toxic materials that could
B = height of channel, m.
causeskinandeyeirritationoncontactandadversephysiologi-
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 consiste
...
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