ASTM D4939-89(1996)

Standard Test Method for Subjecting Marine Antifouling Coating to Biofouling and Fluid Shear Forces in Natural Seawater

SCOPE
1.1 This test method covers the determination of antifouling performance and reduction of thickness of marine antifouling (AF) coatings by erosion or ablation (see Section 3) under specified conditions of hydrodynamic shear stress in seawater alternated with static exposure in seawater. An antifouling coating system of known performance is included to serve as a control in antifouling studies.
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 hazards statement, see Section 8.

General Information

• Status: Historical
• Publication Date: 09-May-1996
• Technical Committee: D01 - Paint and Related Coatings, Materials, and Applications
• Drafting Committee: D01.45 - Marine Coatings

Relations

• Replaced By: ASTM D4939-89(2003) - Standard Test Method for Subjecting Marine Antifouling Coating to Biofouling and Fluid Shear Forces in Natural Seawater
• Effective Date: 10-Mar-2003
• Referred By: ASTM D6990-20 - Standard Practice for Evaluating Biofouling Resistance and Physical Performance of Marine Coating Systems
• Effective Date: 10-May-1996
• Referred By: ASTM D5479-94(2020) - Standard Practice for Testing Biofouling Resistance of Marine Coatings Partially Immersed
• Effective Date: 10-May-1996

Standards Content (Sample)

NOTICE: This standard has either been superceded and replaced by a new version or discontinued.
Contact ASTM International (www.astm.org) for the latest information.
Designation: D 4939 – 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
Subjecting Marine Antifouling Coating to Biofouling and
Fluid Shear Forces in Natural Seawater
This standard is issued under the fixed designation D 4939; 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 3.1.1 ablation—in this test method, the removal or wearing
away of the outer layers of coating caused by the combined
1.1 This test method covers the determination of antifouling
action of hydrolysis and hydrodynamic shear stress. This
performance and reduction of thickness of marine antifouling
action is often, but not necessarily, achieved by the combined
(AF) coatings by erosion or ablation (see Section 3) under
effects of hydrolysis and hydrodynamic shear stress.
specified conditions of hydrodynamic shear stress in seawater
3.1.2 hydrolysis—softens or weakens the outer layers, per-
alternated with static exposure in seawater. An antifouling
mitting the hydrodynamic shear stresses gradually to remove
coating system of known performance is included to serve as a
them, continually exposing a fresh antifouling surface.
control in antifouling studies.
3.1.3 hydrodynamic shear stress—the force tangential to the
1.2 This standard does not purport to address all of the
surface resulting from water in contact with and flowing
safety concerns, if any, associated with its use. It is the
parallel to the surface.
responsibility of the user of this standard to establish appro-
priate safety and health practices and determine the applica-
4. Summary of Test Method
bility of regulatory limitations prior to use. For a specific
4.1 The antifouling coatings to be tested and a control
hazards statement, see Section 8.
coating are applied to steel panels and exposed in natural
2. Referenced Documents seawater at a site where the fouling rate is high. The exposure
consists of alternate static and dynamic cycles of typically 30
2.1 ASTM Standards:
days each for a total length of time to be specified (such as one
A 569/A 569M Specification for Steel, Carbon (0.15 Maxi-
or two years) or until some selected degree of fouling is
mum Percent), Hot-Rolled, Sheet and Strip, Commercial
reached. The static exposure is conducted in accordance with
Quality
Method D 3623 except that the panels are smaller and are
D 1186 Test Methods for Nondestructive Measurement of
preformed to fit a rotating drum. The dynamic exposure
Dry Film Thickness of Nonmagnetic Coatings Applied to
consists of subjecting the test panels to a shear stress by
a Ferrous Base
rotating the drum underwater at some specified revolution rate;
D 2200 Pictorial Surface Preparation Standards for Painting
typically, that rate that gives a peripheral speed of 15 knots (7.6
Steel Surfaces
m/s). See Note 1 for an example. Photographs and film
D 3623 Method for Testing Antifouling Panels in Shallow
thickness measurements (made in accordance with Test Meth-
Submergence
ods D 1186) are taken before exposure to seawater and, along
2.2 U.S. Military Specifications:
with fouling ratings, at intervals during exposure.
MIL-P-24441 Primer, Epoxy (Formula 150, Formula Sheet
24441/1)
NOTE 1—Consider antifouling paint for a ship about 500 ft in length
MIL-P-15931B Paint, Antifouling, Vinyl, Red (Formula that cruises at about 20 knots. From Table 2, the column for 20 knots
shows the hydrodynamic shear stress, t varying from 2.01 to 1.40 lbf/ft
121/63)
over a flat plate with approximately the same length as the ship. From
MIL-S-22698A Steel Plate, Carbon, Structural
Table 1, a rotating drum with a radius of 0.75 ft with a peripheral speed
of 15 knots gives a t of 1.72 lbf/ft . To subject the paint to about the same
3. Terminology
range of t as on the ship, the paint can be tested on the drum with t of 1.72
3.1 Definitions of Terms Specific to This Standard: 2
lbf/ft . Because t for the plate (and ships) decreases from the leading to
the trailing edge, it is considered adequate to select t for the drum as the
approximate midrange of the plate values matched to the length and
This test method is under the jurisdiction of ASTM Committee D-1 on Paint
cruising speed of the vessels of interest.
and Related Coatings, Materials, and Applications and is the direct responsibility of
Subcommittee D01.45 on Marine Coatings.
Current edition approved April 28, 1989. Published June 1989. 5. Significance and Use
Annual Book of ASTM Standards, Vol 01.03.
5.1 Effective antifouling coatings are essential for the reten-
Annual Book of ASTM Standards, Vol 06.01.
Annual Book of ASTM Standards, Vol 06.02. tion of speed and reduction of operating costs of ships. This test
Available from Standardization Documents Order Desk, Bldg. 4 Section D, 700
method is designed as a screening test to evaluate antifouling
Robbins Ave., Philadelphia, PA 19111-5094.
NOTICE: This standard has either been superceded and replaced by a new version or discontinued.
Contact ASTM International (www.astm.org) for the latest information.
D 4939
TABLE 1 Approximate Hydrodynamic Shear Stress, t, For
2 A
Rotating Drum Apparatus, lbf/ft
Peripheral Speed of Drum, knots
Drum Radius, ft
10 15 20 22 25 30
0.75 0.82 1.72 2.91 3.48 4.39 6.14
1.0 0.78 1.64 2.78 3.31 4.19 5.86
1.25 0.75 1.58 2.68 3.20 4.05 5.68
1.5 0.73 1.53 2.60 3.11 3.94 5.52
A
Values calculated as follows:
t5 ⁄2C rv ,
f
v 5 r v
vr
R 5
, Reynolds Number
n
5 −0.6 + 4.07 log [R C ] (from Dorfman, Hydrodynamic Resis-
=
f
=C tance and the Heat Loss of Rotating Solids, Oliver and Boyd,
f
London, 1963, p. 176.
where
t5 shear stress on drum surface, lbf/ft ,
r5 water density 5 1.99 slugs,
v 5 peripheral speed of drum surface, knots,
C 5 shear stress (drag) coefficient,
f
v5 Rotational speed of drum, radions/s, and
r 5 drum radius, ft.
coating systems under conditions of hydrodynamic stress
caused by water flow alternated with static exposure to a
fouling environment. A dynamic test is necessary because of
NOTE 1—Specific components and arrangements may vary to suit user
the increasing availability of AF coatings that are designed to
and site requirements.
ablate in service to expose a fresh antifouling surface. Because
NOTE 2—1 ft 5 305 mm.
no ship is underway continually, a static exposure phase is
FIG. 1 Rotating Drum Assembly
included to give fouling microorganisms the opportunity to
coated surfaces are held vertically in place in spite of the
attach under static conditions. After an initial 30-day static
current and are electrically insulated from metallic contact with
exposure, alternated 30-day dynamic and static exposures are
the rack or other panels. The rack shall be so positioned that the
recommended as a standard cycle. The initial static exposure is
prevailing tidal currents move parallel to the panel face, and
selected to represent vessels coming out of drydock and sitting
the panels are immersed to a depth of a minimum of 1 ft (0.3
pierside while work is being completed. This gives the paint
m) and a maximum of 10 ft (3 m). In a rack where panels are
time to lose any remaining solvents, complete curing, absorb
stacked front to back, they should be spaced at least 2 ⁄2 in. (64
water, and, in general, stabilize to the in-water environment.
mm) apart, with the two end positions filled with blank panels.
5.2 This test method is intended to provide a comparison
In a rack where the panels are mounted side by side, the
with a control antifouling coating of known performance in
distance between adjacent panels should be not less than ⁄2 in.
protecting underwater portions of ships’ hulls. This test method
(13 mm).
gives an indication of the performance and anticipated service
life of antifouling coatings for use on seagoing vessels.
7. Materials
However, the degree of correlation between this test method
7.1 Control Coating System—The control antifouling coat-
and service performance has not been determined.
ing system shall consist of the following system unless an
alternative control coating system is specified.
6. Apparatus
7.1.1 Polyamide Epoxy Anticorrosive Coating, conforming
6.1 Rotating Drum Assembly—The basic system consists of
to U.S. Military Specification MIL-P-24441 (Navy Formula
a rotating drum assembly as shown in Fig. 1. The drum
150, Type I).
diameter and rotational rate shall be calculated to give the
7.1.2 Vinyl Antifouling Coating, conforming to U.S. Mili-
desired hydrodynamic shear stress. The drum diameter shall be
tary Specification MIL-P-15931B (Formula 121/63), B revi-
not less than 18 in. (460 mm).
sion only.
6.2 Panels—The panels shall be made from medium low-
7.2 Test Coating System—The antifouling coating under test
carbon steel plate in accordance with Specification A 569/
may be applied to the control primer system or to any other
A 569M, ⁄8 in. thick by 3 to 6 by 7 to 10 in. (3 mm thick by
suitable anticorrosive primer system agreed upon between the
80 to 150 by 180 to 250 mm) curved to fit the drum surface as
parties concerned. The application procedure is to be in
shown in Fig. 2. Panel length must be selected in order to
accordance with the manufacturer’s instructions.
prevent gaps greater than ⁄16 in. (1.6 mm).
8. Hazards
6.3 Static Exposure Rack—The static exposure rack shall
provide firm positioning of the specimen panels so that the 8.1 Antifouling paints contain toxic materials that could
NOTICE: This standard has either been superceded and replaced by a new version or discontinued.
Contact ASTM International (www.astm.org) for the latest information.
D 4939
coat of the antifouling coating conforming to MIL-P-15931B
to give a nominal dry film thickness of the antifouling paint of
4 mils (100 μm).
9.4 Before immersion permit the second coat of antifouling
coating to dry a minimum of 24 h or until fully cured in
accordance with the manufacturer’s recommendations and a
maximum of one month, the latter time allowing for shipping
the panels to the immersion site. Measure dry film thickness at
ten lo
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