ASTM D4939-89(2007)
(Test Method)Standard Test Method for Subjecting Marine Antifouling Coating to Biofouling and Fluid Shear Forces in Natural Seawater
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 ) 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 The values stated in SI units are to be regarded as the standard. The values given in parentheses are for information only.
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 hazards statement, see Section 8.
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NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
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Designation: D4939 − 89 (Reapproved2007)
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 D4939; 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 2.2 U.S. Military Specifications:
MIL-P-24441 Primer, Epoxy (Formula 150, Formula Sheet
1.1 This test method covers the determination of antifouling
24441/1)
performance and reduction of thickness of marine antifouling
MIL-P-15931B Paint, Antifouling, Vinyl, Red (Formula
(AF) coatings by erosion or ablation (see Section 3) under
121/63)
specified conditions of hydrodynamic shear stress in seawater
MIL-S-22698A Steel Plate, Carbon, Structural
alternated with static exposure in seawater. An antifouling
coating system of known performance is included to serve as a
3. Terminology
control in antifouling studies.
3.1 Definitions of Terms Specific to This Standard:
1.2 The values stated in SI units are to be regarded as the
3.1.1 ablation, n—in this test method, the removal or
standard. The values given in parentheses are for information
wearing away of the outer layers of coating caused by the
only.
combined action of hydrolysis and hydrodynamic shear stress.
1.3 This standard does not purport to address all of the
This action is often, but not necessarily, achieved by the
safety concerns, if any, associated with its use. It is the
combined effects of hydrolysis and hydrodynamic shear stress.
responsibility of the user of this standard to establish appro-
3.1.2 hydrolysis, n—softening or weakening of the outer
priate safety and health practices and determine the applica-
layers, permitting the hydrodynamic shear stresses gradually to
bility of regulatory limitations prior to use. For a specific
remove them, continually exposing a fresh antifouling surface.
hazards statement, see Section 8.
3.1.3 hydrodynamic shear stress, n—the force tangential to
the surface resulting from water in contact with and flowing
2. Referenced Documents
parallel to the surface.
2.1 ASTM Standards:
A569/A569M Specification for Steel, Carbon (0.15
4. Summary of Test Method
Maximum,Percent),Hot-RolledSheetandStripCommer-
4.1 The antifouling coatings to be tested and a control
cial (Withdrawn 2000)
coating are applied to steel panels and exposed in natural
D1186 Test Methods for Nondestructive Measurement of
seawater at a site where the fouling rate is high. The exposure
Dry Film Thickness of Nonmagnetic Coatings Applied to
consists of alternate static and dynamic cycles of typically 30
a Ferrous Base (Withdrawn 2006)
days each for a total length of time to be specified (such as one
D2200 Practice for Use of Pictorial Surface Preparation
or two years) or until some selected degree of fouling is
Standards and Guides for Painting Steel Surfaces
reached. The static exposure is conducted in accordance with
D3623 Test Method for Testing Antifouling Panels in Shal-
Test Method D3623 except that the panels are smaller and are
low Submergence
preformed to fit a rotating drum. The dynamic exposure
consists of subjecting the test panels to a shear stress by
rotating the drum underwater at some specified revolution rate;
This test method is under the jurisdiction of ASTM Committee D01 on Paint
typically,thatratethatgivesaperipheralspeedof15knots(7.6
and Related Coatings, Materials, andApplications and is the direct responsibility of
m/s). See Note 1 for an example. Photographs and film
Subcommittee D01.45 on Marine Coatings.
Current edition approved June 1, 2007. Published August 2007. Originally
thickness measurements (made in accordance with Test Meth-
approved in 1989. Last previous edition approved in 2003 as D4939 - 89 (2003).
ods D1186) are taken before exposure to seawater and, along
DOI: 10.1520/D4939-89R07.
with fouling ratings, at intervals during exposure.
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
the ASTM website. Available from Standardization Documents Order Desk, DODSSP, Bldg. 4,
The last approved version of this historical standard is referenced on Section D, 700 Robbins Ave., Philadelphia, PA 19111-5098, http://
www.astm.org. www.dodssp.daps.mil.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D4939 − 89 (2007)
NOTE 1—Consider antifouling paint for a ship about 500 ft in length
6. Apparatus
that cruises at about 20 knots. From Table 2, the column for 20 knots
shows the hydrodynamic shear stress, τ varying from 2.01 to 1.40 lbf/ft 6.1 Rotating Drum Assembly—The basic system consists of
over a flat plate with approximately the same length as the ship. From
a rotating drum assembly as shown in Fig. 1. The drum
Table 1, a rotating drum with a radius of 0.75 ft with a peripheral speed
diameter and rotational rate shall be calculated to give the
of 15 knots gives aτ of 1.72 lbf/ft . To subject the paint to about the same
desired hydrodynamic shear stress.The drum diameter shall be
rangeofτasontheship,thepaintcanbetestedonthedrumwithτof1.72
not less than 18 in. (460 mm).
lbf/ft . Because τ for the plate (and ships) decreases from the leading to
the trailing edge, it is considered adequate to select τ for the drum as the
6.2 Panels—The panels shall be made from medium low-
approximate midrange of the plate values matched to the length and
cruising speed of the vessels of interest. carbon steel plate in accordance with Specification A569/
A569M, 3 mm thick by 80 to 150 by 180 to 250 mm ( ⁄8 in.
5. Significance and Use
thick by 3 to 6 by 7 to 10 in.) curved to fit the drum surface as
shown in Fig. 2. Panel length must be selected in order to
5.1 Effective antifouling coatings are essential for the reten-
prevent gaps greater than 1.6 mm ( ⁄16 in.).
tionofspeedandreductionofoperatingcostsofships.Thistest
method is designed as a screening test to evaluate antifouling
6.3 Static Exposure Rack—The static exposure rack shall
coating systems under conditions of hydrodynamic stress
provide firm positioning of the specimen panels so that the
caused by water flow alternated with static exposure to a
coated surfaces are held vertically in place in spite of the
fouling environment. A dynamic test is necessary because of
currentandareelectricallyinsulatedfrommetalliccontactwith
the increasing availability of AF coatings that are designed to
therackorotherpanels.Therackshallbesopositionedthatthe
ablate in service to expose a fresh antifouling surface. Because
prevailing tidal currents move parallel to the panel face, and
no ship is underway continually, a static exposure phase is
the panels are immersed to a depth of a minimum of 0.3 m (1
included to give fouling microorganisms the opportunity to
ft) and a maximum of 3 m (10 ft). In a rack where panels are
attach under static conditions. After an initial 30-day static
stacked front to back, they should be spaced at least 64 mm
exposure, alternated 30-day dynamic and static exposures are
(2 ⁄2 in.) apart, with the two end positions filled with blank
recommended as a standard cycle.The initial static exposure is
panels.Inarackwherethepanelsaremountedsidebyside,the
selected to represent vessels coming out of drydock and sitting
distance between adjacent panels should be not less than 13
pierside while work is being completed. This gives the paint
mm ( ⁄2 in.).
time to lose any remaining solvents, complete curing, absorb
water, and, in general, stabilize to the in-water environment.
5.2 This test method is intended to provide a comparison
with a control antifouling coating of known performance in
protectingunderwaterportionsofships’hulls.Thistestmethod
gives an indication of the performance and anticipated service
life of antifouling coatings for use on seagoing vessels.
However, the degree of correlation between this test method
and service performance has not been determined.
TABLE 1 Approximate Hydrodynamic Shear Stress, τ, 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:
τ = ⁄2 C ρv ,
f
v = r ω
vr
R =
, Reynolds Number
v
=
−0.6 + 4.07 log fR C g (from Dorfman, Hydrodynamic Resistance and the Heat
œ f
C
œ f
Loss of Rotating Solids, Oliver and Boyd, London, 1963, p. 176.
where:
τ = shear stress on drum surface, lbf/ft ,
ρ = water density = 1.99 slugs,
v = peripheral speed of drum surface, knots,
NOTE 1—Specific components and arrangements may vary to suit user
C = shear stress (drag) coefficient,
f
and site requirements.
ω = Rotational speed of drum, radions/s, and
r = drum radius, ft. NOTE 2—1 ft = 305 mm.
FIG. 1 Rotating Drum Assembly
D4939 − 89 (2007)
metal (Grade Sa 2 ⁄2 of Pictorial Standard D2200) to obtain a
profile from 1 to 1.5 mils (25 to 40 µm).
9.2 Ontheclean,dry,uncontaminated,blast-cleanedsurface
apply to each standard panel one coat of epoxy polyamide
primer conforming to MIL-P-24441 to give a dry film thick-
ness of approximately 3 mils (75 µm). After about 24 h, (for
temperatures above 70°F and below 90°F), apply a second coat
of the primer to the panels. After a second 24-h period, apply
the third coating of primer to give a total dry film thickness of
approximately 9 mils (230 µm).
9.3 Apply the vinyl antifouling coating conforming to
MIL-P-15931B before the final coat of epoxy paint has
hardened. The epoxy should be slightly tacky when the first
coat of the topcoat is applied. If the epoxy is hard (usually after
8 h) apply a tack or mist coat of 1 to 2 mils wet film thickness
and allow to dry to a slightly tacky state before applying the
first coat of the topcoat. Allowing a minimum of 2 h and a
maximum of 24 h drying after the first coat, apply the second
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 µ m).
9.4 Before immersion, permit the second coat of antifouling
coating to
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