ASTM D4939-89(2003)

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 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.

General Information

• Status: Historical
• Publication Date: 09-Mar-2003
• ICS: 47.020.05 - Materials and components for shipbuilding
• Technical Committee: D01 - Paint and Related Coatings, Materials, and Applications
• Drafting Committee: D01.45 - Marine Coatings

Relations

• Replaces: ASTM D4939-89(1996) - Standard Test Method for Subjecting Marine Antifouling Coating to Biofouling and Fluid Shear Forces in Natural Seawater
• Effective Date: 10-Mar-2003
• Replaced By: ASTM D4939-89(2007) - Standard Test Method for Subjecting Marine Antifouling Coating to Biofouling and Fluid Shear Forces in Natural Seawater
• Effective Date: 01-Jun-2007
• Referred By: ASTM D6990-20 - Standard Practice for Evaluating Biofouling Resistance and Physical Performance of Marine Coating Systems
• Effective Date: 10-Mar-2003
• Referred By: ASTM D5479-94(2020) - Standard Practice for Testing Biofouling Resistance of Marine Coatings Partially Immersed
• Effective Date: 10-Mar-2003

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NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.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:D4939–89(Reapproved2003)
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 MIL-S-22698A Steel Plate, Carbon, Structural
1.1 This test method covers the determination of antifouling
3. Terminology
performance and reduction of thickness of marine antifouling
3.1 Definitions of Terms Specific to This Standard:
(AF) coatings by erosion or ablation (see Section 3) under
3.1.1 ablation, n—in this test method, the removal or
specified conditions of hydrodynamic shear stress in seawater
wearing away of the outer layers of coating caused by the
alternated with static exposure in seawater. An antifouling
combined action of hydrolysis and hydrodynamic shear stress.
coating system of known performance is included to serve as a
This action is often, but not necessarily, achieved by the
control in antifouling studies.
combined effects of hydrolysis and hydrodynamic shear stress.
1.2 This standard does not purport to address all of the
3.1.2 hydrolysis, n—softening or weakening of the outer
safety concerns, if any, associated with its use. It is the
layers, permitting the hydrodynamic shear stresses gradually to
responsibility of the user of this standard to establish appro-
remove them, continually exposing a fresh antifouling surface.
priate safety and health practices and determine the applica-
3.1.3 hydrodynamic shear stress, n—the force tangential to
bility of regulatory limitations prior to use. For a specific
the surface resulting from water in contact with and flowing
hazards statement, see Section 8.
parallel to the surface.
2. Referenced Documents
4. Summary of Test Method
2.1 ASTM Standards:
4.1 The antifouling coatings to be tested and a control
A 569/A 569M Specification for Steel, Carbon (0.15 Maxi-
coating are applied to steel panels and exposed in natural
mum Percent), Hot-Rolled, Sheet and Strip, Commercial
seawater at a site where the fouling rate is high. The exposure
D 1186 Test Methods for Nondestructive Measurement of
consists of alternate static and dynamic cycles of typically 30
Dry Film Thickness of Nonmagnetic Coatings Applied to
3 days each for a total length of time to be specified (such as one
a Ferrous Base
or two years) or until some selected degree of fouling is
D 2200 Pictorial Surface Preparation Standards for Painting
4 reached. The static exposure is conducted in accordance with
Steel Surfaces
Method D 3623 except that the panels are smaller and are
D 3623 Method for Testing Antifouling Panels in Shallow
4 preformed to fit a rotating drum. The dynamic exposure
Submergence
5 consists of subjecting the test panels to a shear stress by
2.2 U.S. Military Specifications:
rotating the drum underwater at some specified revolution rate;
MIL-P-24441 Primer, Epoxy (Formula 150, Formula Sheet
typically,thatratethatgivesaperipheralspeedof15knots(7.6
24441/1)
m/s). See Note 1 for an example. Photographs and film
MIL-P-15931B Paint, Antifouling, Vinyl, Red (Formula
thickness measurements (made in accordance with Test Meth-
121/63)
ods D 1186) are taken before exposure to seawater and, along
with fouling ratings, at intervals during exposure.
This test method is under the jurisdiction of ASTM Committee D01 on Paint
NOTE 1—Consider antifouling paint for a ship about 500 ft in length
and Related Coatings, Materials, andApplications and is the direct responsibility of
that cruises at about 20 knots. From Table 2, the column for 20 knots
Subcommittee D01.45 on Marine Coatings.
shows the hydrodynamic shear stress, t varying from 2.01 to 1.40 lbf/ft
Current edition approved March 10, 2003. Published May 2003. Originally
over a flat plate with approximately the same length as the ship. From
approved in 1989. Last previous edition approved in 1996 as D 4939 - 96.
Table 1, a rotating drum with a radius of 0.75 ft with a peripheral speed
Discontinued; see 2001 Annual Book of ASTM Standards, Vol 01.03.
3 of 15 knots gives a t of 1.72 lbf/ft . To subject the paint to about the same
Annual Book of ASTM Standards, Vol 06.01.
rangeof tasontheship,thepaintcanbetestedonthedrumwith tof1.72
Annual Book of ASTM Standards, Vol 06.02.
lbf/ft . Because t for the plate (and ships) decreases from the leading to
Available from Standardization Documents Order Desk, DODSSP, Bldg. 4,
Section D, 700 Robbins Ave., Philadelphia, PA 19111-5098 the trailing edge, it is considered adequate to select t for the drum as the
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
D4939–89 (2003)
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:
t = ⁄2 C rv ,
f
v = r v
vr
R =
, Reynolds Number
n
= −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
t = shear stress on drum surface, lbf/ft ,
r = water density = 1.99 slugs,
v = peripheral speed of drum surface, knots,
C = shear stress (drag) coefficient,
f
v = Rotational speed of drum, radions/s, and
r = drum radius, ft.
approximate midrange of the plate values matched to the length and
cruising speed of the vessels of interest.
NOTE 1—Specific components and arrangements may vary to suit user
5. Significance and Use
and site requirements.
NOTE 2—1 ft = 305 mm.
5.1 Effective antifouling coatings are essential for the reten-
FIG. 1 Rotating Drum Assembly
tionofspeedandreductionofoperatingcostsofships.Thistest
method is designed as a screening test to evaluate antifouling
coating systems under conditions of hydrodynamic stress
6.2 Panels—The panels shall be made from medium low-
caused by water flow alternated with static exposure to a
carbon steel plate in accordance with Specification A 569/
fouling environment. A dynamic test is necessary because of
A 569M, ⁄8in. thick by 3 to 6 by 7 to 10 in. (3 mm thick by 80
the increasing availability of AF coatings that are designed to
to 150 by 180 to 250 mm) curved to fit the drum surface as
ablate in service to expose a fresh antifouling surface. Because
shown in Fig. 2. Panel length must be selected in order to
no ship is underway continually, a static exposure phase is
prevent gaps greater than ⁄16 in. (1.6 mm).
included to give fouling microorganisms the opportunity to
6.3 Static Exposure Rack—The static exposure rack shall
attach under static conditions. After an initial 30-day static
provide firm positioning of the specimen panels so that the
exposure, alternated 30-day dynamic and static exposures are
coated surfaces are held vertically in place in spite of the
recommended as a standard cycle.The initial static exposure is
currentandareelectricallyinsulatedfrommetalliccontactwith
selected to represent vessels coming out of drydock and sitting
therackorotherpanels.Therackshallbesopositionedthatthe
pierside while work is being completed. This gives the paint
prevailing tidal currents move parallel to the panel face, and
time to lose any remaining solvents, complete curing, absorb
the panels are immersed to a depth of a minimum of 1 ft (0.3
water, and, in general, stabilize to the in-water environment.
m) and a maximum of 10 ft (3 m). In a rack where panels are
5.2 This test method is intended to provide a comparison
stacked front to back, they should be spaced at least 2 ⁄2 in. (64
with a control antifouling coating of known performance in
mm) apart, with the two end positions filled with blank panels.
protectingunderwaterportionsofships’hulls.Thistestmethod
In a rack where the panels are mounted side by side, the
gives an indication of the performance and anticipated service
distance between adjacent panels should be not less than ⁄2 in.
life of antifouling coatings for use on seagoing vessels.
(13 mm).
However, the degree of correlation between this test method
and service performance has not been determined.
7. Materials
6. Apparatus
7.1 Control Coating System—The control antifouling coat-
6.1 Rotating Drum Assembly—The basic system consists of ing system shall consist of the following system unless an
alternative control coating system is specified.
a rotating drum assembly as shown in Fig. 1. The drum
diameter and rotational rate shall be calculated to give the 7.1.1 Polyamide Epoxy Anticorrosive Coating, conforming
desired hydrodynamic shear stress.The drum diameter shall be to U.S. Military Specification MIL-P-24441 (Navy Formula
not less than 18 in. (460 mm). 150, Type I).
D4939–89 (2003)
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 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.
...