ASTM D4938-89(2007)

Standard Test Method for Erosion Testing of Antifouling Paints Using High Velocity Water

SIGNIFICANCE AND USE
This test method is intended to measure the erosion rates of ablative antifouling paint systems exposed to flowing water at velocities designed to subject the paint system to shear stresses experienced in service.  
Measurement of erosion rates are necessary to help in the assessment of ablative antifouling paint film thicknesses required for fouling control between scheduled drydockings of ships, in the selection of materials, in producing quality assurance, and in understanding the performance mechanism.
The test data is intended to serve as a guide for predicting the service life of ablative antifouling paints in order to calculate the necessary paint thickness to fit specified deployment cycles. Erosion rates of antifouling paints in service will vary depending on such factors as: berthing location, geographic area of operation, salinity, pH, and temperature of seawater. It should also be recognized that some areas of the ship are subject to different erosion rates.
The degree of correlation between results obtained from this test method and shipboard service has not been determined.
SCOPE
1.1 This test method covers the determination of erosion rates for marine antifouling paint systems immersed in flowing natural seawater.
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.

General Information

• Status: Historical
• Publication Date: 31-May-2007
• 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 D4938-89(2002) - Standard Test Method for Erosion Testing of Antifouling Paints Using High Velocity Water
• 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: 01-Jun-2007
• Referred By: ASTM D5479-94(2020) - Standard Practice for Testing Biofouling Resistance of Marine Coatings Partially Immersed
• Effective Date: 01-Jun-2007

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:D4938 −89(Reapproved2007)
Standard Test Method for
Erosion Testing of Antifouling Paints Using High Velocity
Water
This standard is issued under the fixed designation D4938; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision.Anumber in parentheses indicates the year of last reapproval.A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope 3. Summary of Test Method
3.1 Steel panels coated with the antifouling paint system
1.1 This test method covers the determination of erosion
under evaluation are positioned in a high velocity water
ratesformarineantifoulingpaintsystemsimmersedinflowing
channel, similar to the type shown in Figs. 1-3, parallel to the
natural seawater.
path of the flowing water.
1.2 This standard does not purport to address all of the
3.2 Exposure conditions shall include at least one series of
safety concerns, if any, associated with its use. It is the
test panels evaluated at the standard water velocity of 12 m/s
responsibility of the user of this standard to establish appro-
and shall specify the length of time, temperature, salinity, and
priate safety and health practices and determine the applica-
pH.Additionalvelocitiesmaybeconductedatthediscretionof
bility of regulatory limitations prior to use. For a specific
the customer.
hazard statement, see Section 7.
3.3 Color photographs and coating thickness measurements
2. Referenced Documents
shallbetakenpriortoexposure,atspecifiedtimeintervals,and
repeated at the end of the test for comparison purposes.
2.1 ASTM Standards:
A569/A569M Specification for Steel, Carbon (0.15
4. Significance and Use
Maximum,Percent),Hot-RolledSheetandStripCommer-
cial (Withdrawn 2000)
4.1 Thistestmethodisintendedtomeasuretheerosionrates
D823Practices for Producing Films of Uniform Thickness
of ablative antifouling paint systems exposed to flowing water
of Paint, Varnish, and Related Products on Test Panels
at velocities designed to subject the paint system to shear
D1889Test Method for Turbidity of Water (Withdrawn
stresses experienced in service.
2007)
4.2 Measurement of erosion rates are necessary to help in
D2200Practice for Use of Pictorial Surface Preparation
the assessment of ablative antifouling paint film thicknesses
Standards and Guides for Painting Steel Surfaces
required for fouling control between scheduled drydockings of
2.2 U.S. Military Specifications:
ships, in the selection of materials, in producing quality
MIL-P-24441Paint, Epoxy-Polyamide
assurance, and in understanding the performance mechanism.
DOD-P-24647Paint, Antifouling, Ship Hull (Metric)
4.3 The test data is intended to serve as a guide for
DOD-P-24655Paint, Underwater Hull, Anticorrosion (Met-
predictingtheservicelifeofablativeantifoulingpaintsinorder
ric)
to calculate the necessary paint thickness to fit specified
deployment cycles. Erosion rates of antifouling paints in
service will vary depending on such factors as: berthing
This test method is under the jurisdiction of ASTM Committee D01 on Paint
location, geographic area of operation, salinity, pH, and tem-
and Related Coatings, Materials, andApplications and is the direct responsibility of
perature of seawater. It should also be recognized that some
Subcommittee D01.45 on Marine Coatings.
areas of the ship are subject to different erosion rates.
Current edition approved June 1, 2007. Published August 2007. Originally
approved in 1989. Last previous edition approved in 2002 as D4938-89(2002).
4.4 Thedegreeofcorrelationbetweenresultsobtainedfrom
DOI: 10.1520/D4938-89R07.
this test method and shipboard service has not been deter-
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM
mined.
Standards volume information, refer to the standard’s Document Summary page on
the ASTM website.
3 5. Apparatus
The last approved version of this historical standard is referenced on
www.astm.org.
5.1 Water Channel:
Available from Standardization Documents Order Desk, DODSSP, Bldg. 4,
5.1.1 High velocity flowing water in a contained channel,
Section D, 700 Robbins Ave., Philadelphia, PA 19111-5098, http://
www.dodssp.daps.mil. similar to the type shown in Figs. 1-3, is used to induce
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D4938−89(2007)
FIG. 1 High Velocity Flow Channel
FIG. 2 Simplified Schematic of Flow Channel
W, mm Velocity, m/s
50 18
hydrodynamic shear stresses on painted panels to determine
60 15
erosion rates of ablative antifouling paints.
75 12
100 9
5.1.2 The basic apparatus consists of a four-walled channel,
150 6
rectangular in cross section, through which natural seawater
300 3
flows at varying linear velocities to simulate ships’ speeds.
5.1.3 All wetted materials supplying seawater to and within FIG. 3 Cross-Section View of Test Panel Mounted in Flow Chan-
nel (Low Velocity Section)
thechannelshallbenonmetallicwiththefollowingexceptions:
5.1.3.1 Channel circulating pump impellers.
5.1.3.2 Thermowells. channel shall provide flow with fully formed turbulent charac-
5.1.3.3 Channel flow orifice plate. teristics. A minimum Reynolds number of 1000000 shall be
5.1.4 One section of the channel shall permit testing of the achieved in each velocity test section. The Reynolds number,
panels at a standard test velocity of 12 m/s.All sections of the R, is calculated as follows:
D4938−89(2007)
R 5 D 3V 3P /U (1) 5.4.3 The coating systems shall be applied in accordance
~ !
with the manufacturer’s instructions for both the anticorrosion
and the antifouling paints.
where:
5.5 Operation—Thechannelshallbeoperatedonacontinu-
D = equivalent diameter=4× (area of flowing liquid/
ous basis during the test period except for downtime for panel
wetted perimeter), m,
inspection and seawater filtering system backwashes.The total
V = velocity, in m/s,
P = density of medium, kg/m , and running time of the test is defined as the total hours of actual
U = viscosity, P/s. channel operation under fully flowing conditions.
For a channel with a rectangular cross section and a test
6. Application of Paints
panel placed in the middle of the channel, the equivalent
6.1 Antifouling paints under evaluation may be applied by
diameter would be calculated as follows:
spray over a primer from the same manufacturer in accordance
4 3 A 3B / 2A12B (2)
@~ ! ~ !#
with the manufacturer’s directions or over 9 mils of epoxy
polyamide paint conforming to Military Specification MIL-P-
24441 with an appropriate tie-coat if necessary. Application
where:
shall be in accordance with Practice D823.
A = width of channel from side wall to panel face, m, and
7. Hazards
B = height of channel, m.
7.1 Antifouling paints contain toxic materials that could
5.2 Erosion Rate Determination—Erosion rates of ablative
cause
...