ASTM_D_4938_-_89_2013.pdf

Designation:D493889(Reapproved 2013)Standard Test Method forErosion Testing of Antifouling Paints Using High VelocityWater1This standard is issued under the fixed designation D4938;the number immediately following the designation indicates the year oforiginal adoption or,in the case of revision,the year of last revision.A number in parentheses indicates the year of last reapproval.Asuperscript epsilon()indicates an editorial change since the last revision or reapproval.1.Scope1.1 This test method covers the determination of erosionrates for marine antifouling paint systems immersed in flowingnatural seawater.1.2 The values stated in SI units are to be regarded asstandard.No other units of measurement are included in thisstandard.1.3 This standard does not purport to address all of thesafety concerns,if any,associated with its use.It is theresponsibility of the user of this standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.For a specifichazard statement,see Section 7.2.Referenced Documents2.1 ASTM Standards:2A569/A569M SpecificationforSteel,Carbon(0.15Maximum,Percent),Hot-Rolled Sheet and Strip Commer-cial(Withdrawn 2000)3D823 Practices for Producing Films of Uniform Thicknessof Paint,Varnish,and Related Products on Test PanelsD1889 Test Method for Turbidity of Water(Withdrawn2007)3D2200 Practice for Use of Pictorial Surface PreparationStandards and Guides for Painting Steel Surfaces2.2 U.S.Military Specifications:4MIL-P-24441 Paint,Epoxy-PolyamideDOD-P-24647 Paint,Antifouling,Ship Hull(Metric)DOD-P-24655 Paint,Underwater Hull,Anticorrosion(Met-ric)3.Summary of Test Method3.1 Steel panels coated with the antifouling paint systemunder evaluation are positioned in a high velocity waterchannel,similar to the type shown in Figs.1-3,parallel to thepath of the flowing water.3.2 Exposure conditions shall include at least one series oftest panels evaluated at the standard water velocity of 12 m/sand shall specify the length of time,temperature,salinity,andpH.Additional velocities may be conducted at the discretion ofthe customer.3.3 Color photographs and coating thickness measurementsshall be taken prior to exposure,at specified time intervals,andrepeated at the end of the test for comparison purposes.4.Significance and Use4.1 This test method is intended to measure the erosion ratesof ablative antifouling paint systems exposed to flowing waterat velocities designed to subject the paint system to shearstresses experienced in service.4.2 Measurement of erosion rates are necessary to help inthe assessment of ablative antifouling paint film thicknessesrequired for fouling control between scheduled drydockings ofships,in the selection of materials,in producing qualityassurance,and in understanding the performance mechanism.4.3 The test data is intended to serve as a guide forpredicting the service life of ablative antifouling paints in orderto calculate the necessary paint thickness to fit specifieddeployment cycles.Erosion rates of antifouling paints inservice will vary depending on such factors as:berthinglocation,geographic area of operation,salinity,pH,and tem-perature of seawater.It should also be recognized that someareas of the ship are subject to different erosion rates.4.4 The degree of correlation between results obtained fromthis test method and shipboard service has not been deter-mined.5.Apparatus5.1 Water Channel:1This test method is under the jurisdiction of ASTM Committee D01 on Paintand Related Coatings,Materials,and Applications and is the direct responsibility ofSubcommittee D01.45 on Marine Coatings.Current edition approved June 1,2013.Published June 2013.Originallyapproved in 1989.Last previous edition approved in 2007 as D4938 89(2007).DOI:10.1520/D4938-89R13.2For referenced ASTM standards,visit the ASTM website,www.astm.org,orcontact ASTM Customer Service at serviceastm.org.For Annual Book of ASTMStandards volume information,refer to the standards Document Summary page onthe ASTM website.3The last approved version of this historical standard is referenced onwww.astm.org.4Available from Standardization Documents Order Desk,DODSSP,Bldg.4,SectionD,700RobbinsAve.,Philadelphia,PA19111-5098,http:/www.dodssp.daps.mil.Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 5.1.1 High velocity flowing water in a contained channel,similar to the type shown in Figs.1-3,is used to inducehydrodynamic shear stresses on painted panels to determineerosion rates of ablative antifouling paints.5.1.2 The basic apparatus consists of a four-walled channel,rectangular in cross section,through which natural seawaterflows at varying linear velocities to simulate ships speeds.5.1.3 All wetted materials supplying seawater to and withinthe channel shall be nonmetallic with the following exceptions:5.1.3.1 Channel circulating pump impellers.5.1.3.2 Thermowells.5.1.3.3 Channel flow orifice