ASTM_D_4939_-_89_2013.pdf

Designation:D493989(Reapproved 2013)Standard Test Method forSubjecting Marine Antifouling Coating to Biofouling andFluid Shear Forces in Natural Seawater1This standard is issued under the fixed designation D4939;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 antifoulingperformance and reduction of thickness of marine antifouling(AF)coatings by erosion or ablation(see Section 3)underspecified conditions of hydrodynamic shear stress in seawateralternated with static exposure in seawater.An antifoulingcoating system of known performance is included to serve as acontrol in antifouling studies.1.2 The values stated in SI units are to be regarded as thestandard.The values given in parentheses are for informationonly.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 specifichazards statement,see Section 8.2.Referenced Documents2.1 ASTM Standards:2A569/A569M SpecificationforSteel,Carbon(0.15Maximum,Percent),Hot-Rolled Sheet and Strip Commer-cial(Withdrawn 2000)3D1186 Test Methods for Nondestructive Measurement ofDry Film Thickness of Nonmagnetic Coatings Applied toa Ferrous Base(Withdrawn 2006)3D2200 Practice for Use of Pictorial Surface PreparationStandards and Guides for Painting Steel SurfacesD3623 Test Method for Testing Antifouling Panels in Shal-low Submergence2.2 U.S.Military Specifications:4MIL-P-24441 Primer,Epoxy(Formula 150,Formula Sheet24441/1)MIL-P-15931BPaint,Antifouling,Vinyl,Red(Formula121/63)MIL-S-22698A Steel Plate,Carbon,Structural3.Terminology3.1 Definitions of Terms Specific to This Standard:3.1.1 ablation,nin this test method,the removal orwearing away of the outer layers of coating caused by thecombined action of hydrolysis and hydrodynamic shear stress.This action is often,but not necessarily,achieved by thecombined effects of hydrolysis and hydrodynamic shear stress.3.1.2 hydrolysis,nsoftening or weakening of the outerlayers,permitting the hydrodynamic shear stresses gradually toremove them,continually exposing a fresh antifouling surface.3.1.3 hydrodynamic shear stress,nthe force tangential tothe surface resulting from water in contact with and flowingparallel to the surface.4.Summary of Test Method4.1 The antifouling coatings to be tested and a controlcoating are applied to steel panels and exposed in naturalseawater at a site where the fouling rate is high.The exposureconsists of alternate static and dynamic cycles of typically 30days each for a total length of time to be specified(such as oneor two years)or until some selected degree of fouling isreached.The static exposure is conducted in accordance withTest Method D3623 except that the panels are smaller and arepreformed to fit a rotating drum.The dynamic exposureconsists of subjecting the test panels to a shear stress byrotating the drum underwater at some specified revolution rate;typically,that rate that gives a peripheral speed of 15 knots(7.6m/s).See Note 1 for an example.Photographs and filmthickness measurements(made in accordance with Test Meth-ods D1186)are taken before exposure to seawater and,alongwith fouling ratings,at intervals during exposure.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 D4939 89(2007).DOI:10.1520/D4939-89R13.2For 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 NOTE1Consider antifouling paint for a ship about 500 ft in lengththat cruises at about 20 knots.From Table 2,the column for 20 knotsshows the hydrodynamic shear stress,varying from 2.01 to 1.40 lbf/ft2over a flat plate with approximately the same length as the ship.FromTable 1,a rotating drum with a radius of 0.75 ft with a peripheral speedof 15 knots gives a of 1.72 lbf/ft2.To subject the paint to about the samerange of as on the ship,th