1、Designation: D4939 89 (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 adopt
2、ion 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 r
3、eduction 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 antifou
4、ling 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
5、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 Specification for Steel, Carbon (0.15Maximum, Percent), Hot-Rolled Sheet an
6、d Strip Commer-cial (Withdrawn 2000)3D1186 Test Methods for Nondestructive Measurement ofDry Film Thickness of Nonmagnetic Coatings Applied toa Ferrous Base (Withdrawn 2006)3D2200 Practice for Use of Pictorial Surface PreparationStandards and Guides for Painting Steel SurfacesD3623 Test Method for T
7、esting Antifouling Panels in Shal-low Submergence2.2 U.S. Military Specifications:4MIL-P-24441 Primer, Epoxy (Formula 150, Formula Sheet24441/1)MIL-P-15931B Paint, Antifouling, Vinyl, Red (Formula121/63)MIL-S-22698A Steel Plate, Carbon, Structural3. Terminology3.1 Definitions of Terms Specific to Th
8、is 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.
9、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 flowingpara
10、llel 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
11、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 subjecti
12、ng 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
13、 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 edit
14、ion 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
15、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,Section D, 700 Robbins Ave., Philadelphia, PA 19
16、111-5098, http:/www.dodssp.daps.mil.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States1NOTE 1Consider antifouling paint for a ship about 500 ft in lengththat cruises at about 20 knots. From Table 2, the column for 20 knotsshows the hydro
17、dynamic 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
18、e paint can be tested on the drum with of 1.72lbf/ft2. Because for the plate (and ships) decreases from the leading tothe trailing edge, it is considered adequate to select for the drum as theapproximate midrange of the plate values matched to the length andcruising speed of the vessels of interest.
19、5. Significance and Use5.1 Effective antifouling coatings are essential for the reten-tion of speed and reduction of operating costs of ships. This testmethod is designed as a screening test to evaluate antifoulingcoating systems under conditions of hydrodynamic stresscaused by water flow alternated
20、 with static exposure to afouling environment. A dynamic test is necessary because ofthe increasing availability of AF coatings that are designed toablate in service to expose a fresh antifouling surface. Becauseno ship is underway continually, a static exposure phase isincluded to give fouling micr
21、oorganisms the opportunity toattach under static conditions. After an initial 30-day staticexposure, alternated 30-day dynamic and static exposures arerecommended as a standard cycle. The initial static exposure isselected to represent vessels coming out of drydock and sittingpierside while work is
22、being completed. This gives the painttime to lose any remaining solvents, complete curing, absorbwater, and, in general, stabilize to the in-water environment.5.2 This test method is intended to provide a comparisonwith a control antifouling coating of known performance inprotecting underwater porti
23、ons of ships hulls. This test methodgives an indication of the performance and anticipated servicelife of antifouling coatings for use on seagoing vessels.However, the degree of correlation between this test methodand service performance has not been determined.6. Apparatus6.1 Rotating Drum Assembly
24、The basic system consists ofa rotating drum assembly as shown in Fig. 1. The drumdiameter and rotational rate shall be calculated to give thedesired hydrodynamic shear stress. The drum diameter shall benot less than 18 in. (460 mm).6.2 PanelsThe panels shall be made from medium low-carbon steel plat
25、e in accordance with Specification A569/A569M, 3 mm thick by 80 to 150 by 180 to 250 mm (18 in.thick by 3 to 6 by 7 to 10 in.) curved to fit the drum surface asshown in Fig. 2. Panel length must be selected in order toprevent gaps greater than 1.6 mm (116 in.).6.3 Static Exposure RackThe static expo
26、sure rack shallprovide firm positioning of the specimen panels so that thecoated surfaces are held vertically in place in spite of thecurrent and are electrically insulated from metallic contact withthe rack or other panels. The rack shall be so positioned that theprevailing tidal currents move para
27、llel to the panel face, andthe panels are immersed to a depth of a minimum of 0.3 m (1ft) and a maximum of 3 m (10 ft). In a rack where panels arestacked front to back, they should be spaced at least 64 mm(212 in.) apart, with the two end positions filled with blankpanels. In a rack where the panels
28、 are mounted side by side, thedistance between adjacent panels should be not less than 13mm (12 in.).TABLE 1 Approximate Hydrodynamic Shear Stress, , ForRotating Drum Apparatus, lbf/ft2 ADrum Radius, ftPeripheral Speed of Drum, knots10 15 20 22 25 300.75 0.82 1.72 2.91 3.48 4.39 6.141.0 0.78 1.64 2.
29、78 3.31 4.19 5.861.25 0.75 1.58 2.68 3.20 4.05 5.681.5 0.73 1.53 2.60 3.11 3.94 5.52AValues calculated as follows: =12 Cfv2v = r R =vrv, Reynolds Number1Cf=0.6 + 4.07 log fRCfg (from Dorfman, Hydrodynamic Resistance and the HeatLoss of Rotating Solids, Oliver and Boyd, London, 1963, p. 176.where = s
30、hear stress on drum surface, lbf/ft2, = water density = 1.99 slugs,v = peripheral speed of drum surface, knots,Cf= shear stress (drag) coefficient, = Rotational speed of drum, radions/s, andr = drum radius, ft.NOTE 1Specific components and arrangements may vary to suit userand site requirements.NOTE
31、 21 ft = 305 mm.FIG. 1 Rotating Drum AssemblyD4939 89 (2013)27. Materials7.1 Control Coating SystemThe control antifouling coat-ing system shall consist of the following system unless analternative control coating system is specified.7.1.1 Polyamide Epoxy Anticorrosive Coating, conformingto U.S. Mil
32、itary Specification MIL-P-24441 (Navy Formula150, Type I).7.1.2 Vinyl Antifouling Coating, conforming to U.S. Mili-tary Specification MIL-P-15931B (Formula 121/63), B revi-sion only.7.2 Test Coating SystemThe antifouling coating under testmay be applied to the control primer system or to any othersu
33、itable anticorrosive primer system agreed upon between theparties concerned. The application procedure is to be inaccordance with the manufacturers instructions.8. Hazards8.1 Antifouling paints contain toxic materials that couldcause skin and eye irritation on contact and adverse physiologi-cal effe
34、cts if ingested or inhaled. In the preparation of panelsand the application of various types of antifouling paints theuse of appropriate protective clothing and equipment is re-quired consistent with applicable regulations, and recognizedindustrial and technical standards. Do not flush spills,oversp
35、ray, and unused material down the drain, but dispose ofas hazardous waste.9. Procedure9.1 Abrasive blast clean the required number of panels (sixpanels for each coating system being tested) to near whitemetal (Grade Sa 212 of Pictorial Standard D2200) to obtain aprofile from 1 to 1.5 mils (25 to 40
36、m).9.2 On the clean, dry, uncontaminated, blast-cleaned surfaceapply to each standard panel one coat of epoxy polyamideprimer conforming to MIL-P-24441 to give a dry film thick-ness of approximately 3 mils (75 m). After about 24 h, (fortemperatures above 70F and below 90F), apply a second coatof the
37、 primer to the panels. After a second 24-h period, applythe third coating of primer to give a total dry film thickness ofapproximately 9 mils (230 m).9.3 Apply the vinyl antifouling coating conforming toMIL-P-15931B before the final coat of epoxy paint hashardened. The epoxy should be slightly tacky
38、 when the firstcoat of the topcoat is applied. If the epoxy is hard (usually after8 h) apply a tack or mist coat of 1 to 2 mils wet film thicknessand allow to dry to a slightly tacky state before applying thefirst coat of the topcoat. Allowing a minimum of 2 h and amaximum of 24 h drying after the f
39、irst coat, apply the secondcoat of the antifouling coating conforming to MIL-P-15931Bto give a nominal dry film thickness of the antifouling paint of4 mils (100 m).9.4 Before immersion, permit the second coat of antifoulingcoating to dry a minimum of 24 h or until fully cured inaccordance with the m
40、anufacturers recommendations and amaximum of one month, the latter time allowing for shippingthe panels to the immersion site. Measure dry film thickness atten locations on the panel in accordance with Test MethodsD1186 prior to immersion at the site. To accurately locate thethickness measurement lo
41、cations on the panels for repeatedmeasurements, use a mask with two rows of five holes equallyspaced over the surface.9.5 Exposure consists of alternating static and dynamicphases at an immersion site with a high incidence of fouling(that is fouling resistance of 50 % or less determined inaccordance
42、 with Test Method D3623) as indicated by attach-ments to a dark nontoxic surface such as slate.9.5.1 Place the panels on the stationary exposure racks,handling them only by the edges, and expose them in accor-dance with Test Method D3623. Static exposure may beaccomplished by leaving the panels atta
43、ched to the drum andnot rotating it. The time the panels are out of the water must bekept to a minimum. When any panels are removed from thestationary racks or the rotating drum, they are to be kept incontainers of seawater except during actual rating,photography, or thickness measurement. If the ti
44、me out ofwater exceeds 10 min, this fact should be recorded andreported.9.5.2 Subject the test panels to dynamic exposure by mount-ing them on the drum and rotating it at a peripheral speedcalculated from the values and formulas given in Table 1 andTables 2 as agreed upon between the parties concern
45、ed.9.6 Evaluate the antifouling panels for surface fouling andphysical condition of the film system at the end of eachexposure or as agreed upon between the parties concerned.Record the evaluation on the report form in Fig. 3.9.6.1 Fouling on SurfaceRate the fouling present on thatportion of the ant
46、ifouling test surface that is intact at the timeNOTE 11 in. = 25.4 mm.FIG. 2 Curved Exposure Panels for Rotating DrumD4939 89 (2013)3of inspection in accordance with Test Method D3623. Ignorefouling present on the substrate or on anticorrosive undercoats.Barnacles, polychaetes, coelenterates, etc. t
47、hat are immature orloosely attached should be so reported in the appropriate spaceon the report form (see Fig. 3). Report fouling by initial algalgermination, low-form algae, and diatoms as“ algal slime.”Report absorbed organic and inorganic chemicals, trapped siltand detritus, and other unidentifie
48、d slimes as “silt.”9.6.2 Physical ConditionRate the condition of coatingfilms in accordance with 10.2. Record qualitative descriptionsof film deterioration and discoloration in the appropriatecolumn in Fig. 3 unless otherwise specified. Indicate deterio-ration of anticorrosive (AC) undercoats, when
49、evident, by thenotation “AC.” For example, “Peeling antifouling film (AF)from AC” or “Chipping, AC from steel.” For ablative coatingwith fouling-free areas, measure total coating thickness inaccordance with Test Methods D1186 using the mask to locatemeasurement spots. If the panel surface is free of fouling,measure thickness at all ten locations given on the mask. If anylocations are obstructed by fouling, note this fact and do notmake measurements at that spot.9.7 Record the start and stop dates of each of the static anddynamic
