1、Designation: D 4939 89 (Reapproved 2007)Standard Test Method forSubjecting Marine Antifouling Coating to Biofouling andFluid Shear Forces in Natural Seawater1This standard is issued under the fixed designation D 4939; the number immediately following the designation indicates the year oforiginal ado
2、ption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon (e) indicates an editorial change since the last revision or reapproval.1. Scope1.1 This test method covers the determination of antifoulingperformance an
3、d 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 anti
4、fouling 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
5、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:2A 569/A 569M Specification for Steel, Carbon (0.15 Maxi-mum Percent), Hot-Rolled, S
6、heet and Strip, Commercial3D 1186 Test Methods for Nondestructive Measurement ofDry Film Thickness of Nonmagnetic Coatings Applied toa Ferrous Base3D 2200 Standard Pictorial Surface Preparation Standardsfor Painting Steel SurfacesD 3623 Test Method for Testing Antifouling Panels inShallow Submergenc
7、e2.2 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 This Standard:3.1.1 ablation, nin this test method
8、, 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
9、 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
10、 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 on
11、eor two years) or until some selected degree of fouling isreached. The static exposure is conducted in accordance withTest Method D 3623 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
12、 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 D 1186) are taken before exposure to seawater and, alongwith fo
13、uling ratings, at intervals during exposure.NOTE 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 hydrodynamic shear stress, t varying from 2.01 to 1.40 lbf/ft2over a flat plate with approximately the same len
14、gth as the ship. FromTable 1, a rotating drum with a radius of 0.75 ft with a peripheral speedof 15 knots gives a t of 1.72 lbf/ft2. To subject the paint to about the same1This test method is under the jurisdiction of ASTM Committee D01 on Paintand Related Coatings, Materials, and Applications and i
15、s the direct responsibility ofSubcommittee D01.45 on Marine Coatings.Current edition approved June 1, 2007. Published August 2007. Originallyapproved in 1989. Last previous edition approved in 2003 as D 4939 - 89 (2003).2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact
16、ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.3Withdrawn.4Available from Standardization Documents Order Desk, DODSSP, Bldg. 4,Section D, 700 Robbins Ave., Philadelphia, PA 19111-5098, ht
17、tp:/www.dodssp.daps.mil.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.range of t as on the ship, the paint can be tested on the drum with t of 1.72lbf/ft2. Because t for the plate (and ships) decreases from the leading tothe traili
18、ng edge, it is considered adequate to select t for the drum as theapproximate midrange of the plate values matched to the length andcruising speed of the vessels of interest.5. Significance and Use5.1 Effective antifouling coatings are essential for the reten-tion of speed and reduction of operating
19、 costs of ships. This testmethod is designed as a screening test to evaluate antifoulingcoating systems under conditions of hydrodynamic stresscaused by water flow alternated with static exposure to afouling environment. A dynamic test is necessary because ofthe increasing availability of AF coating
20、s 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 microorganisms the opportunity toattach under static conditions. After an initial 30-day staticexposure, alternated 30-day dynamic
21、 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 being completed. This gives the painttime to lose any remaining solvents, complete curing, absorbwater, and, in general, stabi
22、lize 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 portions of ships hulls. This test methodgives an indication of the performance and anticipated servicelife of antifouling coatings
23、 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 AssemblyThe basic system consists ofa rotating drum assembly as shown in Fig. 1. The drumdiameter and rotational rate shall be calcula
24、ted 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 plate in accordance with Specification A 569/A 569M, 3 mm thick by 80 to 150 by 180 to 250 mm (18 in.thick by 3 to 6 by 7 to 10 in
25、.) 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 exposure rack shallprovide firm positioning of the specimen panels so that thecoated surfaces are held vertically in place in sp
26、ite 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 parallel 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
27、 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 are mounted side by side, thedistance between adjacent panels should be not less than 13mm (12 in.).7. Materials7.1 Control
28、 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. Military Specification MIL-P-24441 (Navy Formula150, Type I).TABLE 1 Approximate Hydrod
29、ynamic Shear Stress, t, 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 2.78 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:t =12 Cfrv2,
30、v = r vR =vrn, Reynolds Number1=Cf= 0.6 + 4.07 log R =Cf (from Dorfman, Hydrodynamic Resis-tance and the Heat Loss of Rotating Solids, Oliver and Boyd,London, 1963, p. 176.wheret = shear stress on drum surface, lbf/ft2,r = water density = 1.99 slugs,v = peripheral speed of drum surface, knots,Cf= sh
31、ear stress (drag) coefficient,v = Rotational speed of drum, radions/s, andr = drum radius, ft.NOTE 1Specific components and arrangements may vary to suit userand site requirements.NOTE 21 ft = 305 mm.FIG. 1 Rotating Drum AssemblyD 4939 89 (2007)27.1.2 Vinyl Antifouling Coating, conforming to U.S. Mi
32、li-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 othersuitable anticorrosive primer system agreed upon between theparties concerned. The application procedure is to be
33、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 effects if ingested or inhaled. In the preparation of panelsand the application of various types of antifouling pain
34、ts theuse of appropriate protective clothing and equipment is re-quired consistent with applicable regulations, and recognizedindustrial and technical standards. Do not flush spills, over-spray, and unused material down the drain, but dispose of ashazardous waste.9. Procedure9.1 Abrasive blast clean
35、 the required number of panels (sixpanels for each coating system being tested) to near whitemetal (Grade Sa 212 of Pictorial Standard D 2200) to obtain aprofile from 1 to 1.5 mils (25 to 40 m).9.2 On the clean, dry, uncontaminated, blast-cleaned surfaceapply to each standard panel one coat of epoxy
36、 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 primer to the panels. After a second 24-h period, applythe third coating of primer to give a total dry film
37、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 when the firstcoat of the topcoat is applied. If the epoxy is hard (usually after8 h) apply a tack or mist c
38、oat 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 first coat, apply the secondcoat of the antifouling coating conforming to MIL-P-15931Bto give a nominal dry fi
39、lm 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 manufacturers recommendations and amaximum of one month, the latter time allowing for shippingthe panels to th
40、e immersion site. Measure dry film thickness atten locations on the panel in accordance with Test MethodsD 1186 prior to immersion at the site. To accurately locate thethickness measurement locations on the panels for repeatedmeasurements, use a mask with two rows of five holes equallyspaced over th
41、e 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 with Test Method D 3623) as indicated by attach-ments to a dark nontoxic surface such as slate.9.5.1 Place
42、the panels on the stationary exposure racks,handling them only by the edges, and expose them in accor-dance with Test Method D 3623. Static exposure may beaccomplished by leaving the panels attached to the drum andnot rotating it. The time the panels are out of the water must bekept to a minimum. Wh
43、en any panels are removed from thestationary racks or the rotating drum, they are to be kept incontainers of seawater except during actual rating, photogra-phy, or thickness measurement. If the time out of water exceeds10 min, this fact should be recorded and reported.9.5.2 Subject the test panels t
44、o 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 concerned.9.6 Evaluate the antifouling panels for surface fouling andphysical condition of the film system at
45、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 antifouling test surface that is intact at the timeof inspection in accordance with Test Method D 3623. Ig
46、norefouling present on the substrate or on anticorrosive undercoats.Barnacles, polychaetes, coelenterates, etc. that 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
47、as“ algal slime.”Report absorbed organic and inorganic chemicals, trapped siltand detritus, and other unidentified slimes as “silt.”NOTE 11 in. = 25.4 mm.FIG. 2 Curved Exposure Panels for Rotating DrumD 4939 89 (2007)39.6.2 Physical ConditionRate the condition of coatingfilms in accordance with 10.2
48、. Record qualitative descriptionsof film deterioration and discoloration in the appropriatecolumn in Fig. 3 unless otherwise specified. Indicate deterio-ration of anticorrosive (AC) undercoats, when evident, by thenotation “AC.” For example, “Peeling antifouling film (AF)from AC” or “Chipping, AC fr
49、om steel.” For ablative coatingwith fouling-free areas, measure total coating thickness inaccordance with Test Methods D 1186 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 exposures. Record each of the inspection dates.During the exposures, record the range of water depth, tem-perature, salin
