ASTM_G_85-19.pdf

This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for theDevelopment of International Standards,Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade(TBT)Committee.Designation:G85-19NTERNATIONALStandard Practice forModified Salt Spray(Fog)TestingThis standard is issued under the fixed designation G85:the number immediately following the designation indicates the year of originaladoption or,in the case of revision.the year of last revision.A number in parentheses indicates the year of last reapproval.A superscriptepsilon(e)indicates an editorial change since the last revision or reapproval.This standard has been approved for use by agencies of the U.S.Department of Defense.1.ScopeD609 Practice for Preparation of Cold-Rolled Steel Panels1.1 This practice covers and sets forth conditions for fivefor Testing Paint,Varnish,Conversion Coatings,andmodifications in salt spray(fog)testing for specificationRelated Coating Productspurposes.These are in chronological order of their develop-D1141 Practice for the Preparation of Substitute Oceanment:Water1.1.1 Annex A/,acetic acid-salt spray test,continuous.D1193 Specification for Reagent Water1.1.2 Annex A2,cyclic acidified salt spray test.D1654 Test Method for Evaluation of Painted or Coated1.1.3 Annex A3,seawater acidified test,cyclic(SWAAT).Specimens Subjected to Corrosive Environments1.1.4 Annex A4,SO2 salt spray test,cyclic.E70 Test Method for pH of Aqueous Solutions With the1.1.5 Annex A5,dilute electrolyte cyclic fog dry test.Glass Electrode1.2 This practice does not prescribe the type ofmodification,test specimen or exposure periods to be used for3.Significance and Usea specific product,nor the interpretation to be given to the3.1 This practice is applicable to ferrous and nonferrousresults.metals;also organic and inorganic coatings.The variations1.3 The values stated in SI units are to be regarded asdescribed herein are useful when a different or more corrosivestandard.The values given in parentheses after SI units areenvironment than the salt fog described in Practice B117 isprovided for information only and are not considered standard.desired.1.4 This standard does not purport to address all of thesafety concerns,if any,associated with its use.It is the4.Apparatusresponsibility of the user of this standard to establish appro-4.1 Cabinet:priate safety,health,and environmental practices and deter-mine the applicability of regulatory limitations prior to use.4.1.1 The apparatus required for salt spray(fog)testing1.5 This international standard was developed in accor-consists of a fog chamber,a salt solution reservoir,a supply ofsuitably conditioned compressed air,one or more atomizingdance with internationally recognized principles on standard-ization established in the Decision on Principles for thenozzles,specimen supports,provision for heating the chamber,Development of International Standards,Guides and Recom-and necessary means of control.The size and detailed con-mendations issued by the World Trade Organization Technicalstruction of the cabinet are optional,provided the conditionsBarriers to Trade(TBT)Committee.obtained meet the requirements of this practice.The material ofconstruction shall be such that it will not affect the corrosive-2.Referenced Documentsness of the fog.Suitable apparatus that may be used to obtain2.1 ASTM Standards:2these conditions is described in Appendix XI of Practice B117B117 Practice for Operating Salt Spray(Fog)Apparatuswith necessary modifications described in each annex of thispractice.IThis practice is under the jurisdiction of ASTM Committee Gol on Corrosion4.1.2 Design the cabinet so that drops of solution thatof Metals and is the direct responsibility of Subcommittee G01.05 on Laboratoryaccumulate on the ceiling or cover of the chamber do not fallCorrosion Tests.on the specimens being tested.Do not return drops of solutionCurrent edition approved Nov.I.2019.Published December 2019.Originallyapproved in 1985.Last previous edition approved in 2011 as G85-11.DOI:that fall from the specimens to the solution reservoir for10.1520/G0085-19.respraying.2 For referenced ASTM standards,visit the ASTM website,www.astm.org,orcontact ASTM Customer Service at service astm.org.For Annual Book of ASTM4.1.3 Equip the cabinet with one or more timing devices toStandards volume information.refer to the standards Document Summary page onprovide for intermittent spraying or periodic introduction of athe ASTM website.gas,or both.Copyright ASTM Intemational,100 Barr Harbor Drive,PO Box C700.West Conshohocken.PA 19428-2959.United StatesG85-194.2 Air Supply:solution for the chemical cleaning,or passivation,of stainless4.2.1 Make sure the compressed air supply to the nozzle orsteel specimens is permissible when agreed upon between thenozzles for atomizing the salt solution is free of oil and dirt andpurchaser and the seller.Take care that specimens are notmaintain the air supply between 69 and 172 kPa(10 and 25recontaminated after cleaning by excessive or careless han-psi).dling.NorE 1-The air supply may be freed of oil and dirt by passing it5.2.2 Prepare specimens for evaluation of paints and otherthrough a water scrubber or at least 610 mm(2 ft)of suitable cleaningorganic coatings in accordance with applicable specification(s)material such as asbestos,sheeps wool,or activated alumina.for the material(s)being tested,or as agreed upon between the4.2.2 Temperature in the saturator tower(bubble tower)purchaser and supplier.Otherwise,make sure the test speci-varies depending on the test method used.mens consist of steel meeting the requirements of PracticeD609:clean and prepare the specimens for coating in accor-4.3 Conditions in Salt-Spray Chamber:dance with applicable procedure of Practice D609.4.3.1 Temperature-The temperature in the exposure zone5.2.3 Whenever it is desired to determine the developmentvaries with the test method used.For recommended exposureof corrosion from an abraded area in the paint or organiczone temperatures for the various methods,see the annexes incoating,make a scratch or scribed line through the coating withthis practice.Each set point and its tolerance represents ana sharp instrument so that the underlying metal is exposedoperational control point for equilibrium conditions at a singlebefore testing.Use the conditions of making the scratch aslocation in the cabinet which may not necessarily represent thedefined in Test Method D1654,unless otherwise agreed uponuniformity of conditions throughout the cabinet.Record thebetween the purchaser and seller.temperature within the exposure zone of the closed cabinet at5.2.4 Protect the cut edges of plated,coated,or duplexleast twice a day at least 7 h apart(except on weekends andmaterials and areas that contain identification marks or that areholidays,when the salt spray test is not interrupted forin contact with the racks or supports with a suitable coating thatexposing,rearranging,or removing test specimens or to checkis stable under the conditions of the test,such as ceresin waxand replenish the solution in the reservoir).unless otherwise specified.NorE 2-Suitable methods to record the temperature are a continuousNorE 4-Should it be desirable to cut test specimens from parts or fromrecording device or a thermometer which can be read from outside thepreplated,painted,or otherwise coated-steel sheet,protect the cut edgesclosed cabinet.Obtain the recorded temperature with the salt sprayby coating them with paint,wax,tape,or other effective media so that thechamber closed to avoid a false low reading because of wet-bulb effectdevelopment of preferential attack or a galvanic effect between such edgeswhen the chamber is open.and the adjacent plated or otherwise coated-metal surfaces,is prevented.4.3.2 Atomization and Quantity of Fog-Place at least twoclean fog collectors within the exposure zone so that no drops6.Salt Solutionsof solution from the test specimens or any other source can be6.1 Make the salt solutions by using either synthetic sea saltcollected.Position the collectors in the proximity of the testin accordance with Practice D1141 or sodium chloride inspecimens,one nearest to any nozzle and the other farthestaccordance with Practice B117,unless otherwise specified infrom all nozzles.Make sure that for each 80 cm-of horizontal-the appropriate annex.Make-up water shall be distilled orcollecting area fog accumulates in each collector from 1.0 todeionized water conforming to Type IV water in Specification2.0 mL of solution per hour based on an average run of at leastD1193(except that for this practice,limits for chlorides and16 h continuous spray.sodium may be ignored).NorE 3-Suitable collecting devices are glass funnels with the stems6.2 Synthetic Sea Salt Solution(see Annex A3)-Make theinserted through stoppers into graduated cylinders or crystallizing dishes.salt solution so that it consists of 42 g of synthetic sea salt inFunnels and dishes with a diameter of 100 mm have an area of about 80accordance with Practice D1141 per litre of solution(see Notecm25).4.3.3 Direct or baffle the nozzle or nozzles so that none of6.3 Sodium Chloride Solution(Except Annex A3 and Annexthe spray can impinge directly on the test specimens.A5):Prepare the salt solution by dissolving 51 parts by5.Test Specimensweight of sodium chloride in 95 parts of water conforming toType IV water in Specification D1193(except that for this5.1 Define the type and number of test specimens to be used,practice,limits for chlorides and sodium may be ignored)as well as the criteria for the evaluation of the test results in thecontaining not more than 200 ppm of total solids(see Note 5).specifications covering the material or product being tested orHalides(Bromide,Fluoride,and lodide)other than Chlorideupon mutual agreement between the purchaser and the seller.shall constitute less than 0.1 by mass of the salt content.5.2 Preparation of Test Specimens:Copper content shall be less than 0.3 ppm by mass.Sodium5.2.1 Clean metallic and metallic-coated specimens.Thechloride that has had anti-caking agents added shall not be usedcleaning method is optional depending on the nature of thebecause such agents may act as corrosion inhibitors(see Notesurface and the contaminants;however,when using a cleaning6).See Table I for a listing of these impurity restrictions.Uponmethod do not include in the contents abrasives other than aagreement between the purchaser and the seller,analysis maypaste of pure magnesium oxide nor of solvents which maybe required and limits established for elements or compoundsform corrosive or inhibitive films.The use of nitric acidnot specified in the chemical composition given above.G85-19TABLE 1 Maximum Allowable Limits for Impurity Levels in7.1.2 Do not allow contact of the specimens between eachSodium Chlorideother,between any metallic material,or between any materialImpurity DescriptionAllowable Amountcapable of acting as a wick.Total Impurities0.3%Halides(Bromide,Fluoride and lodide)0.1%7.1.3 Place each specimen so as to permit free settling of fogexcluding Chlorideon all specimens.A minimum spacing between specimens ofCopper0.3 ppm30 mm is recommended.Anti-caking AgentsNone Added7.1.4 Do not permit the salt solution from one specimen todrip on any other specimen.7.1.5 It is recommended that placement of replicate speci-NorE 5-The specific gravity of salt solution will change withmens be randomized to avoid possible bias caused by differ-temperature.Table 2 shows salt concentration and density versus tempera-ture and can be used to determine if the sample measured is withinence in spray patterns.Individual specimens may also bespecification.The sample to be measured may be a composite sample fromrotated daily for the same reason.multiple fog-collecting devices within a single cabinet,if necessary,toobtain sufficient solution volume for measurement.7.1.6 Suitable materials for the construction or coating ofTable 2shows the salt concentration and salt density of 4%5%andracks and supports are glass,rubber,plastic,or suitably coated6%salt solution between 20 and 40 C.A measurement that falls withinwood.Do not use bare metal.Support specimens preferablythe range between 4 and 6 is acceptable.from the bottom or the side.Slotted wooden,laminated plastic,It is important to understand the equipment being used to measureor inert plastic strips are suitable for the support of flat panels.specific gravity.One common practice for specific gravity measurement isthe use of a hydrometer.If used,careful attention to the hydrometer typeSuspension from glass hooks or waxed string may be used asis important as most are manufactured and calibrated for measurements atlong as the specified position of the specimens is obtained,and,15.6C.Since salt density is temperature dependent an offset will beif necessary,by means of secondary support at the bottom ofnecessary to make an accurate measurement at other temperatures.Contact the hydrometer manufacturer to find the proper offset for thethe specimens.hydrometer being used.7.2 Continuity of Test-Unless otherwise specified in theNorE 6-A measurable limit for anti-caking agents is not being definedas a result of how salt is manufactured.During salt manufacturing,it isspecifications covering the material or product being tested,thecommon practice to create salt slurry from the raw salt mined.Atest shall be continuous for the duration of the entire testcrystallization process then captures the pure salt from this slurry.Someperiod.Continuous operation implies that the chamber benaturally occurring anti-caking agents can be formed in this process andclosed except for the short daily interruptions necessary toare not removed from the resultant product.Avoid salt products whereextra anti-caking agents are added.Additionally,when doing an elementalinspect,rearrange,or remove test specimens,to check andanalysis of salt there can be trace elements present that either stand alonereplenish the solution in the reservoir,and to make necessaryor are part of an anti-caking agent.It is not economically feasible to knowrecordings as described in 4.3.1,4.3.2,and Section 9.(Seewhere such elements came from due to the long list of possible anti-cakingNote 8.)agents that would have to be tested.Therefore a salt product that meets theimpurity,halide,and copper limits with no anti-caking agents added isNorE 8-Operations should be so scheduled that the cumulativeacceptable.The salt supplier can provide an analysis of the salt with amaximum time for these interruptions are held to 60 min or less per daystatement indicating that anti-caking agents were not added to the product.It is recommended to have only one interruption per day if possible.If6.4 The pH of the salt solutions will vary depending on theinterruption time is longer that 60 min,it should be noted in the test report.test method used.Before the solution is atomized,free it of7.3 Period of Test-Designate the period of test in accor-suspended solids(see Note 7).Take the pH measurementselectrometrically at 25 C(77 F)using a glass electrode withdance with the specifications covering the material or productbeing tested or as mutually agreed upon between the purchasera saturated potassium chloride bridge in accordance with TestMethod E70.and the seller.Exposure periods of multiples of 24 h aresuggested.NorE 7-The freshly prepared salt solution may be filtered or decantedbefore it is placed in the reservoir,or the end of the tube leading from the7.4 Cleaning of Tested Specimens-Unless otherwise speci-solution to the atomizer may be covered with a double layer of cheeseclothfied in the specifications covering the material or product beingor suitable nonmetallic filter cloth to prevent plugging of the nozzle.tested,at the end of the test,specimens may be gently washed7.Procedureor dipped in clean running water no warmer than 38C(100 F)to remove salt deposits from their surface,and then7.1 Position of Specimens During Test:immediately dried.Dry with a stream of clean,compressed air.7.1.1 Unless otherwise specified,support or suspend thespecimens with the surface of interest at an angle between 6NoTE 9-Drying with compressed air may not be desirable forand 45 from the vertical.It is recommended that the orienta-aluminum specimens to be tested for exfoliation corrosion resistance.tion of specimens in the cabinet be consistent to minimizevariability.Note that test severity increases as angle from the8.Evaluation of Resultsvertical increases.8.1 Make a careful and immediate examination for theextent of corrosion of the dry test specimens or for other failureas required by the specifications covering the material or3Thermodynamic Properties of the NaCl H20 system II.ThermodynamicProperties of NaCl(ag).NaCl.2H20(cr).and Phase Equilibria,Journal of Phrysicsproduct being tested or by agreement between the purchaserand Chemistry Reference Data,Vol 21.No.4,1992.and the seller.G85-19TABLE 2 Temperature versus Density DataDensity,g/cmTemperature,C(F)4%Salt5%Salt6%SaltConcentrationConcentrationConcentration20(68)1.0257581.0323601.03886721(69.8)1.0254801.0320671.03856022(71.6)1.0251931.0317661.03824523(73.4)1.0248991.0314581.03792424(75.2)1.0245961.0311421.03759625(77)1.0242861.0308191.03726126(78.8)1.0239691.0304891.03691927(80.6)1.02364310301521.03657028(82.4)1.0233111.0298081.03621529(84.2)1.0229711.0294571.03585330(86)1.0226241.0290991.03548531(87.8)1.0222701.0287351.03511032(89.6)1.0219101.0283641.03472933(91.4)1.0215421.0279861.03434334(93.2)1.0211681.0276021.03395035(95)1.0207871027212103355136(96.8)1.0203991.0268161.03314637(98.61.0200061.0264131.03273538(100.4)1.0196051.0260051.03231939(102.2)1.0191991.0255901.03189740(104)1.0187861.0251701.0314699.Reportfog-collecting devices for concentration or specific gravity at9.1 Record the following information,unless otherwise23 C 3C(73F+5F)of solution collected(see Noteprescribed in the specifications covering the material or prod-11)and pH of collected solution.Sample to be measured mayuct being tested:be a composite sample from multiple fog-collecting devices9.1.1 Type of salt and water used in preparing the salt(within one test chamber),if necessary to obtain sufficientsolution,solution volume for measurement.All records of data obtained9.1.2 All readings of temperature within the exposure zonefor volume of salt solution collected in millilitres per hour perof the chamber.each 80 cm2 fog collecting device.(See 4.3.2.)9.1.3 Weekly or daily records,see Note 10,(depending onNoTE 10-Except on Saturday,Sundays,and holidays,when the test iswhich test annex is being performed)of data obtained fromnot interrupted for exposing,rearranging,or removing test specimens or toeach fog-collecting device for volume of salt solution collectedcheck and replenish the solution in the reservoir(s).in millilitres per hour of operation per 80 cm2 of horizontal9.1.7 Type of specimen and its dimensions,or number orcollection area.description of part,9.1.4 Concentration or specific gravity of collected solution9.1.8 Method of cleaning specimens before and afterand the temperature of that solution when measured.Followtesting,Table 2 for salt concentration and density versus temperature to9.1.9 Method of supporting or suspending article in the saltdetermine that the sample measured is within specification.spray chamber,Sample to be measured may be a composite sample from9.1.10 Description of protection used as required in 5.2.4,multiple fog-collecting devices within a single cabinet,if9.1.11 Exposure period,necessary,to obtain sufficient solution volume for measure-9.1.12 Interruptions in test,cause and length of time,andment.9.1.13 Results of all inspections.9.1.5 pH of collected solution.Sample to be measured mayNorE 11-It is also advisable to record the concentration or specificbe a composite sample from multiple fog collecting devicesgravity of any atomized salt solution that has not made contact with thewithin a single cabinet,if necessary,to obtain sufficienttest specimen and that was returned to the reservoir.solution volume for measurement.9.1.6 Weekly or daily records,see Note 10,(depending on10.Keywordswhich test annex is being performed)of data obtained from10.1 acidic salt spray;corrosion;salt spray4G85-19ANNEXES(Mandatory Information)A1.ACETIC ACID-SALT SPRAY(FOG)TESTINGA1.1 Salt SolutionA1.3 Conditions in the Salt Spray ChamberAl.1.1 A sodium chloride solution made in accordance withA1.3.1 Temperature-Maintain the exposure zone of the6.3.acetic acid-salt spray fog chamber at 35 C+2C(95 F+A1.1.2 Adjust the pH of this solution measured in accor-3 F).Each set point and its tolerance represents an operationaldance with Test Method E70 to range from 3.1 to 3.3 by thecontrol point for equilibrium conditions at a single location inaddition of acetic acid.the cabinet which may not necessarily represent the uniformityNorE A1.1-The initial solution may be adjusted to pH of 3.0 to 3.1of conditions throughout the cabinet.with the expectation that the pH of the collected fog will be within thespecified limits.Base the adjustment of the initial pH for make-up solutionNorE A1.2-This test is particularly applicable to research studies thatupon the requirements to maintain the required pH of the collectedhave the effect of altering parameters of the electroplating process insamples.If less than 0.I or more than 0.3 of the glacial acetic acid isconnection with decorative chromium plating on steel or zinc die-cast baserequired to attain the specified pH,the purity of the water or salt,or bothas well as for the evaluation of the quality of the product.This is truemay not be satisfactory.because of the normal duration of the test,which may be as brief as 16 h.but normally runs for 144 to 240 h or more giving ample opportunity forA1.2 Conditions in Saturator Towerobservations at practical intervals of the effects of minor parameterchanges.A1.2.1 Make sure the temperature in the saturator tower(bubble tower)is47C1C(1172F).A2.CYCLIC ACIDIFIED SALT FOG TESTINGA2.1 Salt SolutionA2.3.3 Cabinet-Equip the chamber with a timing deviceA2.1.1 Use a sodium chloride solution made in accordancethat can be used for the following 6 h repetitive cycles:34 hwith 6.3.spray;2 h dry-air purge;and 31 h soak at high relativehumidity.A2.1.2 Adjust the pH of this solution to range from 2.8 to3.0 by the addition of acetic acid.A2.3.4 Purge-Purging of the fog atmosphere immediatelyafter spraying is the most unique feature of this test.Dry allA2.2 Conditions in Saturator Towerdroplets of water on the specimens and dry the corrosionA2.2.1 Make sure the temperature in the saturator towerproducts so that they are of a white,rather than a damp gray(bubble tower)is57C1C(1352F).appearance.Perform this by electrically switching the air-flowA2.3 Conditions in Salt-Spray Chamberto bypass the saturator tower and aspirator nozzle and allowingit to enter directly into the test chamber for 120 min at an angleA2.3.1 Temperature-Maintain the temperature in the ex-that sweeps the fog out of the peaked lid of the cabinet.Thisposure zone of the salt spray chamber at 49 C+2C(120 Freduces the relative humidity from 40 to 7%,depending on the3F).climatic conditions of the ambient air.After purging,theA2.3.2 Humidity-Although the humidity limits for opti-specimens remain in the closed cabinet until the next spraymum test conditions have not been determined,operate the saltcycle.Since most testing requires a wet bottom,the humidityspray chamber under wet bottom conditions(that is,make suregradually increases from 65 to 95 during this period.an inch or so of water is present in the bottom of the box)formost testing.This ensures that the interior of the box does notA2.3.5 Atomization and Quantiry of Fog-Collect the fog inbecome dry,a condition that decreases corrosion rate.(The drya special continuous spray run of at least 16 h periodicallybottom is recommended,however,for testing 2000-seriesbetween test runs.Determine the proper consumption ofaluminum alloys and paint coatings that require a less aggres-solution by monitoring solution level in the collection devices.sive environment.)44 Personal communication.Alcoa Technical Center.New Kensington.PA.5