ASTM_G_50_-_10_2015.pdf

Designation:G5010(Reapproved 2015)Standard Practice forConducting Atmospheric Corrosion Tests on Metals1This standard is issued under the fixed designation G50;the number immediately following the designation indicates the year of originaladoption or,in the case of revision,the year of last revision.Anumber in parentheses indicates the year of last reapproval.Asuperscriptepsilon()indicates an editorial change since the last revision or reapproval.1.Scope1.1 This practice covers and defines conditions for exposureof metals and alloys to the weather.It sets forth the generalprocedures that should be followed in any atmospheric test.Itis presented as an aid in conducting atmospheric corrosion testsso that some of the pitfalls of such testing may be avoided.Assuch,it is concerned mainly with panel exposures to obtaindata for comparison purposes.1.2 The values stated in inch-pound units are to be regardedas standard.The values given in parentheses are mathematicalconversions to SI units that are provided for information onlyand are not considered standard.1.3 This standard does not purport to address all of thesafety concerns,if any,associated with its use.It is theresponsibility of whoever uses this standard to consult andestablish appropriate safety and health practices and deter-mine the applicability of regulatory limitations prior to use.2.Referenced Documents2.1 ASTM Standards:2A380 Practice for Cleaning,Descaling,and Passivation ofStainless Steel Parts,Equipment,and SystemsD2010/D2010M Test Methods for Evaluation of Total Sul-fation Activity in the Atmosphere by the Lead DioxideTechniqueG1 Practice for Preparing,Cleaning,and Evaluating Corro-sion Test SpecimensG33 Practice for Recording Data from Atmospheric Corro-sion Tests of Metallic-Coated Steel SpecimensG46 Guide for Examination and Evaluation of Pitting Cor-rosionG84 Practice for Measurement of Time-of-Wetness on Sur-faces Exposed to Wetting Conditions as in AtmosphericCorrosion TestingG91 Practice for Monitoring Atmospheric SO2DepositionRate for Atmospheric Corrosivity EvaluationG92 Practice for Characterization of Atmospheric Test SitesG140 Test Method for Determining Atmospheric ChlorideDeposition Rate by Wet Candle Method3.Significance and Use3.1 The procedures described herein can be used to evaluatethe corrosion resistance of metals when exposed to the weather,as well as to evaluate the relative corrosivity of the atmosphereat specific locations.Because of the variability and complexityof weather effects and the industrial and natural factorsinfluencing the atmospheric corrosivity of a test site,a multi-year exposure period should be considered to minimize theirinfluence.Also,as corrosivity may vary at a site from season toseason,exposures should be made either at the same time ofthe year to minimize variability or these differences should beestablished by multiple exposures.3.2 Control specimens should always be employed inweathering tests.The control specimens should be from amaterial having established weathering characteristics.A sub-stantial amount of corrosion data shall have been accumulatedfor the control specimens.It is also good practice to retainsamples of all materials exposed so that possible effects oflong-term aging can be measured.4.Test Sites4.1 Test sites should be chosen at a number of locationsrepresentative of the atmospheric environments where themetals or alloys are likely to be used.If such information is notavailable,the selection should include sites typical ofindustrial,rural,andmarineatmospheres.Testsitecharacterization,if needed,shall be conducted in accordancewith Practice G92.4.2 Exposure racks should be located in cleared,well-drained areas such that the exposed specimens will be sub-jected to the full effects of the atmosphere at the location of thetest site.Shadows of trees,buildings,or structures should notfall on the specimens,and local contamination of the atmo-sphere should be avoided,unless the specific influences of suchconditions are intended to be assessed.4.3 In special cases,the exposure racks may be partiallysheltered to allow accumulation of corrosive materials from the1This practice is under the jurisdiction of ASTM Committee G01 on Corrosionof Metals and is the direct responsibility of Subcommittee G01.04 on AtmosphericCorrosion.Current edition approved Nov.1,2015.Published December 2015.Originallyapproved in 1976.Last previous edition approved in 2010 as G5010.DOI:10.1520/G0050-10R15.2For 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.Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 air but at the same time prevent washing by rain.If shelteringis used,its purpose and configuration should be described indetail.4.4 If local pollution effects are to be investi