ASTM_G_4_-_01_2014.pdf

Designation:G401(Reapproved 2014)Standard Guide forConducting Corrosion Tests in Field Applications1This standard is issued under the fixed designation G4;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 guide covers procedures for conducting corrosiontests in plant equipment or systems under operating conditionsto evaluate the corrosion resistance of engineering materials.Itdoes not cover electrochemical methods for determining cor-rosion rates.1.1.1 While intended primarily for immersion tests,generalguidelines provided can be applicable for exposure of testspecimens in plant atmospheres,provided that placement andorientation of the test specimens is non-restrictive to aircirculation.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.See also 10.4.2.2.Referenced Documents2.1 ASTM Standards:2A262 Practices for Detecting Susceptibility to IntergranularAttack in Austenitic Stainless SteelsE3 Guide for Preparation of Metallographic SpecimensG1 Practice for Preparing,Cleaning,and Evaluating Corro-sion Test SpecimensG15 Terminology Relating to Corrosion and Corrosion Test-ing(Withdrawn 2010)3G16 Guide for Applying Statistics to Analysis of CorrosionDataG30 Practice for Making and Using U-Bend Stress-Corrosion Test SpecimensG36 Practice for Evaluating Stress-Corrosion-Cracking Re-sistance of Metals and Alloys in a Boiling MagnesiumChloride SolutionG37 Practice for Use of Mattssons Solution of pH 7.2 toEvaluate the Stress-Corrosion Cracking Susceptibility ofCopper-Zinc AlloysG41 Practice for Determining Cracking Susceptibility ofMetals Exposed Under Stress to a Hot Salt EnvironmentG44 Practice for Exposure of Metals andAlloys byAlternateImmersion in Neutral 3.5%Sodium Chloride SolutionG46 Guide for Examination and Evaluation of Pitting Cor-rosionG47 Test Method for Determining Susceptibility to Stress-Corrosion Cracking of 2XXX and 7XXX AluminumAlloy ProductsG58 Practice for Preparation of Stress-Corrosion Test Speci-mens for WeldmentsG78 Guide for Crevice Corrosion Testing of Iron-Base andNickel-Base Stainless Alloys in Seawater and OtherChloride-Containing Aqueous Environments2.2 NACE Standard:4RP0497 Field Corrosion Evaluation Using Metallic TestSpecimens3.Significance and UseNOTE1This guide is consistent with NACE Standard RP0497.3.1 Observations and data derived from corrosion testingare used to determine the average rate of corrosion or othertypes of attack,or both(see Terminology G15),that occurduring the exposure interval.The data may be used as part ofan evaluation of candidate materials of construction for use insimilar service or for replacement materials in existing facili-ties.3.2 The data developed from in-plant tests may also be usedas guide lines to the behavior of existing plant materials for thepurpose of scheduling maintenance and repairs.3.3 Corrosion rate data derived from a single exposuregenerally do not provide information on corrosion rate change1This guide is under the jurisdiction of ASTM Committee G01 on Corrosion ofMetals and is the direct responsibility of Subcommittee G01.14 on Corrosion ofMetals in Construction Materials.Current edition approved Nov.1,2014.Published November 2014.Originallyapproved in 1968.Last previous edition approved in 2008 as G401(2008).DOI:10.1520/G0004-01R14.2For 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 NACE International(NACE),1440 South Creek Dr.,Houston,TX 77084-4906,http:/www.nace.org.Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 versus time.Corrosion rates may increase,decrease,or remainconstant,depending on the nature of the corrosion products andthe effects of incubation time required at the onset of pitting orcrevice corrosion.4.Limitations4.1 Metal specimens immersed in a specific liquid may notcorrode at the same rate or in the same manner as in equipmentin which the metal acts as a heat transfer medium in heating orcooling the liquid.In certain services,the corrosion of heat-exchanger tubes may be quite different from that of the shell orheads.This phenomenon also occurs on specimens exposed ingas str