ASTM_G_157_-_98_2013.pdf

Designation:G15798(Reapproved 2013)Standard Guide forEvaluating Corrosion Properties of Wrought Iron-andNickel-Based Corrosion Resistant Alloys for ChemicalProcess Industries1This standard is issued under the fixed designation G157;the number immediately following the designation indicates the year oforiginal adoption 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 guide covers an evaluation approach that is de-signed to provide information on the corrosion properties ofwrought iron-and nickel-based alloys for the chemical processindustries.This guide incorporates test conditions for generalcorrosion measurements in a variety of environments,crevicecorrosion resistance in chloride environments,and stress cor-rosion cracking resistance in chloride environments.1.2 The values stated in SI units are to be regarded asstandard.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 to determine theapplicability of regulatory limitations prior to use.2.Referenced Documents2.1 ASTM Standards:2D1193 Specification for Reagent WaterG1 Practice for Preparing,Cleaning,and Evaluating Corro-sion Test SpecimensG15 Terminology Relating to Corrosion and Corrosion Test-ing(Withdrawn 2010)3G30 Practice for Making and Using U-Bend Stress-Corrosion Test SpecimensG36 Practice for Evaluating Stress-Corrosion-Cracking Re-sistance of Metals and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 SolutionG46 Guide for Examination and Evaluation of Pitting Cor-rosionG48 Test Methods for Pitting and Crevice Corrosion Resis-tance of Stainless Steels and Related Alloys by Use ofFerric Chloride SolutionG123 Test Method for Evaluating Stress-Corrosion Crackingof Stainless Alloys with Different Nickel Content inBoiling Acidified Sodium Chloride Solution3.Terminology3.1 Terms such as crevice corrosion,stress corrosioncracking,and corrosion rate are defined in Terminology G15.4.Significance and Use4.1 This guide is intended to provide a series of evaluationsthat will assist engineers dealing with chemical environmentsin selecting appropriate alloys(1-3).In chemical environments,an important issue for determining general corrosion resistanceis the temperature at which an alloy transitions from corrosionat a low rate to corrosion at a much higher rate.Otherimportant concerns include the tendency towards crevicecorrosion and stress corrosion cracking resistance,especially inhot chloride-containing aqueous environments.4.2 This guide is also intended for alloy developers to assistthem in choosing environments and test methods that are ofparticular interest to the chemical process industries.4.3 The use of this approach will allow direct comparisonsto be made among alloys from various suppliers and,thereby,to assist engineers in selecting the most appropriate materialsfor further testing to determine suitability in their application.5.General Corrosion Resistance5.1 The general corrosion resistance of nickel-and iron-based alloys is determined in 14 test solutions at varioustemperatures to determine the lowest temperature at which thecorrosion rate exceeds 0.13 mm/y(5 mpy).The test solutionsare listed in Table 1.A suggested procedure is provided inAppendix X1.The test is run on three coupons of metal foreach environment.The tests are run for two 48-h exposureswith one specimen exposed for the total 96 h.Welded speci-mens may be used if results are required on weldments.1This guide is under the jurisdiction of ASTM Committee G01 on Corrosion ofMetals and is the direct responsibility of Subcommittee G01.05 on LaboratoryCorrosion Tests.Current edition approved May 1,2013.Published July 2013.Originally approvedin 1998.Last previous edition approved in 2005 as G157 98(2005).DOI:10.1520/G0157-98R13.2For 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.Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 5.2 The corrosion rates are based on mass loss measure-ments with appropriate conversion to thickness loss as shownin Appendix X1.5.3 The results of the tests in each solution should bereported on a summary results sheet.Atypical format is shownin Fig.1 and Fig.2.6.Six Percent Ferric Chloride Solution Critical CreviceCorrosion Temperature6.1 The crevice corrosion resistance of each alloy is to beevaluated as described in Test Methods G48,Method D.Thestandard exposure perio