ASTM_G_97_-_97_2013.pdf

Designation:G9797(Reapproved 2013)Standard Test Method forLaboratory Evaluation of Magnesium Sacrificial Anode TestSpecimens for Underground Applications1This standard is issued under the fixed designation G97;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 test method covers a laboratory procedure thatmeasures the two fundamental performance properties ofmagnesium sacrificial anode test specimens operating in asaturated calcium sulfate,saturated magnesium hydroxideenvironment.The two fundamental properties are electrode(oxidation potential)and ampere hours(Ah)obtained per unitmass of specimen consumed.Magnesium anodes installedunderground are usually surrounded by a backfill material thattypically consists of 75%gypsum(CaSO42H2O),20%ben-tonite clay,and 5%sodium sulfate(Na2SO4).The calciumsulfate,magnesium hydroxide test electrolyte simulates thelong term environment around an anode installed in thegypsum-bentonite-sodium sulfate backfill.1.2 This test method is intended to be used for qualityassurance by anode manufacturers or anode users.However,long term field performance properties may not be identical toproperty measurements obtained using this laboratory test.NOTE1Refer to Terminology G15 for terms used in this test method.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.For specificprecautions,See Section 7 and Paragraph 8.1.1.2.Referenced Documents2.1 ASTM Standards:2D1193 Specification for Reagent WaterG3 Practice for Conventions Applicable to ElectrochemicalMeasurements in Corrosion TestingG15 Terminology Relating to Corrosion and Corrosion Test-ing(Withdrawn 2010)3G16 Guide for Applying Statistics to Analysis of CorrosionData2.2 American National Standard:ANSI/NFPA 480 Storage,Handling,and Processing ofMagnesium,1987 Edition43.Summary of Test Method3.1 A known direct current is passed through test cellsconnected in series.Each test cell consists of a pre-weighedtest magnesium alloy anode specimen,a steel pot containercathode,and a known electrolyte.Test specimen oxidationpotential is measured several times during the 14-day test and1 h after the current is turned off at the end of the test.The totalAh passed through the cells are measured.At the conclusion ofthe test,each test specimen is cleaned and weighed.The Ahobtained per unit mass of specimen lost is calculated.4.Significance and Use4.1 This test is a guide for evaluating magnesium anodes.The degree of correlation between this test and service perfor-mance has not been fully determined.5.Apparatus5.1 The basic test equipment consists of the following:5.1.1 Direct Current Power Source,(optional),capable ofdelivering at least 2 mA and 12 V.5.1.2 Steel Cathode Test Pot,as shown in Fig.1.5.1.3 Copper Coulometer,as shown in Fig.2,or ElectronicCoulometer.5.1.4 Saturated Calomel Reference Electrode.5.1.5 Electrometer,with an input impedance of 107orgreater ohms.5.1.6 Balance,100-g capacity with 0.1 mg sensitivity.5.1.7 Drying Oven,with temperature capability of 110C orhigher.1This test method is under the jurisdiction of ASTM Committee G01 onCorrosion of Metals and is the direct responsibility of Subcommittee G01.10 onCorrosion in Soils.Current edition approved May 1,2013.Published July 2013.Originally approvedin 1989.Last previous edition approved in 2007 as G9797(2007).DOI:10.1520/G0097-97R13.2For 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 National Fire Protection Association(NFPA),1 BatterymarchPark,Quincy,MA 02169-7471,http:/www.nfpa.org.Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 6.Reagents6.1 Test Electrolyte,Saturated Calcium Sulfate-MagnesiumHydroxide SolutionAdd 5.0 g of reagent grade CaSO42H2O,0.1 g of reagent grade Mg(OH)2,to 1000 mL of Type IV orbetter reagent grade water(see Specification D1193).6.2 Coulometer SolutionAdd 235 g of reagent gradeCuSO45H2O,27 mL 98%H2SO4,50 cm3undenatured ethylalcohol to 900 mL of Type IV or better reagent grade water.6.3 Anode Cleaning SolutionAdd 250 g of reagent gradeCrO3to 1000 mL of Type IV or better reagent grade water.7.Precautions7.1 Eye protection and skin protection are required whenhandling the coulometer solution and when handling thecleaning solution.Test specimen