ASTM_B_418_-_16a.pdf

Designation:B41816aStandard Specification forCast and Wrought Galvanic Zinc Anodes1This standard is issued under the fixed designation B418;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.Scope*1.1 This specification covers cast and wrought galvanic zincanodes used for the cathodic protection of more noble metalsand alloys in sea water,brackish water,other salineelectrolytes,or other corrosive environments.1.2 Type I anodes are most commonly used for suchapplications.The Type I anode composition in this specifica-tion meets the chemical composition requirements of MIL-A-18001K.1.3 Zinc anodes conforming to this specification may beused in other waters,electrolytes,backfills,and soils whereexperience has shown that the specified composition is efficientand reliable.Type II anodes are most commonly used for suchapplications.1.4 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.1.5 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 become familiarwith all hazards including those identified in the appropriateSafety Data Sheet(SDS)for this product/material as providedby the manufacturer,to establish appropriate safety and healthpractices,and determine the applicability of regulatory limi-tations prior to use.2.Referenced Documents2.1 ASTM Standards:2B6 Specification for ZincB899 Terminology Relating to Non-ferrous Metals and Al-loysB949 Specification for General Requirements for Zinc andZinc Alloy ProductsE29 Practice for Using Significant Digits in Test Data toDetermine Conformance with SpecificationsE527 Practice for Numbering Metals and Alloys in theUnified Numbering System(UNS)E536 Test Methods for Chemical Analysis of Zinc and ZincAlloys2.2 Military Standard:3MIL-A-18001K w/INT.AMENDMENT 3,24 October2007 Military Specification Anodes Sacrificial Zinc Alloy2.3 ISO Standards:4ISO 3815-1 Zinc and zinc alloys Part 1:Analysis of solidsamples by optical emission spectrometryISO 3815-2 Zinc and zinc alloys Part 2:Analysis byinductively coupled plasma optical emission spectrometry3.Terminology3.1 Terms shall be defined in accordance with TerminologyB899.3.2 Definitions of Terms Specific to This Standard:3.2.1 cathodic protection,nreduction of corrosion bymaking the protected metal the cathode in a conductingmedium by applying direct current.3.2.2 galvanic anode,na metal electrode that sacrificiallycorrodes when coupled to a more noble metal in a conductingmedium,and thereby supplies a protective electric current tothe noble electrode.3.2.3 saline electrolyte,na solution consisting of mainlythe chlorides of the alkali metals.4.Ordering Information4.1 Orders for zinc anodes under this specification shallinclude information as specified in Specification B949.4.2 Additional ordering information specific to this standardis as follows:4.2.1 Type of anode material(see Table 1),4.2.2 Number of anodes,1This specification is under the jurisdiction of ASTM Committee B02 onNonferrous Metals and Alloys and is the direct responsibility of SubcommitteeB02.04 on Zinc and Cadmium.Current edition approved Oct.1,2016.Published November 2016.Originallyapproved in 1964.Last previous edition approved in 2016 as B418 16.DOI:10.1520/B0418-16a.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.3Available from DLA Document Services,Building 4/D,700 Robbins Ave.,Philadelphia,PA 19111-5094,http:/quicksearch.dla.mil.4Available from American National Standards Institute(ANSI),25 W.43rd St.,4th Floor,New York,NY 10036,http:/www.ansi.org.*A Summary of Changes section appears at the end of this standardCopyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 4.2.3 Size of anode and whether contains rod insert and ifso,type of insert and whether contains bolt hole and if so,whether threaded.5.Chemical Requirements5.1 The anode shall be made from Special High Grade zincconforming to Specification B6,with suitable alloying addi-tions for Type I anodes.Composition of the anode alloy contentshall conform to the limits prescribed in Table 1.5.2 Evidence from laboratory tests shows that Type Icomposition may suffer intergranular corrosion.Susceptibilityto intergranular corrosion increases with increasing tempera-ture and is particularly severe above approximately 120F(50C).Intergranular corrosion can be avoided(at tempera