Designation:B418−12
Standard Specification for
Cast and Wrought Galvanic Zinc Anodes1
This standard is issued under thefixed designation B418;the number immediately following the designation indicates the year of original adoption or,in the ca of revision,the year of last revision.A number in parenthes indicates the year of last reapproval.A superscript epsilon(´)indicates an editorial change since the last revision or reapproval.
This standard has been approved for u by agencies of the Department of Defen.
1.Scope*
1.1This specification covers cast and wrought galvanic zinc anodes ud for the cathodic protection of more noble metals and alloys in a water,brackish water,other saline electrolytes,or other corrosive environments.
1.2Type I anodes are most commonly ud for such applications.The Type I anode composition in this specifica-tion meets the chemical composition requirements of MIL-A-18001K.
1.3Zinc anodes conforming to this specification may be ud in other waters,electrolytes,backfills,and soils where experience has shown that the specified composition is efficient and reliable.Type II anodes are most commonly ud for such applications.
1.4The values stated in inch-pound units are to be regarded as standard.The values given in parenthes are mathematical conversions to SI units that are provided for information only and are not considered standard.
1.5This standard does not purport to address all of the safety concerns,if any,associated with its u.It is the responsibility of the ur of this standard to become familiar with all hazards including th
o identified in the appropriate Material Safety Data Sheet(MSDS)for this product/material as provided by the manufacturer,to establish appropriate safety and health practices,and determine the applicability of regulatory limitations prior to u.
2.Referenced Documents
2.1ASTM Standards:2
B6Specification for Zinc
B899Terminology Relating to Non-ferrous Metals and Al-loys
B949Specification for General Requirements for Zinc and Zinc Alloy Products
E29Practice for Using Significant Digits in Test Data to Determine Conformance with Specifications
E527Practice for Numbering Metals and Alloys in the Unified Numbering System(UNS)
E536Test Methods for Chemical Analysis of Zinc and Zinc Alloys
2.2Military Standard:3
MIL-A-18001K w/INT.AMENDMENT3,24October 2007Military Specification Anodes Sacrificial Zinc Alloy 2.3ISO Standards:4
ISO3815-1Zinc and zinc alloys—Part1:Analysis of solid samples by optical emission spectrometry
ISO3815-2Zinc and zinc alloys—Part2:Analysis by inductively coupled plasma optical emission spectrometry 3.Terminology
3.1Terms shall be defined in accordance with Terminology B899.
3.2Definitions of Terms Specific to This Standard:
3.2.1cathodic protection,n—reduction of corrosion by making the protected metal the cathode in a conducting medium by applying direct current.
3.2.2galvanic anode,n—a metal electrode that sacrificially corrodes when coupled to a more noble metal in a conducting medium,and thereby supplies a protective electric current to the noble electrode.
3.2.3ribbon anode,n—a long,continuous sacrificial anode shape,with a diamond,square,rectangular,
oval,or other cross-ction,most commonly made of zinc,magnesium or aluminum,having a core wire normally made of steel,that is usually supplied in coils or reels of100to3600ft depending upon size and cross-ction.
3.2.4saline electrolyte,n—a solution consisting of mainly the chlorides of the alkali metals.
1This specification is under the jurisdiction of ASTM Committee B02on Nonferrous Metals and Alloys and is the direct responsibility of Subcommittee B02.04on Zinc and Cadmium.
Current edition approved May1,2012.Published July2012.Originally approved in1964.Last previous edition approved in2009as B418–09.DOI:10.1520/
B0418-12.
2For referenced ASTM standards,visit the ASTM website,,or contact ASTM Customer Service at For Annual Book of ASTM Standards volume information,refer to the standard’s Document Summary page on the ASTM website.
3Available from Standardization Documents Order Desk,DODSSP,Bldg.4, Section D,700Robbins Ave.,Philadelphia,PA19111-5098, www.dodssp.daps.mil.
4Available from American National Standards Institute(ANSI),25W.43rd St., 4th Floor,New York,NY10036,
*A Summary of Changes ction appears at the end of this standard Copyright©ASTM International,100Barr Harbor Drive,PO Box C700,West Conshohocken,PA19428-2959.United States
4.Ordering Information
4.1Orders for zinc anodes under this specification shall include information as specified in Specification B949,Section 4.:
4.2Additional ordering information specific to this standard is as follows:
4.2.1Type of anode material (e Table 1),4.2.2Number of anodes,
4.2.3Size of anode and whether contains rod inrt and if so,type of inrt and whether contains bolt hole and if so,whether threaded.
5.Chemical Requirements
5.1The anode shall be made from Special High Grade zinc conforming to Specification B6,with suitable alloying addi-tions for Type I anodes.Composition of the anode alloy content shall conform to the limits prescribed in Table 1.
5.2Evidence from laboratory tests shows that Type I composition may suffer intergranular corrosion.Susceptibility to intergranular corrosion increas with increasing tempera-ture and is particularly vere above approximately 120°F (50°C).Intergranular corrosion can be avoided (at tempera-tures above about 120°F)with Type II composition,which must be made from special high-grade zinc with an iron content well below the 0.003%maximum given in Specifica-tion B
6.
5.3Chemical requirement procedures shall be in compli-ance with the provisions of Specification B949,Section 5.2.
6.Sampling for Chemical Analysis
6.1The sample for chemical analysis shall be taken as follows:
6.1.1Selection of Portion—A number of anodes shall be lected at random to give a reprentative sample of the lot.A lot shall consist of not more than 20000lb (9070kg)of zinc anodes cast from a single melt or not more than 5000lb (2268kg)of anodes cast in a single 24-h period from more than one melt.The minimum number of anodes to be sampled shall be as specified in Table 2.
6.1.2Taking Sample for Chemical Analysis—Each lected anode shall be sampled by drilling or machining with a nonferrous tool.The u of a drill with a tungsten carbide tip is recommended.The tool bit or drill shall not penetrate into the core material or a cored anode.The cuttings from all anodes in a lot shall be thoroughly mixed to form a uniform sample of not less than 50g total.
6.1.3Other sampling procedures shall be in compliance with the provisions of Specification B949,Section 6.
7.Methods of Chemical Analysis
7.1The chemical compositions enumerated in this specifi-cation shall,in ca of disagreement,preferably be determined by methods mutually agreed upon or the methods listed in Table 3(note:spectrochemical methods may include ISO 3815-1,ISO 3815-2)approved for referee purpos by ASTM.Test Methods E536shall be ud,except for Type II.
N OTE 1—Test Methods E536is directly applicable,in an unmodified form,only to alloys 3,5,and 7.ISO 3815-1and ISO 3815-2are generic methods applied to zinc and zinc alloys.Each of the methods may be modified and formatted for the alloy to be assayed.An experienced chemist,using suitable and/or traceable standards along with valid quality assurance techniques,will be able to perform and validate the methods and demonstrate acceptable precision and accuracy.
8.Bolt Holes and Threads
8.1For anodes with integral inrts intended for attachment by bolting,it is recommended that a bolt-hole spacing of 6in.(152mm)or even multiples thereof be ud.
8.2Anodes with projecting rod inrts threaded for attach-ment by means of a bolted connection shall have Unified National Coar threads.
9.Workmanship,Finish,and Appearance
9.1The zinc anodes shall be free of flash,burrs,cracks,blow holes,and surface slag,consistent with good commercial practice.Cast anodes shall not have shrinkage cavities exceed-ing 1⁄4the depth of the anode or 1in.(25.4mm),whichever is smaller when measured from a straightedge placed diagona
lly across opposite edges of the anode.Drill holes and saw cuts for sampling shall not be cau for rejection unless they are vere enough to cau premature failure of the anode.10.Rejection and Rehearing
10.1Claims to be considered in accordance with the provi-sions of Specification B949,Section 8.
TABLE 1Chemical Requirements A
Type (UNS)B Aluminum,%Cadmium,%Iron,max,%Lead,max,%Copper,max,%Others,Total,%Zinc C ,%Type I (Z32120)0.1–0.50.025–0.070.0050.0060.0050.1remainder Type II (Z13000)
0.005max
0.003max
0.00140.
remainder
A
The following applies to all specified limits in this table:For purpos of determining conformance with this specification,the obrved value or calculated value obtained from analysis shall be rounded off to the nearest unit in the last right hand place of figures ud in expressing the specified limit,in accordance with the rounding method of Practice E29.B
UNS designations were established in accordance with Practice E527.C
Determined arithmetically by difference.
TABLE 2Minimum Number of Anodes in Sample
Number of Anodes in Lot Minimum Number of Anodes in Sample
1to 5002500to 1000
3
Each additional 1000or part thereof
1
11.Investigation of Claim
11.1Claims shall be investigated in accordance with the provisions of Specification B949,Section 8.
12.Settlement of Claims
12.1Claims shall be ttled in accordance with the provi-sions of Specification B949,Section 8.
13.Product Identification Marking and Packaging 13.1Each slab,block,jumbo or ingot shall be marked for identification in accordance with the provisions of Specifica-tion B949,Section 10.
14.Keywords
14.1cathodic protection;galvanic anodes;zinc;zinc anodes
SUMMARY OF CHANGES
Committee B02has identified the location of lected changes to this standard since the last issue (B418-09)that may impact the u of this standard.(Approved May 1,2012.)
(1)Revisions have been made to Sections 2,4,6,9,10,11,12,and 13to reference Specification B949an
d delete certain portions of tho ctions formerly a part of this standard.
(2)The titles of Sections 5,6,9,10,11,12,and 13have been revid to be in agreement with a standard format for Subcom-mittee B02.04standards.
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TABLE 3Methods of Analysis
Method
ASTM Designation
Spectrochemical Analysis Chemical Analysis Chemical Analysis
Test Methods
E536
