ASTM_D_2688_-_15e1.pdf

Designation:D2688151Standard Test Method forCorrosivity of Water in the Absence of Heat Transfer(Weight Loss Method)1This standard is issued under the fixed designation D2688;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.1NOTEAn editorial correction was made to 13.3.2 in July 2016.1.Scope1.1 This test method covers the determination of the corro-sivity of water by evaluating pitting and by measuring theweight loss of metal specimens.Pitting is a form of localizedcorrosion:weight loss is a measure of the average corrosionrate.The rate of corrosion of a metal immersed in water is afunction of the tendency for the metal to corrode and is also afunction of the tendency for water and the materials it containsto promote(or inhibit)corrosion.1.2 The test method employs flat,rectangular-shaped metalcoupons which are mounted on pipe plugs and exposed to thewater flowing in metal piping in municipal,building,andindustrial water systems using a side stream corrosion speci-men rack.1.3 The values stated in SI units are to be regarded asstandard.The values given in parentheses are mathematicalconversions to inch-pound units that are provided for informa-tion only and are not considered standard.1.4 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.2.Referenced Documents2.1 ASTM Standards:2D1129 Terminology Relating to WaterD2331 Practices for Preparation and Preliminary Testing ofWater-Formed DepositsD2777 Practice for Determination of Precision and Bias ofApplicable Test Methods of Committee D19 on WaterG1 Practice for Preparing,Cleaning,and Evaluating Corro-sion Test SpecimensG16 Guide for Applying Statistics to Analysis of CorrosionData3.Terminology3.1 DefinitionsFor definitions of terms used in thisstandard,refer to Terminology D1129.4.Significance and Use4.1 Since the two tendencies are inseparable for a metal tocorrode and for water and the materials it contains to promoteor inhibit corrosion,the corrosiveness of a material or thecorrosivity of water must be determined in relative,rather thanabsolute,terms.The tendency for a material to corrode isnormally determined by measuring its rate of corrosion andcomparing it with the corrosion rates of other materials in thesame water environment.Conversely,the relative corrosivityof water may be determined by comparing the corrosion rate ofa material in the water with the corrosion rates of the samematerial in other waters.Such tests are useful,for example,forevaluating the effects of corrosion inhibitors on the corrosivityof water.Although this test methods is intended to determinethe corrosivity of water,it is equally useful for determiningcorrosiveness and corrosion rate of materials.Examples ofsystems in which this method may be used include but are notlimited to open recirculating cooling water and closed chilledand hydronic heating systems.5.Composition of Specimens5.1 The specimens shall be similar in composition to thepiping in the system in which the corrosion test is being made.1This test method is under the jurisdiction of ASTM Committee D19 on Waterand is the direct responsibility of Subcommittee D19.03 on Sampling Water andWater-Formed Deposits,Analysis of Water for Power Generation and Process Use,On-Line Water Analysis,and Surveillance of Water.Current edition approved June 1,2015.Published June 2015.Originallyapproved in 1969.Last previous edition approved in 2011 as D2688 11.DOI:10.1520/D2688-15E01.2For 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.Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 6.Effect of Cold Working on Corrosion6.1 Cold working can be important in causing localizedcorrosion;however,plastic deformation can be minimized inspecimen preparation by following proper machining practices(1)3(for example,drilling,reaming,and cutting specimens).7.Types of Corrosion7.1 General CorrosionCharacterized by uniform attack ofthe metal over the entire surface.7.2 PittingA form of localized corrosion,the depth,number,size,shape,and distribution of pits being pertinentcharacteristics.It may be evaluated by counting the number,bynoting the size,shape,and distribution,and by measuring thedepth of pits in representative areas.Both sides of the couponsmust be examined.7.2.1 A system may be devised for grading pitting(2).7.3 Crevice CorrosionA pertinent