ASTM_C_692_-_13.pdf

Designation:C69213Standard Test Method forEvaluating the Influence of Thermal Insulations on ExternalStress Corrosion Cracking Tendency of Austenitic StainlessSteel1This standard is issued under the fixed designation C692;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 test method covers two procedures for the labora-tory evaluation of thermal insulation materials to determinewhether they contribute to external stress corrosion cracking(ESCC)of austenitic stainless steel due to soluble chlorideswithin the insulation.This laboratory procedure is not intendedto cover all of the possible field conditions that contribute toESCC.1.2 While the 1977 edition of this test method(Dana test)isapplicable only to wicking-type insulations,the procedures inthis edition are intended to be applicable to all insulatingmaterials,including cements,some of which disintegrate whentested in accordance with the 1977 edition.Wicking insulationsare materials that wet through and through when partially(50to 75%)immersed in water for a short period of time(10 minor less).1.3 These procedures are intended primarily as a preproduc-tion test for qualification of the basic chemical composition ofa particular manufacturers product and are not intended to beroutine tests for ongoing quality assurance or production lotcompliance.Test Methods C871,on the other hand,is used forconfirmation of acceptable chemical properties of subsequentlots of insulation previously found acceptable by this testmethod.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 establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.2.Referenced Documents2.1 ASTM Standards:2A240/A240M Specification for Chromium and Chromium-Nickel Stainless Steel Plate,Sheet,and Strip for PressureVessels and for General ApplicationsA370 Test Methods and Definitions for Mechanical Testingof Steel ProductsC168 Terminology Relating to Thermal InsulationC795 Specification for Thermal Insulation for Use in Con-tact with Austenitic Stainless SteelC871 Test Methods for Chemical Analysis of Thermal Insu-lation Materials for Leachable Chloride,Fluoride,Silicate,and Sodium IonsG30 Practice for Making and Using U-Bend Stress-Corrosion Test Specimens3.Terminology3.1 Definitions:Refer to Terminology C168 for definitionsrelating to insulation.4.Summary of Test Method4.1 The procedures in this test method consist of using aspecimen of insulation to conduct distilled(or deionized)waterby wicking or dripping to an outside surface,through theinsulation,to a hot inner surface of stressed Type 304 stainlesssteel for a period of 28 days.If leachable chlorides are present,they are carried along with the water and concentrated at thehot surface by evaporation in much the same way as has beenexperienced in actual industrial process situations.4.2 Exposed stainless steel coupons are examined visually,and under 10 to 30 magnification,if necessary,to detectESCC after the prescribed period of exposure.5.Significance and Use5.1 An inherent characteristic of some alloys of austeniticstainless steel is their tendency to crack at stress points when1This test method is under the jurisdiction ofASTM Committee C16 on ThermalInsulation and is the direct responsibility of Subcommittee C16.31 on Chemical andPhysical Properties.Current edition approved May 1,2013.Published May 2013.Originallyapproved in 1971.Last previous edition approved 2008 as C692 081.DOI:10.1520/C0692-13.2For 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 exposed to certain corrosive environments.The mechanisms ofESCC are complex and not completely understood but areapparently related to certain metallurgical properties.Chlorideand fluoride ions have the potential to induce stress corrosioncracking in the absence of inhibiting ions.35.2 Chlorides are common to many environments,so greatcare shall be taken to protect austenitic stainless steel fromchloride contamination.5.3 Most thermal insulations will not,of themselves,causestress corrosion cracking.Preproduction qualification tests areused to evaluate that under the conditions o