ASTM_C_356_-_17.pdf

Designation:C35617Standard Test Method forLinear Shrinkage of Preformed High-Temperature ThermalInsulation Subjected to Soaking Heat1This standard is issued under the fixed designation C356;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.This standard has been approved for use by agencies of the U.S.Department of Defense.1.Scope1.1 This test method covers the determination of the amountof linear shrinkage and other changes that occur when apreformed thermal insulating material is exposed to soakingheat.This test method is limited to preformed high-temperatureinsulation that is applicable to hot-side temperatures in excessof 150F(66C),with the exception of insulating fire brickwhich is covered by Test Method C210.1.2 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.1.3 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.1.4 This international standard was developed in accor-dance with internationally recognized principles on standard-ization established in the Decision on Principles for theDevelopment of International Standards,Guides and Recom-mendations issued by the World Trade Organization TechnicalBarriers to Trade(TBT)Committee.2.Referenced Documents2.1 ASTM Standards:2C168 Terminology Relating to Thermal InsulationC210 Test Method for Reheat Change of Insulating FirebrickC411 Test Method for Hot-Surface Performance of High-Temperature Thermal Insulation3.Terminology3.1 DefinitionsTerminology C168 shall apply to the termsused in this test method.4.Significance and Use4.1 Linear shrinkage,as used in this test method,refers tothe change in linear dimensions that has occurred in testspecimens after they have been subjected to soaking heat for aperiod of 24 h and then cooled to room temperature.4.2 Most insulating materials will begin to shrink at somedefinite temperature.Usually the amount of shrinkage in-creases as the temperature of exposure becomes higher.Even-tually a temperature will be reached at which the shrinkagebecomes excessive.With excessive shrinkage,the insulatingmaterial has definitely exceeded its useful temperature limit.When an insulating material is applied to a hot surface,theshrinkage will be greatest on the hot face.The differentialshrinkage which results between the hotter and the coolersurfaces often introduces strains and may cause the insulationto warp.High shrinkage may cause excessive warpage andthereby may induce cracking,both of which are undesirable.High shrinkage may also open gaps at the insulation joints toan excessive extent rendering the application less efficient andmore hazardous.In order to predict the limit of permissibleshrinkage in service,the degree of linear shrinkage to betolerated by specimens of an insulating material when sub-jected to soaking heat must be determined from experience.4.3 It is recognized that a fixed relation between linearshrinkage under soaking heat and actual shrinkage in servicecannot be established for different types of insulating materials.Generally the amount of shrinkage increases with time ofexposure.The amount and rate of increase varies from onematerial to another.In addition,the various types of materialsmay have different amounts of maximum permissible shrink-age.Therefore,each product must define its own specific limitsof linear shrinkage under soaking heat.5.Apparatus5.1 FurnaceA gas-fired or electrically heated mufflefurnace,having a size sufficient to accommodate at least four1This 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 1,2017.Published June 2017.Originallyapproved in 1960.Last previous edition approved in 2010 as C356 10.DOI:10.1520/C0356-17.2For 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 StatesThis international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for theDevelopment of International Standards,Guides and Recommendations issued by the World Trade Organization Te