ASTM_F_38_-_00_2014.pdf

Designation:F3800(Reapproved 2014)Standard Test Methods forCreep Relaxation of a Gasket Material1This standard is issued under the fixed designation F38;the number immediately following the designation indicates the year of originaladoption or,in the case of revision,the year of last revision.Anumber in parentheses indicates the year of last reapproval.Asuperscriptepsilon()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 These test methods provide a means of measuring theamount of creep relaxation of a gasket material at a predeter-mined time after a compressive stress has been applied.1.1.1 Test Method ACreep relaxation measured by meansof a calibrated strain gauge on a bolt.1.1.2 Test Method BCreep relaxation measured by meansof a calibrated bolt with dial indicator.1.2 The values stated in SI units are to be regarded asstandard.The values given in parentheses are for informationonly.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.2.Referenced Documents2.1 ASTM Standards:2A193/A193M Specification for Alloy-Steel and StainlessSteel Bolting for High Temperature or High PressureService and Other Special Purpose ApplicationsB637 Specification for Precipitation-Hardening and ColdWorked Nickel Alloy Bars,Forgings,and Forging Stockfor Moderate or High Temperature ServiceD3040 Practice for Preparing Precision Statements for Stan-dards Related to Rubber and Rubber Testing(Withdrawn1987)3F104 Classification System for Nonmetallic Gasket Materi-als2.2 ASTM Adjuncts:Relaxometer,Method A(F38)4Relaxometer,Method B(F38)53.Summary of Test Methods3.1 In both test methods the specimen is subjected to acompressive stress between two platens,with the stress appliedby a nut and bolt.3.2 In Test MethodA,normally run at room temperature,thestress is measured by a calibrated strain gauge on the bolt.Inrunning the test,strain indicator readings are taken at intervalsof time,beginning at the loading time,to the end of the test.The strain indicator readings are converted to percentages ofthe initial stress which are then plotted against the log of timein hours.The percentage of initial stress loss or relaxation canbe read off the curve at any given time,within the limits of thetotal test time.3.3 In Test Method B,run at room or elevated temperatures,the stress is determined by measuring the change in length ofthe calibrated bolt with a dial indicator.The bolt length ismeasured at the beginning of the test and at the end of the test;from this the percentage of relaxation is calculated.4.Significance and Use4.1 These test methods are designed to compare relatedmaterials under controlled conditions and their ability tomaintain a given compressive stress as a function of time.Aportion of the torque loss on the bolted flange is a result ofcreep relaxation.Torque loss can also be caused by elongationof the bolts,distortion of the flanges,and vibration;therefore,the results obtained should be correlated with field results.These test methods may be used as a routine test when agreedupon between the consumer and the producer.NOTE1Test Method B was developed using asbestos gasket materials1These test methods are under the jurisdiction of ASTM Committee F03 onGaskets and are the direct responsibility of Subcommittee F03.20 on MechanicalTest Methods.Current edition approved March 1,2014.Published April 2014.Originallyapproved in 1962.Last previous edition approved in 2006 as F38 00(2006).DOI:10.1520/F0038-00R14.2For 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.3The last approved version of this historical standard is referenced onwww.astm.org.4Aprint of this apparatus is available at a nominal cost fromASTM InternationalHeadquarters.Order Adjunct No.ADJF003801.Original adjunct produced in 1965.5Detailed working drawings of this apparatus are available from ASTMInternational Headquarters.Order Adjunct No.ADJF003802.Original adjunctproduced in 1965.Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 and at issuance substantiating data were not available for other gasketmaterials.5.Apparatus5.1 Test Method A:5.1.1 Strain Indicator.5.1.2 Timer.5.1.3 Relaxometer,4composed of two platens,upper andlower;a bolt,with mounted strain gauge;and a thrust bearingas shown in Fig.1.5.1.4 Strain Gauges,6120 resistance with a gauge factorof 2.0 6 0.10%.The gauges shall be mounted to indicatetensile strain and positioned to compensate for torque,temperature,and bending.The gauges sh