1、This 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 Technical Barriers to Trade(
2、TBT)Committee.Designation:F38-18NTERNATIONALStandard Test Methods forCreep Relaxation of a Gasket MaterialThis 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 revisi
3、on.A number in parentheses indicates the year of last reapproval.A superscriptepsilon(e)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been approved for use by agencies of the U.S.Department of Defense.1.Scopedards Related to Rubber and Rubber Testing(Withdrawn
4、1.1 These test methods provide a means of measuring the1987)3amount of creep relaxation of a gasket material at a predeter-F104 Classification System for Nonmetallic Gasket Materi-mined time after a compressive stress has been applied.als1.1.1 Test Method A-Creep relaxation measured by meansF436/F43
5、6M Specification for Hardened Steel Washers Inchof a calibrated strain gauge on a bolt.and Metric Dimensions1.1.2 Test Method B-Creep relaxation measured by means2.2 ASTM Adjuncts:of a calibrated bolt with dial indicator.Relaxometer,Method A(F38)41.2 The values stated in SI units are to be regarded
6、asRelaxometer,Method B(F38)5standard.The values given in parentheses are for information3.Summary of Test Methodsonly.3.1 In both test methods the specimen is subjected to a1.3 This standard does not purport to address all of thecompressive stress between two platens,with the stress appliedsafety co
7、ncerns,if any,associated with its use.It is theby a nut and bolt.responsibility of the user of this standard to establish appro-priate safety,health,and environmental practices and deter-3.2 In Test Method A,normally run at room temperature,themine the applicability of regulatory limitations prior t
8、o use.stress is measured by a calibrated strain gauge on the bolt.In1.4 This international standard was developed in accor-running the test,strain indicator readings are taken at intervalsdance with internationally recognized principles on standard-of time,beginning at the loading time,to the end of
9、 the test.ization established in the Decision on Principles for theThe strain indicator readings are converted to percentages ofDevelopment of International Standards,Guides and Recom-the initial stress which are then plotted against the log of timemendations issued by the World Trade Organization T
10、echnicalin hours.The percentage of initial stress loss or relaxation canBarriers to Trade(TBT)Committee.be read off the curve at any given time,within the limits of thetotal test time.2.Referenced Documents3.3 In Test Method B,run at room or elevated temperatures,2.1 ASTM Standards:2the stress is de
11、termined by measuring the change in length ofA193/A193M Specification for Alloy-Steel and Stainlessthe calibrated bolt with a dial indicator.The bolt length isSteel Bolting for High Temperature or High Pressuremeasured at the beginning of the test and at the end of the test;Service and Other Special
12、 Purpose Applicationsfrom this the percentage of relaxation is calculated.B637 Specification for Precipitation-Hardening and Cold4.Significance and UseWorked Nickel Alloy Bars,Forgings,and Forging Stockfor Moderate or High Temperature Service4.1 These test methods are designed to compare relatedD304
13、0 Practice for Preparing Precision Statements for Stan-materials 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 ofThese test methods are under the jurisdiction of ASTM Committee F0
14、3 onGaskets and are the direct responsibility of Subcommittee F03.20 on MechanicalTest Methods.3The last approved version of this historical standard is referenced onCurrent edition approved Aug.1,2018.Published November 2018.Originallywww.astm.org.approved in 1962.Last previous edition approved in
15、2014 as F38-00(2014).DOI:A print of this apparatus is available at a nominal cost from ASTM International10.1520/F0038-18.Headquarters.Order Adjunct No.ADJF003801.Original adjunct produced in 1965.2 For referenced ASTM standards,visit the ASTM website,www.astm.org,orcontact ASTM Customer Service at
16、serviceastm.org.For Annual Book of ASTMDetailed working drawings of this apparatus are available from ASTMStandards volume information,refer to the standards Document Summary page onInternational Headquarters.Order Adjunct No.ADJF003802.Original adjunctthe ASTM website.produced in 1965.Copyright AST
17、M Intemational,100 Barr Harbor Drive,PO Box C700.West Conshohocken.PA 19428-2959.United StatesCopyright by ASTM Intl(all rights reserved):Fri May 2804:16:18 EDT 2021Downloaded/printed byUniversity of Toronto(University of Toronto)pursuant to License Agreement.No further reproductions authorized.F38-
18、18NUTTHRUSTBEARINGCABLEUPPER PLATENATTACHT0SR4TESTINDICATORSPECIMENCLAMPLOWER PLATENBOLTFIG.1 Relaxometer,Test Method Acreep 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 resu
19、lts.These test methods may be used as a routine test when agreedupon between the consumer and the producer.DIAL INDICATOR0.0001nGRAD筑JATIONSNorE 1-Test Method B was developed using asbestos gasket materialsand at issuance substantiating data were not available for other gasketmaterials.ASSEMBLY-SET
20、SCREW一FLOATING PIN5.Apparatus-ADAPTOR BODY5.1 Test Method A:5.1.1 Strain Indicator.W填SHER5.1.2 TimerPLATENS5.1.3 Relaxometer,composed 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 factorTEST SPECI
21、MENSof 2.0+0.10%The gauges shall be mounted to indicateCALIBRATED BOLTtensile strain and positioned to compensate for torque,ASSEME队Ytemperature,and bending.The gauges shall be mounted on theTEST SPECIMENSsmall diameter of the bolt about 50.8 mm(2 in.)from the head.The bolt with mounted strain gauge
22、s must be calibrated.5.2 Test Method B:PLATEN5.2.1 Relaxometer,Platen Assembly composed of two-Gaps necessary forplatens,specially drilled and calibrated bolt,washer and nutcomposed of Specification A193/A193M Grade B7 or Speci-FLOATING PIN DETAILfication B637 Grade UNS N07718 or other alloys of con
23、struc-FIG.2 Relaxometer,Platen Assembly and Dial Indicatortion that would satisfy the calibration procedure(see Annex)Assembly,Test Method Bfor the test temperature specified,as shown in Fig.2.5.2.2 Dial Indicator Assembly,composed of an adaptor6 The sole source of supply of strain gauges(Type AB-7)
24、known to the committeebody,floating pin,set screw,and dial indicator,as shown inat this time is Baldwin-Lima-Hamilton.If you are aware of alterative suppliers.Fig.2.Dial indicator should have graduations of 0.0025 mmplease provide this information to ASTM International Headquarters.Your com-ments wi
25、ll receive careful consideration at a meeting of the responsible technical(0.0001 in.)or mittee,which you may attend.5.2.3 Box End Wrench-%16 in.,Qty.2.Copyright by ASTM Intl(all rights reserved):Fri May 2804:16:18 EDT 2021 2Downloaded/printed byUniversity of Toronto(University of Toronto)pursuant t
26、o License Agreement.No further reproductions authorized.F38-186.Test Specimen8.2 Test Method B:6.1 Test Method A-The sample size shall be 33.028.2.1 Clean all surfaces and lightly lubricate the washer and0.05 mm(1.300 0.002 in.)in inside diameter and 52.32bolt threads:graphite and molybdenum disulfi
27、de have been0.05 mm(2.060 0.002 in.)in outside diameter.found to be acceptable lubricants.6.2 Test Method B:8.2.2 Place rectangular specimens between the platens in6.2.1 Specimen size shall be 10.16+0.381 mm(0.400accordance with Fig.2 and making sure they are no closer than0.015in.)wide by31.750.381
28、mm(1.2500.015in.)long.2 mm(0.078 in.)to the other pieces and the edge of the platens.Four specimens are required per test.If an annular specimen is used,center the specimen around the6.2.2 An annular specimen with 1290-mm2(2.0-in.2 sur-bolt hole between the platens.If a Type 4 Class 2 specimen isfac
29、e area may also be used.A size of 15.62-mm(0.615-in.)used,center the specimen around the bolt hole between theinside diameter by 43.56-mm(1.715-in.)outside diameter isplatens,being certain that the two ends overlap by a minimumrecommended.of6.35mm(0.25in.).6.2.3 For Type 4 Class 2 materials,specimen
30、 size shall be8.2.3 Place the washer in position and screw on the nut,one continuous length of 152.4 mm(6.0 in.).finger tight.6.3 A minimum of three tests shall be conducted8.2.4 Screw on the dial indicator assembly,finger tight,andset the dial indicator at the zero reading.6.4 Nominal thickness of
31、specimen shall be 0.8 mm8.2.5 Apply stress to the specimens by tightening the nut(0.03 in.)unless otherwise agreed upon between the consumerwith a wrench until the desired dial indicator reading isand the producer.For Type 4 materials the nominal thickness ofreached.Record the reading(Do).Apply the
32、stress in onethe specimen shall be no greater than 1.78 mm(0.07 in.).continuous motion with a maximum loading time of 3 s.A bolt7.Conditioningelongation of 0.1222 to 0.1270 mm(0.00481 to 0.00500 in.)istypical for a compressive force of 26.7 kN(6000 Ibf).Remove7.1 Condition cut specimens in accordanc
33、e with their clas-the dial indicator assembly.(The calibration procedure issification as required in Classification F104.outlined in Annex Al.)8.ProcedureNorE 2-When testing materials thicker than 0.8 mm(0.03 in.),thetime to tighten the nut may be extended to 5 s maximum to allow for the8.1 Test Met
34、hod A:longer are required to apply the test load.8.1.1 Clean all surfaces,platens,and specimen free of wax,8.2.6 Place the specimen unit in a hot air-circulating ovenmold release,and oils.(Remove with isooctane or otherfor 22 h at 100 2C(212 3.6F),unless otherwisesuitable solvent.)Lubricate bolt thr
35、eads.specified.The maximum test temperature for Specification8.1.2 Use an initial stress of 13.8 0.3 MPa(2000+A193/A193M Grade B7 shall not exceed 204.4C(400F)and50 psi)unless otherwise specified.the maximum test temperature for Specification B637 Grade8.1.3 Conduct the test at 20 to 30C(70 to 85F)u
36、nlessUNS N07718 shall not exceed 482.2C(900F).otherwise specified.8.1.4 Disassemble the relaxometer and place the specimen8.2.7 Remove from the oven and cool to room temperature.between platens.The inside diameter of the specimen should8.2.8 Replace the dial indicator assembly,finger tight,andbe nea
37、rly concentric with the inside diameter of the platens.set the dial indicator at the zero reading.Loosen the nut,Screw on the nut and thrust bearing and tighten very slightly,without disturbing the dial indicator assembly,and record theby hand,or just enough to hold the specimen in place duringdial
38、reading(D)subsequent handling.Mount the head of the bolt in a clamp.8.2.9 Calculate the percentage relaxation as follows:8.1.5 Hook up and balance the strain indicator.Record theRelaxation,%=(D。-D,）/D。100(1)reading.Then set the reading on the strain indicator for thespecified initial stress.(The mic
39、roinches that are added to the9.Reportabove reading will vary the stress and the strain gauge bolt9.1 Report the following information:calibration.)8.1.6 Apply stress to the gasket by tightening the nut with a9.1.1 Identification and designation number of the materialsolid wrench until the strain in
40、dicator reaches a balance.Atested,torque of approximately 30 N-m(22 Ibf-ft)is required for a9.1.2 Test temperature,compressive force of 17.8 kN(4000 Ibf).The stress should be9.1.3 Length of the test,in hours,applied at uniform rate such that at the end of 10+2 s the9.1.4 Initial stressused,and the s
41、pecimen thickness,specified stress is reached.This is called the initial stress.9.1.5 Percentage stress loss for each specimen,and8.1.7 Beginning at the time of initial stress,take strain9.1.6 Average of all the results recorded in 9.1.5.indicator readings at intervals of 10 s,I min,6 min,30 min.1 h
42、.5 h.24 h.etc.or until the end of the test.(Check the zeroof the strain indicator after the test.)8.1.8 Convert the strain indicator readings of 8.1.7 to aSome laboratories have found Alloy A-286 meets the calibration standard atpercentage of initial stress.Then plot this percentage ontemperatures u
43、p to 482.2C(900F).The user may specify any alloy of constructionas long as the alloy meets the calibration standard for the desired test temperature.semilog paper against the log of time in hours.Copyright by ASTM Intl(all rights reserved):Fri May 2804:16:18 EDT 20213Downloaded/printed byUniversity
44、of Toronto(University of Toronto)pursuant to License Agreement.No further reproductions authorized.4F38-18Upper YokeQty:1Method B Test Assembly(Includes Dial Indicator Assemblyand Platen Assembly)el PirQty:4PlatensFlat WasherQty:1Flat washer(See Detail A)(Used in place of gasket during calibration.)
45、Lower YokeQty:1DETAIL AFIG.A1.1 Schematic of Bolt Calibration Apparatusassembly.Tighten the nut to load the bolt until a deflection ofA1.3.7 Apply tensile force until a load of 4.45 kN(1000 Ibf)0.130.0013mm(0.005000.00005in.)is obtained.is attained.Maintain this load and record the bolt elongation b
46、yRecord this value as the original deflection.measuring to the nearest 0.0013 mm(0.00005 in.)on the dialA1.3.2 Remove the dial indicator assembly being carefulindicator,estimating between graduations if necessary.Con-not to loosen the bolt and nut,and then place the relaxometertinue loading the bolt
47、 in 4.45 kN(1000 lbf)increments,up toin a circulating air oven preheated to 50F above the intendeda maximum of 26.7 kN(6000 Ibf),stopping to record themaximum test temperature.After 22 h,remove the relaxometerelongation at each 4.45 kN(1000 Ibf)increment.from the oven and allow it to cool to room te
48、mperature.A1.3.8 Remove the tensile load from the relaxometer boltA1.3.3 Install the dial indicator assembly onto the relaxom-and observe the reading on the dial indicator.If the dialeter and then remove the load from the bolt,measuring theindicator does not read zero=0.0025 mm(0.0001 in.),rejectdef
49、lection to the nearest 0.0013 mm(0.00005 in.).Record thisthe data,and repeat the cycle.If after 3 cycles the dial indicatordeflection as the final deflection.does not read zero then reject the bolt.A1.3.4 Repeat this cycle until the original and final deflec-A1.3.9 Reset the dial indicator to zero a
50、nd repeat stepstion differ by a value that is 3%or less difference within eachA1.3.7 to Al.3.8 a total of three consecutive times.cycle,and does not show a trend to decrease further from onecycle to the next.A1.4 Interpretation of ResultsNorE Al.1-Normally,seven cycles or less are sufficient to prec
51、ondi-A1.4.1 Prepare a graph of the bolt calibration data bytion bolts.plotting the average bolt elongation values at each of the loadAl.3.5 Disassemble the relaxometer and reassemble it withvalues.Plot the average bolt elongation values on the y axis,the Flat Washer in place of the gasket.Tighten th
52、e nut fingerwith the bolt load values creating the x axis.tight.A1.4.2 Find the R squared value of the data.The R squaredA1.3.6 Assemble the relaxometer,dial indicator assembly,value should be 0.95 or greater.Otherwise reject the bolt.and bolt calibration apparatus as shown in Fig.Al.1,thenA1.4.3 Sh
53、ould the calibration of a bolt result in an elonga-mount this complete assembly into the tensile testing machine.tion of less than 0.101 mm(0.00400 in.)or more than 0.140With no tensile load applied to the relaxometer bolt,set the dialmm(0.00550 in.)at 26.7 kN(6000 Ibf)after 3 cycles,then theindicator at zero.bolt should be discarded.Copyright by ASTM Intl(all rights reserved):Fri May 2804:16:18 EDT 2021 5Downloaded/printed byUniversity of Toronto(University of Toronto)pursuant to License Agreement.No further reproductions authorized.
