1、Designation: F2836 18Standard Practice forGasket Constants for Bolted Joint Design1This standard is issued under the fixed designation F2836; 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 pa
2、rentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.1. Scope1.1 This practice determines room temperature gasket tight-ness design constants for pressurized bolted flanged connec-tions such as those designed in
3、accordance with the ASMEBoiler and Pressure Vessel Code.1.2 This practice applies mainly to all types of circulargasket products and facings typically used in process or powerplant pressure vessels, heat exchangers, and piping includingsolid metal, jacketed, spiral wound, and sheet-type gaskets. Asa
4、n optional extension of this practice, the maximum assemblystress for those gaskets may also be determined by thisprocedure.1.3 UnitsThe values stated in SI units are to be regardedas the standard, but other units may be included.1.4 This standard does not purport to address all of thesafety concern
5、s, if any, associated with its use. It is theresponsibility of the user of this standard to establish appro-priate safety, health, and environmental practices and deter-mine the applicability of regulatory limitations prior to use.1.5 This international standard was developed in accor-dance with int
6、ernationally 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 ASME Standards:2ASM
7、E B16.5 Steel Pipe Flanges and Flanged FittingsASME B16.20 Metallic Gaskets for Pipe FlangesRing-Joint, Spiral-Wound, and JacketedASME B16.21 Nonmetallic Flat Gaskets for Pipe FlangesASME Boiler and Pressure Vessel Code Section VIII Divi-sion 1, Appendix 23. Terminology3.1 Definitions of Terms Speci
8、fic to This Standard:3.1.1 ASME Class 150, nrefers to the dimensions andpressure rating of Class 150 of standard flanges in ASMEStandard B16.5.3.1.2 flange rotation, nrotation of the flange face surfacesso that the gasket outside diameter (OD) is compressed morethan the gasket inside diameter (ID) w
9、hen the bolts aretightened to compress the gasket.3.1.3 gasket constants, nif a log-log plot of gasket stressversus tightness (Sg-Tp graph) is made and an analysis of thedata is performed in accord with this practice, then (see Fig. 1):(1) The value, Gb, is the stress intercept (at Tp =1)associated
10、with a regression of the Part A tightness data.(2) The value, a, is the slope associated with the PartAdataand combined values of Gb and a describe the seating orloading characteristic of a gasket and give an indication of thegasket capacity to develop tightness upon initial seating.(3) The value, G
11、s, is the stress intercept (at Tp =1)associated with Part B tightness data and values of Gs representthe gasket potential to maintain tightness after pressurizationand during operation and indicate the gaskets sensitivity tounloading excursions or susceptibility to crushing.(4) The combined effect o
12、f constants Gb and a is bestrepresented by the value of STp= Gb Tpacalculated fortypical values of Tp such as 100, 1000, or 10 000 where STptells us what the minimum gasket stress shall be to maintain aspecified level of minimum tightness.(5) The value, Gs, is an independent constant that repre-sent
13、s operation and it characterizes the gasket tightness sensi-tivity to operating bolt load reductions that occur duringpressurization or gasket creep or thermal disturbances.3.1.4 gasket contact area, Ag, ninitial (nominal) area ofthe gasket that is considered to be loaded by the flangesurfaces.3.1.5
14、 gasket stress, Sg, ngasket stress is the ratio of theapplied load by the fixture over the gasket contact area, Ag.3.1.6 gasket types, nfor this practice, it is convenient todifferentiate gasket styles as:(1) Sheet gasket materials typically from 0.5 to 5 mm thickcommonly in use and in which circula
15、r gasket samples are cut,1This practice is under the jurisdiction ofASTM Committee F03 on Gaskets andis the direct responsibility of Subcommittee F03.20 on Mechanical Test Methods.Current edition approved Aug. 1, 2018. Published November 2018. DOI:10.1520/F2836-18.2Available from American Society of
16、 Mechanical Engineers (ASME), ASMEInternational Headquarters, Two Park Ave., New York, NY 10016-5990, http:/www.asme.org.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United StatesThis international standard was developed in accordance with inter
17、nationally 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 (TBT) Committee.1such as compressed or beater-added fiber-reinfor
18、ced, flexiblegraphite and polytetrafluoroethylene (PTFE)-based sheet prod-ucts;(2) Preformed gaskets with a flat seal element that contactsthe raised faced flange surfaces as intended by themanufacturer, such as solid flat metal gaskets with and withoutnubbin, spiral wound gaskets, flat metal jacket
19、ed with nonme-tallic filler gasket, and so on;(3) Preformed gaskets with one or several cambered sealelements in which the nominal contact area is not obvious suchas solid metal oval rings, hollow metal rings, elastomerO-rings, corrugated gaskets, and so on; and(4) Formed-in-place sealing products s
20、uch as expandedPTFE rope and so on.3.1.7 known volumes, nvolume of the internal high-pressure chamber or volume of the external low-pressure leakcollection chamber used, respectively, in pressure decay orpressure rise methods to measure gasket specimen leaks.3.1.8 leakage rate, Lrm, ntotal rate of i
21、nternal fluidleakage around or through the gasket expressed as milligramsper second, Lrm, reduced to standard conditions.3.1.9 maximum assembly stress, Sc, nmaximum gasketstress found to achieve a minimum acceptable tightness whenthe gasket is unloaded to the minimum allowed stress level, S1,of the
22、procedure (see Section 13).3.1.10 maximum and minimum tightness, Tpmax andTpmin, nhighest and lowest level of tightness, Tp, achieved,respectively, during Part A and Part B of the test procedure.3.1.11 nominal pipe size, NPS, “d,”, nrefers to the nomi-nal pipe size in which “d” is the nominal size i
23、n inches, forexample, NPS 12 refers to standard 305-mm pipe.3.1.12 pressure decay method, nthis method measures, atregular intervals of time, the helium pressure decay of theinternal high-pressure chamber of known volume upstream ofthe gasket.3.1.13 pressure rise method, nthis method measures, atreg
24、ular intervals of time, the pressure rise of an externallow-pressure leak collection chamber of known volume built atthe external periphery of the gasket.3.1.14 range of gasket behavior possibilities, nvariousgasket behaviors ranging from tightness softening to extremetightness hardening are illustr
25、ated in Fig. 2(a-f).3.1.15 reference gasket diameter, noutside gasketdiameter, 150 mm (5.9 in.).3.1.16 reference mass leak, Lrm*, ndefined as 1.0 mg/s(0.008 lbm/h) for a gasket of 150 mm outside diameter.3.1.17 tightness hardening, nrefers to behavior in whichlarge increases of gasket stress (Sg) ca
26、use small or no increaseof tightness parameter (Tp).3.1.17.1 DiscussionThere is typically an increasing slopein log-log Sg-Tp plots resulting in a reverse “knee” in the PartA curve see Fig. 2(d-e).3.1.18 tightness parameter, Tp, ndimensionless sealabilitymeasure that is proportional to pressure and
27、inversely propor-tional to the square root of leak rate.3.1.18.1 DiscussionMore precisely, Tp is the pressurerelative to the atmospheric pressure required to cause a heliumleak of 1 mg/s for a 150 mm OD gasket. Since this is about thesame as the OD of an NPS 4 joint, the pressure to cause a leakof 1
28、 mg/s of that joint is its tightness. (Tightness is a measureof the gaskets ability to control the leak rate of the joint for aFIG. 1 Typical Representation of Gasket Constant Gb, a, and GsF2836 182given load. With all other variables equal, a tighter gasketrequires higher internal pressure to push
29、the same rate of fluidthrough the joint. In other words, the tighter the seal, smallerthe leak).Tp 5PP*SLrm*LrmD0.5(1)where:P = fluid pressure (MPa),P* = reference pressure (0.1013 MPa), (14.69 psi),Lrm = mass leak rate (mg/s) of ROTT gasket specimens asdefined per 8.1, andLrm* = unit mass leak rate
30、 equal to1 mg/s for a 150 mm ODgasket in a joint.3.1.18.2 DiscussionThe Tp equation can be rewritten asfollows:Tp 5P0.1013S1LrmD0.5For P in MPa! (2)Tp 5P14.69S1LrmD0.5For P in psi! (3)3.1.19 tightness softening, nrefers to behavior in whichsmall increases of gasket stress (Sg) cause large increases
31、oftightness parameter (Tp).3.1.19.1 DiscussionThere is typically a decreasing slopein log-log Sg-Tp plots resulting in a “knee” in the Part A curve(see Fig. 2a).3.2 Acronyms:3.2.1 AARHarithmetic average roughness height in meters(m)3.2.2 Agnominal contact area of the gasket, mm23.2.3 Aipressurized a
32、rea, mm23.2.4 Dggasket deflection, mm3.2.5 Extended LPextended low-pressure test sequence3.2.6 HPhigh-pressure test sequence. Part B of the testingsequenceFIG. 2 Range and Definition of Typical Behaviors from Softening to Extreme HardeningF2836 1833.2.7 IDidentification of gasket test specimen, mm3.
33、2.8 LPlow-pressure test sequence. Part A of the testingsequence3.2.9 Lrmmass leakage rate, mg/s3.2.10 Lrminminimum mass leakage rate of the system,mg/s3.2.11 Lrm*unit mass leak defined as 1.0 mg/s for a 150mm outside gasket diameter3.2.12 NPSnominal pipe size3.2.13 ODoutside diameter of gasket test
34、specimen, mm3.2.14 Pinternal fluid pressure, MPa3.2.15 P*standard pressure, 0.1013 MPa3.2.16 ROTTroom temperature tightness test procedure3.2.17 RLMratio of mass leak rates, Lrm1 and Lrm2,measured at the same step of the ROTT test procedure (seeTables 1 and 2) in two different ROTT tests performed o
35、n agasket style3.2.18 Slevel of gasket stress defined in Table 3, MPa3.2.19 Scthe highest gasket stress of the optional extendedLP tests preceding the stress level that resulted in Tpc, MPa3.2.20 Sggasket stress calculated from the net appliedload and the nominal area, Ag, MPa3.2.21 slpmstandard lit
36、re per minute3.2.22 Ssgasket stress developed when contact is initiatedwith a compression limiting device, or stop, such as a groovecontaining the gasket, a gage ring, or a stress associated with atightness limit such as Tpmax3.2.23 Ttest fixture temperature in the vicinity of thetested gasket3.2.24
37、 Tptightness parameter (dimensionless)3.2.25 Tpmaxaverage of highest two levels of tightnessobtained from each test3.2.26 Tpminlowest tightness value achieved during PartB of all HP tests3.2.27 Tpcfirst tightness value of the optional extendedLP tests less than Tpmin4. Summary of Practice4.1 This te
38、st procedure consists of two parts (see Fig. 1):4.1.1 Part AAt the fluid test pressure, obtain gasket leakrate and deflection measurements for several levels of gasketstress, each stress level being higher than any previouslyTABLE 1 ROTT HP Test Sequence (with P = 6 MPa)Test Step Test Part“S” Stress
39、LevelGasketStressType ofMeasurementMPa(1) Leakage(2) Mechanical1 A S1 8 (1+2)2 A S2 20 (1+2)3 A S3 30 (1+2)4 A, B1 S4 40 (1+2)5 B1 S1 8 (1+2)6 A, B1 S5 50 (1+2)7 A, B2 S6 60 (1+2)8B 22 2)9 B2 S1 8 (1+2)10 A, B2 S7 70 (1+2)11 A, B3 S8 80 (1+2)12 B3 S3 30 (2)13 B3 S1 8 (1+2)14 A, B3 S9 90 (1+2)15 A, B
40、4 S10 105 (1+2)16 B4 S4 40 (2)17 B4 S1 8 (1+2)18 A, B4 S11 120 (1+2)19 A S12 140 (1+2)20 A, B5 S13 160 (1+2)21 B5 S5 50 (2)22 B5 S1 8 (1+2)TABLE 2 ROTT LP and Extended LP Test Sequences (with P =2MPa)Test Step Test Part“S” StressLevelGasketStressType ofMeasurementMPa(1) Leakage(2) MechanicalOnlyLP T
41、est Sequence1 A S1 8 (1+2)1a A S2 20 (1+2)2 A S3 30 (1+2)3 A S5 50 (1+2)4 A S7 70 (1+2)5 A S10 105 (1+2)6 A S12 140 (1+2)Extended LP Test Sequence7 A S14 170 (1+2)8 B S1 8 (1+2)9 A S15 190 (1+2)10 B S1 8 (1+2)11 A S16 210 (1+2)12 B S1 8 (1+2)13 A S17 230 (1+2)14 B S1 8 (1+2)15 A S18 250 (1+2)16 B S1
42、 8 (1+2)17 A S19 270 (1+2)18 B S1 8 (1+2)TABLE 3 Nominal Values for Gasket Stress LevelsNOTE 1Multiply the gasket stress values by Ag to obtain the total loadrequired for a particular gasket.NOTE 2The nominal “S” load stresses correspond to a low to highrange of typical pipe fitter imposed bolting s
43、tresses. For example, S1 istypical of the low gasket stresses resulting from (69 MPa) bolt stresses ona NPS 12ASME/ANSI cl 68 kg joint and S10 is typical of high (414 MPa)bolt stresses on a NPS 12 ASME/ANSI cl 272 kg joint.(1) S Load ValueGasket StressMPaS1 8S2 20S3 30S4 40S5 50S6 60S7 70S8 80S9 90S
44、10 105S11 120S12 140S13 160F2836 184applied stress. Part A may be interrupted to perform Part Bsequences (see 4.1.2). Part A provides information on initialloading known as gasket seating and yields the constants Gband a (see 3.1.3).4.1.2 Part BObtain gasket leak rate and deflection mea-surements un
45、der fluid pressure for five unload-reload stresscycles. Part B is performed by interrupting Part A at fivespecific stress levels as shown in Fig. 1. Part B providesinformation on the operating gasket performance including itssensitivity to load reductions after initial loading. Part B yieldsthe cons
46、tant Gs (see 3.1.3(5).5. Significance and Use5.1 This practice determines the room temperature gasketconstants Gb and a for initial seating and Gs for operatingconditions as related to the tightness behavior of pressurizedbolted flanged connections. These constants are used in deter-mining the desig
47、n bolt load for gasketed bolted joints.5.2 This practice is suitable for all the types of gaskets andfacings as are considered by the ASME Division 1 Code. Thisincludes ASME B16.5 raised facings, nubbin-type facings,O-ring grooves, and a wide variety of gaskets including spiralwound, flat sheet, sol
48、id metal, jacketed, and other types ofgaskets common to process and power industry pressurizedequipment.5.3 These constants are intended for direct use in determin-ing ASME Code design calculations for bolted flanged joints.An appendix of the ASME Boiler and Pressure Vessel Code,Section VIII, Divisi
49、on 1 will refer to the gasket constants Gb,a, and Gs produced by this practice. The user and bolted jointdesigner are cautioned that gasket constants Gb, a, and Gs andany gasket design stresses calculated from these may not beconservative for design stresses below S1 or beyond S13 asindicated in Table 3.5.4 When required, this practice evaluates both the me-chanical and leakage resistance of gaskets to excessive com-pression to determine their maximum assembly stress, Sc.5.5 This test procedure is a gasket tightness
