ASTM F2836.28800

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 parentheses 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 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. Asan 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 concerns, 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 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 ASME Standards2ASME 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 Specific to This Standard3.1.1 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 when 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 pered in accord with this practice, then see Fig. 11 The value, Gb, is the stress intercept at Tp 1associated 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, Gs, is the stress intercept at Tp 1associated 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 of 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-sents 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 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 as1 Sheet gasket materials typically from 0.5 to 5 mm thickcommonly in use and in which circular 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 s.Current edition approved Aug. 1, 2018. Published November 2018. DOI10.1520/F2836-18.2Available from American Society of 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 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 TBT Committee.1Copyright by ASTM Intl all rights reserved; Mon Jan 14 091022 EST 2019Downloaded/printed byTexas Tech Univ Texas Tech Univ pursuant to License Agreement. No further reproductions authorized.such as compressed or beater-added fiber-reinforced, flexiblegraphite and polytetrafluoroethylene PTFE-based sheet prod-ucts;2 Preed 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 jacketed with nonme-tallic filler gasket, and so on;3 Preed 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; and4 ed-in-place sealing products such 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 s to measure gasket specimen leaks.3.1.8 leakage rate, Lrm, ntotal rate of internal 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 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 in inches, forexample, NPS 12 refers to standard 305-mm pipe.3.1.12 pressure decay , nthis 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 , nthis measures, atregular 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 illustrated in Fig. 2a-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/s0.008 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 cause 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. 2d-e.3.1.18 tightness parameter, Tp, ndimensionless sealabilitymeasure that is proportional to pressure and 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 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 182Copyright by ASTM Intl all rights reserved; Mon Jan 14 091022 EST 2019Downloaded/printed byTexas Tech Univ Texas Tech Univ pursuant to License Agreement. No further reproductions authorized.given load. With all other variables equal, a tighter gasketrequires higher internal pressure to push the same rate of fluidthrough the joint. In other words, the tighter the seal, smallerthe leak.Tp 5PP*SLrm*LrmD0.51whereP 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 equal to1 mg/s for a 150 mm ODgasket in a joint.3.1.18.2 DiscussionThe Tp equation can be rewritten asfollowsTp 5P0.1013S1LrmD0.5For P in MPa 2Tp 5P14.69S1LrmD0.5For P in psi 33.1.19 tightness softening, nrefers to behavior in whichsmall increases of gasket stress Sg cause large increases 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 curvesee Fig. 2a.3.2 Acronyms3.2.1 AARHarithmetic average roughness height in metersm3.2.2 Agnominal contact area of the gasket, mm23.2.3 Aipressurized area, 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 183Copyright by ASTM Intl all rights reserved; Mon Jan 14 091022 EST 2019Downloaded/printed byTexas Tech Univ Texas Tech Univ pursuant to License Agreement. No further reproductions authorized.3.2.7 IDidentification of gasket test specimen, mm3.2.8 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 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 pered on 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 litre 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 Tptightness parameter dimensionless3.2.25 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 test procedure consists of two parts see Fig. 14.1.1 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 MPaTest Step Test Part“S” StressLevelGasketStressType ofMeasurementMPa1 Leakage2 Mechanical1 A S1 8 122 A S2 20 123 A S3 30 124 A, B1 S4 40 125 B1 S1 8 126 A, B1 S5 50 127 A, B2 S6 60 128B 22 29 B2 S1 8 1210 A, B2 S7 70 1211 A, B3 S8 80 1212 B3 S3 30 213 B3 S1 8 1214 A, B3 S9 90 1215 A, B4 S10 105 1216 B4 S4 40 217 B4 S1 8 1218 A, B4 S11 120 1219 A S12 140 1220 A, B5 S13 160 1221 B5 S5 50 222 B5 S1 8 12TABLE 2 ROTT LP and Extended LP Test Sequences with P 2MPaTest Step Test Part“S” StressLevelGasketStressType ofMeasurementMPa1 Leakage2 MechanicalOnlyLP Test Sequence1 A S1 8 121a A S2 20 122 A S3 30 123 A S5 50 124 A S7 70 125 A S10 105 126 A S12 140 12Extended LP Test Sequence7 A S14 170 128 B S1 8 129 A S15 190 1210 B S1 8 1211 A S16 210 1212 B S1 8 1213 A S17 230 1214 B S1 8 1215 A S18 250 1216 B S1 8 1217 A S19 270 1218 B S1 8 12TABLE 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 stresses. 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 MPabolt stresses on a NPS 12 ASME/ANSI cl 272 kg joint.1 S Load ValueGasket StressMPaS1 8S2 20S3 30S4 40S5 50S6 60S7 70S8 80S9 90S10 105S11 120S12 140S13 160F2836 184Copyright by ASTM Intl all rights reserved; Mon Jan 14 091022 EST 2019Downloaded/printed byTexas Tech Univ Texas Tech Univ pursuant to License Agreement. No further reproductions authorized.applied stress. Part A may be interrupted to per Part Bsequences see 4.1.2. Part A provides ination 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 under fluid pressure for five unload-reload stresscycles. Part B is pered by interrupting Part A at fivespecific stress levels as shown in Fig. 1. Part B providesination on the operating gasket perance including itssensitivity to load reductions after initial loading. Part B yieldsthe constant Gs see 3.1.35.5. 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 design 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, solid metal, jacketed, and other type