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~TABLE OF CONTENTS

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Subject PageIntroduction , , , , , ,.., , ,..,... , , 2Section I .Design , ,..., , . 3WhyGasketsAreUsed , , , ... ..., ... ... ... ,.., .., ,..,.. ,...,..,..3Effecting a Seal , , ..", , ' , 3

Gasket Seating , " , , , , , , , ,.., ,..,... 3Table1-GasketMaterialsandContactFacings 4Table2-EffectiveGasketWidth ,..., ,.., 5 'Table3- GasketSeatingSurfaceFinishes , : 6-7ForcesActingonaGasketedJoint 8BoltLoadFormulas , , ...,... ,... ,.., , , ".., 8NotationSymbolsandDefinitions ' ,' ' ' 9Table4-MaximumSgValues , , 9ExampleSampleGasketCalculation- SteamService 10Section II. Selection , " " .." 11Selecting.theProperGasketMaterial , ,.., , ,.., ,.., ,.., , 11Non-MetallicGasketMaterials " ,.., , 11MetallicGasketMaterials , , '..., 13MetalGaskets ,.., , ,...,...,... , ,.., , 15SolidMetalGaskets , ,.., ",.., ,..." 15MetalJacketedGaskets , , ", 17MetalCladandSolidMetalHeatExchangerGaskets 20HeatExchangerGaskets- StandardShapeIndex , 21SpiralWoundGaskets , , " , ,..,.., 22SizingSpiralWoundGaskets , , , , 22Flange Surface Finishes. , , , ,...' 23Available Spiral Seal Styles , , , , , , 23Section III . Installation , , , ,.. 26InstallationandMaintenanceTips , " '",..,..,..,26GasketInstallationProcedures ,... ,.. ,..,26Bolt Torque Sequence. ' , , ...,..,.., ,..,.., ,... 27TorqueValues , , , , ,..,..,...~ , , , 28TroubleShootingLeakingJoints , , ,.., ,.., ,.., ,.29Manway Problems? . , ,... ,.. , ,.., ,...,..,..,.30Manway Application Information Sheet ,...,..., , ,.., , 31Other Problem Areas , , , ...;.."" , 32

Section IV -Appendix , 33ASME SectionVIII,Div.I - DesignConsiderationforBoltedFlangeConnections 33ChemicalResistanceChart- GasketMetals "...35MaximumServiceTemperatures- GasketMetals 37ChemicalResistanceChart- VegetableFiberSheet 37SoftSheetGasketDimensions ,.., , ,..,.. , ', ,.. ,.., 38Chemical Resistance Chart - Grafoil@ " 40Circumferences andAreasofCircles 41Torque Required to Produce Bolt Stress 45Bolting Materials - Stress Table 1 , 46Bolting Data for Standard Flanges " 47

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INTRODUCTIONJ

The costof leakyjoints in industrytodayis staggering.Out-of-pocketcostsrunintobillionsofdollarsannuallyinlostproduction,wasteofenergy,loss of productand, mostrecently,impacton the environment.Theseproblemsareincreasing,notdecreasing.Itbehoovesallof ustoconsoli-dateourknowledgeandexperienceto solveor at leastminimizetheseproblems.This publicationis being producedbecausewe, as gasketmanufacturersandsuppliers,areconstantlycalledupontosolvesealingproblemsafterthefact.Toooftenwefindinsufficienttimeandattentionhasbeengivento:

. properdesignof flangedjoint

. installationproceduresand

. selectionoftheoptimumgasketmaterialrequiredtosolveaparticularsealingproblem.

Wewillendeavortooutlineinthispublicationthoseareaswe believetobe essentialin a properlydesigned,installedand m"aintainedgasketedjoint.

Webelievemostpeopleinvolvedwiththedesign,installation,andmain-tenanceofgasketedjointsrealizethatnosuchthingas"zero"leakagecanbeachieved.Whetherornotajointis"tight"dependsonthesophisticationof the methodsused to measureleakage.In certainapplicationsthedegreeof leakagemaybe perfectlyacceptableifone dropof waterperminuteis notedat the gasketedjoint.Other requirementsare that nobubbleswouldbeobservedifthegasketedjointwassubjectedtoanairorgas test underwateranda stillmorestringentinspectionwouldrequirepassingamassspectrometertest.Therigidityofthetestmethodwouldbedeterminedby:

. thehazardof thematerialbeingconfined

. lossof criticalmaterialsin a processflow

. impactontheenvironmentshoulda particularfluidescapeintotheatmosphere

. dangerof fireor of personalinjuryAll of thesefactorsdictateproperattentionmustbe givento:. designof flangejointsor closures. properselectionof gaskettype. propergasketmaterial. properinstallationprocedures

Care intheseareaswillensurethatthebesttechnologygoes intothetotalpackageandwillminimizeoperatingcosts,pollutionof theenviron-mentandhazardsto employeesandthegeneralpublic.

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2

SECTION I - DESIGNWHY GASKETS ARE USED

Gasketsareusedtocreateastaticsealbetweentwostationarymembersof a mechanicalassemblyandtomaintainthat seal underoperatingconditionswhichmayvarydependentuponchangesin pressuresandtemperatures.Ifitwerepossibletohaveperfectlymatedflangesandif itwerepossibleto maintainan intimatecontactof these perfectlymatedflangesthroughouttheextremesof operatingconditions,a gasketwouldnotbe required.This is virtuallyan impossibilityeitherbecauseof. thesize of thevesseland/ortheflanges. thedifficultyinmaintainingsuchextremelysmooth

flangefinishesduringhandlingandassembly. corrosionanderosionoftheflangesurfacesduring

operations.Asaconsequence,relativelyinexpensivegasketsare

usedtoprovidethesealingelementinthesemechanicalassemblies.In mostcases,thegasketprovidesa sealby externalforcesflowingthegasketmaterialintotheimperfectionsbetweenthematingsurfaces.It followsthenthatin a properlydesignedgasketclosure,threemajorconsiderationsmustbe taken into accountinorderfor a satisfactorysealto be achieved.

. Sufficientforcemustbeavailabletoinitiallyseatthegasket.Statingthisanotherway,adequatemeansmustbeprovidedtoflowthegasketintotheimper-fectionsin thegasketseatingsurfaces.. Sufficientforcesmustbe availableto maintainaresidualstressonthegasketunderoperatingcondi-tionsto ensurethatthegasketwill be in intimatecontactwiththegasketseatingsurfacestopreventblow-byor leakage.

. Theselectionof thegasketmaterialmustbesuchthatitwillwithstandthepressuresexertedagainstthegasket,satisfactorilyresisttheentiretempera-turerangetowhichtheclosurewillbeexposedandwithstandcorrosiveattackoftheconfinedmedium.

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EFFECTING A SEALA sealisaffectedbycompressingthegasketmaterial

and causingit to flow intothe imperfectionson thegasketseatingsurfacessothatintimatecontactismadebetweenthe gasketandthe gasketseatingsurfacespreventingtheescapeof theconfinedfluid.Basicallytherearefourdifferentmethodsthatmaybeusedeithersinglyor incombinationtoachievethisunbrokenbarrier.. Compression(Figure1).This is by far the most

commonmethodofeffectingasealonaflangejointandthecompressionforceis normallyappliedbybolting.

. Attrition(Figure2). Attritionis a combinationof adraggingactioncombinedwithcompressionsuchas in a sparkpluggasketwherethesparkplugisturneddownon a gasketthatis bothcompressedandscrewedintotheflange.

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. By heat,suchas in thecaseof sealinga bellandspigotjointon cast ironpipeby meansof moltenlead.Note,however,thatafterthe moltenlead ispoured,itis tampedintoplaceusinga tampingtoolanda hammer.

. Gasketlip expansion.This is a phenomenonthatwouldoccurduetoedgeswellingwhenthegasketwouldbeaffectedbyconfinedfluid,as inthecaseofelastomericcompoundsaffectedby the confinedfluids,suchassolvents,causingthegasketmaterialto swellandincreasethe interactionof thegasketagainsttheflangefaces.

Generally,gasketsarecalled upontoeffecta sealacrossthefaces ofcontactwiththeflanges. Perme-ationof the mediathroughthe body of thegasket isalsoa possibilitydependingonmaterial,confinedme-dia, and acceptable leakagerate.

GASKET SEATINGThere are two majorfactorsto be consideredwith

regardto gasketseating.The first is the gasket materialitself.'The ASME

UnfiredPressureVesselCode SectionVIII, Division1definesminimumdesignseatingstressesforavarietyofgasketmaterials.Thesedesignseatingstressesrangefromzero psi for so-calledself-sealinggaskettypessuch as low durometerelastomersand O-rings to26,000psi to properlyseat solid flat metalgaskets.Betweenthesetwoextremesthereare a multitudeofmaterialsavailabletothedesignerenablinghimtomakeaselectionbaseduponthespecificoperatingconditionsunder investigation.Table No.1 indicatesthe morepopulartypes of gasketscoveredby ASME UnfiredPressureVesselCode. (can'ton page6)

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TABLE UA-49.1GASKET MATERIALS AND CONTACT FACINGS

*The surface of a gasket having a lap should be against the smooth surface of the facing and not against the nubbin.

Reprinted with permission of ASME

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Gasket Factors (m) for Operating Conditions and Minimum Design Seating Stress (y)NOTE: This tablegives a listof manycommonly used gasket materials and contact facings with suggested designvalues of m and y that have generally proved satisfactory in actual service when using effective gasket seating

Refer to Table

width b given in Table UA-49.2. The design values and other details given inthis table are suggested only and areUA-49.2

not mandatory.Min.

design Sketches UseGasket seating and facing Use

Gasket material factor stress notes sketch columnm y (psi)

Self-Energizingtypes0 Rings.Metallic.Elastomerothergaskettypes 0 0

- - -

consideredas self-sealing -

Elastomerswithoutfabric.

Below75ShoreDurometer 0.50 0

75or higherShoreDurometer 1.00 200

Elastomerswithcottonfabricinsertion 1.25 400 1 (a, b, c, d)4, 5

Vegetablefiber 1.75 1100

Carbon --- IISpiral-woundmetal,withnonmetallicfiller Stainlessor 3.00 10000 r}

Monel 1 (a, b)

Corrugated metal,Soft Aluminum 2.50 2900

Soft copper or brass 2.75 3700double jacketed with Iron or soft steel 3.00 4500nonmetallicfiller Monel or 4-6% chrome 3.25 5500 ,

Stainless steels .. 3.50_- J..-- 6500..-Soft aluminum 2.75 3700

Soft copper or brass 3.00 4500 \;~1 -

-LNj.'

w 114in.2

Location of Gasket Load Reaction

HG

G--.I--hG--1

F~'C~O~!~~ !--~b 1--- I

HG

G ---1--hG ---I,

(con't from page3)The second majorfactortotakeintoconsiderationmust

be the surfacefinishof the gasketseatingsurface.As ageneral rule, it is necessary to have a relativelyroughgasketseatingsurfacefor elastomericand PTFE gasketson theorderofmagnitudeof500microinches.Solidmetalgasketsnormallyrequirea surfacefinishnotrougherthan63 microinches.Semi-metallicgaskets such as spiral-woundfallbetweenthesetwogeneraltypes.The reasonfor the differenceis thatwith non-metallicgaskets suchas rubber, there must be sufficient roughness on thegasket seating surfaces to bite into the gasket therebypreventingexcessiveextrusionand increasingresistanceto gasketblowout.In the case of solid metalgaskets,ex-tremelyhigh unit loads are requiredto flow the gasketinto imperfectionson the gasket seating surfaces. Thisrequiresthat the gasket seatingsurfaces be as smooth

as possibleto ensurean effectiveseal.Spiral-woundgaskets,whichhavebecomeextremelypopularin thelastfifteento twentyyears,do requiresomesurfaceroughnessto preventexcessiveradialslippageof thegasketundercompression.Thecharacteristicsofthetypeof gasketbeinguseddictatetheproperflangesurfacefinishthatmustbetakenintoconsiderationbytheflangedesignerandthereisnosuchthingasasingleoptimumgasketsurfacefinishforalltypesofgaskets.Theproblemof theproperfinishfor gasketseatingsurfaceis furthercomplicatedbythetypeoftheflangedesign.Forexam-plea totallyenclosedfacingsuchastongueandgroovewillpermittheuseof a muchsmoothergasketseatingsurfacethancan be toleratedwitha raisedface.

Table3 includesrecommendationsfornormalfinishesfor thevarioustypesof gaskets.

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TABLE 3

GASKET SEATING SURFACE FINISHES

GasketDescrigtion

Flat- Non-Metallic

Flat - Metallic' SEE NOTE 1

Corrugated metal

Corrugated metalwith soft filler

Metal jacketed gaskets

NOTE: This table gives a listof suggested surface finishesthat have generally proven satisfactory in actual service.They aresuggestedonly andnot mandatory;however,theyare based uponthebest cross-section of successful designexperience currently available.

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Flange SurfaceFinish

"- AARH

250-500

\ ~

~~\~~

63 -..J

63

125

63-80

~\ \, ~."\ \'i:ii,':'}:::'i:::iiiii:i:ii~

\\~

\",.;

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..........

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TABLE 3 - GASKET SEATING SURFACE FINISHES CONT.

Note

FORCES ACTING ON AGASKETED JOINT

BOLT LOADHYDROSTATICEND FORCE

INTERNAL ORBLOW OUTPRESSURE

GASKET

Forces actingon a gasketjoint (Figure 1)

. THE INTERNAL PRESSURE: Thesearetheforcescontinuallytry-ing to unseala gasketedjoint by exertingpressureagainstthegasket(blowoutpressure)andagainsttheflangesholdingthegas-ketin place(hydrostaticendforce).See Figure1.

. THE FLANGE LOAD: The totalforcecompressingthegaskettocreatea seal, Le., the effectivepressureresultingfromthe boltloading.

. TEMPERATURE: Temperaturecreatesthermo-mechanicaleffects,expandingorcontractingthemetals,affectingthegasketmaterialbypromoting"creeprelaxation"whichis a permanentstrainor relax-ationqualityof manysoft materialsunderstress.The effectofcertainconfinedfluidsmaybecomeincreasinglydegradingastem-peraturerisesandattackuponorganicgasketmaterialsissubstan-tiallygreaterthanat theambienttemperatures(about75F).As arule,the higherthe temperature,the morecriticalbecomestheselectionof thepropergasket.

. MEDIUM:The liquidor gas againstwhichthegasketis to seal.

. GENERAL CONDITIONS:Thetypeof flange,theflangesurfaces,thetypeof boltmaterial,thespacingandtightnessofthebolts,etc.

Each of these factorsrequireconsiderationbeforean effectivegasketmaterialis finallychosen.However,the propergasketmay.oftenbe rejectedbecausefailureoccurreddue to a poorlycleanedflangeface,or improperbolting-uppractice.These detailsrequirecarefulattention,butifcompliedwithwillhelpeliminategasketblow-outor failure.

Therearethreeprincipalforcesactingon anygas-ketedjoint.Theyare:. Boltloadand/orothermeansof applyingtheinitial

compressiveloadthatflowsthegasketmaterialintosurfaceimperfectionsto forma seal.

. The hydrostaticend force,thattendsto separateflangeswh~mthesystemis pressurized.

. Internalpressureactingontheportionofthegasketexposedto internalpressure,tendingto blowthegasketoutof thejointand/orto bypassthegasketunderoperatingconditions.

Thereareothershockforcesthatmaybecreatedduetosuddenchangesintemperatureandpressure.Creeprelaxationis anotherfactorthatmaycomeintothepic-ture.Figure1 indicatesthethreeprimaryforcesactingupona gasketedjointwhichwe will considerfor thisdiscussion.The initialcompressionforceappliedto ajointmustserveseveralpurposes.

. It must be sufficientto initiallyseat the gasketandflowthegasketintothe imperfectionson the

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gasKetseatingsurfaces regardlessof operatingconditions.

. Initialcompressionforcemustbe greatenoughtocompensateforthetotalhydrostaticendforcethatwouldbe presentduringoperatingconditions.. It mustbe sufficientto maintaina residualloadonthegasket/flangeinterface.

From a practicalstandpoint,residualgasket loadmustbe"X"timesinternalpressureifatightjointistobemaintained.Thisunknownquantity"X"iswhatis knownas the"m"factorin theASME unfiredpressurevesselcodeandwillvarydependinguponthetypeof gasketbeingused.Actuallythe"m"valueistheratioof residualunitstress(boltload minushydrostaticend force)ongasket(psi) to internalpressureof the system.Thelargerthenumberusedfor"m,"themoreconservativetheflangedesignwouldbe,andthemoreassurancethedesignerhasof obtaininga tightjoint.

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BOLT LOAD FORMULAS*The ASME UnfiredPressureVessel Code, Section

VIII, Division1 definesthe initialbolt load requiredtoseata gasketsufficientlyas:

Wm2 = 1TbGy

The requiredoperatingbolt load mustbe at leastsufficient,underthemostsevereoperatingconditions,to containthehydrostaticendforceand,inaddition,tomaintaina residualcompressionloadonthegasketthatissufficienttoassurea tightjoint.ASME definesthisboltloadas:

Wm1= ~G2P + 2b1TGmP4

After WM1and Wm2are calculated, then the minimumrequired bolt area Amis determined:

A - Wm1

m1 - s:-

Am2 = Wm2

Sa

Am = Am1if Am1 ;; Am2

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AmOR

= Am2 if Am2 ;;;; Am1

Bolts are then selected so thatthe actual bolt area Abis equal to or greater than AmAb = (Number of Bolts) x (Minimum Cross-Sectional

Area of Bolt in Square Inches)

Ab ~ Am

The maximum unit load Sg(max)on th~gasket bearingsurface is equal to the total maximum bolt load inpoundsdividedbytheactualsealingareaof thegasket \in square inches.

Sg - ~Sa(max)-

~[(aD - 0.125)2 - (ID)2] -J

SpiralWoundGaskets

AbSa

Sg(max)= -.I! [(OD)2 - (ID)2]4

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Ail OtherTypesofGaskets

NOTATION SYMBOLS ANDDEFINITIONS

'-'Exceptas noted,thesymbolsand definitionsbe-

lowarethosegiveninAppendix II of the 1977ASMEBoilerand PressureVesselCode, SectionVIII.

Ab = actualtotalcross-sectionalareaofboltsatrootof threador sectionof leastdiameterunderstress,squareinches.

Am = total requiredcross-sectionalarea of bolts,taken as the greaterof Am1or Am2'squareinches.

Am1= totalcross-sectionalarea of bolts at root ofthreadorsectionofleastdiameterunderstress,requiredfortheoperatingconditions.

Am2= totalcross-sectionalarea of bolts at rootofthread or section of least diameterunderstress,requiredfor gasketseating.

b = effectivegasketor joint-contact-surfaceseat-ingwidth,inches.Table2

bo = basicgasketseatingwidth,inches.Table2.

G = diameterat locationof gasketload reaction.Table2.

When bo;; % in., G = mean diameter ofgasket contact face, inches.When bo > % in., G = outside diameter ofgasket contact face less 2b, inches.

m = gasket factor. Table 1.

N = width, in inches, used to determine the basicgasket seating width bo, based upon the pos-sible contact width of the gasket. Table 2.

P = designpressure,poundspersquareinch.

Sa = allowable bolt stress at ambient temperature,pounds per square inch.

Sb = allowable boltstress at operatingtemperature,pounds per square inch.

Sg = Actual unit load at the gasket bearing surface,pounds per square inch.

Wm1= required bolt load for operating conditions,pounds.

Wm2= minimumrequiredbolt load for gasket seating,pounds.

y = gasket or joint-contact-surface unit seatingload, minimum design seating stress, PSITable 1 pounds per square inch.

*ThePressureVesselResearchCouncil(PVRC) hasdevelopeda programto betteridentifyloadsbasedon gasket"sealability".Thus, new design factorsare anticipatedto appear in upcomingrevisionsof the ASME Boilerand

'-" PressureVesselCode. (Lamonsis a sponsorof PVRC research).

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SAMPLE GASKETAPPLICATION PROBLEM

For assistancewitha particulargasketproblemcon-tact LamonsSales Department,or a technicalrepre-sentative.

EXAMPLE CONDITIONS:A designerwantsa gasket recommendationfor a

specialapplicationsealingsteamat600psiand500F.

CONDITIONS:Designpressure- 600psiTestpressure- 900psiDesigntemperature- 500FProcess material- steamFlangedetails-

-Av- 231/16"a.D.

~ '\;-- 2115/16" LD.1/6'~

:+

Detailsof Flange

Bolting- 24- 11/8"- 8 thds.Bolt Material - ASTM A193- B7FlangeMaterial-ASTM A312Type316S.S.Allowableboltstress@AmbientTemperature,accord-ingtoStressTable1,Page45 is only20,000PSI; how-ever,to preventleakageunderhydrotestit is decidedto tightenboltingto 30,000PSI (SeeNoteatbottomofStressTable 1, Page 45; Appendix S, Page 32; and"Note",Page 27.

AllowableStress@500F- 20,000PSI(seeStressTable1 Appendices Page 45.

AnalysisThe pressure-temperatureconditionsindicatea me-tallictypegasketshouldbe used.The conditionsap-peartobesuitableforaspiralwoundgasket.Theflangematerial,316S.S., is compatiblewiththe steamenvi-ronment@500F.Therefore,the logicalchoicefor themetalin the gasket is 316 S.S. Since Grafoil@is alsocompatiblewiththe environment(see page 40), it isselectedas thefillermaterial.

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1. FromTable 1,Page 4m=3y = 10,000

2. Frompage 22, "SizingSpiralWoundGasketsConfinedon 1.0.and 0.0.", thegasketsshouldhavean I.D. of 22"and an 0.0. of 23".Since thefacing is grooveto flatface, thegasketthicknessmustbe .175"*.

FromTable2, Page 5N = 1/2"=0.500"b = 0.250"b0= 0.250"G = 22.5"

3. Fromformulaon page 8.Wm2 = nbGy

= 3.14x 0.250"x 22.5"x 10,000PSI= 176,625Ibs.

W = 11G2P+2bnGmPm1 4Wm1(Design) = 0.785x (22.5")2x 600 PSI +2 x

0.250"x 3.14x 22.5"x 3 x 600PSI

= 238,444+63,585. = 302,029Ibs.= 0.785x (22.5")2x 900 PSI +2 x

0.250"x 3.14x 22.5"x 3 x 900PSI

= 357,666+95,378= 453,043Ibs.

From Table on Page 42 and definitionof Ab,page 8Ab=24 x 0.728= 17.472sq. in.Bolt load @ Test Condition: 30,000 x 17.472 =524,160Ibs.Bolt Load @ Design Condition: 20,000 x 17,472 =349,440Ibs.

It is apparentadequate bolting is available.Mini-mumrequiredbolt loadingfor gasketseating(Wm2)is176,625 Ibs. Available load for gasket seating is524,160Ibs.

Minimum required bolt at design conditions is302,029Ibs. and availableload at design conditionsis 349,440Ibs.

Note:requiredboltloadattestconditionsis453,043Ibs.andavailableboltloadattestconditionsis524,160Ibs.

Since a positivestop is designed into the flange,i.e. grooveto flat, no additionalprecautionsare nec-essary.Any forces in excess of the force requiredtocompressthegasketwill be transmittedto theflangefaces and gasketcrushingcannotoccur.

Fromtheaboveanalysis,itappearsouroriginalas-sumptioniscorrectandtherecommendationwouldbe:

SpiraSealTypeW Gasket- 316S.S./Grafoil@22"10x 23"00 x 0.175"Thick

J

Wm1(Test)

J

*Theoptimumcompressedthicknessfor a .175"thickspiral wound gasket is .130":t .005"(See page 23).The 1/8"groovedepth is withinthis range.

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SECTION II - SELECTION

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SELECTING THE PROPERGASKET MATERIAL

The optimumgasketmaterialwouldhavethefollow-ing characteristics.It wouldhavethe chemicalresis-tance of PTFE, the heat resistanceof graphite,thestrengthof steel,requirea zeroseatingstresssuchassoft rubberandbe inexpensive.Obviouslythereis noknowngasketmaterialthathasallthesecharacteristicsandeachmaterialhascertainlimitationsthatrestrictitsuse. It is possibleto overcomelimitationspartiallybyseveralmethodssuchasincludingtheuseofreinforcinginserts,combiningit withothermaterials,varyingtheconstructionor density,or by designingthejointitselfto overcome some of the limitations. Obviously,mechanicalfactorsare importantin the designof thejointbutthe primaryselectionof a gasketmaterialisinfluencedbythreefactors,. thetemperatureofthefluidorgastobecontained,. thepressureof thefluidor gas to becontained,. thecorrosivecharacteristicsofthefluidorgastobe

contained.Chartsincludedin theappendixindicatesomevery

generalrecommendationsfornon-metallicandmetallicmaterialsagainstvariouscorrosivemedia.Itshouldbepointed out that these charts are general recom-mendationsandtherearemanyadditionalfactorsthat

can influencethe corrosionresistanceof a particularmaterialatoperatingconditions.Someof thesewouldinclude. Concentrationofthecorrosiveagent.(Fullstrength

solutionsarenotnecessarilymorecorrosivethanthose of dilute proportionsand, of course, thereverseis alsotrue.)

. The purityof a corrosiveagent.For example,dis-solvedoxygeninotherwisepurewatermaycauserapidoxidationof steamgenerationequipmentathightemperatures.

. Thetemperatureofthecorrosiveagent.Ingeneral,highertemperaturesof corrosiveagentswillaccel-eratecorrosiveattack.

As aconsequence,itisoftennecessaryto"field-test"materialsfor resistanceto corrosion under normaloperating conditions to determine if the materialselectedwillhavetherequiredresistancetocorrosion.TYPES OF GASKETS

Forthepurposesofthisbulletin,gasketswillbesepa-ratedintotwobroadcategories,non-metallicandmetal-licgaskets.

Of thetwotypes,non-metallicgasketsarebyfarthemostwidelyused.Thisdiscussionwillcoverthevarioustypesofnon-metallicmaterials,generalapplicationdataandtemperaturelimitations.

NON-METALLIC GASKET MATERIALS

~NATURAL RUBBER

Naturalrubberhasgoodresistancetomildacidsandalkalies,saltsandchlorinesolutions.Ithaspoorresis-tancetooilsandsolventsandis notrecommendedforusewithozone.Itstemperaturerangeisverylimitedandis suitableonlyfor usefrom-70F to200F.

SBR (STYRENE-BUTADIENE)SBR is asyntheticrubberthathasexcellentabrasion

resistanceand has good resistanceto weakorganicacids,alcohols,moderatechemicalsandketones.It isnotgoodinozone,strongacids,fats,oils,greasesandmost hydrocarbons.Its temperaturelimitationsareapproximately-65F to 250F.

CR (CIU.OROPRENE) (NEOPRENE)Chloropreneis a syntheticrubberthatis suitablefor

useagainstmoderateacids,alkaliesandsaltsolutions.Ithasgoodresistancetocommercialoilsandfuels.Itisverypooragainststrongoxidizingacids,aromaticandchlorinatedhydrocarbons.Itstemperaturerangewouldbefromapproximately-60F to 250F.

BUNA-N RUBBER (NITRILE, NBR)Buna-Nisasyntheticrubberthathasgoodresistance

to oils andsolvents,aromaticand aliphatichydrocar-bons,petroleumoilsandgasolinesoverawiderangeoftemperature.Italsohasgoodresistancetocausticsandsalts butonlyfairacid resistance.It is poor in strongoxidizingagents,chlorinatedhydrocarbons,ketonesand esters.It is suitableovera temperaturerangeofapproximately-60F to250F.

FLUOROCARBON (VITON)Fluorocarbonelastomerhasgoodresistancetooils,

fuel,chlorinatedsolvents,aliphaticandaromatichydro-

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.

carbons and strong acids. It is not suitable for useagainstamines,esters, ketonesor steam. Its normaltemperaturerangewouldbebetween-15Fand450F.

CIILOROSULFONATED POLYETHELENE(HYPALON)

Thismaterialhasgoodacid,alkaliandsaltresistance.It resistsweathering,sunlight,ozone,oilsandcommer-cialfuelssuchas dieselandkerosene.It is notgoodinaromaticsor chlorinatedhydrocarbonsand has poorresistanceagainstchromicacidandnitricacid.Itsnor-maltemperaturerangewouldbe between-50F and275F.

SILICONES

Silicone rubbers have good resistanceto hot air.They are unaffectedby sunlightand ozone.They arenot,however,suitablefor useagainststeam,aliphaticand aromatichydrocarbons.The temperaturerangewould be between-65Fto 500F.

EPDM (ETHYLENE PROPYLENE),MONOMER

Thissyntheticmaterialhasgoodresistancetostrongacids, alkalies,salts and chlorinesolutions.It is notsuitablefor use in oils,solventsor aromatichydrocar-bons.Itstemperaturerangewouldbebetween- 70Fand350F.

11

GRAFOIL@

This is an all graphitematerialcontainingno resins orinorganic fillers. It is available with or without a metalinsertion,and in adhesive-back tape formfor pipe gas-ketsover24 inches indiameter.Grafoil has outstandingresistanceto corrosion against a wide varietyof acids,alkalies and salt solutions, organic compounds, andheat transferfluids, even at high temperatures.It doesnot melt, but does sublimate at temperatures over6000F. Its use against strong oxidizing agents at ele-vated temperaturesshould be investigatedvery care-fully. In addition to being used as a gasket, Grafoilmakes anexcellentpackingmaterialand is also usedasa filler material in spiral-wound gaskets.

CERAMIC FIBERCeramic fiberis availablein sheetor blanketformand

makes an excellentgasket materialfor hotair ductworkwith lowpressures and lightflanges. It is satisfactoryforservice up to approximately2000F.Ceramic materialisalso used as a filler material in spiral-wound gaskets.

PLASTICSOf alltheplastics,PTFE (polytetrafluoroethylene)has

emergedas themostcommonplasticgasketmaterialPTFE's outstandingpropertiesinclude resistancetotemperatureextremesfrom-140F to450F(forvirginmaterial).PTFEishighlyresistanttochemicals,solvents,causticsandacidsexceptfreefluorineandalkalimetals.It hasa verylowsurfaceenergyand does notadheretotheflanges.PTFEgasketscanbesuppliedina varie-ty of formseitheras virginmaterialor reprocessedmaterialandalsowitha varietyoffillermaterialsuchasglass,"carbon,molybdenumdisulfite,etc.The principaladvantageinaddingfillerstoPTFEistoinhibitcoldflowor creeprelaxation.

PTFE ENVELOPE GASKETS

EnvelopegasketsutilizingPTFEjackethavebecomepopularfor usein severelycorrosiveservicesbecauseof theirlowminimumseatingstresses,excellentcreepresistance,highdeformabilityandchoiceofa varietyof

~ fillermaterialstoassureoptimumperformanceonanyspecificapplication.Fillerssuchascorrugatedmetalandrubbersheetsareavailable.

Therearethreebasicdesignsof envelopes:

Sli t Type

Slit envelopes are sliced fromcylindersand splitfromthe outsidediametertowithinapproximately1/16"of theinside diameter.The bearing surface is determined by12

thefillerdimensions.Clearanceisrequiredbetweenthe1.0.of thefillerandtheenvelopelO. The Gasket0.0.normallyrestswithintheboltholecircleandthe1.0.isapproximatelyequaltothenominal1.0.ofpipe.Availa-ble in sizesto a maximum0.0. of 24". '-"

Milled Type

Milledenvelopesare machinedfromcylinderstock.Thejacketis machinedfromthe0.0. towithinapproxi-mately1/32"its1.0.Thejacket's1.0.fitsflushwithpipeboreandits0.0. nestswithinthebolts.Availableinsizesup to a maximum0.0. of 24". Milledenvelopesaremoreexpensivethanslittypesinceconsiderablymorematerialis lost in machining.

FormedTape Type

Large diameter(over 12" N.P.S.) and irregularlyshaped envelopes are formedfrom tape and heatsealedto producea continuousjacketconstruction.

Filler Materials

The morepopularfillersfor envelopegasketsare:. Rubbersheet. Compressednon-asbestos. Corrugatedmetalinserts. Sandwichconstructionscombiningsomeoftheabove

On vacuumapplications,doubleenvelopesare fre-quentlyusedwheretwojacketsareoverlappedto pro-tectthe0.0. as wellas the I.D.Theycan be slit,milledor formedtapetypes.

~

J

MAXIMUM*TEMPERATURE OF

MATERIALS, of250250500

METALLIC GASKET MATERIALSof800to1650F.whencorrosiveconditionsaresevere.Recommendedmaximumworkingtemperatureof 1400F. Brinellhardnessis approximately160.316-L STAINLESS STEEL

Continousmaxiumumtemperaturerangeof 1400-1500F. Carboncontentheldat a maximumof .03%.Subjecttoa lesserdegreeof stresscorrosioncrackingand also to intergranularcorrosionthan Type 304.Brinellhardnessis about140.321 STAINLESS STEEL

An 18-10Chromium-NickelsteelwithaTitaniumaddi-tion.Type321stainlesshasthesamecharacteristicsasType347.The recommendedworkingtemperatureis1400to1500F.andinsomeinstances1600F.Brinellhardnessis about150.347 STAINLESS STEEL

An 18-10Chromium-NickelsteelwiththeadditionofColumbium.Notassubjectto intergranularcorrosionasisType304.Issubjecttostresscorrosion.Recommend-edworkingtemperatureof14000-1500F.andinsomein-stancesto1700F.Brinellhardnessisapproximately160.410 STAINLESS STEEL

A 12% Chromiumsteel witha maximumtempera-turerangeof 1200F.to 1300F.Used for applicationsrequiringgood resistanceto scaling at elevatedtem-peratures.Is not recommendedfor use whereseverecorrosionisencounteredbutis stillveryusefulforsomechemicalapplications.Maybeusedwheredampness,aloneor coupledwithchemicalpollution,causessteelto fail quickly.Brinellhardnessis around155.502/501

4-6%Chromiumand1/2Molybdenumalloyedformildcorrosiveresistanceand elevatedservice.Maximumworkingtemperatureis 1200F.andhasa Brinellhard-nessofaround130.Ifseverecorrosionisanticipated,abettergradeof stainlesssteelwouldprobablybea bet-ter choice.Becomesextremelyhardwhenwelded.

13

'-"

COMPRESSED NON-ASBESTOS SHEETING

Earlyeffortsto replaceasbestosresultedin the in-troductionandtestingofcompressednon-asbestospro-ductsinthe1970's.Manyof theseproductshaveseenextensiveusesincethatperiodhowevertherehavebeenenoughproblemsto warrantcarefulconsiderationinchoosing a replacementmaterialfor compressedasbestos.Mostmanufacturersof non-asbestossheetmaterialsusesyntheticfibers,likeKevlar@,in conjunc-tionwithanelastomericbinder.Theelastomericbindermakesupa largerpercentageofthissheetandtherebybecomesa moreimportantconsiderationwhendeter-

Note: On page 8, the term"pressuretemperatureconditions"was used indicatingthatthesevaluesareusedto helpdeterminethetypesof materialand con-structionto be used ina gasket.

A "RuleofThumb"guidefor theselectionof gasketmaterialshasevolvedovertheyears.This valueis ar-rivedatby multiplyingoperatingpressuretimesoper-atingtemperature.

MATERIALRubberVegetableFiberSolidFluorocarbon

MAXIMUMP xT15,00040,00075,000

..........

CARBON STEELCommercialqualitysheetsteelwithanuppertemper-

aturelimitofapproximately1OOOF.,particularlyifcondi-tionsareoxidizing.Notsuitableforhandlingcrudeacidsoraqueoussolutionsofsaltsintheneutraloracidrange.A high rateof failuremaybe expectedin hot waterserviceif thematerialis highlystressed.Concentratedacidsandmostalkalieshavelittleor noactionon ironand steelgasketswhichare used regularlyfor suchservices.Brinellhardnessis approximately120.304 STAINLESS STEEL

An 18-8(Chromium18-20%,Nickel8-10%)Stainlesswitha maximumrecommendedworkingtemperatureof1400F.At least80% ofapplicationsfor non-corrosiveservicescanuseType304Stainlessinthetemperaturerangeof - 320F.to 1O00F.Excellentcorrosionresis-tancetoa widevarietyof chemicals.Subjecttostresscorrosioncrackingand to intergranularcorrosionattemperaturesbetween800F.to 1500F.in presenceof certainmediafor prolongedperiodsof time.Brinellhardnessis approximately160.304L STAINLESS STEEL

Carboncontentmaintainedat a maximumof .03%Recommendedmaximumworkingtemperatureof1400FF. Sameexcellentcorrosionresistanceas Type304.This lowcarboncontenttendsto reducetheprecipita-tionofcarbidesalonggrainboundaries.LesssubjecttointergranularcorrosionthanType304.Brinellhardnessis about140

316 STAINLESS STEELAn 18-12Chromium-Nickelsteelwithapproximately

2% of Molybdenumaddedto the straight18-8alloywhichincreasesits strengthat elevatedtemperaturesandresultsinsomewhatimprovedcorrosionresistance.Has the highestcreepstrengthat elevatedtempera-turesofanyconventionalstainlesstype.Notsuitableforextendedservicewithinthecarbideprecipitationrange

'-"

mining applications.@ Kevlarisa registeredtrademarkof E.!.DuPontCo.

VEGETABLE FIBER SHEET

Vegetablefibersheetis a toughpliablegasketmate-rialmanufacturedbypapermakingtechniquesutilizingplant fibers and a glue-glycerineimpregnation.It iswidelyusedforsealingpetroleumproducts,gasesandawidevarietyofsolvents.Itsmaximumtemperaturelimitis 250F.If a morecompressiblematerialis required,acombinationcork-fibersheetis available.Thecork-fibersheethasthesamemaximumtemperaturelimitationasthevegetablefibersheet.

*Temperaturelimitsof gasketingmaterialsare notabsolutefigures. Materialswithinany categorymayvary depending upon a manufacturer'sprocessingtechniques,grades and typesof rawmaterialsused,etc,

Inaddition,flangedesignandapplicationpeculiari-ties mayinfluencethetemperaturelimitof a materialto a greateror fesserdegree.

ADMIRALTYArsenicalAdmiralty443has71% Copper,28%Zinc,

1% Tin andtraceamountsof Arsenic.Highcorrosiveresistance,holdsup extremelywell againstsalt andbrackishwaters,and watercontainingsulfides.Rec-ommendedmaximumworkingtemperatureof 500F.Idealforcarryingcorrosivecoolingwatersat relativelyhightemperatures.Brinellhardnessis about64.

ALLOY 2045% Iron,24% Nickel,20% Chromium,and small

amountsof Molybdenumand Copper.Maximumtem-peraturerangeof1400-1500F.Developedspecificallyforapplicationsrequiringresistancetocorrosionbysul-phuricacid.Brinellhardnessis about160.

ALUMINUMAlloy1100iscommerciallypure(99%minimum).Its

excellentcorrosionresistanceandworkabilitymakesitidealfordoublejacketedgaskets.TheBrinellhardnessis approximately35. For solidgaskets,strongeralloyslike 5052 and 3003 are used. Maximumcontinuousservicetemperatureof 800F.

BRASSYellowbrass268 has 66% Copperand 34% Zinc.

Offersexcellentto goodcorrosionresistancein mostenvironments,butis notsuitableforsuchmaterialsasaceticacid,acetylene,ammonia,and salt.Maximumrecommendedtemperaturelimitof500F.Brinellhard-ness is 58.

COPPER

Nearlypurecopperwithtraceamountsof silveraddedto increase its working temperature. Recommendedmaximumcontinuousworkingtemperatureof 5000F.Brinell hardness is about 80.

CUPRO NICKELContains 69% Copper, 30% Nickel, and small

amountsof Manganeseand Iron.Designedto handlehighstresses,it finds itsgreatestapplicationin areaswherehightemperaturesandpressurescombinedwithhighvelocityanddestructiveturbulencewouldrapidlydeterioratemanyless resistantalloys.Maximumrec-ommendedtemperaturelimitof500F.Brinellhardnessis about70.

HASTELLOY B@26-30%Molybdenum,62% Nickel,and 4-6% Iron.

Maximumtemperaturerangeof 2000F. Resistanttohot, concentratedhydrochloricacid. Also resiststhecorrosiveeffectsof wet hydrogenchlorinegas, sul-phuricandphosphoricacidsandreducingsaltsolutions.Usefulfor hightemperaturestrength.Brinellhardnessis approximately230.

HASTELLOY C-276@16-18%Molybdenum,13-17.5%Chromium,3.7-5.3%

Tungsten,4.5-7% Iron, and the balance is Nickel.Maximumtemperaturerangeof 2000F.Verygoodinhandlingcorrosives.Highresistancetocoldnitricacidof14

varyingconcentrationsaswellas boilingnitricacidupto70% concentration.Good resistanceto hydrochloricacidandsulphuricacid.Excellentresistanceto stresscorrosioncracking.Brinellhardnessis about210.

'-"INCONEL 600@

Recommendedworkingtemperaturesof2000F.andissomeinstances2150F.Isa nickelbasealloycontain-ing77% Nickel,15%Chromiumand7% Iron.Excellenthigh temperaturestrength.Frequentlyused to over-comethe problemof stresscorrosion.Has excellentmechanicalpropertiesat the cryogenictemperaturerange.Brinellhardnessis about150.

INCOLOY 800@32.5%Nickel,46%Iron,21%Chromium.Resistantto

elevatedtemperatures,oxidation,and carburization.Recommendedmaximumtemperatureof 1600F.Brinellhardnessis about150.

MONEL@Maximumtemperaturerangeof 1500F. Contains

67% Nickeland30% Copper.Excellentresistancetomostacidsandalkalies,exceptstrongoxidizingacids.Subjectto stresscorrosioncrackingwhenexposedtofluorosilicacid, mercuricchlorideand mercury,andshould not be used with these media.With PTFE(Polytetrafluoroethylene),it is widelyused for hydro-fluoricacid service.Brinellhardnessis about120.

NICKEL 200@Recommendedmaximumworkingtemperatureis

14000F.and evenhigherundercontrolledconditions.Corrosionresistancemakesitusefulincausticalkaliesandwhereresistanceinstructuralapplicationstocorro-sion is a primeconsideration.Does not havethe all-aroundexcellentresistanceof Monel.Brinellhardnessis about110.

v

PHOSPHOR BRONZE90-95%Copper,5-10%Tin, and traceamountsof

phosphorus.Maximumtemperaturerangeof 500F.Excellentcoldworkingcapacity.Limitedtolowtempera-turesteamapplications.Excellentcorrosionresistance,butnotsuitableforacetylene,ammonia,chromicacid,mercury,and potassiumcyanide.Brinellhardnessisapproximately65.

TITANIUMMaximumtemperaturerangeof 2000F. Excellent

corrosionresistanceevenathightemperatures.Knownasthe"Bestsolution"tochlorideionattack.Resistanttonitricacidinawiderangeoftemperaturesandconcen-trations.Mostalkalinesolutionshavelittleifanyeffectuponit.Outstandinginoxidizingenvironments.Brinellhardnessis about215.

NoteMaximumtemperatureratingsarebaseduponhotair

constanttemperatures.The presenceofcontaminatingfluidsand cyclicconditionsmaydrasticallyaffectthemaximumtemperaturerange.

J

MATERIAL HARDNESS CONVERSION SCALEBrinellhardnessfiguresare approximateguides

only. Most materialsorderedby Lamons are specified"deadsoft";however,differentthicknesses and differ-ent heatsof the same materialwillvary in hardness.

~ Rockwell "B"100

95

9085

80

75

70

65

6055

5040

30

2010

Brinell3000Kg. Load

241

210

183

163

146

134

122

10895

89

8375

67

62

57

'-""

METAL GASKETSMetallic gaskets are available in many forms

including,. solidmetalgasketsthatrequireverysmooth,plain

surfacefinishesandhighclampingforcesinordertoseal,

. combinationswith soft fillers such as double-jacketedandspiral-woundthatcantolerategreatersurfaceroughnessand willseatwithlessercom-pressiveforces,and

. lightcross sectiongasketsthat are self-sealingandrequireminimumclampingforcesforeffectivesealing.

Inallcases,however,carefulattentionmustbegivento machiningdetailsof the flangesand sizingof thegaskets.

SOLID METAL GASKETS

PLAIN FLATMETAL GASKETS

"'"

Flat metalgasketsare best suitedfor applicationssuchasvalvebonnets,ammoniafittings,heatexchang-ers,hydraulicpresses,tongue-and-groovejoints.Theycan be used when compressibilityis not requiredtocompensateforflangesurfacefinish,warpageor mis-alignmentandwheresufficientclampingforceis avail-able to seatthe particularmetalselected.They mustbe sealed by theflowof the gasketmetalintothe im-perfections on the gasket seating surfaces of theflange.This requiresheavycompressiveforces. Thehardnessof gasketmetalmustbe lessthanthe hard-ness of theflanges to preventdamageto the gasketseatingsurfaceof the flange. Flatmetalgasketsarerelativelyinexpensiveto produceand can be madeofvirtuallyany materialthat is availablein sheet form.Size limitationis normallyrestrictedto the sheetsize.Largergasketscan be fabricatedby welding.

KAMMPROFILEKAMMPROTM

Thedesignfeaturesofthegroovesincombinationwiththespecialpropertiesof thefacingmaterialsresultinoptimalperformanceandconsistency.Thesimultaneousactionof highcompressibilityfacingmaterialontheoutsideofthegroovedmetalincombi-nationwithlimitedpenetrationofthetipsofthesolidmetalcoreenhancetheinteractionof thetwomateri-als. Thisallowseachtoperformindividuallytotheiroptimum.LamonsmanufacturesKammproinawiderangeofmetalsandalloystoexactspecifications.

PROFILEGASKETS

Profiletypegasketsofferthe desirablequalitiesofplain washer types and the added advantageof areducedcontactareaprovidedbytheV-shapedsurface.Itisusedwhenasolidmetalgasketis requiredbecauseof pressureor temperatureor becauseof the highlycorrosiveeffectof the fluidto be containedand alsowhenboltingis notsufficientto seata flatwasher.

A PROFILEGASKETWITH AMETALJACKET

It flangeconditionsrequirea profiletypegasket,butflangeprotectionis requiredas well,theprofilegasketmay be suppliedwith either a single-jacketedor adouble-jacketedshield.This willprovideprotectionfortheflangesandwillminimizedamagetotheflangefacesdueto theprofilesurface.NOTE: Withoutexceptionallof thesolidmetalgasketsrequireaveryfinesurfacefinishontheflanges.A flangewith a flange surface roughnessof 63 microinchesorsmootherisdesired.Undernocircumstancesshouldthesurfacefinishexceed125microinches.Inaddition,radialgougesor scoreswouldbealmostimpossibletoseal usingsolidmetalgaskets.

15

ROUND CROSS SECTION,SOLID METALGASKETS

Roundcrosssectionsolidmetalgasketsareusedonspecificallydesignedflangesgroovedorothewisefacedtoaccuratelylocatethegasketduringassembly.Thesegasketssealbya linecontactwhichprovidesan initialhighseatingstressat low bolt loads.This makesanideal gasketfor low pressures.The more commonmaterialsusedforthistypeof gasketwouldbe alumi-num,copper,softironorsteel,Monel@,nickel,and300seriesstainlesssteels.They are fabricatedfromwireformedtosizeandwelded.Theweldisthenpolishedtotheexactwirediameter.

API RINGJOINTGASKETS

API ringjointgasketscome in two basic types,anoval cross section and an octagonal cross section.Thesebasicshapesareused inpressuresupto5,000psi.Thedimensionsarestandardizedandrequirespe-cially grooved flanges. The octagonalcross sectionhasa highersealingefficiencythantheovalandwouldbe the'preferredgasket.However,onlytheovalcrosssection can be used in the old type round bottomgroove,The newerflatbottomgroovedesignwill ac-cepteithertheovalortheoctagonalcrosssection.Thesealing surfaces on the ring joint grooves must besmoothlyfinishedto 63 microinchesand be free ofobjectionableridges,toolor chattermarks.Theysealby an initialline contactor a wedging action as thecompressiveforcesare applied.The hardnessof thering should always be less than the hardnessof theflanges.DimensionsforringjointgasketsandgroovesarecoveredinASME B16.20,API6A, andASME/ANSIB16.5.

BX AND RXRINGGASKETS

The BX ringgasketdiffersfromthestandardovaloroctagonalshape in that it is square in cross sectionand tapers in each corner.They can only be used inAPI 6BX flanges.RX ringgasketsaresimilaris shapeto the standardoctagonal ring jointgasket but theircross section is designed to take advantageof thecontainedfluid pressurein effectinga seal. They arebothmadetoAPI 6A.16

LENS TYPEGASKET

"-.J

A lenstypegasketisa linecontactsealforuseinhighpressurepipingsystemsandinpressurevesselheads.The lenscrosssectionisasphericalgasketsurfaceandrequiresspecialmachiningon theflanges.Thesegas-ketswillseatwithasmallboltloadsincethecontactareais very small and gasketseatingpressuresare veryhigh.Normallythegasketmaterialshouldbesofterthantheflange.Inorderinglensgaskets,completedrawingsand materialspecificationsmustbe supplied.

DELTAGASKET

A deltagasketis a pressureactuatedgasketusedprimarilyonpressurevesselsandvalvebonnetsatveryhighpressuresin excessof 5000psi.As withthelensgasket,completedrawingsand materialspecificationsmustbe supplied.Internalpressureforcesthegasketmaterialto expandwhenthe pressureforcestendtoseparate the flanges. Extremely smooth surfacefinishesof 63 microinchesor smootherare requiredwhenusingthistypeof gasket. '-'

BRIDGEMANGASKET

The Bridgemangasketis a pressureactivatedgasketforuseonpressurevesselheadsandvalvebonnetsforpressuresof 1500psiandabove.The crosssectionofthegasketis suchthatinternalpressureactingagainsttheringforcesitagainstthecontainingsurfacemakingaself-energizedseal.Bridgemangasketsarefrequentlysilverplatedor leadplatedto providea softersurfaceandminimizetheforcerequiredtoflowthegasketmetalintotheflangesurface.

MISCELLANEOUSMETALGASKETS

-..J

In additionto thecommonlyused,above-listedgas-kets,therearespecialtyitemsavailablethat,inspecificapplications,can providea veryeffectiveseal. These

'-"

miscellaneousgasketswould includehollowmetal0-rings, C-seals and V-seals, so-called because theircross sectionis essentiallythesameas thelettersC &V. The hollowmetalO-rings are availableventedforhighpressureapplicationsand pressurefilledfor hightemperatureapplications.They can be obtainedwithvariousplatingsinordertoenhancetheirsealingabili-ties and to meetspecific applicationsrequirements.C-seals can be usedeitherforvacuumapplicationsorfor high pressureapplications.C-seals are self-ener-gized gaskets requiringspecific attentionbe paid tothe design of the groovesto containthe gasket,andsmoothsurfacefinishesarea must.For largequantityapplications,the C~sealcan be a relativelylow costgasket. For small quahtityappllcati,ens;the cost canbe ratherhighbecauseof initialtIIA~fequirements.V-sealsaresimilart8theQ~eale}(ceptfcJrtAefa81thattheyareessEHltiailyFnael1lAeffiI39neht8Wl1iehmakesthe cost df the.ih~IVifJuai~a~etfatherhigh:flleyalrequireverYflhesldftae8tIAIh@and speciallye=signee]gfbo\!esta effectiVelyseal.All thesespecialtyitemsdo reqLilreinitialconsultationwitHthemanufac-turer in order to determinethe practicabilityand theeconomicsinvolved.

,......

METAL JACKETED GASKETS

CONSTRUCTION OF JACKETEDGASKETS

Lamonsjacketedgasketsarenormallysuppliedwitha non-asbestoshightemperaturefiller.Thestandardfilleris normallysufficientforapplicationsupto900F.OthersoftfillersareavailableforhighertemperaturesorspecialapplicationsincludingGrafoil~Standardmetalsusedtomake jacketedgaskets,regardlessof the type, arealuminum,copper,thevariousbrasses,softsteel,nickel,Monel@,Inconel@and stainlesssteeltypes304,316,321,347,410,502.Obviouslythechoiceofthemetalusedforthejacketedpartofthegasketwoulddependuponthecorrosiveconditionsbeingencountered.

DOUBLE-JACKETEDGASKET

"""

Double-jacketedgasketsareprobablythemostcom-monlyusedstyleof gasketin heatexchangerapplica-tions.Theyareavailablein virtuallyanymaterialthatiscommerciallyavailablein26-gaugesheet.Theyarealsoextensivelyusedinstandardflangeswheretheserviceis notcriticaland attemperaturesbeyondwhicha softgasketsuchas rubbercanbeused.Sincemostdouble-jacketedgasketsarecustommade,thereis virtuallynolimitto thesize,shapeor configurationin whichthesegasketscan be made.This particulartype of gasketis very versatileand can be used in a myriadof applications.Since the size and shape are nota problemand sincemostmaterialscan be obtained

commercially,thisparticulargasket styleis very popular.It must be remembered that the primary seal againstleakage, using a double-jacketed gasket, is the metalinner lapwhere the gasket is thickestbeforebeing com-pressed and densest when compressed. This particularsection flows, effectingthe seal. As a consequence theentireinner lap must be under compression. Frequentlythe outer lap is not undercompression and does not aidin the sealing of the gasket. On most heat exchangerapplications the outer lap is also under compression,providinga secondary seal. The intermediatepart of adouble-jacketedgasket does very littleto effectthe seal-ing capabilityof the gasket. In some cases nubbins areprovided on heat exchanger designs to provide anintermediateseal. This nubbin is normally1/64"high by1/8"'wide.Experience has indicated,however,thatthereis littleadvantage to this particulardesign. The primaryseal is still dependent on the inner lap of the gasketabing the brute work and the secondary seal, whenapplicable, would be provided by the outer lap.

Always install double jacketedgasketwith smooth side towardthe nubbin.

DOUBLE-JACKETEDCORRUGATEDGASKETS

The double-jacketed corrugated gasket is animprovementona plainjacketedgasketinthatthecor-rugationson the gasket will provide an additionallabyrinthseal.Italsoprovidestheadvantageofreducingthecontactareaof thegasket,enhancingitscompres-sivecharacteristics.A double-jacketedcorrugatedgas-ket still relieson the primaryseal on the inner lap.

Note: Double-jacketedgasketsare sometimesusedwitha very-lightcoatingof gasketcementor lubricantwhichwillassistinflowingthemetalportionofthegas-ket intothetool markson theflangeseatingsurface.

(Cont.)

17

.m.aa:1I't~.JJ;lJMS:tAd._"...t~~

When using a gasket compound or lubricantit is impor-tantto rememberto useonly a very lightcoating.Exces-sive amountsof lubricantor compound may cause totalgasket failure if thejoint is exposed to hightemperatureand/or pressure.

FRENCH TYPEGASKETS

French type gaskets are available in a one-piecejacketed construction for narrow radial widths notexceeding 1/4" and in two- and three-piece construc-tions, as shown in the sketches, for wider applications.This type of gasket can also be used with the jacket onthe external edge of the gasket when the applicationrequiresthe outer edge of the gasket to be exposed tofluid pressure.The most widely used French type gas-kets are fabricatedusing a copper sheath. The double-jacketed construction is preferred over the French orsingle-jacketed construction, where practical, since itprovidesa totallyshea.thedgasket with none of the softfillerexposed.

SINGLE-JACKETEDGASKET

Single-jacketed gaskets are normally used for rela-tively narrow applications similar to the French type.18

They are madeby encasing a soft filleron one face, bothedges and a portion of the other face with a metal.Themajorityof applications for single-jacketed gaskets arenormally1/4" or less in radialwidth. This type of gasketis widelyused inair toolapplicationsandengine applica-tions where space is limited, gasket seating surfacesare narrow and relatively low compressive forces areavailable for seating the gasket. For applica,tions inexcess of 1/4", a double-jacketed gasket or double-jacketed corrugated gasket is normally recommended.Most single-jacketed gaskets are supplied with copperas the jacketing material,however,other materials areavailable.

v

SINGLE-J ACKETEDOVERLAP

J4d\ii)g~R2..

In the single-jacketed overlap construction themaximumflange width is approximately1/4". This typeof gasket is used when total enclosure of the soft fillermaterialis requiredand when the flange width makes itimpractical to use a double-jacketed gasket.

DOUBLE-JACKETEDDOUBLE-SHELLGASKET

v

The double-jacketed,double-shelled gasket is similarto the double-jacketed gasket except that instead ofusing a shell and a washer, two shells are used in thefabrication of the gasket. It has the advantage of adouble lap at both the 1.0. and the 0.0. of the gasket,adding greaterstabilityto the gasket. The constructionwill withstand higher compressive loads. Double-shellgaskets are normally restrictedto use in high pressureapplications. Its temperature limitations depend uponthe type of metal and filler used in construction.

MODIFIEDFRENCH TYPE

illttboo,;.IitJs~~l

Thisparticulartypeofgasketisnormallyusedwithverylightflangeson ductworkhandlinghotgases.Itscon-structionconsistsof two Frenchtype shieldsweldedtogetherwithaCerafeltfillermaterialoneithersideofthemetal.Metalthicknessis normally26 gauge,rolledonthe 1.0.to actas a shield.

v

~DOUBLE-JACKETEDCORRUGATED GASKETWITH A CORRUGATEDMETAL FILLER

eaD10JJ.$.'~!S~

At temperaturesinexcessof the rangeof 900Fto10000F wherethe standardsoft filler is normallynotrecommended,a double-jacketedcorrugatedmetalgasketwitha corrugatedmetalfilleris frequentlyused.Thisconstructionhasalltheadvantagesof thedouble-jacketedcorrugatedmetalgasketand,inaddition,sincethefiller is normallythe samematerialas thegasketitself,il1@ bJ~pertemperaturelimitwould be determinedby the metal BeihgUet30thistYpeof gasket, dependingupon metal selected, makes an excellent heatexchangergasketfor highpressure,hightemperatureapplications.As in thecase of double-jacketedmetalgasketsanddouble-jacketedcorrugatedmetalaskets,tHeprimarysealwouldbe the innerlap5f metal;thesec8RtJarysea!,wouldbe the outerlap 6f metalandsomedegreeof labyrinthsealingcanbeachievedwiththe corrugations.

- SIZING METAL JACKETED GASKETS-

Thefollowingsizingsandtolerancesarenotmanda-torybutaresuggestedvaluesbaseduponexperience.

,...,...

GASKETS CONFINED ON O.D. AND LD.

Gasket 1.0. = Groove 1.0. +1/16"Gasket0.0. = Groove0.0. -1/16"

GASKETS CONFINED ON O.D. ONLYGasket1.0.= Bore + minimum1/8"Gasket 0.0. = Recess 0.0. - 1/16"

GASKETS UNCONFINED ON O.D. AND I.D.Gasket1.0.= Bore + minimum1/8"Gasket0.0. = Uptoa maximumoftheboltholecircle

diameterminusoneboltholediameterunlessgasketistobefullface.Ifgasketistobefullface,thenthefollowingmustbe specified:

(a)Boltholecirclediameter(b)Boltholediameter(c) Numberof boltholes(d)Desiredgasket0.0.

CORRUGATED AND CORRUGATEDINLAID GASKETS STYLE

Lamons corrugatedgaskets, style360, are eco-nomicalfor use on relativelylow pressure applicationsthat requirelow bolt loads for gasket seating.Because of the corrugationsand thin metalthickness-es (.010"to .031"), relativelylightboltforces arerequiredto flow the gasket materialsat the pointsofcontactwiththe flange. Required bolt loads are sub-stantiallyless tHanthe solia metaltypes such as flatmetal,profile5FerrateaifaBricatedof the samematerial.The corrugationsproviaeresilier1t8,theamountof which depends on their ~itth,depth,andthicknessof material.

A superior sealing surface can be created using.015thick layersof Grafoil@tape appliedto each face,style 360G.

a

TheCMG, similartothe360G,is manufacturedwithflexiblegraphitesheet,insteadoftape,adheredtobothgasketfaces.Thistypeofgasketniakesanexcellentproductforbothstandardflangegasketsandheatexchangertypegasketswherethereis lowboltloador highavailablegasketstresses.On flangewidthlessthan1/2"pleaseconsultLamonsengineer-ingdepartment.Availableinmetalthicknessesof.015"to .032"andflexiblegraphitethicknessin .015"to .030".Alsoavailablewithanti-stickgraphite.

Othermethodsofenhancinga sealincludecementingnon-asbestosor fiberglasscordtothecor-rugatedfacesortheuseofa gasketcompound.Thetemperaturerangeforthistypeofgasketdependsonthemediatobesealedandtheselectionofthemetaland/orfacingmaterials.Corrugatedgasketscanbefabricatedina widevarietyofshapeswithalmostnosize limitation.

19

STANDARD TOLERANCES

GasketDiameter 1-I.D.- __-"'D.+ 1132" + 0Up to 6" - 0 - %2"+ 1116" + 0

6" to 60" - 0 - '/16"+ 3132" + 0

60" and Above - 0 - 3/32"

LAMONSMETAL CLAD AND SOLID METAL HEAT EXCHANGER GASKETS

INFORMATION NEEDEDTO FILL AN ORDER:

1. Outside diameter.2. Inside Diameter3. Shape per Standard Shapes Index4. Lamons style per catalog, or type of construction5. Thickness6. Materials (metalor metal and filler)7. Rib size8. Distancefromcenterlineof gaskettocenterlineof ribs9. Radii

Ct

20

Ct

Examples:

-St

Qty.holes

-cp

J

"

--

'-"

'-"

'"""'"

LAMONS HEAT EXCHANGER GASKETS - STANDARD SHAPE INDEX

08CJOO@8R C-1 C-2 D-1 D-2 E-1 E-2 E-3

8 0e90@~@jE-4 F-1 F-2 F-3 G-1 G-2 G-3 G-4

@8S~EB~@8G-5 G-6 G-7 G-8 G-9 H-1 H-2 H-3

@@e@9~E9H-4 H-5 H-6 H-7 H-8 H-9 H-10 H-11

e @@Cj@@~~H-12 1-1 1-2 1-3 1-4 1-5 1-6 1-7

@@@~-@@EB1-8 1-9 1-10 1-11 J-1 J-2 J-3 J-4

@~E9C9~@~@~ ~ H ~ ~ ~ ~ ~

21

SPIRAL-WOUND GASKETS

SIZING SPIRAL WOUND GASKETSSpiral-woundgasketsmustbe sized to ensurethe

spiral-woundcomponentis seatedbetweenflat sur-faces.Ifitprotrudesbeyonda raisedfaceor intoaflangebore,mechanicaldamageand leakagemayoccur.

Spiral-woundgasketshavebecomeextremelypopulardue tothewidevarietyofavailablestylesand sizes.Spiral-wound gasketscan be fabricatedof any metalwhich isavailablein thinstripand whichcan bewelded;therefore,theycan be used againstvirtuallyanycorrosivem~diumdependent upon the choice of the metaland filler.Theycan be used overthe completetemperaturerangefromcryogenicto approximately2000F.This typegasketcanbe used in all pressuresfrom vacuum to the standard2500 psiflange ratings.They are more resilientthan anyother type of metallic gasket with the exception ofpressuresealing metalgasketsand, as a consequence,can compensateforflangemovementthatmayoccur duetotemperaturegradients,variationsofpressureand vibra-tion.Spiral-woundgasketscan also be manufacturedwithvariable densities,i.e. relativelylow density gaskets forvacuumserviceup to extremelyhighdensitygasketshav-ing a seating stress of approximately30,000 psi. Thesoftergasketswould requirea seatingstressinthe rangeof 5,000 psi.

VARIABLE DENSITY

Spiral-wound gaskets are manufactured by alter-natelywindingstripsof metaland softfillerson the outeredge of winding mandrels that determine the insidedimensions of the wound component. In the windingprocess, the alternating plies are maintained underpressure.Varyingthe pressureduringthewindingoper-ationand/orthethickness of the soft filler,the densityofthe gasket can be controlled over a wide range. As ageneral rule, low winding pressure and thick soft fillersare used for low pressure applications.Thin fillers andhigh pressure loads are used for high pressure applica-tions. This of course would account for the higher boltloads that have to be applied to the gasket in highpressure applications. In addition to all these advan-tages of the spiral-wound gasket, they are a relativelylowcost. When special sizes are required,toolingcostsare very nominal.

22

v

~~i ,.,~LargeTonguean,dGroove

J~jnt"

Small Tongueand GrooveJoint

~~~ un:n?LargeMaleand'femaleJoint

RaisedFaceFlange

,IGASKET CONFINED ON I.D. AND O.D.Gasket I.D. = Groove I.D. +1/16"Gasket a.D. = Groove a.D.-1/16"

GASKET CONFINED ON O.D. ONLYGasketI.D.= Bore+ Minimum1/4"GasketaD. = Recessa.D. - 1/16"

GASKET UNCONFINED I.D. AND O.D.GasketI.D. = SeatingSurface1.0.+ Minimum1/4"Gasketa.D. = SeatingSurfacea.D. - Minimum1/4"Centering Guide aD. = Bolt Circle Diameter - Diam-eter of Bolt

STANDARD TOLERANCES (STYLE W)

Gasket Diameter I 1.0. 0.0.

Up to 1"

1" to 24"

24" to 36"

+'/'6-0

+3/32

60" and above I -0Thickness + .015-.000 on specialGasketswith:a. less than 1" I.D., greater than 26" I.D.b. teflon fillersc. 1" or larger flange width.Thickness + .010-.000 for mostothersizesand materials

36" to 60"

+0-'/'6

+0_3/32 v

+3/64 +0-0 -'/32

+'/32 +0-0 -'/32

+3/64 +0-0 -'/16

"-'"

AVAILABLE SIZES AND THICKNESSES

Lamonsspiral-woundgasketsare availableinthicknessesof ,0625",,100",,125",,175",.250",and,285",Thefollowingchartindicatesthesizerangethatcannormallybefabricatedinthevariousthicknessesalongwiththerecommendedcompressedthicknessofeachandthemaximumflangewidth,

LIMITATIONS OF SIZE AND THICKNESS

Maximum RecommendedGasket Maximum Flange Compressed

Thickness I.D.* Width * Thickness

,0625" 9' 3jg" ,0501.055".100" 12" Vz" ,075/.080".125' 40" 3/4" .0901.100",175" 75" 1" .125/.135",250" 160" 1114" ,1801,200".285" 160" 1114" ,2001.220"

*Theselimitationsareintendedasageneralguideonly.Materialsofconstructionandflangewidthof gasketcandrasticallyaffectthelimitationslisted.

FLANGE SURFACE FINISH

Use of spiral-woundgasketsgivesthedesignerandtheuserawidertoleranceforflangessurfacefinishesthanothermetallicgaskets,Whiletheycan be usedagainstmostcommerciallyavailableflangesurfacefinishes,ex-periencehasindicatedthattheappropriateflangesur-face finishesused withspiral-woundgasketsare asfollows:

~125to 250AARH Optimum500AARH Maximum

StyleW isaspiral-woundsealingcomponentonlythatis normallyusedontongueandgroovejoints,maleandfemaleflangefacingsandgroovetoflatflangefacings.

LAMONS' STYLE WR

...........

StyleWR gasketsconsistof a spiral"woundsealingcomponentwitha solidmetalouterguidering,Thesegasketsareusedonplainflatfaceflangesandonraisedfaceflanges.The outerguideringservestocenterthe

gasketproperlyin the flange joint, acts as an anti-blowoutdevice,providesradialsupportfor thespiral-woundcomponent,andactsas acompressiongaugetoprevent the spiral-wound component from beingcrushed,Normallytheouterguideringsarefurnishedinmildsteel,butcan be suppliedin othermetalswhenrequiredbyoperatingconditions,

LAMONS' STYLE WRI

StyleWRI is identicalto styleWR withthe additionof an inner ring, The inner ring serves several func-tions, It providesradial supportfor the gasketon the1.0,to help preventtheoccurrenceof bucklingor im-ploding, Its 1.0,is normallysized slightlylargerthanthe 1.0,of the flange bore, minimizingturbulenceinprocess flow, After the gasket is compressed, theflangeswouldnormallybe incontactwiththeinnerringand henceerosionand corrosionof theflangesurfacebetweenthe 1.0,of the sealing componentand theflangebore is minimized.The innerringsarenormallysuppliedinthesamematerialas thespiral-woundcom-ponent.Refer to table below for dimensionsof innerring ID,'s forflangesup to24-inchdiameterand 2500PSI,

Standard Inner-Ring Inside Diameters

for Spiral-Wound Gaskets (Inches)

Note: The inner-ring thickness shall be 0.112 - .131 inches. Forsizes NPS 1 1/4 through NPS 3, theIns,de-d,ameter tolerance,s I 0,03 ,nch: for larger sozes the Inside-diameter tolerance IS I 0.06inch See ASME 816.20 for minimum pipe wall fhicknesses that are suitable for use with standardinner rings. ASME 816.20 calls for the use of inner rings with PTFE filled spiral wound gaskets"There are no Class 400 flanges NPS 1/2 through NPS 3 (use Class 6001.Class 900 flanges NPS1/2 through NPS 2 1/2 (use Class 1500), or Class 2500 flanges NPS 14 and larger'The inner-ring inside diameters shown for NPS 1 1/4 through NPS 2 1/2 in Classes 1500 and 2500w,1I produce inner-ring widths of 0.12 ,nch, a pract,cal m,mmum for production purposes'Innerrings are required for Class 900, NPS 24 gaskets; Class 1500, NPS 12 through NPS 24 gas-kets: and Class 2500. NPS 4 through NPS 12 gaskets.

LAMONS'STYLE WR-RJ

ThisstylegasketisidenticaltoaStyleWR inconstruc-tion featuresbut is speciallysized to be used as areplacementgasketforflangesmachinedtoacceptoval

23

Flange P,...",e Cia..SizeINPS) 150 300 400(1) 600 gOO (1, 2) 1500 12,31 2500 11-31

% 0:56 0.56 0.56 0.56 0.56% 0.81 0.81 0.81 0.81 0.81

1 1.06 1.06 1.06 1.06 1.06

1'1, 1.50 1.50 1.50 1.31 1.31

1% 1.75 1.75 1.75 1.63 1.63

2 2.19 219 2.19 2.06 2.06

AVAILABLE SPIRAL SEAL STYLES2'1, 2.62 2.62 2.62 2.50 2.503 3.19 3.19 3.10 3.10 3.10 3.104 4.19 4.19 4.04 4.04 4.04 3.85 3.85

Lamonsspiral-woundgasketsareavailableinavari-5 5.19 5.19 5.05 505 5.05 4.90 4.90

etyofstylestosuittheparticularflangefacingbeing6 6.19 6.19 6.10 6.10 6.10 5.80 5.80

8 8.50 8.50 8.10 8.10 7.75 7.75 7.75

utilizedontheflanges,10 10.56 10.56 10.05 10.05 9.69 9.69 9.69

12 12.50 12.50 12.10 12.10 11.50 11.50 11.50

14 13.75 13.75 13.50 13.50 12.63 12.63

LAMONS' 16 15.75 15.75 15.35 15.35 14.75 14.50STYLE W

18 17.69 17.69 17.25 17.25 16.75 16.75

20 19.69 19.69 19.25 19.25 19.00 18.75

24 23.75 23.75 23.25 23.25 23.25 22.75

oroctagonalringjointgaskets.Thesealingcomponentis locatedbetweenthe1.0.ofthegroovemachinedintheflangeandtheflangebore.These are intendedto beusedas replacementpartsandareconsidereda main-tenanceitem.In newconstruction,wherespiral-woundgasketsare intendedto be used, raisedfaceflangesshouldbeutilized.RefertoLamonSpiraSealCatalogfordimensionsof StyleWR-RJ gasketsforflangesup to24-inchd,ameterand1500psi.

GASKETS WITHWOUND GAUGE RINGS

Whena guideringis requiredthatis too narrowforpracticalfabricationofsolidmetalguiderings,Lamonsspiral-woundgasketsareavailablewitha guidemadeentirelyof spiralmetalwindings.These spiral metalwindingsservethe samebasicpurposeas the solidmetalring,thatisasacompressionlimitingandacenter-ingdevice.Thespirallywoundringis normallysuppliedinthesamemetalasthemetalinthegasket.ThistypeofwoundguideringisnormallylimitedtoaV4"radialwidthor less.

LAMONS' STYLE H

StyleH gasketsare foruse on boilerhandholeandtubecap assemblies. They are available in round,square,rectangular,diamond,obround,ovalandpearshapes. The Lamons Gasket Companyhas toolingavailableformanufacturingmostof thestandardhand-holeandtubecapsizes of thevariousboilermanufac-turers.(RefertoourSpiraSealCatalog.)Thesearealsoavailableinspecialsizesandshapes.Toorderspecialgaskets,dimensionaldrawingsor samplecoverplatesshouldbe providedinorderto assureproperfit.

LAMONS'STYLE MWAND MWC

24

These gasketsareavailablein round,obround,andovalshapesandareusedfor standardmanholecoverplates.(RefertoLamonsSpiraSealCatalogforstandardavailableshapesandsizes.)Whenspecialgasketsarerequired,itis necessarytosubmitcompleteinformation,includinga sketchor blueprintor a samplecoveronwhichthegasketis to be used.

NOTE: When spiral-wound handhole and man-hole gasketswith a straight side are requiredit isnecessarythatsomecurvaturebegivento theflatorstraightside to preventbucklingof thegasket.Thisis due to the fact that spiral-wound gaskets arewrappedundertensionandthereforetendto buckleinward when the gaskets are removed from thewinding mandrel.As a ruleof thumb,theratioof thelong 10to the short 10should not exceed3 to 1.

'-.J

LAMONS'STYLE WPOR WRP

These gasketsaresimilarto StyleWand StyleWRwiththeadditionofpasspartitionsforusewithshellandtubeheatexchangers.Partitionsarenormallysuppliedwitha double-jacketedconstructionof thesamemate-rialasthespiral-woundcomponent.Thepartitionstripscan besoftsoldered,tackweldedor silversolderedtothespiral-woundcomponent.Thedouble-jacketedpar-titionstripsarenormallyslightlythinnerthanthespiral-woundcomponentinordertominimizetheboltloadingrequiredto properlyseatthegasket.

" J

LAMONS'STYLE L

TheLamonsStyleL gasketisavailableforraisedfaceand flat face applicationswhereit is not practicaltosupplyan outergaugering.The spiral-woundcompo-nentsof StyleL areidenticalto thoseof StyleWand inadditionhaveawireloopweldedtotheouterperipheryof the gasket, sized so as to fit over diametricallyoppositebolts,forpropercenteringofthespiral-woundcomponenton the gasketseatingsurface.Wheneverpossible,it is recommendedthata StyleWR gasketbeusedin lieUofa StyleL gasketbecauseof theobviousadvantagesof the outersolid metalgaugering.TheStyleL isconsiderablymoredifficulttoproducethantheStyleWR andthereforemoreexpensive.

J

""-'

STYLE, WR-LC

The needfora lowcompressiveloadspiralwoundgasketin 150#and300#classASME/ANSI B16.5pipeflangeapplicationsresultedin thedevelop-mentof the"WR-LC" spiralwound.The designof ourgasketallowsitto becompressedwithlessboltloadtoseatcomparedto theconventionaltypespirals.The softfillermaterialscommonlyusedare graphiteand PTFE.WhenselectingPTFE foryourfillermaterialtheuse of an innerringis rec-ommended(styleWRI-LC).

WRI HF GASKETS

This gasketwasdevelopedforH.F.acidapplications.Itconsistsofa MonelandPTFE spiralwoundgasketwitha carbonsteelcenteringringandaPTFE innerring.The carbonsteelouterringcan be coatedwithspecialH.F.aciddetectingpaintif desired.The PTFE innerringreducescorrosionto theflangesbetweentheboreof thepipeandtheI.D.of thespiralwoundsealingelement.InnerringI.D.'sarethesameas standardmetalinnerringsunlessotherwiserequested.Thickness of the PTFE inner ring is .150 ::1:.005normally.

'-'"

STYLE, WR-AB

Spiralwoundsthatinwardlybucklearea concernin the industryandLamonshas introduceda spiralwoundthataddressesthishistoricalcon-cern.The traditionalmethodto reduceinwardbucklingis to orderan innerringandthatis stillthebestpracticetoday.Lamonshasa newstylespiralcalled"WR-AB" thatdoes notrequirean innerring.Thereare manyaddi-tionaladvantageousdesignfeaturestothisproductto reduceinwardbuckling.(Contact Lamon's Technical Department regarding flange bore sizes for which this gasket mayor may not be appropriate.)

STYLE, WRI-HTG

Forapplicationsrequiringa spiralwoundwhenoxidationmayoccur,usuallyathighertemperatures,Lamonshasdevelopedthe"WRI-HTG". This gasketcombinesthecorrosionandoxidationresistanceof micawiththeexcel-lentsealabilityof flexiblegraphite.The micaalongwiththemetalwindingservesas a barrierbetweenoxidizingprocessconditionsandtheexternalairandthegraphite.This gasketcan be orderedforanyASME/ANSI B16.5andASME B16.47 seriesA or B flangeor forspecialapplications

WindingGraphiteorPTFEFacing

'-"PTFE-CoatedKammpro

WRI-LP

A Spiralwoundgasketwitha conventionalouterguideringwitha specialinnerringdesign.This specialinnerringdesignis our"Kammpro"profilestyleLP-1.The uniquenessof the"kammpro"designallowsnumerouschoiceson itsconstruction.The "WRI-LP"allowsthespiralwindingto beconstructedwiththerequiredmetalandsoftfillerspecifiedbytheuser.The"Kammpro"innerringmetalcan be orderedwithorwithoutPTFE coatingandthenfacedwitheither.020"thickPTFE, graphiteor othermaterials.

25

SECTION III -RECOMMENDED GASKET INSTALLATION PROCEDURES

INSTALLATION AND MAINTENANCETIPS FOR ALL GASKETS

All toooftenwehear"thegasketleaks."However,thatis notentirelytrue.Technically,it isthejointthatleaks,andthegasketisonlyoneofseveralcomponentsthatmakeupthejoint. Oftentimes,thegasketisexpectedtocompensatefordeficienciesinflangeconnectiondesign,impropergasketinstallationprocedures,andanyflangemovementthatmayoccurduetothermalandpressurechanges,vibration,etc.Inmanycases,thegaskethastheabilitytheovercometheseoccurrances,butonlywhencarefulattentionhasbeengiventoallof theaspectsofgasketselection,includinginstallationprocedures.

Ourexperiencein investigatingleakyjointsovertheyearshasindicatedthatthemostcommoncauseof leakyjointsis theuseofimpropergasketinstallationprocedures.

GASKET INSTALLATION PROCEDURES(ANDBOLT TORQUING)1. Inspectthegasket.It is importantthatthe

correctgaskethasbeenchosenfortheboltedflangeconnection.Verifythatthematerialis asspecifiedandvisuallyinspectthegasketforanyobviousdefectsordamage.

2. Inspectthegasketseatingsurfaces.Lookfortoolmarks,cracks,scratches,orpittingbycorrosion.Radialtoolmarksonagasketseatingsurfacesarevirtuallyimpossibletosealregardlessofthetypeofgasketused.Therefore,everyattemptshouldbemadetominimizethese.

3. Useonlynewstudsorbolts,nutsandwashers.Makesuretheyareofgoodqualityandappropriatefortheapplication.

4. Lubricateallthreadcontactareasandnutfacings.Theimportanceofproperlubricationcannotbeoverstated!A properlubricantwillprovidealowcoefficientof frictionformoreconsistentachievedboltstress.An antiseizecompound,whenusedasaboltandnutlubricant,will facilitatesubsequentdisassembly.

5. Looselyinstallstudbolts.WithRaisedfaceandflatfaceinstallation,looselyinstallthestudboltsonthelowerhalfoftheflange.Insertthegasketbetweentheflangefacingtoallowtheboltstocenterthegasketontheassembly.Installtheremainingboltsandnutsandbringalltoahand-tightorsnugcondition.In arecessedorgroovedinstallation,centerthegasketmidwayintotherecessorgroove.(If thejointis vertical,itmaybenecessarytouseaminimumamountofcupgrease,gasketcement,orsomeotheradhesivecompatiblewiththeprocessfluids,tokeepthegasketinposition

26

untiltheflangesaretightened.)Then,installallboltsandnutstoahand-tightorsnugcondition.

6. Identifytheproperboltingsequenceandnumberboltsaccordingly.Seechartsforrecommendedboltingsequences.Eachboltshouldbenumberedsothatbolttorquesequencescanbeeasilyfollowed.Failuretofollowproperbolttorquesequencescanresultincockingflanges.Then,regardlessoftheamountofsubsequenttorquing,theycannotbebroughtbacktoparallel.Thiscancontributeheavilytoaleakyjoint.

7. TorquetheBolts.Boltsshouldbetorquedin aproperboltingsequence,inaminimumof fourstagesasspecifiedin Steps8,9,10,and11.

8. Torquetheboltsuptoamaximumof30%of thefinaltorque,valuerequiredfollowingtherecommendedbolttorquesequence.

9. RepeatStep8,increasingthetorquetoapproximately60%of thefinaltorquerequired.

10.RepeatStepg,increasingthetorquetothefinaltorquevalue.

11.Retorqueallstuds.All studsshouldberetorquedusingarotationalpatternofretorquingtothefinalvalueof torqueuntilnofurtherrotationofthenutscanbeachieved.Thismayrequireseveralretorquingsastorquingofonestudcausesrelaxationinadjacentstuds.Continuetorquinguntilequilibriumhasbeenachieved.

12. Someflangejointsshouldberetightenedjustbeforebeingputinoperation,toaccountforboltandgasketrelaxation.Successhasalsobeenreportedwithheatexchangers,withcertaingaskettypes*andflangefacings,whenboltingisretightenedduringinitialheatup,beforelossoflubricant(orboltseizing).

J

J

*For specificgaskettypesandapplicationassistancecontactLamonsTechnicalDepartment

J

BOLT TORQUE SEQUENCE

8-Bolts

'"'"

Sequencial Order1-23-45-67-8

RotationalOrder15372648

'-'

16-Bolts

12

..........

SequentialOrder1-23-45-67-89-10

11-1213-1415-16

12-Bolts

SequentialOrder1-23-45-67-89-10

11-12

Rotational Order15937

1126

1048

12

9

11

10

Rotational Order1 29 105 6

13 143 4

11 127 8

15 16

27

20-Bolts 13

4 15

16 3

14

SequentialOrder1-23-45-67-89-10

11-1213-1415-1617-1819-20

2

Rotational Order1 2

13 145 6

17 189 103 4

15 167 8

19 2011 12

24-Bolts 9

12 3

4 11

10 2

SequentialOrder1-23-45-67-89-10

11-1213-1415-1617-1819-2021-2223-24

RotationalOrder1 29 10

17 185 6

13 1421 223 4

11 1219 207 8

15 1623 24

TORQUE VALUESProbablytheonlytruemeasurementofboltstressis

by boltor stud elongation.In practice,however,thiswouldbeanextremelycostlyandimpracticalapproachtodeterminethetruemeasureofboltstress.As a con-

28

sequencethetrendinindustrytodayistheuseoftorquewrenches,tensioningdevices,hydraulicwrenches,ordrillingthe studsand insertingheatersto preheatthestudtoa specifictemperaturethatwillultimatelycreatethepropertensiononthebolt.The useof manpowertotightenthebolts,bysledgehammers,strikingwrenchesandpiecesofpipeontheendofthewrenchisbecominglessandlessa standardpractice.Itistime-consuming,strenuousandis a verydangerouspractice.Thenewertechniquesare muchmorereliable.

I

NOTE: Allowablebolt stresses.SectionVIII of theASME PressureVesselCode,AppendixS, specificallyrecognizesthe problemof initialbolt stresses. Forexample,a flangedesignerwilldeterminehis requiredboltingfor a 600 psi applicationat a givenoperatingtemperaturespecificallyin accordancewithallowablestressesfortheboltmaterialattheoperatingtempera-ture.Theseallowablestressesarebasedontheparticu-larmaterialandtheirstrengthatoperatingtemperature.Inaddition,thesameboltmaterialwillhaveanallowablestressatambientconditionsas specified.As a conse-quence,inmostcasesthedesignof theflangeisbasedupontheallowableboltstressof theparticularmaterialat designtemperatureand at thedesignor operatingpressure.However,in mostcases,thehydrostatictestpressurethattheflangejointmustpassisoneanda halftimesthedesignpressure.As aconsequence,anyjointthat is designedin strictaccordancewiththe ASMEPressureVesselCode and is subjectedto hydrostatictests in excessof the designpressure,will requireahigherinitialstressonthestudtosuccessfullypassthehydrostatictest.AppendixS of Section8 of theASMEPressureVesselCode speaks in greatlengthon thisproblemand, inessence,states,thatinorderto passhydrostatictests,boltsmay be stressedto whateverlevelisrequiredtosatisfactorilypassthetest.This intro-ducesadditionalproblems.Incaseswherelowyieldboltmaterialis beingused,the stressesrequiredin boltssufficienttosatisfactorilypassthetestmayexceedtheyield pointof the boltmaterial.Once this occurs,noadditionalstressingoftheboltwillalleviatetheproblemof leakage.As a consequenceitmaybe necessarytouse hightensileboltsor studs in orderto achieveasatisfactorytest.When this is required,the followingproceduresshouldbe followed.(See Page32)

~

. Use hightensileboltsor studsforhydrostatictestsfollowingtheproceduresoutlinedaboveforgasketinstallation.Aftera successfulhydrostatictesthasbeenachieved,relievetheboltstoapproximately50percentof theprestressrequired.

. Replacethe boltsor studsone at a timewiththepropergradeboltforoperatingconditions.As eachboltis replaced,torqueit to thevalueof theotherbolts.

. Afteralltheboltshavebeenreplaced,retorquetheboltsto100%oftheallowablestressfortheparticu-largradematerial.(Onceagainitis imperativethata proper lubricantbe used on the bolts whenreplacementis beingmade.)

~

TROUBLE SHOOTING LEAKING JOINTSOneofthebestavailabletoolstoaidindeterminingthecauseofleakageisacarefulexaminationofthegasketin

usewhenleakageoccurred.-- -_u ~---~------------'-' Observation~ -------------

n_-

Possible Remedies-~ ~ ~ ~

Gasket badly corroded Select replacement materialwith improved corrosion resistance.n__- _.n.- _no.------

Gasket extrudedexcessively Select replacement material with better cold flow properties, selectreplacementmaterialwithbetterload carryingcapacity~ i.e., moredense.

Gasket grossly crushed

~--~ --- -- n_. -- --------------------------------------------------

Gasketmechanicallydamagedduetooverhangof raisedfaceor flangebore.

No apparentgasketcompressionachieved.

Selectreplacementmaterialwithbetterloadcarryingcapacity,providemeanstopreventcrushingthegasketbyuseofastopringorre-designofflanges.

Reviewgasketdimensionsto insuregasketsare propersize. Makecertaingasketsareproperlycenteredin joint.

Selectsoftergasketmaterial.Select thickergasketmaterial.Reducegasketareato allowhigherunitseatingload.

Gasketsubstantiallythinneron0.0.than1.0.

Gasketunevenlycompressedaroundcircumference

Indicativeof excessive"flangerotation"or bending.Alter gasketdimensionsto movegasket reactioncloser to bolts tominimizebendingmovement.Providestiffnessto flangeby meansofback-uprings.Selectsoftergasketmaterialto lowerrequiredseatingstresses.Reducegasketareato lowerseatingstresses.

Improperboltingup proceduresfollowed.Makecertainpropersequentialboltup proceduresarefollowed.

'-' Gasketthicknessvariesperiodicallyaroundcircumference.

----------------- ---

~---

..........

Indicativeof "flangebridging"betweenboltsorwarpedflanges.Providereinforcingringsforflangesto betterdistributeboltload.Selectgasketmaterialwithlowerseatingstress.Provideadditionalboltsifpossibletoobtainbetterloaddistribution.If flangesarewarped,re-machineor usesoftergasketmaterial.

29

MANWAY PROBLEMS?

If installationandserviceproblemsareexperiencedwithspiralwoundgasketsinmanways,Lamonshastheanswer

In a typicalovalor obroundmanwaycoverassembly,thecover sets insideof the boilerand internalpressureisrelieduponto createthe sealingforce. Normally,theseassemblieshavea couple of bolts to secure the gasketduring installationand providesomedegreeof initialseatingload. Our experienceindicatesthat,in this type ofmanways,thereis oftena largeamountof clearancebetweenthemanwaycoverand theopening in the boiler.

A spiralwoundgasketmustbe installedin such a mannerthatthewindingis compressedacross itsentirefacewithoutinterruption.Ifa spiralwoundgasketfalls intotheclearancesbetweena manwaycoverand boileropening,a "pinching"effectmayoccur,causingmechanicaldamageto thegasket.

It is possibleto "bridge"the clearancesin manyboilerapplicationsutilizingan integralsolid metalringalong theinside circumferenceof the spiralwindings,Lamons style MWI. Essentially,the inner ring helps to positionthegasketonthemanwaycover.The thicknessof thesolid metalringallowsfor adequatecompressionand helps toavoidcrushingof thegasket.

A Lamonstechnicalrepresentativecould help withsizing of the innerringand the sf3in~1WiHaing.The followingpage is an informationsheetthatwouldhelpus to assistyou.

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LAMONS STYLE MWI

StyleMWImanwaygasketsconsistof a windingwitha solidmetalinnerringto positionthewindingandhelpavoidmechanicaldamage.

,

NOTES:

~

30

LAMONS GASKET COMPANY

,..., Application Information Sheet For Oval or Obround Manways

Boiler

1

ManwayCover

~

ID of GasketSurface onCover Dim. (B)

tt

OD ofGasketSurfaceongoyer Dim.(C)

iBoilerOpening

Dim.(A) tOD of Gasket Surface onBoiler Dim. (D)

1

'-"

rBoiler

Please providethefollowinginformation:

Length(Long Side)

Width

(ShortSide)Shape(checkone):Oval c=::JObroundc=::JDim.AOther c=::J (DrawingRequired)

Dim.BPressure

TemperatureDim.C

Dim.DService(TypicallySteam)

'-' Lamons Gasket Co.PO. Box 947Houston,TX 77001Fax (713)547-9502

31

OTHER PROBLEM AREAS

JOINT MUST COMPENSATE FOR WIDETEMPERATURE VARIATIONS:

Solution:Consideruse of sleevearoundboltstoincreaseeffectiveboltlength:

.BOLTWASHER

SLEEVE

FLANGE

GASKET

- FLANGE- WASHER

NUT

FLANGES BADLY COCKED OR SEPA-RATED TOO FAR:

Solution: Do not try to correctproblemwithflangebolts- can overstress.Dousespacerstocorrectproblemwithgas-keton eachside.

SPACER

GASKET IGASKETFlanges too far apart n\

Flanges cocked

TAPERED SPACER

GASKET. J lASKET

Flanges badly mis-aligned GASKET

~

!~

32

j1

Or consideruse of conicalspringwashersin placeofsleevetoeliminatetorquelossesoverwidetemperatureranges. ;

BOLT

GASKET

FLANGE

WASHER

NUT

FLANGES OUT OF PARALLEL:

~'-=f~:

'-',Totalallowableoutof parallel:~1+~2=0.015".

Note- Deviationon rightis lesscriticalthandeviationon leftsincebolttighteningwilltendtobringflangesparallelduetoflangebending.

WAVY SURFACE FINISH

~~ vNote:1. If usingjacketedor spiralwoundgaskets- deviationshouldnot

exceed 0.015".2. If using solid metal gaskets -deviation should not exceed 0.005".3. If using rubber, more leeway is possible - perhaps total of 0.030".

SECTION IV - APPENDIX

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APPENDIX S ASME SECTION VIII DIVISION I PRESSURE VESSELSDESIGN CONSIDERATIONS FOR BOLTED FLANGE CONNECTIONS

.........

The primarypurposeof the rulesfor boltedflangeconnectionsinPartsA andB ofAppendixII isto insuresafety,buttherearecertainpracticalmatterstobetakeninto considerationin order to obtain a serviceabledesign.One of themostimportantof theseis thepro-

f portioningofthebolting,Le.,determiningthenumberandsize of thebolts.

In thegreatmajorityof designsthepracticethathasbeenusedinthepastshouldbeadequate,viz.,tofollowthe designrulesin AppendixII and tightenthe boltssufficientlytowithstandthetestpressurewithoutleak-age.Theconsiderationspresentedin thefollowingdis-cussion will be importantonly when some unusualfeatureexists,such as a very largediameter,a highdesignpressure,a hightemperature,severetempera-turegradients,an unusualgasketarrangement,andso on.

The maximumallowablestress values for boltinggiveninthevarioustablesof SubsectionC aredesignvaluestobeusedindeterminingtheminimumamountof boltingrequiredundertherules.However,a distinc-tionmustbekeptcarefullyinmindbetweenthedesignvalueandtheboltstressthatmightactuallyexistorthatmightbe neededfor conditionsotherthanthedesignpressure.Theinitialtighteningoftheboltsisaprestress-ingoperation,andtheamountofboltstressdevelopedmustbewithinproperlimits,toinsure,ontheonehand,thatit is adequatetoprovideagainstallconditionsthattendtoproducea leakingjoint,andontheotherhand,thatis notso excessivethatyieldingof theboltsand/orflangescan producerelaxationthatalso can resultinleakage.

The firstimportantconsiderationis theneedforthejointto be tightin the hydrostatictest.An initialboltstressofsomemagnitudegreaterthanthedesignvaluethereforemustbeprovided.Ifit is not,furtherboltstraindevelopsduringthetest,whichtendsto partthejointandtherebytodecompressthegasketenoughtoallowleakage.Thetestpressureis usually11/2timesthedesignpressure,andonthisbasisitmaybethoughtthat50percentextraboltstressabovethedesignvaluewillbe sufficient.However,this is an oversimplification,because,on the one hand,the safetyfactoragainstleakageundertestconditionsingeneralneednotbeasgreatas underoperatingconditions.Ontheotherhand,if a stress-strainanalysisof thejoint is made,it mayindicatethatan initialboltstressstillhigherthan11/2timesthedesignvalueis needed.Suchan analysisisone that considersthe changes in bolt elongation,flangedeflection,andgasketloadthattakeplacewiththe applicationof internalpressure,startingfromtheprestressedcondition.Inanyevent,it is evidentthataninitialboltstresshigherthanthedesignvaluemayand,in somecases, mustbe developedin the tighteningoperation,anditis theintentof thisDivisionof SectionVIII that such a practiceis permissible,provideditincludesnecessaryandappropriateprovisiontoinsureagainstexcessiveflangedistortionandgrosscrushingof thegasket.

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Itispossiblefortheboltstresstodecreaseafterinitialtightening,becauseof slow creepor relaxationof thegasket,particularlyin the case of the "softer"gasketmaterials.This may be the cause of leakagein thehydrostatictest,in whichcase it maysufficemerelytoretightenthebolts.A decreasein boltstresscan alsooccurinserviceatelevatedtemperatures,asa resultofcreepin theboltand/orflangeorgasketmaterial,withconsequentrelaxation.When this resultsin leakageunder service conditions,it is commonpracticetoretightenthebolts,andsometimesasinglesuchopera-tion,or perhapsseveralrepeatedat long intervals,issufficienttocorrectthecondition.Toavoidchronicdiffi-cultiesof this nature,however,it is advisablewhendesigninga jointfor high-temperatureserviceto giveattentionto the relaxationpropertiesof the materials-involved,especiallyfortemperatureswherecreepisthecontrollingfactorindesign.Thisprestressshouldnotbeconfusedwithinitialboltstress,S1'usedinthedesignofPart B flanges.

Intheotherdirection,excessiveinitialboltstresscanpresenta problemintheformof yieldingin theboltingitself,andmayoccurin thetighteningoperationto theextentofdamageor evenbreakage.This is especiallylikelywithboltsofsmalldiameterandwithboltmaterialshavinga relativelylowyieldstrength.Theyieldstrengthofmildcarbonsteel,annealedausteniticstainlesssteel,andcertainofthenonferrousboltingmaterialscaneas-ily be exceededwith ordinarywrench effort in thesmallerboltsizes. Even if no damageis evident,anyadditionalload generatedwhen internalpressureisappliedcanproducefurtheryieldingwithpossibleleak-age. Such yieldingcan also occurwhenthereis verylittlemarginbetweeninitialboltstressandyieldstrength.

An increasein boltstress,aboveany thatmaybedueto internalpressure,mightoccurinserviceduringstartupor othertransientconditions,or perhapsevenundernormaloperation.Thiscanhappenwhenthereisan appreciabledifferentialin temperaturebetweentheflangesandthebolts,or whentheboltmaterialhas adifferentcoefficientofthermalexpansionthantheflangematerial.Any increasein boltloaddueto thisthermaleffect,superposedon the load alreadyexisting,cancauseyieldingof the boltmaterial,whereasany pro-nounceddecreaseduetosucheffectscanresultinsucha lossof boltloadas tobeadirectcauseof leakage.Ineithercase,retighteningoftheboltsmaybenecessary,butitmustnotbe forgottenthattheeffectsof repeatedretighteningcanbecumulativeandmayultimatelymakethejointunserviceable.

Inadditiontothedifficultiescreatedbyyieldingoftheboltsas describedabove,thepossibilityof