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    Lortz Manufacturing - Expansion Joints and Metal Bellows

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    severo97
    Introduction to Metal Bellows

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    © All Rights Reserved
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    Lortz Manufacturing - Expansion Joints and Metal Bellows

    Uploaded by

    severo97
    71 views3 pages
    Introduction to Metal Bellows

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    © © All Rights Reserved

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    PDF, TXT or read online from Scribd

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    Introduction to Metal Bellows

    Copyright:

    © All Rights Reserved
    Download as PDF, TXT or read online from Scribd
    Download as pdf or txt
    71 views3 pages

    Lortz Manufacturing - Expansion Joints and Metal Bellows

    Uploaded by

    severo97
    Introduction to Metal Bellows

    Copyright:

    © All Rights Reserved
    Download as PDF, TXT or read online from Scribd
    Download as pdf or txt
    of 3

    BellowsAssetsRecentlyAcquiredbyU.S.Bellows,Inc.

    LocatedinHouston,Texas,U.S.A.
    Phone:(281)2419418TollFree:(855)5910906Fax:(661)5872022Email:info@lortz.com
    Home
    Company
    Capabilities
    ContactUs
    Products
    MetalExpansionJoints
    FabricExpansionJoints
    PressureVessels
    Ducting
    CustomFabrication
    PipeSpoolFabrication
    ProcessSkids
    OnSiteService
    U.S.Bellows,Inc.
    VisitU.S.Bellows'Site

    WHATISAMETALBELLOWS?
    Lortzmetalexpansionjointsutilizeoneormorebellowsthatretainsystempressurewhiledeformingto
    accommodatesystemmovements.Metalbellowsareproducedbeginningwithaweldedtube(seamlesstube
    useisveryrare),andmechanicallyorhydraulicallyformingconvolutionsinthenumberandshapetomeet
    pipingorductingsystemrequirements.Metalbellows,asadetailpart,arerarelyprovidedtocustomersdue
    tothethinmaterialthicknesswhichrequiresspecializedweldingprocessestoattachthebellowstopipeor
    flanges.
    MetalBellows
    HowaBellowsWorks
    MetalBellowsDesign
    MetalApplications
    PipeAnchors&Guides
    StandardFlangeData
    CommonMaterials
    MetalEJComponents
    SingleExpansionJoints
    UniversalJoints
    ExternallyPressurized
    PenetrationSeals
    InstallationInstructions
    MetalWarranty
    HOWABELLOWSWORKS
    Metalbellowsaredesignedtoabsorbthermaland/ormechanicalmovementsinpipingorductingsystemswhileretainingsystemoperating
    pressureatsystemtemperature.Bellowscanabsorbthefollowingmovements:
    Whereasmetalbellowscanbedesignedtoresisttorsionalloads,metalbellowscannottoleratetorsionalmovement.Metalbellowsmustbe
    designedtoavoidsystemresonantvibrationfrequency(ifvibrationexists)inordertopreventimmediatemechanicalbellowsfailure.Failureto
    specifytorsionorvibration(ifeitherexists)canresultinimmediatebellowsfailure.
    BELLOWSPRESSURETHRUST
    Metalbellowscannotrestrainlongitudinalpressureloadswithoutintegralrestraininghardwaresuchastierods,hinges,gimbalsorexternalpipe
    anchors.Longitudinalpressureloadsonabellowsresultsin"pressurethrust".Pressurethrustforceiscreatedbythesystemand/ortestpressure
    actingontheareaofthe"meandiameter"ofthebellows.(Bellowsmeandiameter=bellowsconvolutionI.D.+((O.DI.D)/2).Apressurized,
    unrestrainedmetalbellowsexpansionjointinapipingsystemwithoutanchorswillelongate(extend)duetopressurethrustwhichcanresultin
    immediatebellows"squirm"andfailure.Pressurethrustforcesaretypicallyhigherthanallothersystemforcescombined.
    BELLOWSPRESSURESTRESSES
    Pressureappliedtoabellowsislimitedby"HoopStress"(EJMAS2)and"BulgeStress"(EJMAS4).HoopStressrunscircumferentiallyaroundthe
    bellowsresultingfrompressuredifferentialbetweentheinsideandoutsidediameterofthebellows.Hoopstressiswhatholdsabellowstogether
    similartohoopringsonawoodbarrel.Hoopstressmustbeheldtocodeallowablelevels.BulgeStressrunslongitudinaltothebellowscenterline
    actingonthesidewallofthebellowsconvolutions.BulgeStressisalsocalculatedtocode.
    UnderstandingMetalBellowsPressureThrustisExtremelyImportant
    Withrigidpipeinstalledbetweentwoflangespressurethrustisrestrainedbythestrengthofthepipe.
    Withathinwallconvolutedbellowsweldedtotwoflanges,thebellowsreactiontopressurethrustresultsinthebellowsgrowinginlengthuntilthe
    bellows"squirms"and/ortheconvolutionsstretchouttobecomethetubefromwhichtheywereformed.
    METALBELLOWSPRESSURERETAININGCAPABILITY
    Metalbellowsaredesignedtoretainloadsimposedbyinternaland/orexternalsystempressureand/ortestpressure.Bellowsconvolution
    geometry,numberofconvolutions,materialtypeandmaterialthicknessallaffectbellowspressureretainingcapability.
    Overpressurizationand/orimproperguidingofametalbellowsexpansionjointcancausethebellowsto"squirm".Squirmcanleadtopermenant
    deformationand/orimmediatefailureofthebellows.
    METALBELLOWSSPRINGRATE
    Inadditiontolongitudinalpressurethrustloads,movementwithinabellowsrequiresa"force"tocausethebellowstocompress,extendor
    angulate.Bellows"springrate"isadesignconsideration.Tocalculatetheload(force)imposedonequipmentadjacenttotheexpansionjoint,use
    theequationbelow.
    F=KxX
    FTheload(force)imposedonequipmentoneithersideofthebellows.
    KThebellowsspringrate(expressedaspounds/inchofmovementforaxialandlateralmovements,andinch/poundperdegreefor
    angularmovement)
    XTheanticipatedorspecifiedmovement
    Theresultisreferredtoas"springforce".Forabellowsexpansionjointwithoutintegrallongitudinalpressurerestraininghardware,onemustadd
    thebellowsspringforcetothepressurethrustforcetodeterminethetotalforceimposedonadjacentequipmentorpipeanchors.Otherloadsthat
    mustbeconsideredaredeadweight,frictional,wind,etc.
    METALBELLOWSCYCLELIFE
    Whenabellowscompresses,extendsorangulates,themovementisabsorbedbydeformationofthesidewallsofthebellowsconvolutions.The
    stresscausedbythemovementisreferredtoasthebellowsdeflectionbendingstress(EJMAS6).Thisstressishighestatthe"crest"and"root"of
    thebellowsconvolution.Metalbellowsaredesignedtofunctionwithadeflectionbendingstressvaluethatfarexceedstheyieldstrengthofthe
    bellowsmaterial.Therefore,mostmetalexpansionjointsaredesignedtodeflectinthe"plastic"rangeofmaterialsandthebellowswilltakea
    permanent"set"attheratedbellowsmovements.Bellowsarerarelydesignedtooperateintheelasticrangeofmaterials.Bellowsoperatinginthe
    plasticmaterialrangewilleventuallyfailduetofatigueafterafinitenumberofmovementcycles.Realisticcyclelifeshouldbespecifiedforbellows
    design.Asthechartonpage26shows,thehigherthecyclelife,the"weaker"thebellowsdesignpressurecapability.The"safest"bellowsdesign
    resultsfromrealworldcyclelife,pressure,movementandtemperaturedata.
    BELLOWSDESIGNVARIABLES&THEIRRELATIONSHIPTOBELLOWSDYNAMICS
    Thechartaboveshowsthecomplexityofbellowsdesignwiththerelationshipofbellowsgeometry,materialthickness,pressureandmovement.
    Optimumbellowsdesignrequiresactualpressureandtemperaturetobespecifiedalongwithactualcalculatedthermalmovementtobeabsorbed
    bythebellows.Overstatingsystemdatawillresultinalesssafebellowsdesign.Mostsystemdesignersthinkthatspecifyinganextendedbellows
    cyclelifeincreasessystemreliability,whereasalongerthannecessaryspecifiedbellowscyclelifeinmostcaseshastheoppositeresult.Asthe
    chartaboveshows,therelationshipbetweencyclelifeandpressurestabilityisa"balancingact".Thehigherthecyclelife,thelowerthepressure
    retainingcapabilityofagivenbellowsdesign.Notetheredvaluesinthechart,whencyclelifeishigher,squirmpressureislower.
    TheStandardsoftheExpansionJointManufacturersAssociation(EJMA)coversthesubjectofbellowscyclelifeverywellandLortzrecommends
    thatsystemdesignersrefertothelatesteditionoftheEJMAStandards.
    COMMONBELLOWSMATERIALS
    Bellowsmaterialselectionisdeterminedthroughknowledgeofthesystemprocessandmedia.Responsibilityfortheselectionofbellowsmaterials
    isthatofthesystemprocessdesignerorenduser.
    BELLOWSFORMING
    TypicalExpansionJointApplications
    AxialMovementOnly

    CombinedMovements

    AngularMovements
    Hinge&Gimbal
    MAINANCHORS
    Mainanchorsmustbedesignedtowithstandalloftheforcesandmovementsimposedontheminthepipingsystemsectioninwhichtheyare
    installed.Thisincludesbellowspressurethrust,mediaflow,bellowsspringforceandfrictionalforcesofpipeguides,pipesupports,anddirectional
    anchors.Theweightofthepipe,includingcontentsandforcesand/ormovementsresultingfromwindloadsmayalsohavetobeconsideredinthe
    mainanchordesign.
    INTERMEDIATEANCHORS
    Intermediateanchorsarenotdesignedtowithstandbellowspressurethrustforce.Whenunrestrainedmetalbellowsexpansionjointsareinstalled
    inapipesection,intermediateanchorsmustbedesignedtowithstandallofthenonpressureforcesactinguponitwhichconsistsofbellowsspring
    forceandotherfrictionalforcessuchaspipeguides.
    PIPEGUIDESANDSUPPORTS
    Piperings,Ubolts,rollersupportsandspringhangarsaretypicalpipesupportdevices.Aproperlydesignedpipesupportpermitsfreemovementof
    pipingwhilesupportingthedeadandliveweightofpiping,valvesandothercomponentsofapipingsystem.
    Pipingorductingsystemsinwhichmetalbellowsexpansionjointsareinstalledmustbeproperlyguidedandsupportedinorderfor
    theexpansionjointtofunctionproperly.Itisgenerallyrecommendedthattheexpansionjointbeinstallednearapipeanchorandthatthefirst
    guidebeinstalledamaximumoffour(4)pipediametersawayfromtheexpansionjoint.Thedistancebetweenthefirstandsecondguideshould
    notbegreaterthan14pipediameters.
    Properguidingandsupportingofpipingsystemscontainingexpansionjointsiscritical.
    PIPEGUIDESPACINGCHART
    Thefirstguidemustbelocatedamaximumof4pipediametersfromtheendofthebellowsthesecondguide
    amaximumof14pipediameters.Thechartbelowisforallbellowswithinsidediameterthesameaspiping.
    Thischartisforgeneralreferenceonly.Pipingandductingsystemsshouldbedesignedbyqualifiedengineersandconsiderallsystem
    requirements.
    DuctingSystems|FabricExpansionJoints|MetalBellows|PipeSpools|PressureVessels|ProcessSkids
    CustomFabrication|DesignIntegration|Onsite/Emergency|QualityAssurance|Welding
    LortzManufacturingCompany
    AssetsRecentlyAcquiredbyU.S.Bellows,Inc.ofHouston,TX
    3701HolmesRoad,Houston,TX77054
    Phone:(281)2419418TollFree:(855)5910906Fax:(661)5872022
    Email:info@lortz.comwww.lortz.comwww.usbellows.com

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