flange orifice flow meter - valveit srl · flange orifice flow meter orifice flange assemblies...

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FlangeorificeflowmeterOrificeflangeassembliesDescriptionOrifice flangeassemblies areused in conjunctionwithorificeplates for flowmeasurementof smaller ormedium size pipes at lower ormedium pressure ranges. The flange connection is of a RF type and thedifferentialpressuretappingsystemiswithflangetaps.Specificationorificeflangetypes:

slip-onRFweldingneckring-jointweldingneck–largeorsmalltonguaface

nominaldiameters:

25mm(1”)to500mm(60”)–aboveonrequestflangerating:

ASME, 300, 600, 900, 1500, 2500 lbs (RF, RTJ)(ASMEB16.36–ASMEB16.47AandB

API2000,3000,5000,1000015000(API6°)flangematerial

carbonsteel,StailessSteel,exoticmaterial,duplexmaterial.materialsofboltsandnuts:

studbolts:A193-B7,B8,etc.nuts:A194-2H,8,etc.jackboltsandnuts:A193-B7,B8etc.–

gaskets:

sheetgaskets1.5mm(ASMEB16.21)spiralwoundedgasket4.5mm–(ASMEB16.20)

pipingconnectionmethod:

ANSI:buttweldingtype(ASMEB16.25)


TypeSlip-onflangesTheslip-onflangehasalowhubbecausethepipeslipsintotheflangepriortowelding.It isweldedbothinsideandoutsidetoprovidesufficientstrengthandpreventleakage.Slip-onflangesareallboredslightlylargerthantheO.D.ofthematchingpipe.Theyarepreferredoverweldingneckflangesbymanyusersduetotheirlowerinitialcost,butfinalinstallationcostisprobablynotmuchlessthanthatoftheweldingneckflangebecauseoftheadditionalweldinginvolved.SocketweldingflangesThe socket welding flange is similar to the slip-on flange except it has a bore and a counter boredimension. The counter bore is slightly larger than O.D. of the matching pipe, allowing the pipe to beinsertedintotheflangesimilartoaslip-onflange.ThediameterofthesmallerboreisthesameastheI.D.ofthematchingpipe.Arestrictionisbuiltintothebottomoftheborewhichsetsasashoulderforthepipetothereston.Thiseliminatesanyrestrictionintheflowwhenusingasocketweldingflange.WeldingneckflangesTheweldingneck-flangeisnormallyreferredtoasthe“highhub”flange.Itisdesignedtotransferstressestothepipe,therebyreducinghighstressconcentrationsatthebaseoftheflange.Theweldingneckflangeisthebestdesignedbutt-weldedflangeofthosecurrentlyavailablebecauseofitsinherentstructuralvalue.Itisexpensivebecauseofthedesign.


PressuretapconnectionsPressureconnectionholesinthepipeshouldbe1/2”for4”andlargerlines,3/8”for3”linesand1/4”for2” lines.When flange tapsareused, insertadrillof theproper size through theconnectionholes in theflangesanddrillthroughthepipe.Whenconnectionsinthepipeareused,weldhalf-couplingstothepipeattheproperlocations,insertadrillthroughthem,anddrillthroughthepipe.Roundofftheedgesoftheholesslightlytobesurethatnoburrsremaininthepipe.FlangetapsPressure connection holes are located in the flanges 1” upstream and 1” downstream from thecorrespondingorificeplatefaces(seefig.4andfig.5)

CornertapsOnlinessmallerthan2”,theorificeflangeunionshowninfig.6isused.Theeffectisthatthepressuretapsarerightattheorificeplate.


2,5Dand8Dtaps,alsocalledfull-flowpipetapsConnectionsare installed2,5pipe-diametersupstreamfromtheupstreamfaceof theorificeplateand8pipediametersdownstreamfromtheupstreamfaceoftheorificeplate.

1Dand0,5Dtaps,alsocalledradiustapsThistypeofconnectionismodificationofandhaslargelyreplacedtheVenaContractataps.Ityieldsequallyaccurateresultsandhastheadvantagethatthedownstreamconnectioniseasiertolocate.Theupstreamconnection should be at 1D above the upstream face of the orifice plate, but locationof the upstreamconnectionanywherebetween0,5and2Dintroducesonlynegligibleerror.Thedownstreamconnectionislocated0,5Cfromtheupstreamfaceoftheorificeplate.

“VenaContracta”tapsThe upstream connection (dimensionM)may be located anywhere between 0,5 and 2 pipe diametersabove theupstream faceof theorificeplate. Thedownstreamconnection (dimensionN) ismadeat thepointofmaximumflowconstrictionandisgivenbythetablebelow:


OrificemeterrunsDescriptionOrifice meter runs are used for measuring the flow at higher accuracy. The orifice meter runs aretherefore,nottheonessimplyweldpipestoupstreamanddownstreamsidesoranorificeassembly,buttheonesweldingsmallerinsidediameterpipestosmallerdiameterofflanges,then,finishinsidediameterorthepipe/flangeassemblybyboringorhoningtothespecifieddimensionswiththerequiredtolerancesandsurfaceroughness(seefig.20andfig.21).TypeanddrawingOrificemeterrun(bothsidesfanged):


iOrificemeterrun(buttweldingends)

flange orifice flow meter - valveit srl · flange orifice flow meter orifice flange assemblies...

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