Yuav Ua Li Cas Welded vs Gasketed PTFE Tube-rau-Tubesheet Joints Sib piv hauv kev ntseeg tau thiab kev pabcuam?

Txhua PTFE raj-rau-tubesheet kev sib txuas yog qhov muaj peev xwm xau. Qhov no interface yog kaw nyob rau hauv ob txoj kev sib txawv, mechanical gasketing nrog compression, los yog thermal vuam ntawm PTFE. Qhov kev xaiv no cuam tshuam rau thawj zaug xau nruj thiab kev saib xyuas lub sijhawm ntev. Hauv kev ua tiav cov txheej txheem tshuaj thiab cov txheej txheem tshuaj uas muaj cov kua dej corrosive thiab thermal cycling yog qhov tseem ceeb, nws yog ib qho tseem ceeb kom nkag siab txog kev sib pauv ntawm cov welded thiab gasketed raj - mus rau -tubesheet pob qij txha kom txhim khu kev qha tshav kub exchanger.

Lub Crucial Sealing Interface
Hauv lub plhaub PTFE-thiab- raj kub exchanger, txhua lub raj yuav tsum tau kho kom nruj rau cov ntawv raj ntawm ib lossis ob qho kawg. Lub hlws ris yuav tsum tiv taus qhov sib txawv ntawm qhov sib txawv, thermal expansion, tshuaj tua kab mob, thiab inhibit qhov xau ntawm lub raj sab dej thiab lub plhaub sab dej. Qhov teeb meem sealing no yog sib xyaw ua ke los ntawm qhov tsis tshua muaj zog saum npoo thiab qhov tseem ceeb ntawm thermal expansion ntawm PTFE, nyuaj rau kev sib khi ntau dua li cov raj hlau.

Ob txoj hauv kev sib txawv tseem ceeb tau tsim:

Gasketed (mechanical compression) cov pob qij txha - Qhov kawg ntawm lub raj yog flared thiab ib tug nyias gasket (PTFE, elastomer los yog encapsulated) yog compressed ntawm lub raj flare thiab lub tubesheet los ntawm ib tug threaded haum los yog thaub qab nplhaib.

Welded (thermal fusion) pob qij txha. Lub raj kawg yog thermally fused ncaj qha mus rau PTFE tubesheet los yog PTFE liner uas txuas mus rau ib tug hlau tubesheet, uas ua rau ib tug nruam, homogenous PTFE qauv.

Gasketed PTFE Tube-rau-Tubesheet Joint
Nyob rau hauv ib tug gasketed tsim txhua lub raj ntawm PTFE yog dhau los ntawm ib lub qhov nyob rau hauv lub tubesheet. Lub raj yog cua sov thaum kawg thiab flared los ua ib tug dab tshos. Lub gasket thib ob (feem ntau yog PTFE, PFA lossis PTFE-encapsulated elastomer) yog muab tso rau nruab nrab ntawm lub raj nplaim hluav taws thiab lub qhov hluav taws xob hauv lub raj. Lub axial quab yuam ntawm ib tug threaded txiv ntseej, nraub qaum nplhaib lossis compression phaj compresses lub gasket thiab tsim ib lub foob.

Cov txiaj ntsig ntawm Gasketed Joints
Field Serviceability - Ib leeg leeg tuaj yeem hloov pauv hauv daim teb yam tsis tau hloov tag nrho. Yog hais tias ib lub raj xau los yog puas lawm, lub txiv ntoo yog loosened, lub raj qub tau muab tshem tawm, lub raj tshiab flared thiab haum thiab hloov gasket. Qhov no yog qhov txiaj ntsig tseem ceeb hauv cov chaw uas lub sijhawm poob qis yuav tsum raug txo kom tsawg thiab cov raj seem muaj.

Cov cuab yeej siv qis dua - Cov cuab yeej Flaring thiab cov khoom sib dhos yog tus nqi pheej yig heev piv rau cov khoom siv vuam tshwj xeeb. Feem ntau, kev sib txuas gasketed yog tus nqi ntau dua - siv tau rau me me - nplai lossis kev cai hloov pauv hluav taws xob.

Kev kam rau lub raj misalignment - Lub tshuab compression sib koom ua ke tuaj yeem txais qhov sib txawv me me ntawm lub raj ntev thiab txoj hauj lwm, ua kom yooj yim sib dhos.

Disassembly rau kev tshuaj xyuas - Lub hnab ntim cov raj tuaj yeem raug tshem tawm ib feem los tshuaj xyuas cov tube kawg, gaskets thiab tubesheet yam tsis muaj kev puas tsuaj rau cov khoom.

Qhov zoo thiab qhov tsis zoo ntawm Gasketed Joints
Gasket so thiab creep - PTFE thiab elastomeric gaskets nyiam so nrog lub sijhawm, tshwj xeeb tshaj yog thaum caij tsheb kauj vab. Lub compressive load ntawm lub gasket yog txo thiab to yuav tshwm sim. Cov txiv ntseej compression yuav tsum tau ncua sij hawm re-torquing uas tuaj yeem muaj teeb meem hauv kev sib pauv hloov pauv channel.

Ntau txoj hauv kev tawm - Txhua lub raj xaim muaj peb qhov sib cuam tshuam tau xau: raj - mus rau -gasket, gasket- mus rau -tubesheet, thiab cov xov lossis lub nplhaib rov qab foob. Raws li kev txheeb cais, nrog ntau pua lub raj hauv ib pob, qhov txawv ntawm qhov xau ntau dua.

Kev pheej hmoo ntawm crevice corrosion - PTFE muaj qhov zoo corrosion tsis kam, tab sis qhov chaw gasket compression tuaj yeem tsim cov crevices uas cov txheej txheem corrosive tuaj yeem raug daig thiab tawm tsam cov hauv paus hlau tubesheet Cheebtsam yog PTFE liner tawg.

Kev tswj torque - Kev tswj lub zog kom raug yog qhov tseem ceeb rau kev sib dhos kom raug. Nyob rau hauv torquing ua rau xau, tshaj torquing tuaj yeem tawg lub PTFE flare los yog ua puas rau lub tubesheet.

Cov hneev taw loj dua - Cov iav compression (cov txiv ntseej, cov nplhaib nraub qaum) xav tau chav ntxiv ntawm cov ntawv raj, txwv cov raj uas tuaj yeem ntim tau rau hauv lub plhaub taub.

Welded PTFE Tube rau Tubesheet Joints
Nyob rau hauv ib tug welded configuration qhov kawg ntawm PTFE hlab yog thermally koom los ntawm ib tug PTFE tubesheet los yog rau ib tug PTFE liner uas yog mechanically tsau rau ib tug hlau tubesheet. Nyob rau hauv cov txheej txheem vuam, lub raj kawg thiab lub tubesheet nto yog rhuab mus rau ib tug kub ntawm lub melting point ntawm PTFE (nyob ib ncig ntawm 327 degree) siv lub siab thiaj li yuav tau ib homogeneous fusion cheeb tsam. Lub raj thiab tubesheet ua ib qho txuas ntxiv ntawm PTFE tom qab txias.

Cov txiaj ntsig ntawm Welded Joints
Tsis muaj kev ncaj ncees - Lub welded hlws ris yog homogeneous PTFE, tsis muaj kev sib tshuam, gaskets lossis crevices. Yog tias ua tau zoo, nws yuav xau- nruj rau lub neej ntawm tus exchanger. Tsis muaj gaskets kom loosen los yog retorque.

Tsis muaj kev saib xyuas - Ib qho kev sib txuas welded tsis xav tau kev tu ncua sijhawm. Qhov no yog qhov zoo tshaj plaws hauv qhov chaw nkag tsis tau lossis thaum kev saib xyuas kev ua haujlwm raug nqi.

Nce lub raj ntom ntom - Yog tsis muaj compression hardware, cov raj tuaj yeem ntim tau nruj dua, muab cov cua kub hloov mus rau hauv tib lub plhaub txoj kab uas hla.

Kev sib raug zoo tshuaj lom neeg zoo dua - Tsis muaj elastomer lossis cov gaskets kaw txhais tau tias tsis muaj kev txhawj xeeb txog tshuaj tua kab mob ntawm cov khoom tsis yog -PTFE. Ntshiab PTFE ntawm tag nrho cov ntub dej.

Txhim kho kev ua haujlwm zoo rau kev caij tsheb kauj vab cua sov - Lub fused hlws ris nthuav dav thiab cog lus tsis tu ncua nrog lub raj. Tsis muaj gasket kom poob compression nrog lub cyclic kub hloov pauv.

Drawbacks ntawm Welded Joints
Tsis yog- pabcuam tau - Yog tias ib lub raj xau, nws tsis tuaj yeem hloov pauv tus kheej. Cov txheej txheem kho cov pa yog ntsaws lub raj xau (tsav lub PTFE ntsaws rau hauv lub raj kawg thiab vuam nws). Lub active tshav kub hloov chaw yog txo los ntawm plugging. Yog tias ntau tshaj ib lub raj xau tag nrho cov pob yuav tsum tau hloov.

Vuam txheej txheem tshwj xeeb yuav tsum tau - PTFE vuam tsis yog ib qho kev txawj ntse muaj nyob rau hauv lub khw. Xav tau kev tswj qhov kub thiab txias, qhov chaw huv si thiab cov khoom siv sophisticated (kub platens, siab applicators) Ua tsis zoo welds nrog cov kab noj hniav zais los yog cov kab mob yuav ua rau ua tsis tiav thaum ntxov.

Cov nqi pib siab rau cov ntim me me - Cov cuab yeej thiab txheej txheem kev txhim kho rau cov pob qij txha welded yog kim dua li cov cuab yeej flaring. Rau cov pob me me (tsawg dua 50 lub raj), gasketed junctions yuav pheej yig dua.

Nyuaj hauv Kev Tshawb Fawb - Welded pob qij txha yog qhov nyuaj rau kev tshuaj xyuas tsis yog- puas tsuaj. PTFE welds feem ntau tsis yog X-ray lossis ultrasonic kuaj. Kev ua tau zoo yog tswj xyuas los ntawm kev tswj xyuas cov txheej txheem thiab cov qauv kev puas tsuaj.

Tsis teb weldable - Vuam ntawm cov pob qij txha yuav tsum tau ua nyob rau hauv lub Hoobkas raws li kev tswj xyuas. Ib lub raj tsis tuaj yeem hloov pauv hauv daim teb. Yog tias qhov xau tshwm sim hauv kev pabcuam, tag nrho cov pob yuav raug capped lossis hloov.

PTFE Vuam txheej txheem xav txog
Ntshiab PTFE tsis ntws sai vim nws cov viscosity siab heev thiab yog li tsis yooj yim welded. Yog li ntawd, ntau "welded" PTFE cua sov exchangers yeej siv PFA (perfluoroalkoxy) hlab thiab tubesheets. PFA muaj cov tshuaj tiv thaiv zoo sib xws thiab cov yam ntxwv kub zoo li PTFE tab sis tuaj yeem yaj- ua tiav thiab fusion welded siv cov tsoos kub - phaj lossis rhuab - txheej txheem cuab yeej. Thaum qhia txog qhov sib txuas welded nws yog ib qho tseem ceeb los qhia seb cov khoom puas yog PTFE lossis PFA raws li kev ntseeg tau ntawm cov vuam sib txawv.

Ib qho tshwj xeeb sintering lossis cua sov- cov txheej txheem fusion yog ua haujlwm rau cov ntawv thov xav tau PTFE tiag. Ob lub raj kawg thiab cov tubesheet yog rhuab kom ze rau melting thiab thawb ua ke thiab txias nyob rau hauv kev tswj xyuas. Txoj kev no yog cov kab mob rhiab heev thiab xav tau chav huv huv kom tau txais txiaj ntsig zoo tshaj plaws.

Cov txheej txheem welded muaj cov txheej txheem monolithic PTFE uas tsis muaj gaskets, tsis muaj fissures thiab tsis muaj txij nkawm. Welded junctions: Tseem ceeb heev - purity loops zoo li dej tshuaj, semiconductor ntau lawm, thiab ultrapure chemical txheej txheem siv welded junctions raws li tus qauv.

Table 2 Kev sib piv ntawm Welded thiab Gasketed PTFE Tube rau tubesheet sib koom
Feature Welded Joint Gasketed (Mechanical) Joint
Leak Integrity Zoo heev - homogenous fusion, tsis muaj interfaces Zoo - nyob ntawm lub gasket compression thiab lub torque
Muaj peev xwm Leak PathsOne (kev sib koom ua tsis tiav, tsis yog lub raj tawg nkaus xwb) Peb lossis ntau dua rau ib lub raj (tube-rau-gasket, gasket-rau-tubesheet, hardware)
Gasket Relaxation/Creep Tsis siv tau Yog - re-torque ntawm lub sijhawm
Field Repairability Tsis muaj - cov raj xau yuav tsum raug kaw; Kev hloov pauv rau ntau qhov xauYes - cov leeg ib leeg yog qhov hloov pauv tau
Cov nyhuv ntawm thermal cycling .Zoo heev – sib koom tes qhib thiab kaw qhov sib npaugFair - kev caij tsheb kauj vab tuaj yeem txo cov load ntawm lub gasket
Thawj Tus Nqi (Cov Pob me me, tsawg dua 50 lub raj) Siab dua (cov cuab yeej tshwj xeeb) qis dua (cov ntsiab lus compression & flaring)
Initial Cost (Large Bundle, >200 lub raj) Cov khoom siv tsawg dua (ntau lub raj ib square inch) Siab dua (ntau cov txiv ntseej & cov nplhaib txhawb nqa)
Tube Packing Density High (tsis muaj compression hardware) qis (qhov chaw xav tau rau kho vajtse)
Kev kho zaus Tsis muaj - ncua sij hawm ntsaws tsuas yog lub raj tsis ua haujlwmPeriodic - gasket hloov thiab rov-torquing
Crevice Corrosion RiskPTFE, Tsis yog-HomogeneousLow mus rau nruab nrab - Gasket crevices tam sim no
Yam khoom PFA (nyiam dua) PTFE (tshwj xeeb txheej txheem) PTFE (tube flared) nrog PTFE lossis FEP gasket
Inspection Method Txheej txheem tswj + kev puas tsuaj qauv testVisual, torque check, siab test
Daim Ntawv Qhia Tshwj Xeeb
Thaum Yuav Siv Gasketed Connections
Gasketed PTFE raj - mus rau - tubesheet couplings yog qhia rau:

Qhov tseem ceeb yog qhov yooj yim ntawm kev pabcuam hauv thaj chaw. Kev hloov cov raj ntawm ib tus neeg tuaj yeem ua tau zoo nyob rau hauv ib qho chaw uas muaj cov khoom seem uas tsis muaj peev xwm lossis lub sij hawm ua cov hmoov txhuas ntev rau cov khoom hloov.

Lub tshav kub exchanger yog me me (chaw tsawg dua 1 m2) los yog muaj ob peb raj (tsawg dua 50). Tus nqi ntawm cov cuab yeej vuam tsis tsim nyog.

Cov pob khoom yuav tsum raug puas tsuaj (xws li vim yog cov cuab yeej tu hnyav lossis cov khoom siv hauv cov txheej txheem ua kua) thiab cov raj yuav tsum tau hloov.

Cov neeg saib xyuas paub yuav ua li cas rov- torque thiab muaj kev nkag mus rau lub raj xa mus rau kev kuaj xyuas raws sij hawm.

Kev siv yog nyob rau hauv tus txheej txheem kev lag luam chemical uas cov xau me me tuaj yeem zam tau thiab kho txhua lub sijhawm.

Teb-cov qauv tsim siv tau siv cov pob qij txha gasketed raws li cov qauv kev lag luam pov thawj.

Thaum siv Welded Joints
Qhov twg welded pob qij txha zoo dua:

Leak kev ncaj ncees yuav tsum yog kiag li. High purity loops, tshuaj dej tshuab, semiconductor ntub lub rooj ntev zaum thiab nuclear daim ntaub ntawv tsis pub muaj kev sib kis ntawm lub raj sab thiab lub plhaub sab dej.

Lub tshuab hluav taws xob kub yuav raug siv nyob rau hauv ib qho chaw uas lub sij hawm re-torqueing tsis tau (xws li rau hauv lub tank, nyob rau hauv lub siab hlab ntsha, los yog nyob rau hauv ib cheeb tsam hluav taws xob).

Thermal cycling feem ntau hnyav heev. Ib qho ntawm cov txiaj ntsig tseem ceeb ntawm kev sib koom ua ke welded yog nws lub peev xwm nthuav dav tusyees yam tsis muaj loosening ntawm gasket.

Cov pob khoom loj heev (ntau pua lub raj). Qhov siab ntawm lub raj muaj zog thiab kev tshem tawm ntawm cov khoom siv txo qis tag nrho qhov loj thiab cov nqi ntawm cov khoom sib hloov.

Kev tu-dawb, lub neej ua haujlwm ntev yog qhov tsim nyog. Ib txoj hlua khi PFA raug cai tuaj yeem kav ntev li 10-15 xyoo yam tsis muaj kev saib xyuas ntawm kev sib tshuam.

Nyob rau hauv cov ntaub ntawv tseem ceeb heev - purity loops, tsuas yog welded xaiv yog tso cai.

Mixed Designs
Qee cov tuam ntxhab siv cov qauv tsim hybrid. Ib lub raj xaim txuas nrog rau cov raj los ntawm kev vuam thiab lwm lub raj xaim muaj qhov sib txuas los yog qhov sib txuas kom haum rau thermal expansion. Los yog ib daim ntawv tube yuav muaj PTFE liner welded rau cov hlab. Lub liner yog lub cev ruaj ntseg rau ib lub raj hlau. Cov hybrids nrhiav kev sib xyaw ua ke ntawm kev ncaj ncees ntawm kev sib txuas nrog kev pabcuam ntawm cov khoom siv sib txuas, tab sis lawv ntxiv qhov nyuaj thiab tus nqi.

Nto Finishing Practical Considerations
Nyob rau hauv feem ntau cov ntaub ntawv tiav (electroplating, anodising, pickling, thiab lwm yam), kev txiav txim siab siv welded los yog gasketed kev twb kev txuas yog ib tug muaj nuj nqi ntawm da dej chemistry thiab txij nkawm lub tswv yim:

Electroless npib tsib xee plating - Cov da dej no tuaj yeem decompose spontaneously yog tias muaj kuab paug nrog qee yam hlau. Kev da dej yuav tshwm sim yog tias lub plhaub sab dej (steam lossis dej kub) xau rau hauv da dej. Txhawm rau tiv thaiv qhov no, welded pob qij txha feem ntau muab.

Hard chrome plating - Lub da dej yog me ntsis corrosive, tab sis tsis rhiab heev rau kev sib kis. Gasketed pob qij txha yog nquag vim nws xav tau los hloov cov leeg ib leeg thaum muaj kev puas tsuaj tshwm sim thaum lub sij hawm khib nyiab.

Anodising da dej (sulphuric acid) - Cov kev xav tau purity nruab nrab Ob hom pob qij txha siv.

Pickling da dej (hydrochloric los yog nitric/hydrofluoric acid) - corrosive heev.

Tsis tas li ntawd, nws yuav tsum tau muab sau tseg tias lub raj mus rau tubesheet sib koom ua ke tsis yog tib txoj kev tuaj yeem xau. Tsis tas li ntawd, soj ntsuam cov tubesheet rau plhaub gasket, lub plhaub nozzles thiab expansion pob qij txha. Lub welded raj hlws ris ntawm ib qho kev sib hloov gasketed tseem nyob ntawm lub plhaub gasket los muab kev ncaj ncees tag nrho.

Cov lus xaus.