Puas yog Crevice Corrosion Resistance ntawm Super Duplex Stainless Steel piv rau PTFE hauv Seawater?

Cov cua kub sib txawv rau cov dej ntsev txias yog tsim los ntawm ob qho tib si super duplex stainless hlau thiab PTFE, tab sis lawv tiv thaiv lawv tus kheej hauv ntau txoj hauv kev. Super duplex cia siab rau cov txheej nyias nyias oxide txheej uas tuaj yeem ua rau hauv zos degraded hauv qhov tawg. PTFE tsis muaj peev xwm ua rau corrode chemically, tsis muaj oxide zaj duab xis lossis hlau qauv.

Qhov no yog qhov tseem ceeb tshwj xeeb tshaj yog nyob rau hauv cov dej hiav txwv sov uas qhov chaw nyob ruaj khov, tso nyiaj thiab cov pob qij txha nruj tsis tuaj yeem zam tau. Nyob rau hauv tam sim no engineering kev sib tham ntawm super duplex piv rau PTFE crevice corrosion seawater, nws tsis yog ib qho teeb meem ntawm kev sib piv ob cov ntaub ntawv, tab sis ob tug tag nrho txawv corrosion cwj pwm.

Vim li cas Crevice Corrosion Matters rau Seawater Systems
Cov dej hiav txwv yog ib qho ntawm cov kua dej uas muaj kev ua phem tshaj plaws uas tshwm sim hauv qhov xwm txheej. Lub siab concentration ntawm chloride, yaj oxygen, lom lom thiab conductivity muab tej yam kev mob zoo meej rau localized corrosion.

Crevices feem ntau pom muaj nyob rau hauv lub tshuab cua txias ntawm:

Tube rau tubesheet sib txuas

Gasket interfaces

Fouling films thiab deposits

Flange ntsej muag

Fastening Interfaces

Tsawg-Flow Stagnant Regions

Txawm tias cov ntaub ntawv uas muaj kev tiv thaiv zoo corrosion tuaj yeem ua tsis tau sai hauv cov geometries txwv.

Corrosion Resistance ntawm Super Duplex Stainless Hlau
Super duplex stainless hlau xws li 2507 cia siab rau chromium - nplua nuj passive oxide txheej uas loj hlob ib txwm nyob rau saum npoo hlau los muab kev tiv thaiv corrosion.

Cov txheej txheem passive no yog ib qho kev thaiv me me ntawm cov hlau thiab ib puag ncig marine. Cov yeeb yaj kiab yog tus kheej- kho tau raws li cov xwm txheej ntws ib txwm muaj uas qhia txog kev puas tsuaj me me.

Kev tiv thaiv yog txhim kho los ntawm ntau lub ntsiab lus alloying:

Chromium txhim kho passivation

Molybdenum txhim khu kev tiv thaiv rau pitting

Cov zaj duab xis passive yog stabilized los ntawm nitrogen.

Nickel pab duplex theem sib npaug

Yog li ntawd, cov hlau no tshwj xeeb tshaj yog haum rau ntau daim ntawv thov marine piv rau cov tsoos stainless hlau.

Disadvantage ntawm Super Duplex: Crevice Corrosion
Super duplex stainless hlau muaj kev tiv thaiv corrosion zoo heev tab sis muaj kev cuam tshuam rau hauv cheeb tsam crevice nres nyob rau hauv qee yam mob.

Oxygen Starvation hauv Crevice
Dissolved oxygen yog depleted sai heev nyob rau hauv ib tug nqaim qhov sib txawv. Qhov kev ntxiv ntawm cov pa oxygen yog txwv thiab yog li cov txheej txheem oxide passive tsis tuaj yeem tswj hwm nws tus kheej zoo.

Thaum cov yeeb yaj kiab passive raug rhuav tshem:

Chloride ions concentrate nyob rau hauv lub crevice

Nce acidity hauv zos

Hlau dissolution ceev

Corrosion yog tus kheej - nrawm.

Cov duab txwv tsis pub muaj tshuaj lom neeg muaj zog micro-ib puag ncig, cais tawm ntawm cov dej hiav txwv ib puag ncig.

Critical Crack Temperature
Rau super duplex 2507 nyob rau hauv dej hiav txwv qhov tseem ceeb crevice kub yog feem ntau nyob ib ncig ntawm 35℃mus rau 40 degree.

Thaum qhov pib no dhau lawm, qhov tshwm sim ntawm kev ua yeeb yaj kiab tsis sib haum xeeb yog ntau dua, tshwj xeeb tshaj yog nyob rau hauv qhov tsis txaus siab lossis tsis txaus.

Qhov ntsuas kub no feem ntau tshaj thaum lub sijhawm ua haujlwm ntawm cov cua sov hauv hiav txwv cua txias:

Tropical dej, hiav txwv kev pab.

Condenser khiav, sov

Khoom siv raws li txoj cai: nyob ruaj ruaj

Fouled heat exchanger ua haujlwm

Circulation eventsPoor

Thaum pib, crevice corrosion tuaj yeem propagate sai txawm tias zoo corrosion kuj ntawm alloy.

PTFE thiab nws cov cwj pwm sib txawv hauv kev tiv thaiv corrosion
PTFE mus rau txoj kev sib txawv heev rau cov dej qab ntsev.

Super duplex tab tom ua tsov rog electrochemical. PTFE tsuas yog tsis xav koom nrog.

PTFE yog ib qho fluorinated polymer uas tsis muaj hlau nplaum, tsis muaj ib thaj tsam lis thiab tsis muaj peev xwm electrochemical. PTFE yog impervious rau qhov tsis ua hauj lwm mechanism vim crevice corrosion yog cov txheej txheem electrochemical.

Vim li cas PTFE tsis tuaj yeem raug Crevice Corrosion
PTFE yog intrinsically resistant rau cov hauv qab no yog vim li cas:

Tsis muaj rupture ntawm passive oxide zaj duab xis

Tsis muaj peev xwm galvanic tsim

Tsis muaj tshuaj tiv thaiv electrochemical yog tshwm sim los ntawm chloride

Tsis muaj anodic dissolution hauv zos "

PTFE yog chemically ruaj khov nyob rau hauv seas stagnant, nyob rau hauv oxygen -depleted zones los yog nyob rau hauv deposits.

Qhov kev tiv thaiv no yog unconditional, tsis conditional.

Tus cwj pwm kub hauv dej hiav txwv
PTFE muaj tshuaj tiv thaiv zoo heev hauv dej hiav txwv ntawm qhov kub thiab txias.

PTFE yog ntsuas rau cov kev pabcuam dej tas mus li rau ib txwm mus txog kwv yees li:

Ua haujlwm kub tsis tu ncua 110 degree

Qhov ntau yam no yog qhov muaj txiaj ntsig ntau dua li qhov kev ua haujlwm ntawm feem ntau cov dej hiav txwv cua txias.

Ntawm qhov tsis sib xws, kev ua haujlwm corrosion ntawm super duplex ua rau muaj kev nkag siab ntau dua thaum qhov kub ntawm cov dej ntsev nce mus txog lossis siab dua qhov kub ntawm qhov tseem ceeb.

Xov xwm phem ntawm PTFE
Thaum PTFE muaj kev tiv thaiv tag nrho rau crevice corrosion, muaj kev lag luam tawm -offs cuam tshuam nrog nws siv.

Txo Thermal conductivity
PTFE yog ib tug tsis zoo conductor ntawm tshav kub piv rau hlau alloys.

Qhov tseem ceeb ntawm thermal conductivity:

Khoom siv kwv yees Thermal Conductivity (W / mK)
Super Duplex Stainless Hlau ~ 14-19 W / m·K PTFE ~ 0.25 W / m·K
Qhov kev tsis sib haum xeeb no txo ​​qis kev ua haujlwm ntawm kev thauj mus los ntawm tshav kub thiab tej zaum yuav xav tau:

Exchangers nrog nce saum npoo

Thinner phab ntsa

Lwm yam geometry rau exchangers

Tsawg- Muaj peev xwm siab
Lub zog txhua yam ntawm PTFE yog qis dua super duplex steel.

Yog li:

Txo cov kev ntsuas siab

Kev txhawb nqa tus qauv yog qhov tseem ceeb dua

Creep cwj pwm yuav tsum tau coj mus rau hauv tus account

Kev siv lub tshuab nqus tsev yuav xav tau kev txhawb nqa

Stability ntawm Dimension
Lub thermal expansion ntawm PTFE yog ntau dua li ntawm cov hlau, li no, tus tsim ntawm lub exchanger thiab cov kav dej yuav tsum tau ua tib zoo xav txog.

Qhov twg PTFE muaj qhov kev ntseeg siab loj dua
Nyob rau hauv ntau lub marine systems nws yuav luag tsis yooj yim sua kom tshem tawm tag nrho cov khoob.

Piv txwv li:

Tube pob

Gasketed sib koom

Fouling prone exchangers

Biofilm chaw khaws cia

Standby iav nyob rau hauv txoj hauj lwm

Hauv cov chaw no, tus qauv kev ntseeg siab rau PTFE yog qhov sib txawv, vim tias tsis muaj kev cuam tshuam hauv zos los pib.

Cov cwj pwm no tuaj yeem pab tau tshwj xeeb hauv:

Offshore cua txias systems

Ntsev- tshem tawm cov nroj tsuag

Marine chemical ua

Condensers sov dej hiav txwv

Cua txias circuits txuag

Nyob rau hauv daim ntawv thov qhov kev tshuaj ntsuam xyuas yog txwv los yog repercussions ntawm tsis ua hauj lwm yog hnyav, qhov tsis zoo ntawm PTFE nyob rau hauv cov nqe lus ntawm thermal thiab mechanical zog tej zaum yuav offset los ntawm tshem tawm cov corrosion mechanism tag nrho.

Super Duplex vs PTFE rau Seawater Service
Qhov sib txawv ntawm ob cov ntaub ntawv tuaj yeem pom meej dua ntawm lawv cov hom tsis ua haujlwm tseem ceeb.

Khoom Plig Super Duplex 2507 PTFE
Passive oxide tiv thaiv. Corrosion Mechanism .Chemically inert
Zoo li Crevice CorrosionNone Ua tau siab dua 35-40 degree
Thermal conductivity siab heev tsawg
Siab muaj peev xwm zoo txwv
Mechanical Strength High nruab nrab
Electrochemical Activity Yog Tsis yog
Dej ntws hauv continuoGreat nrog txwv mus txog ~ 110 degree
Qhov kev sib piv no yog ib qho piv txwv zoo ntawm vim li cas super duplex vs PTFE crevice corrosion seawater kev ntsuam xyuas yog li nyob ntawm qhov ua haujlwm tseem ceeb ntawm qhov system.

Xaus
PTFE yog ib qho tseem ceeb ntawm cov kev daws teeb meem zoo tshaj plaws tiv thaiv kev xeb ntau dua li cov khoom kim heev super duplex stainless hlau rau seawater heat exchangers thiab cua txias tshuab qhov twg stagnant crevices tsis tuaj yeem tshem tawm tag nrho. Alloys xws li 2507 super duplex muaj kev tiv thaiv zoo heev nyob rau hauv ntau yam marine ib puag ncig tab sis lawv kev tiv thaiv nyob ntawm kev saib xyuas ntawm cov yeeb yaj kiab tsis muaj zog oxide uas tuaj yeem ua rau hauv zos tawg hauv qhov tawg tsis muaj oxygen saum toj li 35℃txog 40 degree.

PTFE, ntawm qhov tod tes, tsis muaj cov txheej txheem electrochemical corrosion txhua. Nws yog ib qho fluorinated polymer tag nrho uas tiv thaiv chloride nres, dej hiav txwv stagnant thiab thaj chaw crevice chemistry.

Kev lag luam tawm -tawm yog txo qis thermal conductivity, txo qis muaj peev xwm, thiab ntau dua kev tsim kho tshuab. Txawm li cas los xij, nyob rau hauv daim ntawv thov qhov kev ntseeg siab ntawm corrosion yog qhov tseem ceeb tshaj li thermal efficiency, PTFE muab ib qho kev pheej hmoo tiag tiag rau kev tiv thaiv corrosion crevice.

Kev tiv thaiv zoo tshaj plaws hauv kev tsim kho corrosion tsis yog qhov zoo dua rau tus kheej - kho cov txheej txheem, tab sis cov khoom uas tsis xav tau.