Corrosion Protection for Chemical Steel Structures: A Practical Coating Guide

Taug kev los ntawm txhua qhov chaw ua tshuaj thiab koj yuav pom cov hlau txhua qhov chaw. Cov yeeb nkab racks, cia tank, reactor txhawb nqa, stair stringers. Nws nqa cov load, muaj cov xov xwm, thiab ua kom cov haujlwm khiav haujlwm. Nws kuj corrodes.

Hauv thaj chaw tshuaj lom neeg hnyav tshaj plaws, cov pa roj carbon steel uas muaj cov txheej txheem tsawg tuaj yeem xav tau hloov hauv tsawg li ob mus rau peb xyoos. Acid fumes condense rau ntawm qhov chaw tsis muaj kev tiv thaiv. Alkaline daws drips los ntawm cov qog valve. Solvent vapors soften cov txheej qub. Kuv tau tshuaj xyuas cov chaw uas cov pa roj carbon steel hlau tau poob ib nrab ntawm nws cov thickness nyob rau hauv qis dua xya xyoo, thiab nyob rau hauv ib cheeb tsam nruj dua cov tswv cuab tau raug pauv tawm ntawm ob - mus rau - peb - xyoo mus.

Kab lus no taug kev los ntawm cov txheej txheem txheej txheej uas tau ua haujlwm ntseeg tau thoob plaws cov chaw tshuaj lom neeg thiab petrochemical. Nws ua kekub-dip galvanizingnrog cov txheej txheem organic topcoats kom zoo, ua raws li ISO 1461, ASTM A123, thiab ISO 12944. Lub hom phiaj tsis yog qhov tuab lossis kim tshaj plaws. Nws yog txoj cai system rau qhov tseeb raug.

Feem ntau atmospheric corrosion ua raws li tus qauv xav tau. Oxygen thiab noo noo ncav cuag cov hlau nto, hlau oxide cov ntaub ntawv, thiab cov txheej txheem accelerates raws li cov oxide txheej spalls. Chemical ib puag ncig ntxiv qhov sib txawv uas cov txheej txheem atmospheric tsis tau tsim los daws.

Acid pos nkag mus rau micro- pores hauv cov zaj duab xis txheej, mus txog lub substrate, thiab pib cov tshuaj tiv thaiv electrochemical uas thawb cov txheej hauv qab. Chloride ions ua ib yam nkaus thiab hnyav dua, uas yog vim li cas cov chaw siv tshuaj lom neeg nyob hauv ntug dej hiav txwv ntsib qee qhov luv tshaj txheej txheej hauv lub neej hauv kev lag luam.

Alkaline tej yam kev mob muaj ib qho teeb meem sib txawv. Ntau cov organic coatings ua tau zoo nyob rau hauv nruab nrab los yog me ntsis acidic ib puag ncig tab sis soften los yog saponify nyob rau hauv sustained siab pH. Ib txheej txheej uas kav kaum tsib xyoos ntawm lub tsev rau khoom sab nrauv yuav ua tsis tiav hauv peb xyoos ntawm sab nrauv ntawm lub tank caustic.

Kub cycling compounds tag nrho cov no. Hnub- hmo ntuj nthuav dav thiab kev sib cog lus, txheej txheem cua sov los ntawm cov khoom siv, thiab cov huab cua hloov raws caij nyoog tsim kev ntxhov siab ntawm txheej txheej - substrate interface. Cov teeb meem me dhau los ua loj delaminations. Qhov no yog vim li cas ib qho -coat- haum-txhua txoj hauv kev tsis tshua ua haujlwm hauv kev pabcuam tshuaj, thiab vim li cas ntau cov nroj tsuag pom lawv tus kheej hloov cov qauv hlau ntawm ob-rau- peb- xyoo tig nyob rau hauv siab - thaj chaw raug.

Kub-dip galvanizinglos ntawm nws tus kheej yog pov thawj corrosion barrier. Cov zinc txheej metallurgically bonds rau cov hlau, muab kev tiv thaiv cathodic ntawm cov npoo txiav thiab khawb, thiab feem ntau xa tawm ntau xyoo ntawm kev pab cuam nyob rau hauv nruab nrab atmospheric raug. ISO 1461 thiab ASTM A123 tswj cov txheej txheem thiab teeb tsa qhov tsawg kawg nkaus txheej thickness raws li steel seem thickness.

Nyob rau hauv ib puag ncig tshuaj, galvanizing ib leeg feem ntau tsis txaus. Zinc reacts nrog acids thiab muaj zog alkalis. Agalvanized kev them nyiaj yugnyob rau hauv ib cheeb tsam nrog cov kua qaub tsis tu ncua tuaj yeem haus nws cov zinc txheej hauv tsib mus rau yim xyoo. Txoj kev daws teeb meem yog ntxiv cov organic txheej txheej rau saum cov galvanized substrate.

Qhov system dual no ua haujlwm vim tias txhua txheej ua ib yam dab tsi uas lwm tus ua tsis tau. Cov zinc muab kev tiv thaiv cathodic thiab ib puag ncig zoo ib yam. Cov organic coatings muab cov tshuaj tiv thaiv kab mob uas cais cov zinc los ntawm kev tawm tsam hnyav. Ua ke lawv tsim kev tiv thaiv hauv qhov tob uas tsis ua tiav ib leeg.

Qhov tseem ceeb yog compatibility. Ob -Ib feem epoxies tsim rau galvanized substrates, ua raws li polyurethane lossis polysiloxane topcoats, tau dhau los ua cov qauv sib xyaw ua ke rau cov tshuaj lom neeg hauv huab cua. Rau cov kev pabcuam raus dej lossis cov ntaub hauv lub tank sab hauv, phenolic epoxies thiab iav -flake reinforced coatings yog qhov tsim nyog dua.

Kuv tau pom cov nroj tsuag sim txuag nyiaj los ntawm kev siv cov txheej txheem kev lag luam enamel ncaj qhagalvanizing. Nws feem ntau ua tsis tau li ntawm kaum yim hli. Lub zog saum npoo ntawm cov zinc tshiab yog tsawg, thiab tsis muaj qhov profile lossis cov primer sib xws, lub tsho sab saum toj tsuas yog tsis tuav.

ISO 12944 txhais cov corrosivity pawg los ntawm C1 txog CX thiab muab cov txheej txheem pom zoo thiab cov yeeb yaj kiab qhuav rau txhua qhov. Cov chaw tshuaj lom neeg feem ntau poob rau hauv C3, C4, lossis C5-M pawg.

 C3 Ib puag ncig

C3 npog qhov cuam tshuam nruab nrab, xws li cov yeeb nkab npog hauv qhov qis -emission area los yog sab nrauv txhawb upwind ntawm cov txheej txheem units. Ib txwm C3 system dhaugalvanizingkhiav mus txog 160 microns tag nrho cov zaj duab xis qhuav tuab, nrog epoxy primer nyob ib ncig ntawm 60 microns thiab polyurethane topcoat ntawm 100 microns. Kev pabcuam lub neej feem ntau ncav cuag kaum tsib mus rau nees nkaum xyoo nrog kev tshuaj xyuas niaj hnub.

 C4 thiab C5-M Environments

Cov txheej txheem tshuaj lom neeg sab nraum zoov feem ntau tsaws hauv C4, thaum cov chaw ntug dej hiav txwv thiab thaj chaw uas muaj cov tshuaj chloride hnyav lossis kua qaub feem ntau xav tau C5-M specifications. Rau C4 kev pab cuam tshaj galvanized steel, npaj rau peb lub tsho tiv no tag nrho ntawm 200 mus rau 240 microns, nrog rau epoxy primer, epoxy intermediate tsim lub tsho, thiab polyurethane los yog polysiloxane topcoat.

C5-M thawb tag nrho rau 280 txog 320 microns lossis ntau dua. Tib yam peb-coat architecture siv, tab sis txhua txheej yog thicker thiab cov topcoat feem ntau hloov kho mus rau fluoropolymer los yog polysiloxane formulation. Kuv tau teev C5-M tshuab rau cov chaw ua liaj ua teb ntug dej hiav txwv uas cov txheej txheem C4-rated yav dhau los tau ua tsis tiav nyob rau hauv rau xyoo. Cov txheej txheem kho dua tshiab tau ua haujlwm rau ntau tshaj kaum xyoo nrog tsuas yog qhov chaw kov-ups.

Immersion thiab Internal Linings

Lub tank sab nrauv yuav pom C4 atmospheric raug thaum sab hauv tuav 98 feem pua ​​​​sulfuric acid lossis ntau cov kuab tshuaj. Phenolic epoxies tuav cov kua qaub zoo tab sis tsis kam rau siab pH. iav-flake vinyl esters muaj kev tiv thaiv zoo rau ntau yam tshuaj. Kev xaiv ib txwm rov qab los rau qhov tseeb tshuaj, concentration, kub, thiab seb qhov kev pabcuam txuas mus ntxiv lossis cuam tshuam. ISO 12944 tsis them tag nrho cov kev pabcuam raus dej, yog li xa mus rau NACE / AMPP cov qauv thiab cov chaw tsim khoom txheej txheej cov kab kos tshuaj tiv thaiv.

Kuv tsis tuaj yeem hais ntau npaum li cas txheej txheej tsis ua haujlwm rov qab mus rau qhov chaw npaj, tsis yog rau cov khoom siv txheej txheem nws tus kheej. Cov txheej txheem hwm zoo siv rau saum qhov chaw npaj tsis zoo yuav ua tsis tau sai dua li nruab nrab -tier txheej siv hla lub substrate npaj kom zoo.

Raugalvanized hlau, zinc tshiab muaj tus du, qis - profile nto thiab nqa zinc ntsev uas yuav tsum tau muab tshem tawm. Cov txheej txheem txoj hauv kev yog cheb blasting ntawm qhov tsis tshua muaj siab los tsim lub teeb profile yam tsis tau tshem tawm cov zinc, ua raws li cov khoom sib xyaw ua ke.

Rau thaj chaw hlau liab qab xws li welds thiab bolted kev sib txuas, abrasive blasting rau Sa 2.5 nyob ze - hlau dawb yog qhov tsawg kawg nkaus rau C4 thiab C5-M kev pabcuam. Rau immersion linings, Sa 3 dawb hlau feem ntau yuav tsum tau. Daim ntawv thov khw yog ib txwm nyiam rau daim ntawv thov teb, tab sis thaum tsim nyog ua haujlwm, nws tsuas yog yuav tsum tau ua nyob rau hauv cov xwm txheej uas ua tau raws li cov txheej txheem tsim cov txheej txheem kub thiab av noo.

Ib tus kws tsim tshuaj tshwj xeeb hauv Ohio tau hloov cov qauv hlau nyob ib puag ncig lawv cov sulfuric acid tank ua liaj ua teb txhua ob mus rau peb xyoos. Qhov kev teeb tsa thawj zaug siv cov pa roj carbon steel nrog ib lub khw lub tsho ntawm cov xim alkyd. Nyob rau hauv lub thib ob xyoo ntawm lub neej, lub welded thiab bolts tau los ntawm lub qhov. Los ntawm xyoo peb, ntu ntawm cov qauv kev txhawb nqa tau poob qis dua -cov kabmob muaj peev xwm.

Lawv hloov mus raugalvanized kev txhawb nqanrog peb -coat epoxy-polyurethane system ntawm 280 microns rau sab nrauv thiab iav -flake vinyl ester hauv ob sab phlu rau lub tank sab hauv. Lub tank tau mus ua haujlwm kaum ob xyoos dhau los. Lawv qhov kev soj ntsuam tag nrho zaum kawg pom cov txheej txheem siab tshaj 95 feem pua ​​​​ntawm sab nrauv thiab tsis muaj cov txheej txheem degradation. Cov nroj tsuag kwv yees lawv tau zam plaub qhov kev hloov pauv tag nrho ntawm lub tank ua liaj ua teb ib leeg.

Lub chaw cog qoob loo ntawm ntug dej hiav txwv ntsib cov tshuaj chloride-laden cua noj los ntawm cov yeeb nkab racks txhawb nqa, nrog cov tswv cuab ntawm cov hlau tsis zoo hauv ob mus rau peb xyoos. Tom qab galvanizing cov hlau hloov thiab siv C5-M-rated polysiloxane topcoat, cov kev txhawb nqa tau ua haujlwm tau cuaj xyoo uas tsis pom muaj cov qauv corrosion.

Txawm tias qhov zoo tshaj plaws txheej txheej xav tau kev saib xyuas. Tshawb xyuas txhua xyoo, lossis ob xyoos ib zaug hauv C5-M thaj chaw. Tsom ntsoov rau cov ntsiab lus hnav siab xws li tes tuav, stair treads, thiab cov yeeb nkab txhawb nqa. Kov cov chaw puas hauv tib lub caij lawv pom. Khaws cov ntaub ntawv tuab tuab kom taug qab qhov degradation dhau sijhawm.

Raugalvanized substrate, saib cov xeb dawb, uas tsim thaum cov galvanizing tshiab yog khaws cia rau hauv cov av ntub, tsis muaj cua nkag. Yog hais tias dawb xeb tshwm nyob rau hauv ib tug twb coated system, nws feem ntau txhais tau hais tias lub topcoat tau raug cuam tshuam.

Lub sijhawm zoo tshaj plaws los xav txog kev tiv thaiv corrosion yog thaum tsim. Qhia tshwj xeeb galvanizing rau cov qauv hlau hauv tshuaj lom neeg lossis cov ntug dej hiav txwv raug, thiab xyuas kom cov galvanizer paub tias cov hlau yuav topcoated. Sau ibtxheej specificationTS EN ISO 12944 los ntawm qeb corrosivity, naming tus naj npawb ntawm cov tsho tiv no, yam tsawg kawg nkaus qhuav zaj duab xis thickness, thiab tus qauv npaj nto. Qhov tsis meej spec ua rau cov txiaj ntsig tsis meej.

Cov lus nug nquag

 

 

01.Koj puas tuaj yeem pleev xim ncaj qha los ntawm kub -dip galvanizing?

Tsuas yog nrog cov coatings formulated rau galvanized substrates thiab tom qab kev npaj kom zoo. Cov galvanizing tshiab xav tau lub teeb profileing lossis ib qho etch primer. Kev siv tus qauv alkyd ncaj qha rau un- npaj galvanizing feem ntau ua rau tev tawm hauv ib mus rau ob xyoos.

02.Dab tsi yog qhov txawv ntawm epoxy thiab polyurethane topcoats?

Epoxies muaj tshuaj tiv thaiv zoo heev tab sis chalk thiab ploj mus nyob rau hauv UV raug. Polyurethanes muab UV stability zoo dua thiab gloss retention, ua rau lawv nyiam topcoat rau kev pab sab nrauv. Ib qho system siv epoxy primers thiab intermediates nrog polyurethane topcoat.