Hauv kev lag luam kev lag luam tiag tiag, feem ntau kev puas tsuaj ntxov ntawm 316 stainless hlau cua sov raj tsis yog los ntawm cov khoom siv tsis zoo, tab sis tsim tsis tsim nyog, kev teeb tsa tsis raug, kev ua haujlwm tsis tu ncua thiab ib puag ncig tsis zoo. Systematic sorting ntawm ib txwm tsis ua hauj lwm hom thiab cov hauv paus ntsiab lus tuaj yeem coj cov hom phiaj kev ua kom zoo dua qub thiab txo qhov seem ntawm cov khoom siv cua sov.
Thawj feem ntau tsis ua haujlwm yog pitting perforation. Lub ntsiab inducement yog chloride ion yaig. kais dej, circulating dej txias, brine thiab cov txheej txheem dej khib nyiab tag nrho muaj cov tshuaj chloride. Thaum lub hauv paus scaling los yog sediment tsim me me qhov khoob ntawm lub raj nto, cov tshuaj chloride ions sib sau ua ke thiab mloog zoo rau hauv cheeb tsam occlusion, rhuav cov zaj duab xis passive los tsim cov ntsiab lus me me anode corrosion. Raws li kev ua haujlwm ntev - lub sijhawm ua haujlwm, cov pits txuas ntxiv mus rau sab hauv kom txog thaum nkag mus rau phab ntsa yeeb nkab. Cov hauv paus ntsiab lus feem ntau suav nrog cov dej pleev tsis tau lim dej, lub sijhawm kaw ntev - ua rau cov dej stagnation, thiab tsis muaj kev saib xyuas tsis tu ncua.
Qhov thib ob loj tsis ua hauj lwm hom yog kev nyuaj siab corrosion cracking (SCC). Peb yam tseem ceeb nyob ua ke: tensile residual stress, chloride -muaj nruab nrab thiab kub siab tshaj 60℃. Vuam, khoov thiab ua haujlwm txias yuav ua rau muaj kev ntxhov siab loj hauv cov yeeb nkab lub cev; yuam kev kho thaum lub sij hawm installation yuav kuj qhia los ua ke kev nyuaj siab. Thaum cov cua sov nruab nrab muaj cov tshuaj chloride thiab qhov ua haujlwm kub nkag mus rau lub sijhawm rhiab heev, kev tawg tawm yuav tshwm sim sai sai yam tsis muaj qhov pom tseeb ntawm sab nraud corrosion, uas ua rau cov yeeb nkab tawg sai sai. Weld cov chaw thiab cov ntu khoov yog qhov siab tshaj plaws - txoj haujlwm txaus ntshai rau qhov ua tsis tiav no.
Thirdly, intergranular corrosion feem ntau tshwm sim nyob rau hauv welded cua sov kav. Thaum vuam cua sov thiab txias txias, chromium carbide precipitates raws li ib thaj tsam ntawm cov nplej, ua rau chromium depletion ntawm grain ciam teb thiab poob ntawm anti- muaj peev xwm corrosion. Corrosion kis tau raws li cov khoom sib txawv ntawm sab nraud mus rau sab hauv, ua rau cov hlau nkig thiab yooj yim tawg nyob rau hauv me ntsis sab nraud quab yuam. Qhov teeb meem no tau txo qis los ntawm kev siv 316L qis- cov khoom siv carbon, tab sis tom qab-weld stress relief annealing tseem xav tau rau cov kav dej tuab -cov kav dej ua haujlwm nyob rau hauv ib puag ncig corrosive.
Plaub, corrosion corrosion tshwm sim nyob rau hauv siab -flow scouring ib puag ncig xws li cov kav xa dej. High- cov kua ceev ceev nqa cov khoom ua kom tsis tu ncua ntxuav cov yeeb nkab nto, mechanically stripping lub tiv thaiv zaj duab xis passive. Cov hlau tsis muaj steel tsis tuaj yeem tsim ua tiav oxide zaj duab xis nyob rau lub sijhawm, uas ua rau muaj qhov sib txawv ntawm cov phab ntsa tuab. Qhov kev ua tsis tiav no feem ntau tshwm sim ntawm cov kua dej nkag thiab tig txoj haujlwm ntawm lub raj cua sov.
Thib tsib, microbial corrosion yog yooj yim overlooked nyob rau hauv kaw circulating dej systems. Sulfate-txo cov kab mob thiab cov kab mob hlau txuas rau saum npoo los ua biofilms, tsim kom muaj ib qho chaw hauv zos anaerobic acidic nyob rau hauv cov yeeb yaj kiab, ua kom lub zos pitting. Cov kab ke uas tsis tshua muaj khiav ceev thiab ntev - lub sij hawm standby yog heev yooj yim rau qhov no zais corrosion puas.
Table 1 Tej yam tshwm sim tsis ua hauj lwm, hauv paus ua rau thiab kev txhim kho txoj kev npaj ntawm 316 cua sov Tubes
表格
| Failure Phenomenon | Core Root Ua | Kev daws teeb meem zoo |
|---|---|---|
| Hauv zos me me qhov perforation | Chloride enrichment nyob rau hauv scale sediment | Tsis tu ncua descaling, electropolishing, dej zoo softening |
| Brittle tawg ze vuam / dabtsi yog khoov | Residual tensile stress + chloride + kub | Siv 316L, tom qab-weld kho cua sov, tsis txhob yuam kev |
| Weld embrittlement thiab peeling | Grain ciam teb chromium depletion tom qab vuam | Cov txheej txheem vuam nruj, tswj cov cua txias |
| Zuag qhia tag nrho phab ntsa thinning ntawm inflow port | Cov kua dej erosion | Ua kom cov yeeb nkab phab ntsa thickness, ntxiv tsis baffles |
| Random tawg pitting nrog sludge | Biofilm microbial corrosion | Cov tshuaj tua kab mob tsis tu ncua, nce cov kav dej ntws ntws |
Los ntawm kev taug qab lub hauv paus ua rau tsis ua hauj lwm ntau dua li tsuas yog hloov cov khoom puas, cov lag luam tuaj yeem txiav ntev - cov nqi hloov khoom siv thiab txhim kho kev ruaj ntseg ntawm cov cua sov.
