1. Hastelloy G-3 feem ntau piav raws li kev txhim kho corrosion-resistant thiab fabricable rau Hastelloy G (UNS N06007). Cov kev txhim kho tshwj xeeb dab tsi tau tsim, thiab hauv cov ntawv thov kev lag luam tseem ceeb twg qhov no txhais tau tias muaj txiaj ntsig zoo dua?
G-3 yog cov lus teb ncaj qha rau cov kev txwv ntawm Hastelloy G, nrog rau kev tsom mus rau kev txhim kho corrosion, thermal stability, thiab weldability.
Kev txhim kho tseem ceeb ntawm Hastelloy G:
Nce Chromium (Cr): ~ 22% hauv G-3 vs. ~ 22% hauv G. Thaum zoo sib xws, qhov sib npaug nrog lwm cov ntsiab lus yog optimized.
Nce Molybdenum (Mo): ~ 7% hauv G-3 vs. ~ 6.5% hauv G. Ib qho tseem ceeb boost rau pitting thiab crevice corrosion kuj.
Kev txo qis ntawm Niobium (Nb) & Titanium (Ti): G-3 muaj<0.5% Nb+Ti combined, down from ~2% in G. These elements were prone to forming harmful secondary phases (e.g., Laves phase, carbides) in the weld heat-affected zone (HAZ), causing knife-line attack and reducing ductility. This is the single most important improvement for fabricability.
Cov pa roj carbon qis (C):<0.015% in G-3, reducing the risk of chromium carbide precipitation during welding.
Kev ua tau zoo zoo hauv cov ntawv thov tseem ceeb:
Kev ntub dej -Process Phosphoric Acid (WPA) Production: Daim ntawv thov tseem ceeb. G-3 muaj kev tiv thaiv zoo tshaj rau qhov kub, paug phosphoric acid uas muaj fluorides, chlorides, thiab sulfuric acid hauv evaporators, cua sov, thiab kav dej. Nws txhim kho weldability tso cai rau txhim khu kev qha fabrication ntawm cov hlab ntsha loj.
Kev Pabcuam Sulfuric Acid: Kev tiv thaiv zoo thoob plaws ntau qhov ntau thiab qhov kub thiab txias, tshwj xeeb tshaj yog thaum muaj kab mob. Nws ua haujlwm zoo dua cov hlau tsis muaj steel thiab yog tus nqi ntau dua - zoo dua C-276 rau ntau lub luag haujlwm sulfuric acid.
Flue Gas Desulfurization (FGD) Systems: Siv nyob rau hauv cov cheeb tsam tsawg dua li C-276 (piv txwv li, inlet ducting, qee qhov chaw ntxhua khaub ncaws) qhov twg nws ua ke ntawm cov pitting zoo thiab cov nqi qis dua yog qhov zoo tshaj plaws.
Pulp & Ntawv Kev Lag Luam: Rau cov tshuab zom thiab cov khoom siv tshuaj tua kab mob los tuav cov tshuaj chlorinated thiab acidic cawv.
Qhov Kev Txiav Txim Kho Dua: G-3 yog qhov tseem ceeb "weldable, txhim khu kev qha G" nrog zoo dua tag nrho corrosion kuj. Nws tshem tawm cov teeb meem weld lwj ntawm nws cov thawj coj, ua rau nws cov khoom siv ntseeg siab rau fabricated, welded lug nyob rau hauv complex acidic ib puag ncig.
2. Rau lub nkoj phosphoric acid evaporator tsim los ntawm welded G-3 phaj, cov txheej txheem vuam tshwj xeeb thiab tom qab-weld kho cua sov yuav tsum tau ua los xyuas kom cov weldments tiv taus cov tshuaj fluoride/chloride-muaj cov kua qaub?
Thaum G-3 yog qhov sib txuas ntau dua li G, cov txheej txheem tsim nyog tseem yog qhov tseem ceeb kom tsis txhob muaj kev cuam tshuam hauv cheeb tsam hauv HAZ.
Cov txheej txheem vuam:
Filler Metal: Siv cov khoom sib xyaw ua ke hlau, tshwj xeeb ERNiCrMo-9 (AWS A5.14). Qhov muab tub lim no yog tsim los rau G-3 thiab muaj tib yam kev ua kom zoo qis Nb + Ti chemistry los tiv thaiv HAZ rhiab heev.
Cov txheej txheem: Siv cov kev siv hluav taws xob tsawg: cov hlaws dai, tsis muaj kev sib tsoo, thiab kev tswj ntawm qhov kub thiab txias (<250°F / 120°C). This minimizes the time the HAZ spends in the sensitization temperature range (~1200-1600°F / 650-870°C).
Kev huv huv: Txheem siab -nickel alloy xyaum- kev tu kom zoo kom tsis txhob muaj kab mob sib kis los ntawm leej faj, phosphorus, thiab qis- melting- taw tes hlau.
Tshaj tawm -Weld Heat Treatment (PWHT):
Nws puas yuav tsum tau? Rau G-3 nyob rau hauv feem ntau corrosive cov kev pab cuam, ib tug tag nrho cov tshuaj anneal yog pom zoo kom pom zoo thiab feem ntau teev. Nws yog tib txoj hauv kev los lav qhov zoo tshaj plaws corrosion kuj nyob rau hauv vuam.
Cov txheej txheem: Ua kom sov tag nrho cov khoom sib dhos rau cov tshuaj annealing kub ntau ntawm 2100℃F - 2200℃F (1150℃- 1205 degree), tuav kom txaus lub sijhawm, ua raws li cov dej quenching.
Lub hom phiaj: Qhov kev kho no dissolves ib qho teeb meem thib ob theem uas yuav tau tsim nyob rau hauv HAZ (carbides, nitrides) thiab homogenizes microstructure, kom ntseeg tau tias qhov weld cheeb tsam phim lub hauv paus hlau corrosion kuj.
Lwm txoj hauv kev (Rau Tsis yog-Kev Pabcuam Tseem Ceeb): Hauv qee qhov qis- kev ntxhov siab, tsis tshua muaj kev siv zog, G-3 tuaj yeem siv tau raws li -welded mob tom qab pickling thiab tu kom zoo, ua tsaug rau nws txo Nb+Ti cov ntsiab lus. Txawm li cas los xij, qhov no yog qhov kev txiav txim siab pheej hmoo.
3. Hastelloy G-3 piv rau cov Alloy 825 (UNS N08825) ntau npaum li cas ntawm kev tiv thaiv corrosion profile thiab nqi? Thaum twg tus engineer xaiv G-3 tshaj 825 rau cov kua qaub sib xyaw?
Qhov no yog ib qho kev sib piv ntawm ob qhov nruab nrab - ntau yam, ntau yam alloys. G-3 feem ntau nyob hauv qib siab dua.
Kev sib piv Corrosion Resistance:
Alloy 825: A Ni-Fe-Cr alloy nrog ntxiv ntawm Mo (~ 3%) thiab Cu (~ 2%). Zoo rau sulfuric thiab phosphoric acids, tab sis nws cov ntsiab lus molybdenum tsawg dhau rau kev txhim khu kev qha rau cov tshuaj chloride pitting thiab crevice corrosion nyob rau hauv stagnant los yog qis dua -flow.
Hastelloy G-3: Nrog ~ 7% Mo thiab ~ 22% Cr, nws muaj ntau dua Pitting Resistance Equivalent Number (PREN). Qhov no ua rau nws muaj kev tiv thaiv zoo tshaj plaws rau chloride-induced localized corrosion thiab zoo tag nrho kev ua tau zoo hauv cov kua qaub sib xyaw uas muaj halides.
Tus nqi sib piv: G-3, nrog nws cov ntsiab lus ntau dua nickel thiab molybdenum, feem ntau yog 20-40% kim dua Alloy 825 hauv cov ntawv sib npaug (phaj, yeeb nkab, bar).
Txoj Cai Xaiv - Xaiv G-3 tshaj 825 thaum:
Cov txheej txheem dej muaj chlorides lossis fluorides ntxiv rau cov kua qaub (xws li cov kab mob phosphoric lossis sulfuric acid).
Cov kev pabcuam cuam tshuam nrog kev nyob ruaj khov lossis qis dua -ntev cov xwm txheej uas pitting / crevice corrosion yog qhov txaus ntshai.
Qhov kub thiab txias yog nyob ntawm qhov txwv ntawm 825 lub peev xwm; G-3 muaj cov kab kev nyab xeeb loj dua.
Ntev - kev cia siab rau lub sij hawm yog qhov tseem ceeb tshaj qhov pib nqi ntawm cov khoom siv, thiab ib puag ncig yog nruj heev rau 825 tus qis PREN.
Hauv qhov tseeb, Alloy 825 yog qhov zoo, kev xaiv nyiaj txiag raume me mus rau nruab nrabtov acid kev pab tsis muaj halides. Hastelloy G-3 yog qhov kev xaiv raunruab nrab mus rau hnyavkev pabcuamnroghalides los yog qhov twg yuav tsum muaj kev ntseeg siab dua.
4. Dab tsi yog qhov tseem ceeb ntev - lub sij hawm degradation mechanisms rau G-3 cov khoom hauv cov kev pabcuam kub kub phosphoric acid, thiab cov txheej txheem tshuaj xyuas dab tsi yog siv rau kev ntsuas lub neej?
Txawm tias siab -kev ua tau zoo alloys degrade hauv cov kev pabcuam hnyav tshaj plaws.
Thawj Degradation Mechanisms:
General Corrosion: Ib qho yooj yim, nyias nyias. Tus nqi yog kwv yees tau los ntawm iso- kab kos duab corrosion tab sis tuaj yeem nrawm yog tias cov txheej txheem hloov pauv (nce fluoride / chloride, kub).
Kev Tawm Tsam Hauv Ib Cheeb Tsam hauv Kev Tso Nyiaj: Gypsum (calcium sulfate) lossis lwm cov khib nyiab tuaj yeem tso rau ntawm phab ntsa ntawm cov hlab ntsha, tsim cov crevices uas cov kua qaub tuaj yeem mloog zoo, ua rau hauv qab - deposit corrosion.
Intergranular Attack (IGA): Yog tias cov khoom siv tsis raug welded los yog cua sov- kho, rhiab heev (chromium carbide nag lossis daus) tuaj yeem tshwm sim ntawm cov ciam teb hauv HAZ, ua rau lawv muaj kev cuam tshuam rau kev nyiam corrosion.
Kev yaig-Corrosion: Nyob rau hauv cov cheeb tsam uas muaj kuab heev tshaj tawm los yog muaj slurries.
Kev Tshawb Fawb & Kev Ntsuas Lub Neej:
Ultrasonic Thickness (UT) Daim Ntawv Qhia: Cov cuab yeej tseem ceeb. Tsis tu ncua daim ntawv qhia phab ntsa thickness thoob plaws lub nkoj, them tshwj xeeb mloog mus rau weld seams, nozzles, thiab tej thaj chaw uas muaj feem rau deposit tsim. Trending cov ntaub ntawv kwv yees lub neej seem.
Kev soj ntsuam pom (feem ntau nrog Borescope): Saib rau cov cim ntawm pitting, crevice corrosion, thiab deposit buildup.
Dye Penetrant Testing (PT): Ntawm qhov tseem ceeb welds txhawm rau txheeb xyuas qhov chaw - tawg tawg.
Replication Metallography (rau forensic tsom xam): Yog hais tias ib tug tsis ua hauj lwm tshwm sim, ib tug replica ntawm lub microstructure yuav txheeb xyuas seb puas los yog lwm yam metallurgical degradation yog lub hauv paus.
5. Los ntawm kev xav txog kev yuav khoom, cov ntaub ntawv pov thawj tseem ceeb yog dab tsi thiab cov kev xeem ntxiv uas yuav tsum tau xav tau thaum xaj G-3 phaj lossis yeeb nkab rau kev tsim kho cov hlab ntsha tseem ceeb?
Txhawm rau kom cov khoom ua tau raws li qhov xav tau, daim ntawv xaj yuav tsum yog cov txheej txheem tshwj xeeb.
Cov ntaub ntawv tseem ceeb (Raws li ASTM B582 - Plate lossis B619 - Welded Pipe):
Daim Ntawv Ceeb Toom Mill Test (CMTR) yog qhov yuav tsum tau ua, qhia tag nrho ua raws li ASTM specification.
Nws yuav tsum muaj xws li: Tag nrho cov tshuaj ntsuam xyuas (tseem ceeb C tsawg, tswj Nb + Ti), cov khoom siv kho tshuab, thiab cov lus qhia txog kev kho cua sov (kev daws teeb meem annealed).
Pom zoo Cov Lus Qhia Ntxiv (kom teev nyob rau hauv PO):
Corrosion Test Daim Coupon Cov Ntaub Ntawv: Thov kom lub zeb muab cov txiaj ntsig ntawm kev kuaj corrosion ntawm tus qauv los ntawm cov khoom cua sov. Rau kev pabcuam phosphoric acid, ASTM G31 xeem hauv cov txheej txheem simulated cawv (tshwj xeeb concentration, kub, nrog F⁻ / Cl⁻) yog qhov zoo tagnrho. Qhov siab tshaj plaws tau txais corrosion (piv txwv li,<5 mpy) should be agreed upon.
Intergranular Corrosion (IGC) Test: Qhia txog ASTM G28 Method A kuaj ntawm tus qauv sensitized. Qhov no txheeb xyuas cov alloy lub hauv paus tsis kam rau weld lwj.
Tshaj tawm -Kev ntsuas qhov ntsuas kub ntawm Weld Heat Treatment: Rau cov khoom tsim, xav tau cov ntaub ntawv (cov kab hluav taws xob hluav taws xob) ua pov thawj tias lub nkoj ua tiav tau txais kev daws teeb meem tag nrho ntawm lub voj voog uas xav tau.
Thib peb-Kev Tshawb Fawb Txog Kev Tshawb Fawb: Tuav txoj cai rau tus neeg soj ntsuam ywj pheej los tshuaj xyuas cov ntawv pov thawj zeb thiab cov pov thawj.
Procurement Specification Piv txwv:
*"Hastelloy G-3 (UNS N06985) Phaj rau ASTM B582, Solution Annealed. Muab CMTR. Cov Lus Qhia Ntxiv: Mill yuav tsum muab ASTM G28 Txoj Kev Ib qho kev ntsuam xyuas rau cov cua kub ntau, uas qhia txog corrosion <20 mpy. Khoom siv rau ASME Tshooj VIII, Div. 1 kev tsim kho. "*
Hauv cov ntsiab lus, Hastelloy G-3 yog ib qho muaj peev xwm, fabricable, thiab txhim khu kev qha nruab nrab alloy uas daws cov teeb meem loj weldability ntawm nws cov neeg ua ntej. Nws dominates tshwj xeeb niches zoo li phosphoric acid thiab complex tov kua qaub cov kev pab cuam, muab ib tug superior tshuav nyiaj li cas thiab kev ua tau zoo piv rau ob qho tib si qis alloys xws li 825 thiab kim kim kev xaiv xws li C-276. Nws txoj kev vam meej siv pob khawm ntawm qhov zoo vuam / PWHT thiab cov khoom siv nrog cov ntaub ntawv pov thawj corrosion kuj.
