1. Nyob rau hauv ib puag ncig corrosive chemical processing ib puag ncig, yog vim li cas Hastelloy C (tshwj xeeb yog C-276) flanges feem ntau teev dhau flanges ua los ntawm cov qauv stainless hlau zoo li 316L, thiab lawv cov kev txwv tseem ceeb yog dab tsi?
Hastelloy C-276 flanges tau teev tseg rau cov kev pabcuam hnyav tshaj plaws uas cov qauv stainless hlau tsis ua haujlwm ntxov. Lawv qhov zoo tshaj plaws yog nyob rau hauv lawv qhov tshwj xeeb, dav -spectrum corrosion kuj, enabled los ntawm ib tug tshwj xeeb nickel-chromium- molybdenum-tungsten alloy muaj pes tsawg leeg (kwv yees. Ni-57%, Cr-15.5%, Mo-16%, W-3.7%, Fe-5.5%).
Cov Kev Tiv Thaiv Tseem Ceeb: Lawv muab kev tiv thaiv zoo tshaj plaws tiv thaiv:
Localized Attack: Kev tiv thaiv zoo tshaj plaws rau pitting thiab crevice corrosion hauv chloride -cov kev daws teeb meem (xws li dej hiav txwv, tshuaj dawb).
Oxidizing & Reducing Media: Siv tau zoo rau ob qho tib si oxidizing acids (xws li ferric thiab cupric chlorides, chlorine ntub dej) thiab txo cov kua qaub (sulfuric, hydrochloric), tshwj xeeb tshaj yog nyob rau hauv cov tshuaj chlorides.
Stress Corrosion Cracking (SCC): Cov tshuaj tiv thaiv zoo heev rau cov tshuaj chloride-induced SCC, ib hom tsis ua hauj lwm rau 316L stainless hlau nyob rau hauv tensile stress nyob rau hauv sov chloride ib puag ncig.
Qhov no ua rau C-276 flanges tseem ceeb rau kev sib txuas cov kav dej thiab cov hlab ntsha hauv cov tshuaj, tshuaj, petrochemical (kua roj), pulp / ntawv, thiab flue gas desulfurization (FGD) systems. Lawv cov kev txwv tseem ceeb yog tus nqi (tseem ceeb dua li cov hlau tsis muaj steel) thiab qhov kub thiab txias hauv oxidizing cua. Thaum zoo heev hauv kev txo qhov chaw mus txog ~ 1900℃F (1040 degree), hauvheev oxidizingCov xwm txheej saum toj no ~ 1100℃F (595 degree), alloys nrog ntau dua chromium (piv txwv li, Hastelloy C-22) yuav tsim nyog dua vim qhov zoo dua oxide adhesion.
2. Dab tsi yog qhov tseem ceeb ntawm kev tsim khoom thiab kev tswj xyuas kom zoo rau kev ua kom muaj kev ncaj ncees thiab kev ua haujlwm ntawm forged Hastelloy C-276 flanges?
Kev tsim khoom ncaj ncees yog qhov tseem ceeb vim yog lub luag haujlwm ntawm flange raws li lub siab tseem ceeb - muaj cov khoom. Cov kauj ruam tseem ceeb suav nrog:
Cov txheej txheem Forging: Flanges feem ntau tuag-forged los ntawm cov cua sov puag ncig lossis cov ntawv ua ntej-. Forging refines cov qauv nplej, txhim kho cov khoom siv kho tshuab (lub zog, toughness), thiab xyuas kom meej cov nplej ntws uas contours mus rau lub flange zoo (nyob ib ncig ntawm lub hub thiab los ntawm lub bolt qhov), pab txhawb kev qaug zog.
Solution Annealing: Tom qab forging thiab tag nrho cov machining, flanges yuav tsum undergo tag nrho cov tshuaj annealing. Qhov no suav nrog cua sov mus rau 2050-2250℃F (1120-1230 degree) tom qab quenching sai (dej tsuag los yog zoo sib xws). Cov kauj ruam tseem ceeb no ua rau cov theem thib ob (xws li kev puas tsuaj mu-theem lossis carbides) uas yuav tau tsim thaum lub sijhawm ua haujlwm kub, rov ua kom siab tshaj corrosion thiab ductility.
Cov ntaub ntawv pov thawj & Traceability: Txhua flange ntau yuav tsum muaj tag nrho traceability nrog Mill Test Certificate (MTC) ib ASTM B574. Qhov no tau lees paub cov tshuaj muaj pes tsawg leeg raws li UNS N10276 specs thiab txhua yam khoom (yield / tensile zog, elongation) tiav.
Tsis yog -Kev kuaj kev puas tsuaj (NDT): Common NDT suav nrog:
Dye Penetrant Testing (PT): Applied to all machined surfaces to detect surface-breaking defects.
Ultrasonic Testing (UT): Feem ntau ua rau ntawm forging dawb paug txhawm rau txheeb xyuas qhov tsis sib xws ua ntej kawg machining.
3. Thaum txhim kho Hastelloy C-276 flanges hauv cov kav dej, cov kev xav tshwj xeeb yuav tsum tau hais txog kev xaiv gasket, bolting, thiab kev sib dhos los tiv thaiv kev ua tsis tiav?
Kev txhim kho kom zoo yog qhov tseem ceeb rau kev siv lub zog ntawm cov hlau tsis muaj zog. Kev sib dhos tsis raug tuaj yeem tsim cov ntsiab lus tsis ua haujlwm hauv cheeb tsam.
Gasket Xaiv: Lub gasket yuav tsum tau sib xws nrog ob qho tib si txheej txheem xov xwm thiab lub ntsej muag flange. Cov kev xaiv dav dav yog:
PTFE-raws li: Flexible graphite nrog PTFE los yog mica barriers los tiv thaiv chloride kev nyuaj siab corrosion ntawm flange backside.
Tsis yog -Asbestos Compressed (NAB) nplooj ntawv nrog cov ntaub ntawv tsim nyog.
Kauv- qhov txhab gaskets nrog Hastelloy C-276 windings thiab hloov tau yooj yim graphite muab tub lim. Lub nplhaib puab yuav tsum yog C-276 los tiv thaiv crevice corrosion.
Bolting: Bolts, studs, thiab txiv ntseej yuav tsum yog qhov zoo tshaj plaws ntawm kev sib tw siab -kev ua tau zoo alloy. Kev siv qis dua - qib bolts tsim ob peb galvanic; Txawm li cas los xij, yog tias ua tiav, yuav tsum tau ua tib zoo rwb thaiv tsev (piv txwv li, PTFE lub tes tsho / ntxhua khaub ncaws) yuav tsum tau ua. Tightening yuav tsum ua raws li tus ntoo khaub lig- qauv torque ib ntus (xws li, ASME PCC-1) kom ntseeg tau tias txawm tias gasket compression thiab tiv thaiv flange warpage.
Kev txiav txim siab tseem ceeb:
Crevice Corrosion: Lub gasket / flange interface yog qhov chaw tseem ceeb rau kev tawm tsam. Lub gasket loj npaum li cas (tsis overhanging rau hauv lub bore) thiab txaus bolt load rau kaw lub crevice yog ib qho tseem ceeb heev.
Galvanic Corrosion: Tsis txhob sib cuag ncaj qha nrog cov pa roj carbon steel kev txhawb nqa lossis cov qauv; siv cov khoom siv dielectric rwb thaiv tsev yog tias tsim nyog.
Kev huv huv: Tag nrho cov khoom yuav tsum tsis muaj cov kab mob hlau (xws li, los ntawm cov cuab yeej, kev sib tsoo plua plav) uas tuaj yeem cuam tshuam cov txheej txheem oxide passive thiab pib pitting.
4. Rau cov kev pabcuam qaub (H2S- muaj) thiab cov ntawv thov sab nrauv, qhov kev qhia tshwj xeeb ntxiv thiab kev sim dab tsi feem ntau tswj hwm kev yuav khoom ntawm Hastelloy C-276 flanges?
Cov ntawv thov no thov kom muaj kev ruaj ntseg zoo dua vim muaj kev pheej hmoo ntawm Sulfide Stress Cracking (SSC) nyob rau hauv kev sib koom ua ke ntawm tensile stress, ntub H2S, thiab chlorides.
Kev Tswj Xyuas Cov Lus Qhia: Flanges yuav tsum ua raws li NACE MR0175/ISO 15156-3 (Cov khoom siv rau hauv H2S-muaj ib puag ncig hauv kev tsim roj thiab roj). Cov qauv no qhia txog cov khoom yuav tsum tau tiv thaiv SSC.
Kev Xav Tau Ntxiv:
Hardness Control: Qhov siab tshaj plaws hardness txwv yog nruj me ntsis txwv (feem ntau Rockwell C 22 HRC los yog Brinell 237 HB rau C-276). Hardness yog ib qho qhia ncaj qha ntawm susceptibility; tshaj qhov txwv yuav ua rau muaj kev pheej hmoo SSC. Hardness yuav tsum tau txheeb xyuas ntawm txhua flange (feem ntau nyob rau ntawm qhov kawg weld los yog hub).
Txhim kho Melting Practice: Cov khoom feem ntau yuav tsum tau ua los ntawm Electro-Slag Remelting (ESR) lossis Vacuum Arc Remelting (VAR). Cov txheej txheem thib ob no muab kev ua kom zoo dua qub, cov hlau huv huv (tsawg dua sulfur / phosphorus), thiab zoo dua los ntawm - cov khoom tuab.
Cov ntaub ntawv: MTC yuav tsum qhia meej txog kev ua raws li NACE MR0175 thiab qhia txog qhov tseem ceeb ntawm qhov hardness.
5. Yuav ua li cas welding ntawm piping rau Hastelloy C-276 flanges txawv ntawm vuam carbon steel flanges, thiab dab tsi yog qhov tseem ceeb ntawm kev coj ua kom muaj kev tiv thaiv corrosion ntawm qhov sib txuas?
Vuam C-276 yuav tsum muaj cov txheej txheem meej los tiv thaiv nws cov corrosion-tiv thaiv microstructure nyob rau hauv tshav kub-tshem tawm tsam (HAZ).
Qhov Tseem Ceeb Sib Txawv: Tsis zoo li carbon steel, lub hom phiaj tsis yog kom ua tiav lub zog siab los ntawm kev hloov pauv theem tab sis txo qis kev hloov pauv microstructural uas degrade corrosion kuj.
Cov kev coj ua tseem ceeb:
Filler Hlau: Siv ntau dua - sib piv cov hlau nplaum uas zoo sib xws lossis zoo dua corrosion, xws li ERNiCrMo-4 (sib npaug rau C-276 vuam hlau) rau GTAW (TIG) lossis SMAW (stick) electrodes xws li ENiCrMo-4.
Kev Tsim Kho & Kev huv: Bevel lub ntsej muag yuav tsum tau ua tib zoo ntxuav ntawm oxides, roj, thiab noo noo. Txhua qhov sib xyaw hlau (los ntawm cov hlau txhuam hlau) yuav ua rau pitting sai. Siv cov txhuam hniav stainless hlau tshwj xeeb rau cov nickel alloys.
Thaum tshav kub kub input Control: Siv cov tswv yim uas tsis muaj cua sov input: tsawg amperage, ceev ceev mus txawv tebchaws, thiab tsis txhob ntau heev weaving. Kev siv hluav taws xob siab lossis kev ua kom txias qeeb txhawb cov nag lossis daus ntawm cov theem cuam tshuam (mu-theem) nyob rau hauv HAZ, tsim kom muaj ib cheeb tsam raug corrosive nres.
Interpass Kub: nruj me ntsis tswj kom siab tshaj plaws, feem ntau 250℃F (120 degree). Qhov no tiv thaiv thaj tsam weld los ntawm kev siv sijhawm ntau dhau ntawm qhov kub thiab txias.
Ncej -Kev kho Weld: Tsis txhob ua tom qab-weld kub ntxhov siab. Lub flange thiab weld yog tsim los ua raws li -welded mob. Qhov kev tshaj tawm nkaus xwb -weld kev ua haujlwm yuav tsum tau ua kom huv si thiab kev kho mob passivation (xws li, nrog nitric acid) los kho cov txheej txheem oxide tiv thaiv.
