Cov Txheej Txheem Vuam Hlau Nickel rau Kev Lag Luam Petrochemical
Kev lag luam petrochemical ua haujlwm nyob rau hauv cov xwm txheej hnyav: kub siab, siab siab, thiab raug rau cov xov xwm corrosive xws li chloride, sulfur, H₂S, CO₂, thiab ntau yam acidic compounds. Hauv cov chaw no, kev xaiv cov khoom siv yog qhov txiav txim siab hauv kev ntseeg siab ntawm cov khoom siv txheej txheem. Cov hlau nickel-based (nickel thiab nws cov alloys) yog siv dav vim lawv qhov kev tiv thaiv corrosion zoo dua, kev ruaj khov kub siab, thiab muaj peev xwm tiv taus kev ntxhov siab corrosion tawg. Txawm li cas los xij, cov txiaj ntsig no tsuas yog ua tiav yog tias cov txheej txheem vuam tau ua tiav siv cov txheej txheem zoo, vim tias vuam tuaj yeem hloov pauv cov khoom siv microstructure, ua rau muaj kev tawg kub, porosity, lossis txo qhov kev tiv thaiv corrosion hauv thaj chaw vuam.
1. Lub luag haujlwm ntawm cov hlau nickel hauv cov roj av petrochemicals
Cov hlau nickel xws li Nickel 200/201, Monel (Ni-Cu), Inconel (Ni-Cr-Fe), Incoloy, thiab Hastelloy (Ni-Mo-Cr) feem ntau siv rau hauv cov khoom hloov pauv cua sov, cov kab distillation, reactors, cov kav dej ua haujlwm, cov khoom siv desulfurization, thiab cov kab ke uas cuam tshuam nrog cov kua qaub thiab chlorides. Piv txwv li, Ni-Cr alloys muaj kev tiv thaiv oxidation zoo ntawm qhov kub siab, thaum Ni-Mo alloys zoo tshaj plaws hauv kev txo cov chaw ib puag ncig thiab qee cov kua qaub. Kev vuam cov hlau no yuav tsum tau tswj hwm cov hlau cov khoom sib xyaw kom tswj hwm qhov kev tiv thaiv corrosion zoo tshaj plaws.
2. Cov teeb meem tshwj xeeb hauv kev vuam nickel
Feem ntau, cov hlau nickel muaj cov thermal conductivity qis dua li cov hlau carbon thiab muaj cov coefficient ntawm thermal expansion siab. Kev sib xyaw ua ke no ua rau muaj cua sov ntau dua hauv thaj chaw vuam thiab tuaj yeem ua rau muaj kev cuam tshuam ntau ntxiv. Ntxiv mus, qee cov hlau nickel muaj kev cuam tshuam rau:
- Kub tawg (solidification cracking) vim yog kev sib cais ntawm cov ntsiab lus ntawm cov ciam teb thaum lub sijhawm khov ntawm cov hlau vuam.
- Porosity feem ntau yog tshwm sim los ntawm kev ua qias tuaj, dej noo, lossis cov pa roj uas raug ntes.
- Kev ua rau muaj kev tsis haum lossis txo qis ntawm qhov tsis kam ntawm kev xeb hauv zos yog tias cov txheej txheem vuam tsis raug, tshwj xeeb tshaj yog rau qee cov hlau alloys.
- Kev ua qias tuaj ntawm hlau/carbon los ntawm cov cuab yeej ua haujlwm hlau tuaj yeem ua rau muaj kev tiv thaiv xeb, tshwj xeeb tshaj yog nyob rau hauv cov chaw muaj tshuaj lom neeg hnyav.
Yog li ntawd, kev tswj kev huv, kev xaiv cov khoom sau, thiab cov kev ntsuas kub yog qhov tseem ceeb.
3. Kev xaiv cov txheej txheem vuam: GTAW, GMAW, SMAW, thiab SAW
Qee cov txheej txheem vuam rau cov hlau nickel hauv petrochemicals suav nrog:
a) GTAW (TIG)
GTAW feem ntau yog txoj kev zoo tshaj plaws rau kev hla cov hauv paus yeeb nkab, kev ua haujlwm raug, thiab cov khoom nyias. Nws cov txiaj ntsig suav nrog kev tswj cua sov zoo thiab kev vuam huv. Kev tiv thaiv roj argon ntshiab feem ntau siv; hauv qee qhov kev siv, helium tuaj yeem ntxiv rau kom txhim kho kev nkag mus.
b) GMAW (MIG) thiab pulsed GMAW
GMAW yog qhov tsim nyog rau kev tsim khoom sai dua, tshwj xeeb tshaj yog hauv kev tsim khoom hauv chaw ua haujlwm. Hom pulsed pab txo cov cua sov nkag thiab spatter, nrog rau kev txhim kho kev tswj hwm hauv cov chaw vuam nyuaj. Cov hlau vuam yuav tsum tau khaws cia thiab tuav kom zoo kom tsis txhob muaj kuab paug.
c) SMAW (electrode vuam)
SMAW siv dav rau kev kho vaj kho tsev vim nws cov khoom siv yooj yim. Txawm li cas los xij, kev pheej hmoo ntawm kev khaws hydrogen thiab kev suav nrog slag yuav tsum tau tswj hwm los ntawm kev xaiv electrode kom raug, cov txheej txheem ci electrode, yog tias tsim nyog, thiab cov txheej txheem ntxuav interlayer.
d) SAW
SAW siv tau zoo rau cov phaj tuab thiab cov vuam ntev, xws li ntawm cov hlab siab lossis lub plhaub. Kev xaiv cov dej ntws thiab cov hlau yuav tsum tsim nyog kom ntseeg tau tias cov hlau sib xyaw ua ke tswj tau qhov kev tiv thaiv xeb xav tau.
4. Kev npaj khoom siv thiab kev ntxuav qhov chaw
Kev vam meej ntawm kev vuam nickel alloy yog cuam tshuam los ntawm kev npaj nto. Cov kev coj ua niaj hnub hauv kev lag luam petrochemical suav nrog:
- Siv cov tshuaj solvent uas tsim nyog los tshem tawm cov roj/rog.
– Siv txhuam hlau tsis xeb tshwj xeeb los ntxuav cov oxide (tsis txhob siv txhuam hlau carbon).
– Siv cov cuab yeej sib cais: cov tshuab sib tsoo, cov discs flap, thiab cov txhuam yuav tsum tau siv rau cov khoom siv nickel/stainless kom tiv thaiv kev sib kis kab mob.
- Kev sib haum xeeb thiab kev tswj qhov sib txawv kom txo tau qhov kev pheej hmoo ntawm kev tsis sib xyaw lossis hlawv.
Txawm tias cov khoom me me tuaj yeem ua rau muaj porosity thiab txo qhov zoo ntawm cov hlaws weld.
5. Kev xaiv cov hlau nplaum thiab kev sib haum xeeb
Kev xaiv cov hlau filler yuav tsum tsis txhob ua raws li lub hauv paus ntsiab lus "khoom siv sib npaug rau cov khoom siv". Hauv kev xyaum ua lag luam petrochemical, cov fillers feem ntau raug xaiv los ua kom zoo dua qhov tawg thiab tiv taus xeb. Piv txwv ntawm cov hauv paus ntsiab lus dav dav:
- Siv cov khoom sau uas tiv taus qhov tawg kub zoo thiab muaj cov khoom sib xyaw ua ke uas txhawb nqa kev khov kho ruaj khov.
- Rau kev vuam sib txawv (piv txwv li nickel alloy rau stainless hlau lossis alloy hlau), feem ntau xaiv cov nickel filler tshwj xeeb uas tuaj yeem ua siab ntev rau qhov sib txawv ntawm kev nthuav dav thermal thiab txo cov teeb meem dilution.
- Xyuas kom tseeb tias cov khoom sau ua tau raws li cov qauv AWS/ASME thiab ua tau raws li cov lus qhia ntawm qhov project.
Hauv ntau daim ntawv thov, qhov corrosion yog qhov tseem ceeb dua li lub zog tensile yog li kev xaiv cov khoom sau yog hais txog kev paub txog kev pabcuam thiab cov lus pom zoo ntawm cov lej.
6. Kev tswj cov cua sov nkag, preheat, thiab interpass kub
Feem ntau cov hlau nickel tsis xav tau kev kub ua ntej zoo li qee cov hlau sib xyaw, tab sis kev tswj qhov kub tseem ceeb heev:
- Kev nkag cua sov ntau dhau tuaj yeem ua rau HAZ (cheeb tsam cuam tshuam los ntawm cua sov) dav dua, ua rau muaj kev cuam tshuam ntau ntxiv, thiab ua rau muaj kev sib cais uas ua rau muaj kev tawg kub.
- Qhov kub ntawm qhov interpass yuav tsum tsis txhob siab dhau, kom cov microstructure thiab corrosion resistance raug tswj.
- Cov txheej txheem hla ntau zaus nrog cov chaw teeb tsa tam sim no / voltage ruaj khov feem ntau siv rau ntawm cov phaj tuab kom tswj tau qhov zoo.
Cov kev ntsuas tseeb feem ntau yog txiav txim siab los ntawm WPS (Welding Procedure Specification) thiab sim los ntawm PQR (Procedure Qualification Record).
7. Cov txheej txheem vuam kom txo qhov tsis zoo
Qee cov txheej txheem siv tau uas feem ntau siv rau kev vuam nickel rau petrochemicals:
- Cov hlaws dai Stringer nyiam dua li kev xaws dav dav, kom txo qhov kub nkag thiab txo qhov sib cais.
- Kev ntxuav cov txheej txheem interlayer yog qhov tseem ceeb heev, tshwj xeeb tshaj yog hauv SMAW thiab SAW, kom tiv thaiv kev suav nrog slag.
- Kev tswj qhov pib-nres: lub qhov av yuav tsum tau sau kom zoo kom tiv thaiv lub qhov av tawg.
- Rov qab purging ntawm GTAW yeeb nkab vuam (nrog argon) kom cov hauv paus hniav tsis muaj oxidation.
- Siv cov roj tiv thaiv zoo thiab xyuas kom meej tias tsis muaj qhov xau uas ua rau oxidation lossis porosity.
8. Kev kho cua sov tom qab vuam (PWHT) thiab kev txiav txim siab txog kev siv hlau
Tsis yog txhua yam hlau nickel xav tau PWHT. Feem ntau, PWHT tuaj yeem ua rau muaj qee theem nag lossis daus, uas tuaj yeem txo qhov kev tiv thaiv xeb lossis kev tawv, nyob ntawm hom hlau. Yog li ntawd:
– PWHT tsuas yog ua thaum xav tau los ntawm cov cai (ASME) lossis tsim qauv, lossis thaum ib yam khoom siv xav tau nws.
- Kev ntsuam xyuas qhov kev pheej hmoo ntawm carbide / intermetallic theem nag lossis daus yuav tsum xav txog qhov kub thiab txias thiab qhov chaw corrosive.
- Rau qee qhov kev siv, yuav tsum tau siv tshuaj annealing lossis kev kho cua sov tshwj xeeb, tab sis qhov no feem ntau ua tiav hauv qhov chaw tsim nyog thiab raws li cov lus qhia ntawm cov khoom siv.
9. Kev tshuaj xyuas, kev sim thiab cov qauv siv
Hauv petrochemicals, kev vuam ntawm cov khoom siv nickel feem ntau ua raws li ASME Tshooj IX rau cov txheej txheem thiab cov kev tsim nyog ntawm tus kws vuam, thiab ASME Tshooj VIII (cov hlab siab) lossis B31.3 (cov kav dej ua haujlwm). Cov txheej txheem tshuaj xyuas feem ntau suav nrog:
– VT (Kev Kuaj Pom) los xyuas seb lub hlaws zoo li cas, txiav hauv qab, thiab sib tshooj.
- PT (Kev Ntsuas Kua Nkag) muaj txiaj ntsig zoo rau kev ntes cov kab nrib pleb ntawm qhov chaw hauv cov khoom siv uas tsis yog ferromagnetic.
- RT/UT los nrhiav cov teeb meem sab hauv xws li porosity, tsis muaj fusion, lossis slag inclusion.
– Tej zaum yuav xav tau kev ntsuam xyuas ntxiv xws li kev ntsuas ferrite (yog tias muaj feem xyuam), kev ntsuam xyuas qhov nyuaj, lossis kev ntsuam xyuas xeb nyob ntawm qhov kev pabcuam.
Qhov zoo ntawm cov ntaub ntawv (WPS, PQR, WPQ, kev taug qab cov ntaub ntawv, tus lej cua sov) kuj tseem ceeb heev hauv cov haujlwm petrochemical.
10. Txoj kev
Cov txheej txheem vuam hlau nickel rau kev lag luam petrochemical xav tau kev ua raws li kev huv, cov txheej txheem thiab kev xaiv cov khoom sau, thiab kev tswj cua sov. Cov hlau nickel muab kev ua tau zoo heev hauv cov chaw ua haujlwm corrosive thiab kub siab, tab sis lawv qhov kev nkag siab rau kev ua qias tuaj thiab kev tawg kub xav tau kev tsim qauv thiab kev ua tiav ntawm cov txheej txheem vuam. Los ntawm kev siv WPS kom raug, kev tswj hwm parameter, cov txheej txheem vuam kom raug, thiab kev tshuaj xyuas kom meej raws li ASME cov qauv, cov pob qij txha vuam nickel tuaj yeem ua tiav kev ntseeg siab mus sij hawm ntev thiab txo qhov kev pheej hmoo ntawm kev ua tsis tiav ntawm cov khoom siv tseem ceeb hauv cov chaw petrochemical.
Yog tias koj xav tau, kuv tuaj yeem kho cov ntawv no kom muaj kev txawj ntse ntxiv los ntawm kev suav nrog cov piv txwv ntawm WPS (tam sim no / voltage ntau yam, shielding gas hom, siab tshaj plaws interpass), lossis tsom mus rau ib qho tshwj xeeb alloy xws li Inconel 625 lossis Hastelloy C-276.
